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Alcohol use disorder and depression are highly comorbid, and both conditions exhibit important sexual dimorphisms. Here, we aimed to investigate voluntary alcohol consumption after 6 weeks of chronic mild stress (CMS) in Wistar rats – employed as an animal model of depression. Male and female rats were investigated, and changes in several molecular markers were analysed in frontal cortex (FCx) and hippocampal formation (HF). CMS induced depressive-like responses in the forced swimming test - increased immobility time - in male and female animals, without affecting anhedonia (sucrose preference test) nor motor activity (holeboard); body weight gain and food intake were diminished only among CMS males. Voluntary alcohol consumption was evaluated in a two-bottle choice paradigm (ethanol 20% versus tap water) for 4 consecutive days; females exhibited a higher preference for alcohol compared to male animals. In particular, alcohol consumption was significantly higher among CMS females compared to CMS male animals. Remarkably, similar changes in both male and female animals exposed to CMS were observed regarding the expression levels of NCAM-140 KDa (decrease), GFAP and CB1R expression (increase) within the FCx as well as for HF PSD-95 levels (increase). However, contrasting effects in males and females were reported in relation to synaptophysin (SYN) protein levels within the FCx, HF CB1R expression (a decrease among male animals but an increase in females); while the opposite pattern was observed for NCAM-140 KDa protein levels in the HF. A decrease in CB2R expression was only observed in the HF of CMS-females. The present study suggests that male and female animals might be differentially affected by CMS regarding later voluntary alcohol consumption. In this initial approach, cortical SYN, and NCAM-140 KDa, CB1R and CB2R expression within the HF have arisen as potential candidates to explain such sex differences in behaviour. However, the depression-alcoholism relationship still deserves further investigation.

Cannabis is the most commonly used illicit drug among adolescents and young adults, including pregnant women. There is substantial evidence for a significant association between prenatal cannabis exposure and lower birth weight in offspring, and mixed results regarding later behavioural outcomes in the offspring. Adolescent cannabis use, especially heavy use, has been associated with altered executive function, depression, psychosis and use of other drugs later in life. Human studies have limitations due to several confounding factors and have provided scarce information about sex differences. In general, animal studies support behavioural alterations reported in humans and have revealed diverse sex differences and potential underlying mechanisms (altered mesolimbic dopaminergic and hippocampal glutamatergic systems and interference with prefrontal cortex maturation). More studies are needed that analyse sex and gender influences on cannabis-induced effects with great clinical relevance such as psychosis, cannabis use disorder and associated comorbidities, to achieve more personalized and accurate treatments.

Polydrug use is a widespread phenomenon, especially among adolescents and young adults. Synthetic cathinones are frequently consumed in combination with other drugs of abuse. However, there is very little information regarding the consequences of this specific consumption pattern. The aim of this review is to introduce this topic and highlight the gaps in the existing literature. In three different sections, we focus on specific interactions of synthetic cathinones with alcohol, cannabinoids, and the stimulants nicotine and cocaine. We then dedicate a section to the existence of sex and gender differences in the effects of synthetic cathinones and the long-term psychophysiological consequences of adolescent and prenatal exposure to these drugs. Epidemiological studies, case reports, and results obtained in animal models point to the existence of pharmacological and pharmacokinetic interactions between synthetic cathinones and other drugs of abuse. This pattern of polyconsumption can cause the potentiation of negative effects, and the dissociation between objective and subjective effects can increase the combined use of the drugs and the risk of toxicity leading to serious health problems. Certain animal studies indicate a higher vulnerability and effect of cathinones in females. In humans, most of the users are men and case reports show long-term psychotic symptoms after repeated use. The co-use of synthetic cathinones and the other drugs of abuse analyzed indicates potentiation of diverse effects including dependence and addiction, neurotoxicity, and impaired cognition and emotional responses. The motivations for and effects of synthetic cathinone use appear to be influenced by sex/gender. The long-term consequences of their use by adolescents and pregnant women deserve further investigation.

BACKGROUND: Alcohol binge drinking is one of the most common patterns of excessive alcohol use and recent data would suggest that histone deacetylases (HDACs) gene expression profiling could be useful as a biomarker for psychiatric disorders. METHODS: This study aimed to characterize the gene expression patterns of Hdac 1-11 in samples of rat peripheral blood, liver, heart, prefrontal cortex, and amygdala following repeated binge alcohol consumption and to determine the parallelism of Hdac gene expression between rats and humans in peripheral blood. To accomplish this goal, we examined Hdac gene expression following 1, 4, or 8 alcohol binges (3 g/kg, orally) in the rat, in patients who were admitted to the hospital emergency department for acute alcohol intoxication, and in rats trained in daily operant alcohol self-administration. RESULTS: We primarily found that acute alcohol binging reduced gene expression (Hdac1-10) in the peripheral blood of alcohol-naïve rats and that this effect was attenuated following repeated alcohol binges. There was also a reduction of Hdac gene expression in the liver (Hdac2,4,5), whereas there was increased expression in the heart (Hdac1,7,8) and amygdala (Hdac1,2,5). Additionally, increased blood alcohol concentrations were measured in rat blood at 1 to 4 hours following repeated alcohol binging, and the only group that developed hepatic steotosis (fatty liver) were those animals exposed to 8 alcohol binge events. Finally, both binge consumption of alcohol in humans and daily operant alcohol self-administration in rats increased Hdac gene expression in peripheral blood. CONCLUSIONS: Our results suggest that increases in HDAC gene expression within the peripheral blood are associated with chronic alcohol consumption, whereas HDAC gene expression is reduced following initial exposure to alcohol. This work was supported by The European Foundation for Alcohol Research (to JAL-M, FRdF, RM, RN, and MPV), the Fondo de Investigación Sanitaria (Red de Trastornos Adictivos, FEDER, RD12/0028/0015 to JAL-M, RD12/0028/001 to FRdF, RD12/0028/023 to RM, RD12/0028/0014 to RN, RD12/0028/1021 to MPV, RD12/0028/0008 to F-JL; and PI10/01692 to MM), and Ministerio de Ciencia e Innovación (SAF2011-26818 to JAL-M)

NMDA receptor hypofunction could be involved, in addition to the positive, also to the negative symptoms and cognitive deficits found in schizophrenia patients. An increasing number of data has linked schizophrenia with neuroinflammatory conditions and glial cells, such as microglia and astrocytes, have been related to the pathogenesis of schizophrenia. Cannabidiol (CBD), a major non-psychotomimetic constituent of Cannabis sativa with anti-inflammatory and neuroprotective properties induces antipsychotic-like effects. The present study evaluated if repeated treatment with CBD (30 and 60 mg/kg) would attenuate the behavioral and glial changes observed in an animal model of schizophrenia based on the NMDA receptor hypofunction (chronic administration of MK-801, an NMDA receptor antagonist, for 28 days). The behavioral alterations were evaluated in the social interaction and novel object recognition (NOR) tests. These tests have been widely used to study changes related to negative symptoms and cognitive deficits of schizophrenia, respectively. We also evaluated changes in NeuN (a neuronal marker), Iba-1 (a microglia marker) and GFAP (an astrocyte marker) expression in the medial prefrontal cortex (mPFC), dorsal striatum, nucleus accumbens core and shell, and dorsal hippocampus by immunohistochemistry. CBD effects were compared to those induced by the atypical antipsychotic clozapine. Repeated MK-801 administration impaired performance in the social interaction and NOR tests. It also increased the number of GFAP-positive astrocytes in the mPFC and the percentage of Iba-1-positive microglia cells with a reactive phenotype in the mPFC and dorsal hippocampus without changing the number of Iba-1-positive cells. No change in the number of NeuN-positive cells was observed. Both the behavioral disruptions and the changes in expression of glial markers induced by MK-801 treatment were attenuated by repeated treatment with CBD or clozapine. These data reinforces the proposal that CBD may induce antipsychotic-like effects. Although the possible mechanism of action of these effects is still unknown, it may involve CBD anti-inflammatory and neuroprotective properties. Furthermore, our data support the view that inhibition of microglial activation may improve schizophrenia symptoms.

