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If stress and disease impose fitness costs, and if those costs vary as a function of group size, then stress and disease should exert selection pressures on group size. We assessed the relationships between group size, stress, and parasite infections across nine groups of red colobus monkeys (Procolobus rufomitratus) in Kibale National Park, Uganda. We used fecal cortisol as a measure of physiological stress and examined fecal samples to assess the prevalence and intensity of gastrointestinal helminth infections. We also examined the effect of behaviors that could potentially reduce parasite transmission (e.g., increasing group spread and reducing social interactions). We found that cortisol was not significantly related to group size, but parasite prevalence was negatively related to group size and group spread. The observed increase in group spread could have reduced the rate of parasite transmission in larger groups; however, it is not clear whether this was a density-dependent behavioral counter-strategy to infection or a response to food competition that also reduced parasite transmission. The results do not support the suggestion that gastrointestinal parasitism or stress directly imposed group-size-related fitness costs, and we cannot conclude that they are among the mechanisms limiting group size in red colobus monkeys., (Copyright 2008 Wiley-Liss, Inc.)

The disruption of endoplasmic reticulum function leads to an accumulation of unfolded proteins, which results in endoplasmic reticulum stress. In the present study, we investigated the effect of vanadate on such stress. Endoplasmic reticulum stress increased glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP) expressions in glial cell cultures. We found that vanadate inhibited the endoplasmic reticulum stress-induced increase in GRP78 and CHOP expressions at both mRNA and protein levels. Thus, these results suggest that vanadate modulates endoplasmic reticulum stress responses and that novel vanadate-responsive protein(s) might be involved in these processes.

Hystricomorph rodents have a divergent insulin molecule with only 1-10% of the biological activity in comparison to other mammalian species. In this study, we used the subterranean rodent Ctenomys talarum as a model and performed blood glucose tolerance tests (GTTs) with trained and untrained individuals to evaluate blood glucose regulation and the possible role of physical activity as a compensatory mechanism. Additionally, we evaluated the variations in blood glucose during acute and chronic stress and gathered data in the field to evaluate natural-occurring variations in blood glucose levels. The GTTs showed that C. talarum have a diminished capacity of regulating blood glucose levels in comparison to other mammals and suggest that unexplored differences in the compensatory mechanisms, insulin structure and/or glucose transporters exist within species of hystricomorph rodents. However, blood glucose levels in the field stayed within the normal mammalian range. Physical activity did not prove to be a compensatory mechanism for blood glucose regulation. The individuals did not display important increases in blood glucose after acute stressors and managed to adequately regulate blood glucose during chronic stress. We suggest that the species may not face a selective pressure favoring a more tightly, mammalian like, capacity of regulating blood glucose levels.

Ultra-endurance exercise, such as an Ironman triathlon, induces muscle damage and a systemic inflammatory response. As the resolution of recovery in these parameters is poorly documented, we investigated indices of muscle damage and systemic inflammation in response to an Ironman triathlon and monitored these parameters 19 days into recovery. Blood was sampled from 42 well-trained male triathletes 2 days before, immediately after, and 1, 5 and 19 days after an Ironman triathlon. Blood samples were analyzed for hematological profile, and plasma values of myeloperoxidase (MPO), polymorphonuclear (PMN) elastase, cortisol, testosterone, creatine kinase (CK) activity, myoglobin, interleukin (IL)-6, IL-10 and high-sensitive C-reactive protein (hs-CRP). Immediately post-race there were significant (P < 0.001) increases in total leukocyte counts, MPO, PMN elastase, cortisol, CK activity, myoglobin, IL-6, IL-10 and hs-CRP, while testosterone significantly (P < 0.001) decreased compared to prerace. With the exception of cortisol, which decreased below prerace values (P < 0.001), these alterations persisted 1 day post-race (P < 0.001; P < 0.01 for IL-10). Five days post-race CK activity, myoglobin, IL-6 and hs-CRP had decreased, but were still significantly (P < 0.001) elevated. Nineteen days post-race most parameters had returned to prerace values, except for MPO and PMN elastase, which had both significantly (P < 0.001) decreased below prerace concentrations, and myoglobin and hs-CRP, which were slightly, but significantly higher than prerace. Furthermore, significant relationships between leukocyte dynamics, cortisol, markers of muscle damage, cytokines and hs-CRP after the Ironman triathlon were noted. This study indicates that the pronounced initial systemic inflammatory response induced by an Ironman triathlon declines rapidly. However, a low-grade systemic inflammation persisted until at least 5 days post-race, possibly reflecting incomplete muscle recovery.

Fasting-induced changes in fatty acid composition have been reported to occur within the body lipids of several types of animals; however, little is known about the changes in fatty acid profiles exhibited by reptiles subjected to prolonged fasting. This study characterizes the fatty acid profiles of six reptile species subjected to sublethal periods of fasting lasting 0, 56, 112, and 168 days. Analyses of fatty acid methyl esters (FAMEs) conducted on the total body lipids of rattlesnakes (Crotalus atrox), ratsnakes (Elaphe obsoleta), pythons (Python regius), boas (Boa constrictor), true vipers (Bitis gabonica), and monitor lizards (Varanus exanthematicus) revealed that all of the species exhibited similar characteristic changes in their fatty acid profiles during starvation stress. According to ANOVAs, the four most effective indicators of the onset of starvation were significant increases in the [1] fatty acid unsaturation index as well as ratios of [2] linoleic to palmitoleic acid, [3] oleic to palmitic, and [4] arachidonic to total fatty acid concentrations. The results of this study suggest that FAME analyses might be useful for identifying nutritional stress and/or starvation among squamate reptiles; however, forthcoming studies will be required to validate the generality of these responses. I also review the potential limitations of this approach, and suggest experiments that will be important for future applications of FAME analyses. Ultimately, it is hoped that FAME analyses can be used in conjunction with current practices as an additional tool to characterize the prevalence of starvation experienced by free-living reptiles.

The stresses of transportation, weaning and commingling are associated with an increased incidence of bacterial and viral pneumonia in cattle. Proteins expressed in the epithelial lining fluid (ELF) of the lungs, in conjunction with resident leukocytes, represent the first line of defence against opportunistic pathogens, and stress-induced alterations in their expression may reveal markers of disease susceptibility. Bronchoalveolar lavage fluid was sampled in weaned and transported calves and ELF protein expression was compared to a control group of calves using two-dimensional electrophoresis (2DE). Serum and pulmonary haptoglobin were increased following stress concurrent with the number of blood neutrophils. Using 2DE, significant changes in expression were observed in spots identified by mass spectrometry as annexin A1 and A5, odorant-binding protein (OBP), isocitrate dehydrogenase, fibrinogen, heme-binding protein, alpha-2-HS-glycoprotein, alpha-1-antichymotrypsin and albumin. Quantification of OBP mRNA by real-time RT-PCR and OBP protein by western blot revealed gender-dependent differences in relative OBP expression in response to stress. These findings reveal stress-associated protein changes in pulmonary ELF and suggest a mechanism through which stress alters respiratory disease susceptibility.

