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BACKGROUND AND OBJECTIVE: Neuropathic pain is a common complication of diabetes. Today opioid analgesics such as morphine, use for the management of neuropathic pain. Since the respiratory effects of morphine have not been studied in diabetes, the aim of this study was to investigate the effect of chronic hyperglycemia on the effects of morphine on respiration. METHODS: 32 Male Wister rats were randomly allocated into control group (injection of citrate buffer as streptozotocin solvent), morphine group (injection of citrate buffer as STZ solvent and injection of morphine before respiratory recording) group, hyperglycemia group (STZ injection), and hyperglycemia-morphine group (STZ injection and morphine injection before respiratory recording). Hyperglycemia was induced by injecting streptozotocin (35 mg/kg, i.p.). Respiration was recorded by plethysmography after which respiratory volume, inter-breath interval, and respiratory rate were quantified using MATLAB. FINDINGS: Mean of respiratory rate (in the hyperglycemia was 83±3.9 and control was 101±4 (p<0.05)), coefficient of variation of respiratory rates (in the hyperglycemia was 0.615±0.1 and control was 1.05±0.07 (p<0.05)), mean of respiratory volume (in the hyperglycemia was 1.44±0.19 and was control 1.1±0.11 (p<0.05)), and mean of inter-breath interval (in the hyperglycemia was 1.28±0.01 and control was 0.93±0.03 (p<0.05)). coefficient of variation of respiratory volumes (in the hyperglycemia-morphine was 1.14±0.16 and was morphine was 1.68±0.1 (p<0.05)), mean of respiratory rate (in the hyperglycemia-morphine was 1.24±0.34 and morphine was 0.37±0.04 (p<0.05)), and mean of inter-breath interval (in the hyperglycemia-morphine was 1.09±0.07 and morphine was 0.74±0.05 (p<0.01)). CONCLUSION: Our results show that chronic hyperglycemic changed breathing pattern and respiratory response to morphine. [ABSTRACT FROM AUTHOR]