Early life stress, in the form of MD (24 h at pnd 9), interferes with brain developmental trajectories modifying both behavioral and neurobiochemical parameters. MD has been reported to enhance neuroendocrine responses to stress, to affect emotional behavior and to impair cognitive function. More recently, changes in body weight gain, metabolic parameters and immunological responding have also been described. Present data give support to the fact that neuronal degeneration and/or astrocyte proliferation are present in specific brain regions, mainly hippocampus, prefrontal cortex and hypothalamus, which are particularly vulnerable to the effects of neonatal stress. The MD animal model arises as a valuable tool for the investigation of the brain processes occurring at the narrow time window comprised between pnd 9 and 10 that are critical for the establishment of brain circuitries critical for the regulation of behavior, metabolism and energy homeostasis. In the present review we will discuss three possible mechanisms that might be crucial for the effects of MD, namely, the rapid increase in glucocorticoids, the lack of the neonatal leptin surge, and the enhanced endocannabinoid signaling during the specific critical period of MD. A better understanding of the mechanisms underlying the detrimental consequences of MD is a concern for public health and may provide new insights into mental health prevention strategies and into novel therapeutic approaches in neuropsychiatry. Sin financiación 8.580 JCR (2015) Q1, 3/51 Behavioral Sciences, 16/256 Neurosciences UEM

The experience of social stress during adolescence is associated with higher vulnerability to drug use. Increases in the acquisition of cocaine self-administration, in the escalation of cocaine-seeking behavior, and in the conditioned rewarding effects of cocaine have been observed in rodents exposed to repeated social defeat (RSD). In addition, prolonged or severe stress induces a proinflammatory state with microglial activation and increased cytokine production. The aim of the present work was to describe the long-term effects induced by RSD during adolescence on the neuroinflammatory response and synaptic structure by evaluating different glial and neuronal markers. In addition to an increase in the conditioned rewarding effects of cocaine, our results showed that RSD in adolescence produced inflammatory reactivity in microglia that is prolonged into adulthood, affecting astrocytes and neurons of two reward-processing areas of the brain (the prelimbic cortex, and the nucleus accumbens core). Considered as a whole these results suggest that social stress experience modulates vulnerability to suffer a loss of glia-supporting functions and neuronal functional synaptic density due to drug consumption in later life.

The endocannabinoid system is involved in several physiological and pathological states including anxiety, depression, addiction and other neuropsychiatric disorders. Evidence from human and rodent studies suggests that exposure to early life stress may increase the risk of psychopathology later in life. Indeed, maternal deprivation (MD) (24 h at postnatal day 9) in rats induces behavioural alterations associated with depressive-like and psychotic-like symptoms, as well as important changes in the endocannabinoid system. As most neuropsychiatric disorders first appear at adolescence, and show remarkable sexual dimorphisms in their prevalence and severity, in the present study, we analysed the gene expression of the main components of the brain cannabinoid system in adolescent (postnatal day 46) Wistar male and female rats reared under standard conditions or exposed to MD. For this, we analysed, by real-time quantitative PCR, the expression of genes encoding for CB1 and CB2 receptors, TRPV1 and GPR55 (Cnr1, Cnr2a, Cnr2b, Trpv1, and Gpr55), for the major enzymes of synthesis, N-acyl phosphatidyl-ethanolamine phospholipase D (NAPE-PLD) and diacylglycerol lipase (DAGL) (Nape-pld, Dagla and Daglb), and degradation, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) (Faah, Magl and Cox-2), in specific brain regions, that is, the frontal cortex, ventral and dorsal striatum, dorsal hippocampus and amygdala. In males, MD increased the genetic expression of all the genes studied within the frontal cortex, whereas in females such an increase was observed only in the hippocampus. In conclusion, the endocannabinoid system is sensitive to early life stress at the gene expression level in a sex-dependent and region-dependent manner, and these changes are already evident in the adolescent brain.

Background and Purpose Many young people consume ecstasy as a recreational drug and often in combination with cannabis. In this study, we aimed to mimic human consumption patterns and investigated, in male and female animals, the long-term effects of Δ9-tetrahydrocannabinol (THC) and 3,4-methylenedioxymethamphetamine (MDMA) on diverse neuroinflammation and neurotoxic markers. Experimental Approach Male and female Wistar rats were chronically treated with increasing doses of THC and/or MDMA during adolescence. The effects of THC and/or MDMA on glial reactivity and on serotoninergic and cannabinoid systems were assessed by immunohistochemistry in the hippocampus and parietal cortex. Key Results THC increased the area staining for glial fibrilar acidic protein in both sexes. In males, both drugs, either separately or in combination, increased the proportion of reactive microglia cells [ionized calcium binding adaptor molecule 1 (Iba-1)]. In contrast, in females, each drug, administered alone, decreased of this proportion, whereas the combination of both drugs resulted in a ‘normalization’ to control values. In males, MDMA reduced the number of SERT positive fibres, THC induced the opposite effect and the group receiving both drugs did not significantly differ from the controls. In females, MDMA reduced the number of SERT positive fibres and the combination of both drugs counteracted this effect. THC also reduced immunostaining for CB1 receptors in females and this effect was aggravated by the combination with MDMA. Conclusions and Implications Adolescent exposure of rats to THC and/or MDMA induced long-term, sex-dependent neurochemical and glial alterations, and revealed interactions between the two drugs. Linked Articles This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6

The central endocannabinoid system (eCB system) sustains the activity of the hypothalamus–pituitary–adrenal (HPA) axis in mediating individual emotional responses. Deviation in maturational trajectories of these two physiological systems, may persistently adjust individual behavioral phenotype. We investigated, in outbred CD1 male mice, whether exposure to prenatal stress may influence short- and long-term emotional and neurochemical responses to a pharmacological stimulation of the eCB system during adolescence. To mimic prenatal stress, pregnant mice were supplemented with corticosterone in the drinking water (33.3 mg/l); their adolescent male offspring received daily injections of the fatty acid amide hydrolase inhibitor, URB597 (0.4 mg/kg), in order to enhance eCB signaling. Mice were then tested for: locomotor activity during adolescence and locomotor activity, anxiogenic, and anhedonic profiles in adulthood. We analyzed the expression of CB1 receptors (CB1Rs) in prefrontal cortex, hippocampus, striatum, and cerebellum in adulthood. Corticosterone administration (PC group) resulted, in adolescence, in a reduction in body weight and locomotion, while in adulthood, in increased anxiety-related behavior and reduced CB1Rs expression in cerebellum. URB597 exposure reduced locomotor activity and increased anhedonia in adulthood. CB1Rs were up-regulated in striatum and hippocampus and down-regulated in the cerebellum. PC-URB597 mice failed to show reductions in locomotion; exhibited increased risk assessment behavior; and showed reduced CB1Rs expression within the prefrontal cortex. Present results provide support to the hypothesis that precocious manipulations mapping onto the HPA axis and eCB system may persistently adjust individual emotional responses and eCB system plasticity.

The early neonatal stage constitutes a sensitive period during which exposure to adverse events can increase the risk of neuropsychiatric disorders. Maternal deprivation (MD) is a model of early life stress that induces long-term behavioural and physiological alterations, including susceptibility to different drugs of abuse. In the present study we have used the conditioned place preference (CPP) paradigm to address the influence of MD on the rewarding effects of 3,4-methylenedioxymetamphetamine (MDMA) in adolescent animals of both sexes. We have previously observed in adolescent rats that MD induces modifications in the serotonergic and endocannabinoid systems, which play a role in the rewarding effects of MDMA. In light of this evidence, we hypothesized that MD would alter the psychobiological consequences of exposure to MDMA. Neonatal Wistar rats underwent MD (24 h, on PND 9) or were left undisturbed (controls). The animals were conditioned with 2.5 mg/kg MDMA during the periadolescent period (PND 34–PND 43) and were tested in the open-field test at the end of adolescence (PND 60). Animals were sacrificed on PND 68–75 and levels of serotonin (5-HT) and its metabolite 5-hydroxyindole acetic acid were measured in the striatum, hippocampus and cortex, while the expression of hippocampal CB1 cannabinoid receptor (CB1R) and circulating levels of corticosterone and leptin were also measured. Control males showed CPP after administration of MDMA. However, no MDMA-induced CPP was detected in control females or MD males, and MD had no effect on open field activity in any group. A reduction in striatal and cortical 5-HT levels, increased expression of hippocampal CB1R and a marked trend towards higher circulating leptin levels were observed in MDMA-treated MD males. Our results demonstrate for the first time that MD reduces the rewarding effects of MDMA in a sex-dependent manner. We propose that this effect is related, at least in part, with alterations of the serotonergic and cannabinoid systems.