The acute responses to cocaine and its withdrawal contribute to cocaine dependence and potentiate relapse, with gender being one of the genetic factors affecting the outcome. Here we report that in both male and female zebrafish (Danio rerio, AB strain), an initial low-dose cocaine treatment (1.5 muM, immersion) does not acutely change their behavior. The cocaine withdrawal, however, is associated with an anxiety-like state that develops earlier in female zebrafish but is more robust and persistent in males, and can be acutely attenuated by cocaine administration. This is not a result of gender differences in the expression of anxiety-like state, since behavioral responses to an anxiogenic drug, FG-7142, are similar in male and female zebrafish. The basal brain dopamine (DA) levels and the expression of dopamine transporter mRNA (zDAT) show no significant sexual dimorphism. Acute cocaine exposure does not significantly change DA or zDAT. Withdrawal from repeated cocaine administration results in an overall reduction in zDAT, as well as an increase in DA levels. Neither treatment leads to significant gender differences in brain DA or zDAT. The common and gender-specific effects of cocaine on zebrafish, a well-characterized model of vertebrate development and genetics, should help in understanding the mechanisms involved in the anxiety associated with cocaine withdrawal and provide new opportunities in search for therapeutic solutions.

Optimal functioning of the hypothalamo-pituitary-adrenal (HPA) axis is paramount to maximizing fitness in vertebrates. Research in laboratory mammals has suggested that maternally-induced stress can cause significant variation in the responsiveness of an offspring's HPA axis involving both pre- and post-natal developmental mechanisms. However, very little is known regarding effects of maternal stress on the variability of offspring adrenocortical functioning in free-living vertebrates. Here we use an experimental approach that independently lowers the quality of both the pre- and post-natal developmental environment to examine programming and plasticity in the responsiveness of the HPA axis in fledglings of a free-living passerine, the European starling (Sturnus vulgaris). We found that mimicking a hormonal signal of poor maternal condition via an experimental pre-natal increase in yolk corticosterone decreased the subsequent responsiveness of the HPA axis in fledglings. Conversely, decreasing the quality of the post-natal developmental environment (by decreasing maternal provisioning capability via a maternal feather-clipping manipulation) increased subsequent responsiveness of the HPA axis in fledglings, apparently through direct effects on nestling body condition. The plasticity of these responses was sex-specific with smaller female offspring showing the largest increase in HPA reactivity. We suggest that pre-natal, corticosterone-induced, plasticity in the HPA axis may be a 'predictive adaptive response' (PAR): a form of adaptive developmental plasticity where the advantage of the induced phenotype is manifested in a future life-history stage. Further, we introduce a new term to define the condition-driven post-natal plasticity of the HPA axis to an unpredictable post-natal environment, namely a 'reactive adaptive response' (RAR). This study confirms that the quality of both the pre- and post-natal developmental environment can be a significant source of variation in the responsiveness of the HPA axis, and provides a frame-work for examining ecologically-relevant sources of stress-induced programming and plasticity in this endocrine system in a free-living vertebrate, respectively.

Circadian rhythms control several behaviors through neural networks, hormones and gene expression. One of these outputs in invertebrates, vertebrates and plants is the stress resistance behavior. In this work, we studied the circadian variation in abiotic stress resistance of adult C. elegans as well as the genetic mechanisms that underlie such behavior. Measuring the stress resistance by tap response behavior we found a rhythm in response to osmotic (NaCl LC50 = 340 mM) and oxidative (H2O2 LC50 = 50 mM) shocks, with a minimum at ZT0 (i.e., lights off) and ZT12 (lights on), respectively. In addition, the expression of glutathione peroxidase (C11E4.1) and glycerol-3-phosphate dehydrogenase (gpdh-1) (genes related to the control of stress responses) also showed a circadian fluctuation in basal levels with a peak at night. Moreover, in the mutant osr-1 (AM1 strain), a negative regulator of the gpdh-1 pathway, the osmotic resistance rhythms were masked at 350 mM but reappeared when the strain was treated with a higher NaCl concentration. This work demonstrates for the first time that in the adult nematode, C. elegans stress responses vary daily, and provides evidence of an underlying rhythmic gene expression that governs these behaviors.

Context: Physical exercise-related stress activates hypothalamus-pituitary-adrenal (HPA) axis; nitric oxide is one of the mediators of the HPA axis response to stress, and phosphodiesterase type 5 inhibitors influences nitric oxide-linked biological activities., Objective: The objective of the study was to investigate whether a single oral long half-life phosphodiesterase type 5 inhibitor (tadalafil) administration influences the HPA axis response to exercise-related stress., Design: This was a double-blind, cross-over trial., Participants: Participants included nine healthy male athletes., Interventions: All subjects performed a maximal exercise test in normoxia, after which they received a single oral administration of tadalafil or placebo. Then after a 2-wk washout period, they were crossed over and repeated the exercise test. Each subject was his own control. Salivary collections, for steroid evaluations [cortisol, dehydroepiandrosterone sulphate (DHEAS), testosterone] and respective ratio calculation (DHEAS to cortisol, testosterone to cortisol, testosterone to DHEAS), were performed before each exercise (Pre-Ex), immediately after (Post-Ex), and at 30 min during recovery., Results: As expected, mean salivary cortisol concentration increased immediately after exercise after both tadalafil and placebo (P = 0.014 and P =0.036 vs. Pre-Ex, respectively); however, the cortisol increase was significantly higher after tadalafil administration (P = 0.034 vs. placebo). Furthermore, an increased salivary testosterone after exercise was observed only after tadalafil administration (P = 0.029 vs. Pre-Ex). No effects of either exercise and/or tadalafil administration on salivary DHEAS concentrations were observed. DHEAS to cortisol and testosterone to cortisol ratios significantly decreased after exercise after tadalafil administration (P = 0.037, and P = 0.02 vs. placebo, respectively)., Conclusion: Tadalafil administration amplified the salivary cortisol and testosterone responses to a maximal exercise-related stress in healthy trained humans.

Pulmonate land snails often are able to estivate to survive dry hot seasons were water and food are scarce. The aperture of the shell is closed with an epiphragm, and metabolism is depressed to approximately one fourth of basal metabolism. We investigated a molecular aspect of estivation focussing on the heat shock protein 70 (Hsp70) stress response during estivation in the Mediterranean Grunt Snail Cantareus apertus. Sequences of a new inducible hsp70 and of actin are presented and expression of the hsp70 gene as well as Hsp70 protein content was measured in estivating animals. Both Hsp70 protein and mRNA do not show a significant change from the control, although there is a trend that hsp70 mRNA is less abundant in estivating specimens. After heat shock, the expression of hsp70 increased and a higher Hsp70 protein content was detected. Water relations were also investigated. After a period of 6 months in the dormant state, the snails contained 14% less water than active ones, implying a constricted protection against desiccation, compared to the desert snail Sphincterochila zonata, and a Mediterranean-type water economy.