Allergic rhinitis (AR) is a chronic inflammatory disorder associated with a high prevalence of anxiety symptoms and respiratory disorders that adversely affect the quality of life. Studies have shown that allergen exposure induces anxiety-like behaviors. On the other hand, stress impairs the breathing pattern. However, the effect of stress on respiration and the relationship between anxiety-like behavior and stress-induced changes in breathing pattern has not been evaluated in AR. We assessed the impact of ovalbumin (OVA)-induced anxiety-like behaviors on stress-induced breathing pattern changes. Our findings showed that the allergic rhinitis induced by OVA challenge in sensitized rats induces anxiety-like behavior. Also, we found that stress decreases respiratory irregularity and increases respiratory variability, as well as the synchronization between IBI and RV time-series in AR animals. Moreover, in AR animals, we found a significant positive correlation between anxiety-like behavior and respiratory irregularity under non-stress conditions. Besides, a significant negative correlation was observed under stress conditions. The findings showed that anxiety-related behaviors may contribute to respiratory impairments under stress conditions in AR., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The clinical use of opioids is restricted by its deleterious impacts on respiratory system. Gaining a better understanding of an individual's susceptibility to adverse opioid effects is important to recognize patients at risk. Ancestral drug addiction has been shown to be associated with alterations in drug responsiveness in the progenies. In the current study, we sought to evaluate the effects of preconception paternal morphine consumption on respiratory parameters in response to acute morphine in male offspring during adulthood, using plethysmography technique. Male Wistar rats administered 10 days of increasing doses of morphine in the period of adolescence. Thereafter, following a 30-day abstinence time, adult males copulated with naïve females. The adult male offspring were examined for breathing response to morphine. Our results indicated that sires who introduce chronic morphine during adolescence leads to increase irregularity of respiratory pattern and asynchronization between inter-breath interval (IBI) and respiratory volume (RV) time series in male offspring. These findings provide evidence that chronic morphine use by parents even before pregnancy can affect respiratory pattern and response to morphine in the offspring., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objectives: Phytocannabinoids beyond the Δ9-tetrahy-drocannabinol have shown anticonvulsive effects. Also, alkylamides from Echinacea purpurea have been proved as cannabinomimetics. We examined the effect of the hydroalcoholic root extract of E. purpurea on pentylenetetrazol (PTZ)-induced tonic-clonic seizures and kindling model of epileptogenesis and the involvement of CB2 receptors as the mediator of this effect., Methods: Male Wistar rats (200 ± 20 g) were used. Single intraperitoneal (i.p.) injection of PTZ (80 mg/kg) was used to induce tonic-clonic seizures. The kindling model of epileptogenesis was induced by daily injections of PTZ (37 mg/kg; i.p. for 15 days). Latency and duration of the stages were monitored for analysis. The hydroalcoholic root extract of E. purpurea was injected (i.p.) 20 min before seizure induction at the doses of 10, 50, 100 and 200 mg/kg. CB2 receptor antagonist SR144528 was injected (0.1 mg/kg; i.p.) 20 min before the Echinacea injection., Results: In the tonic-clonic model, pretreatment with E. purpurea at the doses of 100 and 200 mg/kg significantly increased latencies to S2-S6, while it significantly decreased S6 duration and mortality rate. SR144528 injection before the injection of 100 mg/kg of E. purpurea significantly prevented the effects of the extract on S4-S6 latencies. In the kindling model, E. purpurea at the doses of 100 and 200 mg/kg significantly delayed epileptogenesis and decreased mortality rate, while SR144528 injection before the injection of 100 mg/kg of E. purpurea significantly blocked this effect of the extract., Conclusions: These findings revealed the anticonvulsive and antiepileptogenesis effects of the E. purpurea root extract, which can be mediated by CB2 receptors., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Recent studies have shown that mesenchymal stem cells (MSCs) and their conditioned medium (CM) have potential therapeutic effects in animal models of neuropathic pain (NP). However, the mechanisms underlying these effects are not fully understood. Because of the leading involvement of purinergic receptors in the pathogenesis of NP, this study aimed to investigate the effect of MSCs-CM on the expression levels of P2X4 and P2X7 receptors in a rat model of NP induced by chronic constriction injury (CCI) of the sciatic nerve. CM was prepared from the rats' bone marrow-derived MSCs culture. After that, NP rats were treated by intraperitoneal injection of CM, or Dulbecco's modified Eagle's medium (DMEM) 1 day before and 7 and 11 days after CCI surgery. The NP status was assessed in the treated animals using behavioral tests, including mechanical allodynia and thermal hyperalgesia, on days - 1, 3, 6, 9, 12, and 15 of the study. At the end of the study (Day 15), the animals were sacrificed, and the relative gene expression of P2X4 and P2X7 receptors were measured in the spinal cord using quantitative real-time PCR. The results demonstrated that in the CM-treated NP rats, mechanical allodynia and thermal hyperalgesia were significantly reduced compared with the DMEM-treated group. In addition, the expression levels of P2X4 and P2X7 receptors were noticeably prevented in the CM-treated group than the control group. These findings indicate that the antinociceptive effects of CM in the NP rats are partly mediated through preventing the upregulation of P2X4 and P2X7 receptors in the spinal cord.

Objectives: The modulatory effect of deep inspiration (DI) on airway constriction is impaired in asthma. However, mechanisms underlying this impairment are not clear. Since there is evidence indicating that Rho-kinase activation mediates force maintenance under oscillatory strain, we investigated the impact of Rho-kinase inhibition on the bronchodilatory effect of DI in ovalbumin (OVA) sensitized guinea pigs., Materials and Methods: forty-eight male Dunkin Hartley guinea pigs were divided into 8 groups including saline/ constant, saline/DI, OVA/constant, OVA/DI, Rho-I/OVA/constant, Rho-I/OVA/DI, OVA-Rho-I/MCh/constant, and OVA-Rho-I/MCh/DI. Animals were subjected to 12 inhalations of OVA or saline aerosol. Guinea pigs in Rho-I/OVA/constant or DI groups were treated with the Rho-kinase inhibitor (Rho-I) (Y-27632, 1 mM aerosols) prior to the last 8 allergen inhalations and OVA-Rho-I/MCh/constant or DI groups received Y-27632 at the end of allergen sensitization protocol before methacholine challenge. The bronchodilatory effect of DI in guinea pigs that were exposed to methacholine was assessed by using an animal ventilator. The bronchodilatory effect was assessed using several parameters: the airway pressure maintenance, airway pressure recovery, and decline of airway pressure., Results: Results indicated that application of Y-27632 prior to methacholine challenge reduces the airway smooth muscle ability to maintain pressure and also causes further decline in airway pressure in OVA-sensitized animals undergone DI. However, the inhibition of Rho-kinase before OVA inhalations had minimal effect., Conclusion: We propose that alteration of Rho-kinase signaling pathway may be one of the mechanisms underlying the impairment of DI-induced bronchodilation in OVA-sensitized guinea pigs.