Traumatic brain injury (TBI) and its consequences represent one of the leading causes of death in young adults. This lesion mediates glial activation and the release of harmful molecules and causes brain edema, axonal injury, and functional impairment. Since glial activation plays a key role in the development of this damage, it seems that controlling it could be beneficial and could lead to neuroprotective effects. Recent studies show that minocycline suppresses microglial activation, reduces the lesion volume, and decreases TBI-induced locomotor hyperactivity up to 3 months. The endocannabinoid system (ECS) plays an important role in reparative mechanisms and inflammation under pathological situations by controlling some mechanisms that are shared with minocycline pathways. We hypothesized that the ECS could be involved in the neuroprotective effects of minocycline. To address this hypothesis, we used a murine TBI model in combination with selective CB1 and CB2 receptor antagonists (AM251 and AM630, respectively). The results provided the first evidence for the involvement of ECS in the neuroprotective action of minocycline on brain edema, neurological impairment, diffuse axonal injury, and microglial activation, since all these effects were prevented by the CB1 and CB2 receptor antagonists., This work has been supported by GRUPOS UCM-BSCH 951579; Delegación del Gobierno para el Plan Nacional sobre Drogas (Orden SAS/1250/2009); Instituto de Salud Carlos III; Redes temáticas de Investigación Cooperativa en salud, Red de Trastornos Adictivos (RD06/0001/1013 and RD2012/0028/0021) to M.P.V.; Ministerio de Economía y Competividad, Spain (BFU2011-30217-C03-01) to L.M.G.S., and the nonprofitable organization “Fondation des Gueules cassées” to E.S. and M.J.T.

Data from both human and animal studies suggest that exposure to stressful life events at neonatal stages may increase the risk of psychopathology at adulthood. In particular, early maternal deprivation, 24 h at postnatal day (pnd) 9, has been associated with persistent neurobehavioural changes similar to those present in developmental psychopathologies such as depression and schizophrenic-related disorders. Most neuropsychiatric disorders first appear during adolescence, however, the effects of MD on adolescent animals' brain and behaviour have been scarcely explored. In the present study, we aimed to investigate the emotional and cognitive consequences of MD in adolescent male and female rats, as well as possible underlying neurobiological mechanisms within frontal cortex and hippocampus. Animals were exposed to a battery of behavioural tasks, from pnd 35 to 42, to evaluate cognitive [spontaneous alternation task (SAT) and novel object test (NOT)] and anxiety-related responses [elevated plus maze (EPM)] during adolescence. Changes in neuronal and glial cells, alterations in synaptic plasticity as well as modifications in cannabinoid receptor expression were investigated in a parallel group of control and adolescent (pnd 40) male and female animals. Notably, MD induced a significant impairment in recognition memory exclusively among females. A generalized decrease in NeuN expression was found in MD animals, together with an increase in hippocampal glial fibrillar acidic protein (GFAP) expression exclusively among MD adolescent males. In addition, MD induced in the frontal cortex and hippocampus of male and female adolescent rats a significant reduction in brain derived neurotrophic factor (BDNF) and postsynaptic density (PSD95) levels, together with a decrease in synaptophysin in frontal cortex and neural cell adhesion molecule (NCAM) in hippocampus. MD induced, in animals of both sexes, a significant reduction in CB1R expression, but an increase in CB2R that was statistically significant only for the frontal cortex. Taken together, these results indicate that adolescent females are more vulnerable than males to the cognitive deficits derived from MD despite the changes in neural cells, cannabinoid receptors, as well as the reduction in neural plasticity seem to be similar in both sexes. Further investigation is needed to understand the neurobiological mechanisms underlying the sexual dimorphisms associated to the MD effects, and thus, for a better understanding of the specific sex-dependent vulnerabilities to early life stress. This article is part of the Special Issue entitled ‘Neurodevelopmental Disorders’.

The incidence of traumatic brain injuries (TBIs) in humans has rapidly increased in the last ten years. The most common causes are falls and car accidents. Approximately 80 000-90 000 persons per year will suffer some permanent disability as a result of the lesion, and one of the most common symptoms is the decline of hormone levels, also known as post-TBI hormonal deficiency syndrome. This issue has become more and more important, and many studies have focused on shedding some light on it. The hormonal decline affects not only gonadal steroid hormones but also neuroactive steroids, which play an important role in TBI recovery by neuroprotective and neurotrophic actions. The present work used an adolescent close-head murine model to analyze brain and plasma neurosteroid level changes after TBI and to establish correlations with edema and neurological impairments, 2 of the hallmarks of TBI. Our results showed changes in brain pregnenolone, testosterone, dihydrotestosterone (DHT), and 3α-diol levels whereas in plasma, the changes were present in progesterone, DHT, 3α-diol, and 3β-diol. Within them, pregnenolone, progesterone, DHT, and 3α-diol levels positively correlated with edema formation and neurological score, whereas testosterone inversely correlated with these 2 variables. These findings suggest that changes in the brain levels of some neuroactive steroids may contribute to the alterations in brain function caused by the lesion and that plasma levels of some neuroactive steroids could be good candidates of blood markers to predict TBI outcome.

The neonatal leptin surge, occurring from postnatal day (PND) 5 to 13 and peaking at PND9 in rodents, is important for the development of neuroendocrine circuits involved in metabolic control and reproductive function. We previously demonstrated that treatment with a leptin antagonist from PND 5 to 9, coincident with peak leptin levels in the neonatal surge, modified trophic factors and markers of cell turnover and neuronal maturation in the hypothalamus of peri-pubertal rats. The kisspeptin system and metabolic neuropeptide and hormone levels were also modified. Here our aim was to investigate if the timing of pubertal onset is altered by neonatal leptin antagonism and if the previously observed peripubertal modifications in hormones and neuropeptides persist into adulthood and affect male sexual behavior. To this end, male Wistar rats were treated with a pegylated super leptin antagonist (5 mg/kg, s.c.) from PND 5 to 9 and killed at PND102–103. The appearance of external signs of pubertal onset was delayed. Hypothalamic kiss1 mRNA levels were decreased in adult animals, but sexual behavior was not significantly modified. Although there was no effect on body weight or food intake, circulating leptin, insulin and triglyceride levels were increased, while hypothalamic leptin receptor, POMC and AgRP mRNA levels were decreased. In conclusion, alteration of the neonatal leptin surge can modify the timing of pubertal onset and have long-term effects on hypothalamic expression of reproductive and metabolic neuropeptides.

Maternal deprivation (MD) during neonatal life has diverse long-term effects, including modification of metabolism. We have previously reported that MD modifies the metabolic response to high-fat diet (HFD) intake, with this response being different between males and females, while previous studies indicate that in mice with HFD-induced obesity, endocannabinoid (EC) levels are markedly altered in various brown and white adipose tissue depots. Here, we analyzed the effects of MD (24 h at postnatal day 9), alone or in combination with a HFD from weaning until the end of the experiment in Wistar rats of both sexes. Brown and white perirenal and subcutaneous adipose tissues were collected and the levels of anandamide (AEA), 2-arachidonoylglycerol (2-AG), palmitoylethanolamide (PEA), and oleoylethanolamide (OEA) were determined. In males, MD increased the content of OEA in brown and 2-AG in subcutaneous adipose tissues, while in females the content of 2-AG was increased in perirenal fat. Moreover, in females, MD decreased AEA and OEA levels in perirenal and subcutaneous adipose tissues, respectively. HFD decreased the content of 2-AG in brown fat of both sexes and OEA in brown and subcutaneous adipose tissue of control females. In contrast, in subcutaneous fat, HFD increased AEA levels in MD males and OEA levels in control and MD males. The present results show for the first time that MD and HFD induce sex-dependent effects on the main ECs, AEA, and 2-AG, and of AEA-related mediators, OEA and PEA, in the rat brown and white (visceral and subcutaneous) adipose tissues.