The resistance of courtship behavior and communicative sound production to heat shock (37 degrees C, 30 min) was studied in wild-type Canton S (CS) male Drosophila melanogaster and males of two strains with defects in the kynurenine pathway of tryptophan metabolism (KPTM) caused by mutations cinnabar (block at the level of kynurenine-3-hydroxylase leading to accumulation of kynurenic acid, a neuroprotective metabolite, in the brain) and cardinal (block at the level of phenoxazinone synthetase causing accumulation of 3-hydroxykynurenine, an oxidative stress generator, in the brain). Males of each strain were divided into four groups. Males from control groups were not exposed to heat shock. The other groups were exposed to heat shock at the late embryonic/early larval (the first instar) developmental stage, when mushroom bodies are formed (HS1 groups); at the prepupal stage, when the brain central complex develops (HS2 groups); or at the imago stage 1 h before the experiment (HS groups). All males were tested at an age of five days. Virgin and fertilized five-day-old CS females served as courtship objects. The courtship behavior and singing of control CS and cinnabar males were similar. Control cardinal males also had high motivation, but their courtship efficiency was lower because of less precise movements (wing vibration was often not accompanied by sound production) and hyperexcitability. Exposure of first-instar larvae to heat shock had almost no effect on behavior or singing of adult males of any strain. In cardinal males exposed to heat shock at the prepupal stage or, especially, at the imago stage 1 h before the test (the HS2 and HS groups), courtship was strongly impaired, and various distortions appeared in their sound signals, which indicated disturbance of coordination between elements of the song center and their interaction with pacemakers. These effects were much milder or absent altogether in HS2 and HS wild-type males and, especially, cinnabar males. Thus, permanent excess of 3-hydroxykynurenine in the male brain dramatically decreased their stress resistance. In contrast, excess of kynurenic acid alleviated the consequences of stress.

A variety of mechanisms are used to signal extracytoplasmic conditions to the cytoplasm. These mechanisms activate extracytoplasmic function (ECF) sigma factors which recruit RNA-polymerase to specific genes in order to express appropriate proteins in response to the changing environment. The two best understood ECF signaling pathways regulate sigma(E)-mediated expression of periplasmic stress response genes in Escherichia coli and FecI-mediated expression of iron-citrate transport genes in E. coli. Homologues from other Gram-negative bacteria suggest that these two signaling mechanisms and variations on these mechanisms may be the general schemes by which ECF sigma factors are regulated in Gram-negative bacteria.

Citrus trees are subject to several abiotic constraints such as salinity. Providing new rootstocks more tolerant is thus a requirement. In this article, we investigated salt stress tolerance of three tetraploid rootstock genotypes when compared to their respective diploid rootstocks (Poncirus trifoliata, Carrizo citrange, Cleopatra mandarin). Plant growth, leaf fall and ion contents were investigated. At the end of the experiment, leaf fall was observed only for diploid Poncirus trifoliata plants as well as chlorosis symptoms for Poncirus trifoliata and Carrizo citrange diploid plants. The diploid Cleopatra mandarin plants growth rate was not affected by salt stress and has even been increased for tetraploid Cleopatra mandarin. Ion contents investigation has shown lower accumulations of chloride ions in leaves of the tetraploid plants when compared to diploid plants. Our results suggest that citrus tetraploid rootstocks are more tolerant to salt stress than their corresponding diploid.

Dinoflagellate bioluminescence serves as a model system for examining mechanosensing by suspended motile unicellular organisms. The response latency, i.e. the delay time between the mechanical stimulus and luminescent response, provides information about the mechanotransduction and signaling process, and must be accurately known for dinoflagellate bioluminescence to be used as a flow visualization tool. This study used a novel microfluidic device to measure the response latency of a large number of individual dinoflagellates with a resolution of a few milliseconds. Suspended cells of several dinoflagellate species approximately 35 microm in diameter were directed through a 200 microm deep channel to a barrier with a 15 microm clearance impassable to the cells. Bioluminescence was stimulated when cells encountered the barrier and experienced an abrupt increase in hydrodynamic drag, and was imaged using high numerical aperture optics and a high-speed low-light video system. The average response latency for Lingulodinium polyedrum strain HJ was 15 ms (N>300 cells) at the three highest flow rates tested, with a minimum latency of 12 ms. Cells produced multiple flashes with an interval as short as 5 ms between individual flashes, suggesting that repeat stimulation involved a subset of the entire intracellular signaling pathway. The mean response latency for the dinoflagellates Pyrodinium bahamense, Alexandrium monilatum and older and newer isolates of L. polyedrum ranged from 15 to 22 ms, similar to the latencies previously determined for larger dinoflagellates with different morphologies, possibly reflecting optimization of dinoflagellate bioluminescence as a rapid anti-predation behavior.

MICA and MICB are stress-induced ligands recognized by the activating receptor NKG2D. A microRNA encoded by human cytomegalovirus downregulates MICB expression by targeting a specific site in the MICB 3' untranslated region. As this site is conserved among different MICB alleles and a similar site exists in the MICA 3' untranslated region, we speculated that these sites are targeted by cellular microRNAs. Here we identified microRNAs that bound to these MICA and MICB 3' untranslated region sequences and obtained data suggesting that these microRNAs maintain expression of MICA and MICB protein under a certain threshold and facilitate acute upregulation of MICA and MICB during cellular stress. These microRNAs were overexpressed in various tumors and we demonstrate here that they aided tumor avoidance of immune recognition.

Hypoxia-inducible transcription factor-1 (HIF-1) is the most important component of cellular and molecular adaptive responses to hypoxia. We aimed to analyze effects of systemic hypoxia and CO exposure on the oxygen-regulated alpha-subunit of HIF-1 and HIF-1-dependent vasoactive target genes in rat brain. Brains of adult Sprague-Dawley rats were investigated after incubation for 3 and 12 h under normoxia, hypoxia (8% O(2)) and CO 0.1% (n = 10 per group). Upon 3 h of exposure, hypoxia and CO-induced accumulation of HIF-1alpha protein in brain homogenates assessed by Western blot analysis. In contrast to hypoxia HIF-1alpha signals decreased markedly during 12 h-exposure to CO. By immunohistochemistry, intensive HIF-1alpha-positive staining was found in neurons of the cortex and hippocampus. Cerebral expression of vasoactive target genes adrenomedullin (ADM) and vascular endothelial growth factor (VEGF) showed up-regulation during both hypoxia and CO exposure indicating functional activation of HIF-1. Hypoxia increased ADM (P < 0.05) and VEGF mRNA levels within 3 h (P < 0.01) which persisted up to 12 h of exposure (ADM, P < 0.05; VEGF, P < 0.001). Similarly, CO inhalation led to early up-regulation of VEGF (3 h: P < 0.05; 12 h: P < 0.01), but a more delayed increase of ADM mRNA levels (3 h: n.s., 12 h: P < 0.01). We suggest that CO-induced oxygen deprivation is a potent stimulus to cerebral HIF-1-regulated hypoxic stress responses even though its effects are more transient than exposure to hypoxia.

The present study set out to investigate the thermal limits of the Mediterranean bivalve Modiolus barbatus, acclimated to various temperatures, and includes a comparison of laboratory determined limits with its temperature-dependent restriction to deeper water layers in its natural habitat. Thermal responses and limits were determined by integrating information from various levels of biological organization, including the expression of Hsp70 and Hsp90, the phosphorylation of stress-activated protein kinases, p38 mitogen-activated protein kinase (p38 MAPK) and cJun-N-terminal kinases (JNKs) as well as metabolic adjustments. The latter were assessed by examining temperature effects on the activity of the key glycolytic enzyme pyruvate kinase (PK). The expression of Hsp70 and Hsp90 was activated when mussels were acclimated to temperatures above 20 degrees C. Increased phosphorylation of p38 MAPK and JNKs at about the same temperatures indicate activation of MAPK signaling cascades and their potential involvement in the induction of Hsp genes. As indicated by the activity of PK, Modiolus barbatus maintains some aerobic capacity when acclimated to temperatures up to 24 degrees C, while further warming probably caused metabolic depression and a shift from aerobic to anaerobic metabolism. An increase in mortality occurred in parallel, during acclimation to temperatures above 24 degrees C. Our results indicate that both the biochemical stress indicators and metabolic status respond in parallel once hypoxemia becomes extreme. Comparison with our previous study of thermal limits and vertical distribution in M. galloprovincialis dwelling in shallow waters emphasizes the relevance of maintained aerobic scope over that of passive tolerance for permanent vertical zonation at higher temperatures in the field. These findings and conclusions are in line with the concept of oxygen and capacity limited thermal tolerance and the associated systemic to molecular hierarchy of thermal limitation.