Asthma represents an episodic and fluctuating behavior characterized with decreased complexity of respiratory dynamics. Several evidence indicate that asthma severity or control is associated with alteration in variability of lung function. The pathophysiological basis of alteration in complexity of breathing pattern in asthma has remained poorly understood. Regarding the point that Rho-kinase is involved in pathophysiology of asthma, in present study we investigated the effect of Rho-kinase inhibition on complexity of respiratory dynamics in a guinea pig model of asthma. Male Dunkin Hartley guinea pigs were exposed to 12 series of inhalations with ovalbumin or saline. Animals were treated by the Rho-kinase inhibitor Y-27632 (1mM aerosols) prior to each allergen challenge. We recorded respiration of conscious animals using whole-body plethysmography. Exposure to ovalbumin induced lung inflammation, airway hyperresponsiveness and remodeling including goblet cell hyperplasia, increase in the thickness of airways smooth muscles and subepithelial collagen deposition. Complexity analysis of respiratory dynamics revealed a dramatic decrease in irregularity of respiratory rhythm representing less complexity in asthmatic guinea pigs. Inhibition of Rho-kinase reduced the airway remodeling and hyperreponsiveness, but had no significant effect on lung inflammation and complexity of respiratory dynamics in asthmatic animals. It seems that airway hyperresponsiveness and remodeling do not significantly affect the complexity of respiratory dynamics. Our results suggest that inflammation might be the probable cause of shift in the respiratory dynamics away from the normal fluctuation in asthma.

The impact of mechanical forces on pathogenesis of airway remodeling and the functional consequences in asthma remains to be fully established. In the present study, we investigated the effect of repeated bronchoconstriction induced by methacholine (MCh) on airway remodeling and airway hyperresponsiveness (AHR) in rats with or without sensitization to an external allergen. We provide evidence that repeated bronchoconstriction, using MCh, alone induces airway inflammation and remodeling as well as AHR in non-allergen-sensitized rats. Also, we found that the airways are structurally and functionally altered by bronchoconstriction induced by either allergen or MCh in allergen-sensitized animals. This finding provides a new animal model for the development of airway remodeling and AHR in mammals and can be used for studying the complex reciprocal relationship between bronchoconstriction and airway inflammation. Further studies on presented animal models are required to clarify the exact mechanisms underlying airway remodeling due to bronchoconstriction and the functional consequences.

Background: inefficient remyelination of demyelinated plaques in multiple sclerosis (ms) leads to secondary axon degeneration and progressive disability. therapies that potentiate remyelination would be of immense help for managing MS., Objective: Here, we report the effects of valproic acid (VPA) on focal experimental autoimmune encephalomyelitis (fEAE)., Methods: fEAE was induced in Wistar rats by immunizing the animals with guinea pig spinal cord homogenate emulsified in complete Freund's adjuvant and with pertussis toxin (PT) injection into the spinal cord at the level of T8 vertebra on day 18 after immunization. VPA 300 mg/kg was applied for 4 days after or 8 days before PT administration. Behavioral evaluation, histological assessment and immunohistofluorescence assays were used to evaluate the outcomes., Results: VPA administration had no effect on the development of symptoms, but after discontinuing VPA, animals showed faster recovery. Eight days of pretreatment with VPA accelerated the recovery phase of EAE and increased the number of remyelinated axons in the lesion area. VPA pretreatment also increased the recruitment of neural stem cells and oligodendrocyte precursors within the lesion., Conclusions: Results suggest VPA as a potential therapy for remyelinating the lesions in MS and for faster recovery from disease relapses. The effect of VPA seems to be mediated by endogenous progenitors recruitment., (Copyright © 2013 S. Karger AG, Basel.)