It is clear that the prenatal and early neonatal environments are important for determining the metabolic equilibrium in the adult animal, with prenatal/neonatal leptin levels being at least one of the factors involved. Leptin modulates hypothalamic development and, in particular, the neuronal circuits involved in metabolic control. We have recently reported that maternal deprivation (MD) for 24 h on postnatal day (PND) 9 modifies trophic factors and markers of cell turnover and neuronal maturation in the hypothalamus, as well as body weight and circulating leptin levels at PND13, with long- term effects on weight gain and circulating metabolic hormones in the adult. Moreover, these responses are sexually dimorphic. During MD, a dramatic decline in leptin levels is observed; thus, we aimed to determine which of the previously observed changes in markers of hypothalamic development might be attributed to the decline in this metabolic signal. Accordingly, male and female rats were treated with a pegylated leptin antagonist on PND9. In both sexes, hypothalamic signal transducer and activator of transcription 3 activation in response to acute leptin treatment was blocked by the antagonist. In females, hypothalamic mRNA levels for brain-derived neurotrophic factor, cocaine- and amphetamine-regulated transcript and the leptin receptor were increased, as were nestin and vimentin levels. There was also an increase in cell death in the hypothalamus, with a shift towards an anti-apoptotic balance in the Bcl2/BAX ratio. No hypothalamic effects were seen in males. Because antagonism of the actions of leptin at this specific neonatal stage affects hypothalamic cell turnover and maturation in a sex-specific manner, changes in this hormone, at least at this postnatal age, may differentially affect hypothalamic development in males and females, and may explain some of the reported sexually dimorphic responses to modifications in the early nutritional environment.

Animal models have greatly contributed to the understanding of neuropsychiatric disorders and have provided extensive evidence for the "neurodevelopmental hypothesis." In this regard, a single and prolonged episode (24 h) of early maternal deprivation early in life, on postnatal day 9, has been proposed as an animal model for the investigation of certain neuropsychiatric disorders, including schizophrenia. Since metabolic changes in hippocampus (HIP) and prefrontal cortex (PFC) have been described among schizophrenic patients by using ex vivo high-resolution magic angle spinning (HR-MAS) proton ((1)H) nuclear magnetic resonance spectroscopy, in the present study we aimed to investigate the effects of maternal deprivation (MD) on the metabolite profiles of the developing brain by using the HR-MAS technique. MD significantly altered the hippocampal and cortical metabolic profile of neonatal rats (PND 13) in a sex-dependent manner. Glutamine and glutamate (Glx) and taurine of male and female rat pups were altered in both brain areas analyzed. Differences in hippocampal phosphorylethanolamine have also been found as a function of the MD protocol. In addition, MD induced some other region- and sex-dependent effects, including changes in N-acetyl aspartate and total choline signals in the hippocampi of male pups. Present findings indicate a different brain metabolic profile in our animal model of early life stress suggesting its potential utility in the implementation of translational neuropsychiatric research.

Resumen La aplicacion de modelos animales en diversos campos de las neurociencias, incluyendo la psiquiatria y la adiccion, es una herramienta fundamental para la investigacion de las bases neurobiologicas de tales patologias desde una perspectiva translacional. A pesar de sus limitaciones, estos modelos resultan de gran importancia para la investigacion de los mecanismos neurobiologicos subyacentes a los dimorfismos sexuales que se observan en diferentes aspectos de la psicobiologia del individuo. En este articulo nos centraremos en los descritos en el ambito de las enfermedades psiquiatricas y en los procesos de adiccion, a los que no se les ha prestado una atencion suficiente en los ultimos anos. Presentamos y discutimos datos procedentes de modelos animales de alteraciones en el neurodesarrollo y prestamos especial atencion a dos periodos criticos, las etapas neonatal y adolescente, al sistema endocannabinoide como sistema regulador y al cannabis como droga de abuso. Exponemos evidencias acerca de los cambios observados en el sistema endocannabinoide como consecuencia de un episodio de separacion materna temprana, y tratamos tambien las consecuencias del consumo de cannabis en edad adolescente, centrando la atencion en los procesos de dependencia y de mayor riesgo de padecer enfermedades neuropsiquiatricas. En su conjunto, estos datos ponen de manifiesto la importancia del factor “sexo” y la necesidad de tener en cuenta su influencia tanto en la investigacion preclinica, como en la clinica y la epidemiologia. Proponemos, ademas, la profundizacion en una comunicacion fluida entre estas tres aproximaciones, todo ello para el establecimiento de mejores estrategias de prevencion y tratamiento.

Early life experiences such as maternal deprivation (MD) exert long-lasting changes in adult behaviour and reactivity to stressors. Adolescent exposure to cannabinoids is a predisposing factor in developing certain psychiatric disorders. Therefore, the combination of the two factors could exacerbate the negative consequences of each factor when evaluated at adulthood. The objective of this study was to investigate the long-term effects of early MD [24 hours at postnatal day (PND) 9] and/or an adolescent chronic treatment with the cannabinoid agonist CP-55,940 (0.4 mg/kg, PND 28-42) on diverse behavioural and physiological responses of adult male and female Wistar rats. We tested them in the prepulse inhibition (PPI) of the startle response and analysed their exploratory activity (holeboard) and anxiety (elevated plus maze, EPM). In addition, we evaluated their adrenocortical reactivity in response to stress and plasma leptin levels. Maternal behaviour was measured before and after deprivation. MD induced a transient increase of maternal behaviour on reuniting. In adulthood, maternally deprived males showed anxiolytic-like behaviour (or increased risk-taking behaviour) in the EPM. Adolescent exposure to the cannabinoid agonist induced an impairment of the PPI in females and increased adrenocortical responsiveness to the PPI test in males. Both, MD and adolescent cannabinoid exposure also induced sex-dependent changes in plasma leptin levels and body weights. The present results indicate that early MD and adolescent cannabinoid exposure exerted distinct sex-dependent long-term behavioural and physiological modifications that could predispose to the development of certain neuropsychiatric disorders, though no synergistic effects were found.

We have analysed the long-term psychoneuroendocrine effects of maternal deprivation (MD) [24 h at postnatal day (PND) 9] and/or exposure to chronic unpredictable stress (CUS) during the periadolescent period (PND 28 to PND 43) in male and female Wistar rats. Animals were tested in the elevated plus maze (EPM, anxiety) at PND 44 and in two memory tests, spontaneous alternation and novel object recognition (NOT) in adulthood. The expression of hippocampal glucocorticoid (GR) and mineralocorticoid (MR) receptors, as well as of synaptophysin, neural cell adhesion molecule and brain-derived neurotrophic factor, was analysed by in situ hybridisation in selected hippocampal regions. Endocrine determinations of leptin, testosterone and oestradiol plasma levels were carried out by radioimmunoassay. Young CUS animals showed decreased anxiety behaviour in the EPM (increased percentage of time and entries in the open arms) irrespective of neonatal treatment. Memory impairments were induced by the two stressful treatments as was revealed by the NOT, with males being most clearly affected. Although each stressful procedure, when considered separately, induced different (always decrements) effects on the three synaptic molecules analysed and affected males and females differently, the combination of MD and CUS induced an unique disruptive effect on the three synaptic plasticity players. MD induced a long-term significant decrease in hippocampal GR only in males, whereas CUS tended to increase MR in males and decrease MR in females. Both neonatal MD and periadolescent CUS induced marked reductions in testosterone and oestradiol in males, whereas MD male animals also showed significantly decreased leptin levels. By contrast, in females, none of the hormones analysed was altered by any of the stressful procedures. Taking our data together in support of the 'two-hit' hypothesis, MD during neonatal life and/or exposure to CUS during the periadolescent period induced a permanent deficit in memory, which was accompanied by a decrement in markers for hippocampal plasticity. The long-term effects on body weight and hormone levels, particularly among males, might reflect sex-dependent lasting metabolic alterations as well as an impaired reproductive function.