The tumour suppressor p53 is activated following stress and initiates a heterogeneous response in a cell-, tissue- and stress-dependent manner. This heterogeneity is reflected in the different physiological outcomes that follow p53 activation. One mechanism that may contribute to this variability is the promoter selectivity of p53 target genes. p53 is at the hub of numerous signalling pathways that are triggered in response to particular stresses, all of which can leave their mark on p53 by way of post-translational modifications and interactions with cofactors. The precise combination of these marks, much like the bars in a barcode, dictates the behaviour of p53 in any given situation.

Corticotropin-releasing hormone (CRH) plays a central role in controlling stress response. In this study, we aimed to identify the regulatory effect of estrogen receptor (ER) on CRH and the underlying mechanism. We investigated the regulation of CRH mRNA in the BE(2)-C cell line, a human neuroblastoma cell line which express endogenous CRH. Quantitative reverse transcriptase-polymerase chain reactions showed that in the presence of estradiol overexpressing ER alpha or ER beta in BE(2)-C cells increased the transcription of CRH. Chromatin immunoprecipitation assays in this cell line also showed that both ER alpha and ER beta can be recruited to the CRH promoter with the treatment of estradiol. However, electrophoretic mobility shift assays did not show direct binding between estrogen receptors and two estrogen response elements (ERE) half sites in the CRH promoter. To clarify the regulatory mechanism, site-directed mutagenesis and reporter gene assay in the CHO cell line were used. When the ERE half sites and the cAMP regulatory element (CRE) in the CRH promoter were disrupted, ER-mediated up-regulation of CRH promoter activity reduced. Between the two ERE half sites studied, the -316 ERE half site contributed more to the constitutive CRH expression induced by ER. In summary, our results confirm the stimulation of ER alpha and ER beta on CRH expression and demonstrate the important roles of the ERE half sites and CRE for the action of ER alpha and ER beta.

Two experiments were conducted to investigate the effect of acute preslaughter stress mimicked by exogenous corticosterone (CORT) administration on postmortem muscle metabolism of broiler chickens. Altered protein metabolism, glycogen depletion, and meat quality characteristics were investigated in the musculus pectoralis major (PM) and musculus biceps femoris of broiler chickens. Results showed that CORT administration resulted in increased proteolysis and gluconeogenesis, whereas the capacity for protein synthesis was not obviously changed. Plasma levels of glucose, urate, and total free amino acids were all significantly decreased by CORT treatment. The effect of CORT administration on muscle R-values remained uncertain. The initial muscle buffer capacity was increased by CORT treatment in both musculus pectoralis major and musculus biceps femoris. The results suggested that the acute premortem up-regulation of CORT decreased muscle ultimate pH by increasing the antemortem muscle glycogen content and its depletion rate postmortem, which in turn induced a decrease in water-holding capacity. Muscle buffering capacity might be altered by CORT administration, and its involvement in the change of muscle pH needs to be investigated further.

Obesity and elevated cytokine secretion result in a chronic inflammatory state and may cause the insulin resistance observed in type 2 diabetes. Recent studies suggest a key role for endoplasmic reticulum stress in hepatocytes and adipocytes from obese mice, resulting in reduced insulin sensitivity. To address the hypothesis that thiazolidinediones, which improve peripheral insulin sensitivity, act in part by reducing the endoplasmic reticulum stress response, we tested subcutaneous adipose tissue from 20 obese volunteers treated with pioglitazone for 10 wk. We also experimentally induced endoplasmic reticulum stress using palmitate, tunicamycin, and thapsigargin in the human HepG2 liver cell line with or without pioglitazone pretreatment. We quantified endoplasmic reticulum stress response by measuring both gene expression and phosphorylation. Pioglitazone significantly improved insulin sensitivity in human volunteers (P = 0.002) but did not alter markers of endoplasmic reticulum stress. Differences in pre- and posttreatment endoplasmic reticulum stress levels were not correlated with changes in insulin sensitivity or body mass index. In vitro, palmitate, thapsigargin, and tunicamycin but not oleate induced endoplasmic reticulum stress in HepG2 cells, including increased transcripts CHOP, ERN1, GADD34, and PERK, and increased XBP1 splicing along with phosphorylation of eukaryotic initiation factor eIF2alpha, JNK1, and c-jun. Although patterns of endoplasmic reticulum stress response differed among palmitate, tunicamycin, and thapsigargin, pioglitazone pretreatment had no significant effect on any measure of endoplasmic reticulum stress, regardless of the inducer. Together, our data suggest that improved insulin sensitivity with pioglitazone is not mediated by a reduction in endoplasmic reticulum stress.

To identify and isolate genes related to abiotic stresses (salinity and drought) tolerance in grapevine, a candidate gene approach was developed and allowed isolating a full-length cDNA of rd22 gene from the Cabernet Sauvignon variety. The latter, named Vvrd22, is a dehydration-responsive gene that is usually induced by the application of exogenous ABA. Details of the physicochemical parameters and structural properties (molecular mass, secondary structure, conserved domains and motives, putative post-translational modification sites...) of the encoded protein have also been elucidated. The expression study of Vvrd22 was carried out at the berry growth stages and at the level of plant organs and tissues as well as under both drought and salt stresses. The results showed that Vvrd22 is constitutively expressed at a low level in all analyzed tissues. Moreover, salt stress induced Vvrd22 expression, particularly for the tolerant variety (Razegui), contrary to the sensitive one (Syrah), which did not display any expression variation during the stress, which means that Vvrd22 is involved in salt stress response and that its expression level depends on regulatory mechanisms that are efficient only for the tolerant variety. On the other hand, under drought stress, Vvrd22 is induced in an identical manner for both tolerant and sensitive varieties. In addition, stress signal molecules such as ABA (lonely applied or in combination with sucrose) induced Vvrd22 expression, even at a low level. A minimal knowledge about the role and the functionality of this gene is necessary and constitutes a prerequisite condition before starting and including Vvrd22 in any program of improvement of grapevine's abiotic stress tolerance.

Elevated prenatal cortisol has been associated with several negative conditions including aborted fetuses, excessive fetal activity, delayed fetal growth and development, prematurity and low birthweight, attention and temperament problems in infancy, externalizing problems in childhood, and psychopathology and chronic illness in adulthood. Given that maternal prenatal cortisol crosses the placenta and influences other aspects of the prenatal environment, these effects on the fetus and later development are not surprising. Cortisol would appear to be a mediating variable, resulting from prenatal stress in several forms including depression, anxiety, anger, and daily hassles. Cortisol effects are further complicated by its interaction with neurotransmitters such as norepinephrine, which may itself.

We investigated how mercury (Hg) as an example of a widespread pollutant, can influence the tolerance of low temperature stress in the springtail, Folsomia candida. Springtails were exposed to aqueous solutions with a range of concentrations of HgCl2 and subsequently exposed to a range of low temperatures (cold shock) in order to model the dose-response surface (using survival as toxicity parameter). The data fitted a multiplicative model well (R2=0.99), and there was a highly significant synergistic interaction between Hg and cold shock. Our results indicate that the assessment of the toxicity of Hg by traditional laboratory studies where test organisms are exposed to only one stress factor and otherwise optimal conditions, may well underestimate the impact of the pollutant on the survival of field populations if stressful climatic conditions prevail. This conclusion is likely to apply to many other species and possibly other toxic chemicals as well. We propose that the present and similar research is needed for improvement of the scientific basis for setting safety factors in sound risk assessment of polluting chemicals.

This study aimed to assess the effects of examination stress on salivary cortisol, immunoglobulin A (IgA), and chromogranin A (CgA) in nursing students. Saliva samples were collected from 15 healthy females before and immediately after the one-hour examination, and two hours after the examination. Salivary cortisol, IgA, and CgA concentrations were determined by enzyme-linked immunosorbent assay. Both IgA and CgA concentrations statistically increased immediately after the examination (P < 0.05) and decreased two hours after the examination. No significant differences were observed between before and after the examination in the salivary cortisol concentration. These findings suggest that the acute stress due to the examination is associated with raised salivary IgA and CgA, but not cortisol.

Seasonal modulation of the adrenocortical response to stress appears to be ubiquitous in arctic-breeding and temperate-zone-breeding birds, but has not been well investigated in alpine-breeding species at mid-latitude. We examined the adrenocortical response to acute stress (capture, handling and restraint) in populations of Eurasian tree sparrow (Passer montanus) among seasons and migratory house sparrow (P. domesticus bactrianus) in pre-breeding on the Qinghai-Xizang Plateau (the Tibetan Plateau). A population of house sparrow (Passer domesticus domesticus) was also sampled in lowland Phoenix, Arizona during breeding and wintering stages. In Eurasian tree sparrows, baseline corticosterone (CORT) does not differ among life history stages, but stress-induced CORT level (maximal CORT, total and corrected integrated CORT) is significantly higher in late breeding stage than those in early breeding and prebasic molt stages. In house sparrows, stress-induced CORT level does not differ between sites and life history stages, but baseline CORT is significantly lower in pre-breeding from Qinghai compared with those in breeding and wintering stages from Phoenix. Interestingly, both baseline CORT and maximal CORT do not differ between the populations of Eurasian tree sparrow and house sparrow in early/pre-breeding stage although tree sparrow is resident species whereas house sparrow is migratory in Qinghai. Our results suggest that the extreme environment of the Tibetan Plateau does not have significant effects on adrenocortical responses to acute stress in Eurasian tree sparrows and house sparrows, which may be a result of masking by human activities. These invasive human commensals may have a unique HPA axis response to different environments because they can take advantage of human food sources and shelter (i.e. buildings).

It had been shown that the reaction of conversion of corticosterone (CS) to 11-dehydrocorticosterone (11-DHCS) was increased in chronic intermissions, but not in sharp stress influences in male rats, especially under dehydroepiandrosterone sulfate (DHEAS) employment. The injection of naltrexone 20 min before DHEAS in dose 0.1 mg/kg which selectively blocked the mu-opiate receptors canceled this effect that indicated the participation of in-opiate receptors in such regulation. The DHEAS effect realized through the endogenous ACTH, and such was of the central nature. On the base of ourselves and the literature dates we intraduced the scheme of DHEAS- and mu-opiate-dependent regulation of CS/11-DHCS interchangings.

Hsp70B' is the only major human isoform in the hsp70 family that is strictly stress-inducible, and therefore available to function only in stressed cells. Since Hsp70B' is evolutionarily closely related to human Hsp72, they are thought to function similarly, but direct evidence of Hsp70B' function in stressed cells has been lacking. Here we showed that both Hsp70B' and Hsp72 are essential relatively early after heat stress in the acquisition of cytoprotection by two human colon cell lines. Using flow cytometry to count viable cells, we also showed that cytoprotection is more pronounced in cultures grown at low cell number (LCN), where there is an ample amount of both Hsp70s. siRNA knock-down of either Hsp70B' or Hsp72 severely handicapped the ability of cells to acquire cytoprotection. Hsp70B' and Hsp72 were found to form a complex following stress that included the co-chaperone HOP. These results taken together support the hypothesis that Hsp70B' and Hsp72 play cooperative roles in cell survival of proteotoxic stress. In addition there are implications for chemotherapy protocols and for pathological conditions in which the contributions to cytoprotection of both Hsp70B' and Hsp72 are modulated by cell numbers or density.

Study of the hypothalamic-pituitary adrenal (HPA) axis has been critical to advancing our understanding of human adaptation to stress. The cortisol response to awakening (CRA) is a potentially useful measure for understanding group and individual differences in HPA axis regulation. In this study, the CRA was examined in the context of a naturalistic stressor--a 6-week voyage of work and study aboard an oceangoing ship, including both experienced and novice sailors. Thirty-one subjects provided weekday and weekend baseline CRA data onshore prior to boarding, followed by three CRAs at sea and one shore leave CRA. Subjective measures of sleep, stress and control were also collected. Results suggest that novice sailors' cortisol response to awakening was elevated at sea relative to both a shoreside weekend and a shore leave during the voyage, but the most striking elevation was found during a workday onshore. Inexperienced students' profiles changed differently over the course of the voyage from those of professional crew. CRAs were not affected by sleep variables and were not predicted by subjective ratings. These data support the value of the cortisol response to awakening as a neuroendocrine marker of HPA regulatory responses to a naturalistic stressor, influenced by changes in work and living environment, and perhaps prior experience with the stressor.

Stress is a major risk factor in drug addiction development and relapse. Virtually all drugs of abuse act by increasing extracellular dopamine levels in the striatum. To gain an understanding of the interaction between stress and drug exposure, we studied the effects of concomitant chronic nicotine and chronic stress exposure on mouse striatal dopamine levels. C57Bl6/J mice were treated with nicotine in the drinking water or control solution for at least 6 weeks. Some mice were chronically stressed by daily exposure to cold, shaking or restrain. Nicotine-treated mice showed up-regulation of epibatidine binding in several brain regions. In mice treated with both chronic nicotine and stress, epibatidine binding was increased in all studied areas except the dorsal striatum. Therefore, microdialysis was used to measure extracellular dopamine levels in the dorsal striatum of mice chronically treated with nicotine, stress, or both. To have a measure of striatal response to different challenges, we performed microdialysis after acute injection of saline, nicotine, and cocaine. Chronic nicotine enhanced nicotine-dependent dopamine release, while chronic stress blunted the response to cocaine. When mice were subjected to both chronic nicotine and chronic stress, nicotine- and cocaine-dependent dopamine release was undistinguishable from that of control animals. In conclusion, our data suggest that chronic stress and chronic nicotine counteract each other's effect on dopamine release in the striatum. This effect might be mediated by changes in nicotinic acetylcholine receptor up-regulation. This "normalization" of striatal function when both nicotine and stress are present might help explain the comorbidity between stress-related disorders and drug abuse.