Autism spectrum disorders (ASDs) are heterogenous neurodevelopmental disorders characterized by impairment in social, communication skills and stereotype behaviors. While autism may be uniquely human, there are behavioral characteristics in ASDs that can be mimicked using animal models. We used the BTBR T+tf/J mice that have been shown to exhibit autism-like behavioral phenotypes to 1). Evaluate cannabinoid-induced behavioral changes using forced swim test (FST) and spontaneous wheel running (SWR) activity and 2). Determine the behavioral and neurochemical changes after the administration of MDMA (20 mg/kg), methamphetamine (10 mg/kg) or MPTP (20 mg/kg). We found that the BTBR mice exhibited an enhanced basal spontaneous locomotor behavior in the SWR test and a reduced depressogenic profile. These responses appeared to be enhanced by the prototypic cannabinoid, Δ(9)-THC. MDMA and MPTP at the doses used did not modify SWR behavior in the BTBR mice whereas MPTP reduced SWR activity in the control CB57BL/6J mice. In the hippocampus, striatum and frontal cortex, the levels of DA and 5-HT and their metabolites were differentially altered in the BTBR and C57BL/6J mice. Our data provides a basis for further studies in evaluating the role of the cannabinoid and monoaminergic systems in the etiology of ASDs.

Rats subjected to a single prolonged episode of maternal deprivation (MD) [24h, postnatal days 9-10] show, later in life, behavioural alterations that resemble specific signs of schizophrenia and other neuropsychiatric signs including increased levels of impulsivity and an apparent difficulty to cope with stressful situations. Some of these behavioural modifications are observable in the periadolescent period. However there is no previous information regarding the possible underlying neurochemical correlates at this critical developmental period. In this study we have addressed the effects of MD on the levels of serotonin (5-HT), dopamine (DA) and their respective metabolites in prefrontal cortex, hippocampus, striatum, midbrain and cerebellum of male and female periadolescent Wistar rats. MD rats showed significantly increased levels of 5-HT in all regions studied with the exception of cerebellum. In addition, MD animals showed increased levels of DA in PFC as well as increased levels of DA and a decrease of DOPAC/DA and HVA/DA ratios in striatum. The effect of MD on the monoaminergic systems was in several cases sex-dependent.

Pathological outcomes, including metabolic and endocrine disturbances, of maternal deprivation (MD) in Wistar rats depend on gender and the timing of deprivation during development. We analyzed the effect of MD between postnatal days 9 and 10, a critical period in hypothalamic development, on circulating hormones and local production of trophic factors involved in this process, as well as on markers of cell turnover and maturation. Males and females were studied 12 and 24 h after MD and 12 h (MD36) after returning the dam to her pups. Circulating corticosterone levels were increased and glucose and leptin levels decreased throughout the study in both sexes. Hypothalamic mRNA levels of leptin receptor increased significantly at MD24 in both sexes, normalizing in females at MD36, but not in males. In male rats insulin-like growth factor mRNA levels were significantly decreased at MD24 and brain derived neurotrophic factor mRNA levels decreased at MD12 and MD24, with both trophic factors unaffected in females. In males cell proliferation was significantly decreased at MD36, as were the glial structural proteins, glial fibrillary acidic protein and vimentin. In females, nestin levels decreased significantly at MD24. These results indicate that MD differently affects trophic factors and cell-turnover in the hypothalamus of males and females, which may underlie the sex differences seen in the endocrine and metabolic outcome.

Alcoholism is characterized by successive periods of abstinence and relapse, resulting from long-lasting changes in various circuits of the central nervous system. Accumulating evidence points to the endocannabinoid system as one of the most relevant biochemical systems mediating alcohol addiction. The endocannabinoid system regulates adult neurogenesis, a form of long-lasting adult plasticity that occurs in a few areas of the brain, including the dentate gyrus. Because exposure to psychotropic drugs regulates adult neurogenesis, it is possible that neurogenesis might be implicated in the pathophysiology, and hence treatment, of neurobiological illnesses related to drugs of abuse. Here, we investigated the sensitivity of adult hippocampal neurogenesis to alcohol and the cannabinoid receptor agonist WIN 55,212-2 (WIN). Specifically, we analysed the potential link between alcohol relapse, cannabinoid receptor activation, and adult neurogenesis. Adult rats were exposed to subchronic alcohol binge intoxication and received the cannabinoid receptor agonist WIN. Another group of rats were subjected to an alcohol operant self-administration task. Half of these latter animals had continuous access to alcohol, while the other half were subjected to alcohol deprivation, with or without WIN administration. WIN treatment, when administered during alcohol deprivation, resulted in the greatest increase in alcohol consumption during relapse. Together, forced alcohol binge intoxication and WIN administration dramatically reduced hippocampal neurogenesis. Furthermore, adult neurogenesis inversely correlated with voluntary consumption of alcohol. These findings suggest that adult hippocampal neurogenesis is a key factor involved in drug abuse and that it may provide a new strategy for the treatment of alcohol addiction and dependence.

Cannabis abuse and endocannabinoids are associated to schizophrenia. It is important to discern the association between schizophrenia and exogenous Cannabis sativa, on one hand, and the endogenous cannabinoid system, on the other hand. On one hand, there is substantial evidence that cannabis abuse is a risk factor for psychosis in genetically predisposed people, may lead to a worse outcome of the disease, or it can affect normal brain development during adolescence, increasing the risk for schizophrenia in adulthood. Regarding genetic predisposition, alterations affecting the cannabinoid CNR1 gene could be related to schizophrenia. On the other hand, the endogenous cannabinoid system is altered in schizophrenia (i.e., increased density of cannabinoid CB1 receptor binding in corticolimbic regions, enhanced cerebrospinal fluid anandamide levels), and dysregulation of this system can interact with neurotransmitter systems in such a way that a “cannabinoid hypothesis” can be integrated in the neurobiological hypotheses of schizophrenia. Finally, there is also evidence that some genetic alterations of the CNR1 gene can act as a protectant factor against schizophrenia or can induce a better pharmacological response to atypical antipsychotics. Cannabis abuse is a risk factor for psychosis in predisposed people, it can affect neurodevelopment during adolescence leading to schizophrenia, and a dysregulation of the endocannabinoid system can participate in schizophrenia. It is also worth noting that some specific cannabinoid alterations can act as neuroprotectant for schizophrenia or can be a psychopharmacogenetic rather than a vulnerability factor.

Early maternal deprivation (MD) in rats (24 h, postnatal day 9-10) is a model for neurodevelopmental stress. There are some data proving that MD affects the endocannabinoid system (ECS) in a gender-dependent manner, and that these changes may account for the proposed schizophrenia-like phenotype of MD rats. The impact of MD on cannabinoid receptor distribution in the hippocampus is unknown. The aim of this study is to evaluate the expression of CB(1) and CB(2) receptors in diverse relevant subregions (DG, CA1, and CA3) of the hippocampus in 13-day-old rats by immunohistochemistry and densitometry. MD induced a significant decrease in CB(1) immunoreactivity (more marked in males than in females), which was mainly associated with fibers in the strata pyramidale and radiatum of CA1 and in the strata oriens, pyramidale, and radiatum of CA3. In contrast, MD males and females showed a significant increase in CB(2) immunoreactivity in the three hippocampal areas analyzed that was detected in neuropil and puncta in the stratum oriens of CA1 and CA3, and in the polymorphic cell layer of the dentate gyrus. A marked sex dimorphism was observed in CA3, with females exhibiting higher CB(1) immunoreactivity than males, and in dentate gyrus, with females exhibiting lower CB(2) immunoreactivity than males. These results point to a clear association between developmental stress and dysregulation of the ECS. The present MD procedure may provide an interesting experimental model to further address the role of the ECS in neurodevelopmental mental illnesses such as schizophrenia.