Chronic stress is closely linked to clinical depression, which could be assessed by a chronic unpredictable mild stress (CUMS) animal model. We present here a GC/MS-based metabolic profiling approach to investigate neurochemical changes in the cerebral cortex, hippocampus, thalamus, and remaining brain tissues. Multi-criteria assessment for multivariate statistics could identify differential metabolites between the CUMS-model rats versus the healthy controls. This study demonstrates that the significantly perturbed metabolites mainly involving amino acids play an indispensable role in regulating neural activity in the brain. Therefore, results obtained from such metabolic profiling strategy potentially provide a unique perspective on molecular mechanisms of chronic stress.

Background: The placenta is an important site for iron metabolism in humans. It transfers iron from the mother to the fetus. One of the major iron transport proteins is transferrin, which is a blood plasma protein crucial for iron uptake. Its localization and expression may be one of the markers to distinguish placental dysfunction., Methods: In the experimental study we used antibody preparation, mass spectrometric analysis, biochemical and immunocytochemical methods for characterization of transferrin expression on the human choriocarcinoma cell line JAR (JAR cells), placental lysates, and cryostat sections. Newly designed monoclonal antibody TRO-tf-01 to human transferrin was applied on human placentae from normal (n = 3) and abnormal (n = 9) pregnancies., Results: Variations of transferrin expression were detected in villous syncytiotrophoblast, which is in direct contact with maternal blood. In placentae from normal pregnancies, the expression of transferrin in the syncytium was significantly lower (p < 0.001) when compared to placentae from abnormal ones (gestational diabetes, pregnancy induced hypertension, drug abuse)., Conclusion: These observations suggest that in the case of abnormal pregnancies, the fetus may require higher levels of transferrin in order to prevent iron depletion due to the stress from the placental dysfunction.

Antioxidants protect against free-radical damage, and free radicals, in turn, are thought to underlie aging. Thus, measuring antioxidants may aid field ecologists in understanding the physiological mechanisms that underlie life-history trade-offs. Antioxidant levels are known to vary markedly in response to the stress of capture in many birds. These changes in antioxidants could result from regulation (e.g., by stress-related hormones) or consumption (e.g., by an increase in free radicals due to increased metabolic rate). Here we experimentally test the effect of increased metabolic rate on circulating antioxidant and corticosterone concentrations in two wild passerine bird species, house sparrows (Passer domesticus) and gray catbirds (Dumetella carolinensis). We increased metabolic rate via exposure to low ambient temperatures overnight in captivity and measured circulating antioxidant capacity, uric acid, corticosterone, and oxygen consumption in cold-exposed and control individuals. Both species showed increases rather than decreases in all antioxidant parameters overnight, contradicting a consumption-by-energy-expenditure hypothesis. Both positive and negative correlations between antioxidant response and corticosterone response were occasionally but not consistently present, refuting a generalized regulation-by-corticosterone hypothesis. High baseline uric acid predicted diminished response of corticosterone and all antioxidants. Thus, high uric acid may reflect recent stress, poor condition, or a compensatory response. Relationships among metabolic rate, antioxidants, and corticosterone differed qualitatively between the species.

Antiglutamatergic agents, such as lamotrigine, have been used successfully for the treatment of posttraumatic stress disorder (PTSD). They could be potentially acting through the stabilization of the corticotropin-releasing factor (CRF) systems. Glutamate mediates CRF release in various brain regions involved in the pathophysiology of PTSD, antiglutamatergic agents could stabilize the CRF system and, thereby, improve the symptom complex of PTSD (reexperiencing, hyperarousal, and avoidance). The role of glutamate and CRF in PTSD and other anxiety disorders are still being elucidated. However, it is clear that the glutamatergic systems play a role in the pathophysiology of PTSD.

During two studies, effects of recombinant bovine somatotropin (rbST) on plasma and milk IGF's in cows adapted to summer (S; 12 cows) or winter (W; 12 cows) conditions were evaluated. Each study consisted of on-farm periods (30 days) followed by climatology chamber periods (CC; 30 days). Cows were given daily injections of rbST, Sometribove, USAN (25mg/day; 6 cows each study) or saline (control; 6 cows each study). During on-farm periods, blood and milk (am and pm) samples were collected once weekly. During CC periods, blood samples were collected every 2 days and milk samples (am and pm) were collected daily. Plasma IGF-I and IGF-II were increased in cows treated with rbST. A pronounced seasonal pattern in basal and rbST-stimulated plasma IGF-I but not IGF-II was detected. Higher basal and rbST-stimulated plasma IGF-I concentrations in S occurred despite large decreases in feed intake and energy balance. Milk IGF-I and IGF-II was not affected by rbST treatment or season. Although milk IGF-I and IGF-II concentrations were unaffected by rbST treatment, total IGF-output increased due to increased milk yield. The observed seasonal patterns in plasma IGF-I may be indicative of seasonal differences in the coupling of the somatotropin-IGF axis. In particular, we failed to detect an uncoupling of the somatotropin-IGF-I axis in S despite an induced negative energy balance during thermal stress.

Glucocorticoids (GCs) have profound effects on the immune and nervous systems during development. However, circulating GC levels are low neonatally and show little response to stressors. This paradox could be resolved if immune and neural tissues locally synthesize GCs. Here, we measured baseline corticosterone and cortisol levels in plasma, immune organs, and brain regions of developing zebra finches. Steroids were extracted using solid phase-extraction and quantified using specific immunoassays. As expected, corticosterone was the predominant GC in plasma and increased with age. In contrast, cortisol was the predominant GC in immune tissues (bursa of Fabricius, thymus, spleen) and decreased with age. Cortisol levels in immune tissues were higher than cortisol levels in plasma. In the brain, corticosterone and cortisol levels were similarly low, providing little evidence for local synthesis of GCs in the brain. This is the first study to measure 1) cortisol in the plasma of songbirds, 2) corticosterone or cortisol in the brain of songbirds, and 3) corticosterone or cortisol in the immune system of any species. Despite the prevailing dogma that corticosterone is the primary GC in birds, these results indicate that cortisol is the predominant GC in the immune system of developing zebra finches. These results raise the hypothesis that cortisol is synthesized de novo from cholesterol in the immune system as an "immunosteroid," analogous to neurosteroids synthesized in the brain. Local production of GCs in immune tissues may allow GCs to regulate lymphocyte selection while avoiding the costs of high systemic GCs during development.

The current study was conducted to investigate the influence of microwave toe treatment and an increasing photoperiod on stress and fear levels in broiler chickens. Upon delivery from the hatchery, the toe tips of 364 male and 364 female broilers were exposed to microwave energy to restrict claw growth, whereas the same numbers of birds retained intact toes. Birds from each sex and toe treatment were grown under 23 h of light or increasing photoperiods, with 4 replicates of each treatment combination. Elevated activity of plasma creatine kinase (CK) and increased heterophil to lymphocyte (H/L) ratios were employed as indicators of stress. Tonic immobility (TI) was conducted on d 10, 22, and 36 and used as an index of fear response. Males had lower plasma CK activity and H/L ratios (P < 0.05). Birds on 23 h of light had a higher activity of plasma CK (P < 0.05) but similar H/L ratios compared with birds on the increasing photoperiod. Microwave toe treatment did not affect the activity of plasma CK or H/L ratios. Photoperiod, microwave toe treatment, or sex did not affect the number of attempts required to induce TI. The increasing lighting program decreased the duration of TI on d 10 (P < 0.05), had no effect on d 22, and increased duration of TI on d 36 (P < 0.05). There was no microwave toe treatment or sex effect on the duration of TI at any ages tested.

Baseline and stress-induced corticosterone (CORT), heart rate (fH), and energy expenditure were measured in eight captive European starlings Sturnus vulgaris during and following a prebasic molt. The fH and oxygen consumption (V O2 ) were measured simultaneously across a range of heart rates, and energy expenditure (kJ/d) was then calculated from data. Energy expenditure and fH were strongly and positively correlated in each individual. Baseline fH and energy expenditure were significantly higher during molt. Molting starlings expended 32% more energy over 24 h than nonmolting birds, with the most significant increase (60%) occurring at night, indicating a substantial energetic cost to molt. Furthermore, the cardiac and metabolic responses to stress during molt were different than during nonmolt. Birds were subjected to four different 30-min acute stressors. The fH and CORT responses to these stressors were generally lower during molt. Although restraint caused a 64% increase in daily energy expenditure during nonmolt, no other stressor caused a significant increase in energy expenditure. Overall, our data suggest that molt is not only energetically expensive but that it also alters multiple stress response pathways. Furthermore, most acute stressors do not appear to require a significant increase in energy expenditure.

Stress is a known inhibitor of reproductive function. The mechanisms by which stress acts to influence the reproductive axis have been intensely studied and appear to be extremely varied. Gonadotropin-releasing hormone (GnRH) is a critical component of the vertebrate reproductive axis and directly causes pituitary gonadotropin synthesis and release. A second neuropeptide, gonadotropin-inhibitory hormone (GnIH), directly inhibits pituitary gonadotropin synthesis and release in birds. We hypothesized that stress effects upon reproduction are mediated via the hypothalamic GnIH system. We examined the effects of capture-handling stress in the hypothalamus of male and female adult house sparrows (Passer domesticus) at the start (spring) and end of the breeding season (fall). We quantified numbers of GnIH neurons to provide an estimate of hypothalamic GnIH content. In addition, we quantified the expression of the protein product of the immediate-early gene, EGR-1, using this as an indicator of neuronal activation. We saw an increase in EGR-1 positive cells in the paraventricular nuclei of stressed birds as opposed to controls at both collecting times, but this stress response was more apparent in the spring as opposed to the fall. There were more GnIH-positive neurons in fall birds versus those sampled in the spring, and a significant increase in GnIH positive neurons was seen in stressed birds only in spring. GnIH cells show little to no activation of EGR-1, suggesting that EGR-1 is not involved in GnIH transcription in response to capture-handling stress. These data imply an influence of stress upon the paraventricular nucleus and the GnIH system that changes over the annual cycle of reproduction.

Background: We designed and tested, in vitro, an adenoviral construct containing the feline interleukin-12 (IL-12) gene under control of the heat-inducible promoter HSP70B. This construct, AdhspfIL12, was used in a phase I trial in feline soft tissue sarcomas. During the course of our experiments, we noted that IL-12 was being produced in the transfected Crandell Feline Kidney (CrFK) cells under certain conditions even in the absence of hyperthermia. This observation was further explored to identify the cause of this unintended HSP70B induction., Materials and Methods: We used real-time PCR as a sensitive method to quantitatively detect the presence of even small amounts of IL-12 mRNA. This served as a surrogate indicator of HSP70B induction. Various conditions were tested to induce the heat shock promoter, including nutritional deprivation, radiation and changes in pH., Results: Nutritional stresses, specifically the absence of glucose and glutamine, could induce the heat shock promoter, thus, resulting in production of the downstream gene product. Other factors known to trigger the heat shock response, pH change, and reactive oxygen species production were also studied but were not found to contribute to heat shock promoter induction in our setting., Conclusions: The human heat shock promoter (HSP70B) is reported to be an efficient and tightly regulated promoter. We discovered, using sensitive real-time PCR techniques, that it can also be induced in response to cellular nutrient stresses. The pros and cons of this phenomenon and its implications for cancer gene therapy are discussed.

O-acetylation is one of the major modifications of sialic acids that significantly alters biological properties of the parent molecule. These O-acetylated forms are components of the cellular membrane and can affect physiological and pathological responses. Understanding the role of N-glycans in physiology is of increasing relevance to cellular biologists in various disciplines who study glycoproteomics yet lack information regarding the function of the attached glycans. It is well known that stress may decrease immune function in fish; however, there are only few suitable biomarkers available to monitor the physiological responses under the stress conditions. This study is the first report on the effect of stress on the profile of O-acetylation of sialic acids in fish serum. In order to preserve the relevant structural characteristics as much as possible, native N-glycans were directly analyzed using CE-MS. We have characterized the N-glycans in serum of salmon (Salmo salar) exposed to long-term handling stress (15 s out of the water, daily for 4 wk) and compared with the results obtained from sera of control fish. The results indicated that major N-glycans in salmon serum contained mono-acetylated sialic acids (83%), and that the O-acetylation pattern of sialic acids could be altered by long-term stress.

The aim of this study was 2-fold: (i) to demonstrate influences of roasted coffee bean aroma on rat brain functions by using the transcriptomics and proteomics approaches and (ii) to evaluate the impact of roasted coffee bean aroma on stress induced by sleep deprivation. The aroma of the roasted coffee beans was administered to four groups of adult male Wistar rats: 1, control group; 2, 24 h sleep deprivation-induced stress group (the stress group); 3, coffee aroma-exposed group without stress (the coffee group); and 4, the stress with coffee aroma group (the stress with coffee group). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of some known genes responsive to aroma or stress was performed using total RNA from these four groups. A total of 17 selected genes of the coffee were differently expressed over the control. Additionally, the expression levels of 13 genes were different between the stress group and the stress with coffee group: Up-regulation was found for 11 genes, and down-regulation was seen for two genes in the stress with coffee group. We also looked to changes in protein profiles in these four samples using two-dimensional (2D) gel electrophoresis; 25 differently expressed gel spots were detected on 2D gels stained by silver nitrate. Out of these, a total of nine proteins were identified by mass spectrometry. Identified proteins belonged to five functional categories: antioxidant; protein fate; cell rescue, defense, and virulence; cellular communication/signal transduction mechanism; and energy metabolism. Among the differentially expressed genes and proteins between the stress and the stress with coffee group, NGFR, trkC, GIR, thiol-specific antioxidant protein, and heat shock 70 kDa protein 5 are known to have antioxidant or antistress functions. In conclusion, the roasted coffee bean aroma changes the mRNA and protein expression levels of the rat brain, providing for the first time clues to the potential antioxidant or stress relaxation activities of the coffee bean aroma.