Environmental rearing conditions during the neonatal period are critical for the establishment of neurobiological factors controlling behavior and stress responsiveness. Early maternal deprivation (MD), consisting of a single 24-h maternal deprivation episode during early neonatal life, has been proposed as an animal model for certain psychopathologies including anxiety, depression and schizophrenic-related disorders. Despite first onset of mental disorders usually occur during adolescence, characterization of MD has been mostly developed in adult animals. We review here a series of experiments that were conducted on rats and mice, in which we analyzed the psychoimmunoendocrine outcomes of MD at both adolescence and adulthood. As a whole our results indicate that MD might promote a depressive-like trait that may be present from adolescence to maturity. Maternally deprived adolescent animals also displayed altered locomotor responses, a reduced interest for social investigation and seemed prone for impulsive behavior. Therefore, MD in rodents is further confirmed as a suitable animal model for the study of neuropsychiatric disorders that might become evident during adolescence. Given the increasing consumption of cannabis derivatives among the juvenile population and the reported comorbidity of neuropsychiatric symptoms with cannabis abuse, we also discuss our results indicating altered responses of maternally deprived adolescent animals to cannabinoid compounds.

Despite the alarming increment in the use and abuse of cannabis preparations among young people, little is known about possible long-term consequences of targeting the endocannabinoid system during the critical developmental period of adolescence. Therefore, we aimed to analyze possible long-lasting neurobiological consequences of enhancing endocannabinoid signalling during adolescence, by means of blocking anandamide (AEA) hydrolysis. Adolescent Wistar male rats were administered an inhibitor of AEA hydrolysis, i.e. URB597 (0, 0.1 or 0.5 mg/kg/day from postnatal days 38 to 43). The expression of brain cannabinoid receptor type 1 (CB1R) was then analyzed by [3H]CP-55,940 auto-radiographic binding at adulthood. Repeated URB597 administration during adolescence persistently modified CB1R binding in a region-dependent manner. A long-lasting decrease of CB1R binding levels was found in caudate-putamen, nucleus accumbens, ventral tegmental area and hippocampus, while an opposite increment was observed in the locus coeruleus. Present results provide evidence for long-lasting effects of adolescent URB597 administration. Activation of endocannabinoid transmission during the still plastic phase of adolescence may have implications for the maturational end-point of the endocannabinoid system itself, which could lead to permanent alterations in neuronal brain circuits and behavioural responses. Insights into the developmental trajectories of this neuromodulatory system may help us to better understand and prevent outcomes of neonatal and adolescent cannabis exposure.

Adult animals that had been subjected to a single prolonged episode of maternal deprivation (MD) [24 h, postnatal day (PND) 9-10] show long-term behavioral alterations that resemble specific symptoms of schizophrenia. Moreover, at adolescence MD rats showed depressive-like behavior and altered motor responses. According to the neurodevelopmental hypothesis, certain behavioral abnormalities observed in MD animals may be related to altered neurodevelopmental processes triggered by MD-induced elevated glucocorticoids in relevant specific brain regions. We review here these neuroendocrine effects and show new data indicating that the MD procedure induces diverse detrimental effects on the immune system that are already revealed in the short term (PND 13) and persist into adulthood. These long-lasting effects might be related to altered hypothalamus-pituitary-adrenal axis activity and to social as well as nutrition-related factors. In fact, MD induces long-lasting decreases in body weight. In view of our findings we propose the present MD procedure as a potentially useful model to analyze developmental interactions between early psychophysiological stress and immunodeficient states.

JOURNAL ARTICLE; Intermittent alcohol exposure is a common pattern of alcohol consumption among adolescents and alcohol is known to modulate the expression of the endocannabinoid system (ECS), which is involved in metabolism and inflammation. However, it is unknown whether this pattern may have short-term consequences on the ECS in the spleen. To address this question, we examined the plasma concentrations of metabolic and inflammatory signals and the splenic ECS in early adult rats exposed to alcohol during adolescence. A 4-day drinking in the dark (DID) procedure for 4 weeks was used as a model of intermittent forced-alcohol administration (20%, v/v) in female and male Wistar rats, which were sacrificed 2 weeks after the last DID session. First, there was no liver damage or alterations in plasma metabolic parameters. However, certain plasma inflammatory signals were altered according to sex and alcohol exposition. Whereas fractalkine [chemokine (C-X3-C motif) ligand 1] was only affected by sex with lower concentration in male rats, there was an interaction between sex and alcohol exposure in the TNF-α and interleukin-6 concentrations and only female rats displayed changes. Regarding the mRNA and protein expression of the ECS, the receptors and endocannabinoid-synthesizing enzymes were found to be altered with area-specific expression patterns in the spleen. Overall, whereas the expression of the cannabinoid receptor CB1 and the nuclear peroxisome proliferator-activated receptor PPARα were lower in alcohol-exposed rats compared to control rats, the CB2 expression was higher. Additionally, the N-acyl-phosphatidylethanolamine-specific phospholipase D expression was high in female alcohol-exposed rats and low in male alcohol-exposed rats. In conclusion, intermittent alcohol consumption during adolescence may be sufficient to induce short-term changes in the expression of splenic endocannabinoid signaling-related proteins and plasma pro-inflammatory cytokines in young adult rats with a strong sexual dimorphism. The potential impact of these alterations in early adulthood remains to be elucidated. Yes

There is evidence for the existence of functional interactions between nicotine and cannabinoids and opioid compounds in adult experimental animals. However, there is scarce information about these relationships in young animals. In the present study we evaluated short and long-term effects of a subchronic nicotine treatment [0.4 mg/kg daily i.p. injections from postnatal day (PND) 34 to PND 43], upon hippocampal and striatal cannabinoid-CB(1) and mu-opioid receptors in Wistar rats of both genders. Rats were sacrificed 2 h after the last nicotine injection (short-term effects, PND 43) or one month later (long-term effects, PND 75). Hippocampal and striatal cannabinoid CB(1) and mu-opioid receptors were quantified by Western blotting. The subchronic nicotine treatment induced a region-dependent long-lasting effect in cannabinoid CB(1) receptor: a significant increase in hippocampal cannabinoid CB(1) receptors and a significant decrease in striatal cannabinoid CB(1) receptors, with these effects being similar in males and females. With respect to mu-opioid receptors, subchronic nicotine induced a significant down-regulation in hippocampal and striatal mu-opioid receptors in the long-term, and within the striatum the effects were more marked in adult males than in females. The present results indicate that juvenile nicotine taking may have implications for the endocannabinoid and endogenous opioid function and for the behaviors served by those systems, this includes possible modification of the response of adults to different psychotropic drugs, i.e. cannabis and morphine/heroin when taken later in life.

Pharmacological modulation of the endocannabinoid system is a novel but poorly explored field for potential therapy. Early maternal deprivation represents an animal model for specific aspects of neuropsychiatric disorders. This study explored whether a pharmacological manipulation of the endocannabinoid system at adolescence may restore altered phenotypes resulting from early maternal deprivation. Wistar male rats, maternally deprived for 24 h on postnatal day (PND) 9, were administered the fatty-acid amide hydrolase (FAAH) inhibitor URB597 (0, 0.1 or 0.5 mg/kg/day) for six days during adolescence (PND 31–43), while tested in the intolerance-to-delay task. Deprived (DEP) adolescent rats showed a trend for higher impulsivity levels and an increased locomotor response to novelty when compared to non-deprived (NDEP) controls. The low dose of URB597 effectively decreased impulsive behaviour specifically in DEP subjects. Moreover, long-term metabolic brain changes, induced by drug treatment during adolescence, were detected in DEP animals using proton magnetic resonance spectroscopy ( 1 H MRS). Significant changes were only found within the hippocampus: N -acetyl-aspartate and total creatine were up-regulated by the low dose; glutamate and glutamate plus glutamine were conversely down-regulated by the higher dose. In summary, administration of URB597 during adolescence increased self-control behaviour and produced enduring brain biochemical modifications, in a model for neuropsychiatric disorders.

The intensity of behavioral and neuroendocrine responses to stressful stimuli in rodent strains seems to be inversely related to their life span. We have previously shown that interindividual differences in members of outbred Swiss and inbred BALB/c mouse populations, both male and female, may be related to their behavior in a simple T-maze test. The animals that explore the maze slowly show impaired neuromuscular vigor and coordination, decreased locomotor activity, increased level of emotionality/anxiety, decreased levels of brain biogenic amines as well as immunosenescence and decreased life span, when compared to their control counterparts, which quickly explore the maze. These traits are similar to some of the alterations previously observed in aging animals and therefore we proposed that those ‘slow mice’ are biologically older than the fast animals and may be a model of prematurely aging mice (PAM). Although most of our work on this model has been performed on chronologically adult-mature animals, we have also shown that certain characteristics of PAM, such as increased anxiety and deficient immune response, are already present in chronologically young animals. Thus, it is tempting to hypothesize that chronic hyperreactivity to stress (trait anxiety) leading to immune dysfunction may have a causal relationship with impaired health and premature aging. In view of the link between oxidative stress and the aging process, the redox state of peritoneal leukocytes from PAM has been studied, showing an oxidative stress situation. In the present work we have determined the levels of a key antioxidant, reduced glutathione (GSH), and the oxidant malondialdehyde (MDA), a marker of lipid peroxidation, both in the spleen and brain of male and female PAM and non-PAM (NPAM). We found that GSH and MDA are decreased and increased, respectively, in PAM with respect to NPAM. Moreover, diet supplementation with antioxidants showed to be an effective strategy for protection against early immune and behavioral decline, altered redox state of leukocytes and premature mortality in PAM, which supports the validity of this model of premature aging as well as its link with oxidative stress.

[Background and purpose]: The rates for traumatic brain injury (TBI) have risen in the last decade. Studies in animal models and clinical trials have not yet resulted in an effective treatment for TBI. Leptin, a 16 kDa peptidic hormone is mainly known as a regulator of energy balance and has been shown to exert neuroprotective effects in different models of brain pathology. In this study, we have assessed whether leptin exerts protective actions in a TBI mouse model. In addition, the possible implication of CB2 cannabinoid receptor in leptin actions has been explored, since it is known that the endocannabinoid system interacts with leptin and actively participates in brain recovery after lesions. [Methods]: Swiss (CD1) male mice were subjected to weigh-drop model for TBI. Prior to the lesion, mice were injected with an antagonist of CB2 receptor (AM630) or the vehicle and immediately after TBI, they received leptin or vehicle treatment. Data were analyzed using a two-way ANOVA or the non-parametric test Kruskal-Wallis when appropriate. For correlation analyses, Spearman's rho test, followed by linear regression test, was used. [Results]: TBI induced a neurological deficit, which was improved by leptin treatment. Leptin recovered several parameters affected by TBI, including the expression of cannabinoid receptors, axonal injury marker and neuroinflammatory components. The effects of leptin were prevented or reduced when it was administered in combination with the CB2 receptor antagonist, AM630. [Conclusions and implications]: Since some of the beneficial effects of leptin were not evident in the presence of AM630, our results suggest that CB2 receptor might be involved in the full expression of the neuroprotective effects of the hormone. These findings open new avenues for the study of leptin as a therapeutic treatment for TBI and enhance the importance of CB2 receptor in TBI pathophysiology and recovery., We acknowledge financial support from the Ministerio de Economía y Competitividad, Spain (BFU2011-30217-C03-01 and BFU2012-38144), Redes temáticas de Investigación Cooperativa en Salud, Red de Trastornos Adictivos (RD2012/0028/0021-FEDER), GRUPO UCM (951579) and Precipita-FECYT Crowd funding program.

The present study aimed to better understand the role of the neonatal leptin surge, which peaks on postnatal day (PND)9–10, on the development of the hippocampal formation. Accordingly, male and female rats were administered with a pegylated leptin antagonist on PND9 and the expression of neurones, glial cells and diverse markers of synaptic plasticity was then analysed by immunohistochemistry in the hippocampal formation. Antagonism of the actions of leptin at this specific postnatal stage altered the number of glial fibrillary acidic protein positive cells, and also affected type 1 cannabinoid receptors, synaptophysin and brain-derived neurotrophic factor (BDNF), with the latter effect being sexually dimorphic. The results indicate that the physiological leptin surge occurring around PND 9–10 is critical for hippocampal formation development and that the dynamics of leptin activity might be different in males and females. The data obtained also suggest that some but not all the previously reported effects of maternal deprivation on hippocampal formation development (which markedly reduces leptin levels at PND 9–10) might be mediated by leptin deficiency in these animals.

Leptin (Lep) is important in the development of neuroendocrine circuits involved in metabolic control. Because both Lep and metabolism influence pubertal development, we hypothesized that early changes in Lep signaling could also modulate hypothalamic (HT) systems involved in reproduction. We previously demonstrated that a single injection of a Lep antagonist (Antag) on postnatal day (PND)9, coincident with the neonatal Lep peak, induced sexually dimorphic modifications in trophic factors and markers of cell turnover and neuronal maturation in the HT on PND13. Here, our aim was to investigate whether the alterations induced by Lep antagonism persist into puberty. Accordingly, male and female rats were treated with a pegylated super Lep Antag from PND5 to PND9 and killed just before the normal appearance of external signs of puberty (PND33 in females and PND43 in males). There was no effect on body weight, but in males food intake increased, subcutaneous adipose tissue decreased and HT neuropeptide Y and Agouti-related peptide mRNA levels were reduced, with no effect in females. In both sexes, the Antag increased HT mRNA levels of the kisspeptin receptor, G protein-coupled recepter 54 (Gpr54). Expression of the Lep receptor, trophic factors, and glial markers were differently affected in the HT of peripubertal males and females. Lep production in adipose tissue was decreased in Antag-treated rats of both sexes, with production of other cytokines being differentially regulated between sexes. In conclusion, in addition to the long-term effects on metabolism, changes in neonatal Lep levels modifies factors involved in reproduction that could possibly affect sexual maturation.

The present article focuses on psychoneuroendocrine effects of cannabinoids in developing animals, with special emphasis on the perinatal, periweanling and periadolescent periods. We describe and discuss published data dealing with acute and long-term effects of exposure to cannabinoid agonists in such critical periods. Human studies have demonstrated that the consumption of marijuana by women during pregnancy affects the neurobehavioural development of their children. Investigations using animal models provide useful information for a better understanding of the long-lasting deleterious consequences of cannabis exposure during pregnancy and lactation. The increasing use of cannabis among adolescents and its associated public health problems have led to a parallel increase in basic research on appropriate animal models. Chronic administration of cannabinoid agonists during the periadolescent period causes persistent behavioural alterations in adult animals. Some of these alterations may be related to a possible increased risk of psychosis and other neuropsychiatric disorders in early onset cannabis users.

The left common carotid artery was ligated in anaesthetized 7-day-old Wistar rats (P7), prior to asphyxia by inhaling 100% nitrogen for 9 min. Pups recovered from asphyxia received i.p. saline (n = 16), or L-Arg 300 mg/kg (n = 14). Pups undergoing sham operation remained as controls (n = 12). At day 14, the amount of surviving or degenerating neurons was quantified under optical microscopy by Nissl technique or by Fluoro-Jade B (FJB) in CA1 area of hippocampus and in parietal cortex. In these areas, asphyxia reduced the neuronal density by 23.6 and 30%, and increased the proportion of degenerating neurons two and four times, respectively. L-Arg administration to asphyxiated pups reduced the neuronal loss and the proportion of degenerating neurons by 50% (p < 0.05). We conclude that L-Arg administration after acute severe asphyxia in newborn rats is neuroprotective, reducing early and delayed neuronal loss.