Both serotonin and NMDA signaling in prefrontal cortex (PFC) are implicated in mental disorders, including depression and anxiety. To understand their potential contributions to PFC neuronal excitability, we examined the effect of co-activation of 5-HT and NMDA receptors on action potential firing elicited by depolarizing current injection in PFC pyramidal neurons. In the presence of NMDA, a low concentration of the 5-HT(1A) agonist 8-OH-DPAT substantially reduced the number of spikes, and a low concentration of the 5-HT(2A/C) agonist alpha-Me-5HT significantly enhanced it, while both agonists were ineffective when applied alone. The 8-OH-DPAT effect on firing was mediated by inhibition of protein kinase A (PKA), whereas the alpha-Me-5HT effect was mediated by activation of protein kinase C (PKC). Moreover, the extracellular signal-regulated kinase (ERK), a signaling molecule downstream of PKA and PKC, was involved in both 5-HT(1A) and 5-HT(2A/C) modulation of neuronal excitability. Biochemical evidence showed that 5-HT(1A) decreased, whereas 5-HT(2A/C) increased the activation of ERK in an NMDA-dependent manner. In animals exposed to acute stress, the enhancing effect of 5-HT(2A/C) on firing was lost, while the decreasing effect of 5-HT(1A) on firing was intact. Concomitantly, the effect of 5-HT(2A/C), but not 5-HT(1A), on ERK activation was abolished in stressed animals. Taken together, our results demonstrate that distinct 5-HT receptor subtypes, by interacting with NMDA receptors, differentially regulate PFC neuronal firing, and the complex effects of 5-HT receptors on excitability are selectively altered under stressful conditions, which are often associated with mental disorders.

Recently, we observed that central administration of L-arginine attenuated stress responses in neonatal chicks, but the contribution of nitric oxide (NO) to this response was minimal. The sedative and hypnotic effects of L-arginine may be due to L-arginine itself and/or its metabolites, excluding NO. To clarify the mechanism, the effect of intracerebroventricular (i.c.v.) injection of L-arginine metabolites on behavior under social separation stress was investigated. The i.c.v. injection of agmatine, a guanidino metabolite of L-arginine, had no effect during a 10 min behavioral test. In contrast, the i.c.v. injection of L-ornithine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior. The L-ornithine concentration in the telencephalon and diencephalon increased following the i.c.v. injection of L-arginine. In addition, several free amino acids including L-alanine, glycine, L-proline and L-glutamic acid concentrations increased in the telencephalon. In conclusion, it appears that L-ornithine, produced by arginase from L-arginine in the brain, plays an important role in the sedative and hypnotic effects of L-arginine observed during a stress response. In addition, several other amino acids having a sedative effect might partly participate in the sedative and hypnotic effects of L-arginine.

Interleukin-18 (IL-18) is a pro-inflammatory cytokine believed to play a role in a variety of conditions and diseases including infections, autoimmunity, cancer, diabetes and atherosclerosis. IL-18 is also a possible contributor to the sickness syndrome by inducing anorexia and sleep. Originally recognized to be produced by cells of the immune system, IL-18 is also found in endocrine tissues, including the adrenal and the pituitary glands, and in the central nervous system where it is produced by microglial and ependymal cells as well as by neurons of the medial habenular nucleus. IL-18 is produced constitutively and its levels can increase during infection but also during stress in the absence of an exogenous stimulus. IL-18 levels are elevated by activation of the hypothalamic-pituitary-adrenal (HPA) axis in a tissue specific way via differential promoter and splicing usage, and may be down-regulated by the activation of the para-sympathetic system. This suggested the possibility that IL-18 may participate in the regulation of the HPA axis or that it may have a role in mediating the CNS dependent effects on the susceptibility to or the progression of diseases. This review summarizes the evidence linking stress and IL-18 and discusses the possible implication of the neuro-immuno-modulatory action of IL-18.

STAT3 is a major signaling molecule for many neurotrophic factors but its direct role in the protection of neurons in response to stress has not been addressed. We have studied the role of STAT3 in protecting retinal neurons from damage induced by ischemia/reperfusion and glutamate excitotoxicity by using adenovirus constructs to introduce active, normal or inactive STAT3 into retinal ganglion cells in culture and cells of the ganglion cell layer in the intact retina. Transient ischemia/reperfusion was induced in adult CD1 mice by elevating the intraocular pressure to the equivalent of 120mmHg for 60min, followed by a return to normal pressure. The levels, activation and distribution of STAT3 protein were evaluated by Western blot and immunocytochemistry. A transient peak of STAT3 activation was seen at 24h post ischemia and a strong increase in STAT3 protein levels 24h later. The increase in levels of STAT3 was detected in both ganglion cell bodies and processes in the plexiform layers by immunocytochemistry. The time course of STAT3 increase was slower than the time course of ganglion cell death as measured by TUNEL assay. Intravitreal injection of NMDA led to peak increases in activated STAT3 and STAT3 at 12 and 24h post insult respectively. Purified RGCs were infected with recombinant wild-type STAT3, constitutively active and dominant negative forms of STAT3 adenoviruses or control empty virus and then treated with glutamate. Surviving infected cells were counted 24 and 48h later. Infection with constitutively active STAT3 gave substantial protection when compared to the other constructs. Similarly, intravitreal injection of constitutively active STAT3 adenovirus one day before ischemia-reperfusion resulted in a decreased neural cell death in the ganglion cell layer compared with GFP adenovirus control. Our results suggest that persistent activation of STAT3 by neurotrophic factors provides strong neuroprotection and will be an effective strategy in a number of chronic retinal diseases.

Rats of the JCR:LA-cp strain, which are homozygous for the cp gene (cp/cp), are obese, insulin-resistant, and hyperinsulinemic. They exhibit associated micro- and macrovascular disease and end-stage ischemic myocardial lesions and are highly stress sensitive. We subjected male cp/cp rats to pair feeding (providing the rats each day with the amount of food eaten by matched freely fed animals), a procedure that alters the diurnal feeding pattern, leading to a state of intermittent caloric restriction. Effects on insulin, glucose, and lipid metabolism, response to restraint stress, aortic contractile/relaxant response, and myocardial lesion frequency were investigated. Pair-fed young (12-wk-old) cp/cp rats had lower insulin and glucose levels (basal and following restraint), consistent with increased insulin sensitivity, but a greater increase in plasma nonesterified fatty acids in response to restraint. These effects were unrelated to lipolytic rates in adipose tissue but may be related to reduced fatty acid oxidation in skeletal muscle. Older (24-wk-old) pair-fed cp/cp rats had significantly reduced plasma triglyceride levels, improved micro- and macrovascular function, and reduced severity of ischemic myocardial lesions. These changes indicate a significant amelioration of end-stage disease processes in this animal model and the complexity of metabolic/physiological responses in studies involving alterations in food intake. The effects illustrate the sensitivity of the JCR:LA-cp rat, an animal model for the metabolic syndrome and associated cardiovascular disease, to the environmental and experimental milieu. Similar stress-related mechanisms may play a role in metabolically induced cardiovascular disease in susceptible human beings.

Recent studies provide some evidence that the HtrA2 protein is intimately associated with the pathogenesis of neurodegenerative disorders and that endoplasmic reticulum (ER) quality control and ER stress-associated cell death play critical roles in neuronal cell death. However, little is known about the intimate relationship between HtrA2 and ER stress-associated cellular responses. In the present study, we have demonstrated that the HtrA2 protein level was gradually and significantly increased by up to 10-fold in the mitochondria under tunicamycin (Tm)-induced ER stress, which eventually promoted cell death through the release of HtrA2 into the cytoplasm. Using an ecdysone-inducible mammalian expression system, we demonstrate that the extent of cell death in 293-HtrA2 cells was approximately 20 times higher under Tm-induced ER stress, indicating that the increase in the HtrA2 protein level in the mitochondria itself is necessary but not sufficient for the promotion of cell death. Taken together, these results suggest that HtrA2 may serve as a mediator of ER stress-induced apoptosis and ER-mitochondrial cross-talk in some cellular processes.