Rationale: Despite the increasing use of cannabis among adolescents, there is scarce information about the long-term effects of cannabinoid receptor agonists in appropriate animal models. Objectives: We aimed to investigate the behavioural features of adult male and female Wistar rats that had been exposed to a chronic treatment with the cannabinoid receptor agonist CP 55,940 (CP) during the juvenile period. Methods: CP (0.4 mg/kg i.p.) or its corresponding vehicle was administered once daily, from day 35 to day 45. In adulthood, the animals were tested in the holeboard, the open field and the elevated plus-maze, under different stress (illumination) conditions. After a resting period, the serum corticosterone levels (radioimmunoassay) of the animals were measured. The effects of CP on food intake and somatic growth were monitored throughout the experimental period. Results: The CP treatment induced significant sex-dependent effects on holeboard activity, as well as a decrease in the level of emotionality/anxiety in the open field and in the plus-maze. The animals receiving CP also showed diminished food intake and body weights during the treatment period, but both parameters recovered normal values during the period after treatment. No significant effect of the CP treatment on corticosterone levels was found. Conclusions: The results demonstrate that chronic administration of CP during the peri-adolescent period resulted in marked behavioural effects in adulthood. The nature of these effects depended on the sex of the animals and on the specific behavioural test. The possible neurobiological substrates underlying the effects of CP are discussed.

Background: Preclinical and clinical data suggest that cannabidiol (CBD), a major non-psychotomimetic compound from Cannabis sativa , induces antipsychotic-like effects. However, the antipsychotic properties of repeated CBD treatment have been poorly investigated. Behavioral changes induced by repeated treatment with glutamate N-methyl-D-aspartate receptor (NMDAR) antagonists have been proposed as an animal model of schizophrenia-like signs. In the present study, we evaluated if repeated treatment with CBD would attenuate the behavioral and molecular modifications induced by chronic administration of one of these antagonists, MK-801. Methods: Male C57BL/6J mice received daily i.p. injections of MK-801 (0.1, 0.5, or 1mg/kg) for 14, 21, or 28 days. Twenty-four hours after the last injection, animals were submitted to the prepulse inhibition (PPI) test. After that, we investigated if repeated treatment with CBD (15, 30, and 60mg/kg) would attenuate the PPI impairment induced by chronic treatment with MK-801 (1mg/kg; 28 days). CBD treatment began on the 6th day after the start of MK-801 administration and continued until the end of the treatment. Immediately after the PPI, the mice brains were removed and processed to evaluate the molecular changes. We measured changes in FosB/ΔFosB and parvalbumin (PV) expression, a marker of neuronal activity and a calcium-binding protein expressed in a subclass of GABAergic interneurons, respectively. Changes in mRNA expression of the NMDAR GluN1 subunit gene (GRN1) were also evaluated. CBD effects were compared to those induced by the atypical antipsychotic clozapine. Results: MK-801 administration at the dose of 1mg/kg for 28 days impaired PPI responses. Chronic treatment with CBD (30 and 60mg/kg) attenuated PPI impairment. MK-801 treatment increased FosB/ΔFosB expression and decreased PV expression in the medial prefrontal cortex. A decreased mRNA level of GRN1 in the hippocampus was also observed. All the molecular changes were attenuated by CBD. CBD by itself did not induce any effect. Moreover, CBD effects were similar to those induced by repeated clozapine treatment. Conclusions: These results indicate that repeated treatment with CBD, similar to clozapine, reverses the psychotomimetic-like effects and attenuates molecular changes observed after chronic administration of an NMDAR antagonist. These data support the view that CBD may have antipsychotic properties.

In the present study, we aimed to assess the impact of early life stress, in the form of early maternal deprivation (MD, 24 h on postnatal day, pnd, 9), on voluntary alcohol intake in adolescent male and femaleWistarrats. During adolescence, from pnd 28 to pnd 50, voluntary ethanol intake (20%, v/v) was investigated using the two-bottle free choice paradigm. To better understand the relationship between stress and alcohol consumption, voluntary alcohol intake was also evaluated following additional stressful events later in life, that is, a week of alcohol cessation and a week of alcohol cessation combined with exposure to restraint stress. Female animals consumed more alcohol than males only after a second episode of alcohol cessation combined with restraint stress. MD did not affect baseline voluntary alcohol intake but increased voluntary alcohol intake after stress exposure, indicating that MD may render animals more vulnerable to the effects of stress on alcohol intake. During adolescence, when animals had free access to alcohol, MD animals showed lower body weight gain but a higher growth rate than control animals. Moreover, the higher growth rate was accompanied by a decrease in food intake, suggesting an altered metabolic regulation in MD animals that may interact with alcohol intake.

© 2015 Lopez-Rodriguez et al., Traumatic brain injury (TBI) incidence rises during adolescence because during this critical neurodevelopmental period some risky behaviors increase. The purpose of this study was to assess the contribution of cannabinoid receptors (CB1 and CB2), blood brain barrier proteins (AQP4) and astrogliosis markers (vimentin) to neurological deficit and brain edema formation in a TBI weight drop model in adolescent male mice. These molecules were selected since they are known to change shortly after lesion. Here we extended their study in three different timepoints after TBI, including short (24h), early mid-term (72h) and late mid-term (two weeks). Our results showed that TBI induced an increase in brain edema up to 72 h after lesion that was directly associated with neurological deficit. Neurological deficit appeared 24 h after TBI and was completely recovered two weeks after trauma. CB1 receptor expression decreased after TBI and was negatively correlated with edema formation and behavioral impairments. CB2 receptor increased after injury and was associated with high neurological deficit whereas no correlation with edema was found. AQP4 increased after TBI and was positively correlated with edema and neurological impairments as occurred with vimentin expression in the same manner. The results suggest that CB1 and CB2 differ in the mechanisms to resolve TBI and also that some of their neuroprotective effects related to the control of reactive astrogliosis may be due to the regulation of AQP4 expression on the end-feet of astrocytes., Support was provided by the Ministerio de Economía y Competitividad, Spain (BFU2011-30217-C03-01 and BFU2012-38144), Instituto de Salud Carlos III, Redes temáticas de Investigación Cooperativa en Salud, Red de Trastornos Adictivos (RD2012/0028/0021) and GRUPO UCM (951579).

Cannabis sativa preparations are among the illicit drugs most commonly used by young people, including pregnant women. The endocannabinoid (eCB) system, which is involved in the regulation of emotional and motivational homeostasis, synaptic plasticity and cognitive functions, also plays a critical role in diverse phases of brain development. Both perinatal and periadolescent periods are critical for brain eCB system development. Thus, interference of endocannabinoid signalling by cannabis exposure may contribute to explain the enduring negative impact of cannabis on neurodevelopmental processes and the resulting psycho-physio-pathological consequences. In the present chapter we describe and discuss published data dealing with the long-term neurobehavioural effects of cannabis exposure during the prenatal and adolescent periods. Human studies have demonstrated that marijuana consumption by pregnant women critically affects the neurobehavioural development of their children. Investigations using animal models provide useful information for a better understanding of the long-lasting deleterious consequences of cannabis exposure during pregnancy and lactation. Increasing use of cannabis among adolescents is a matter of great public concern that has led to a parallel increase in research on appropriate animal models. Chronic administration of cannabinoid agonists during the periadolescent period causes persistent behavioural alterations related to cognitive deficits, increased risk of psychosis, mood disorders and addiction to cannabis and other drugs of abuse. The underlying mechanisms by which cannabis use may lead to these disorders, including genetic vulnerability and the increasing content of the main psychoactive ingredient in cannabis preparations, delta-9-tetrahydrocannabinol (THC), will be discussed. To conclude, prevention and therapeutic strategies based on scientific knowledge will be proposed.