Objective(s): There are many reports about the role of rostral ventromedial medulla (RVM) in modulating stress-induced analgesia (SIA). In the previous study we demonstrated that temporal inactivation of RVM by lidocaine potentiated stress-induced analgesia. In this study, we investigated the effect of permanent lesion of the RVM on SIA by using formalin test as a model of acute inflammatory pa...

introduction: different mechanisms are involved in stress induced analgesia (sia) and hyperalgesia (sih). repeated stress induces development of tolerance to sia. the role of hpa axis and gs signaling pathway in these effects are investigated in the current study. methods: forced swim stress (5 min/day) in water (20±1 ºc) was employed to adult male wistar rats (200-250 g). the nociceptive thres...

Analgesic efficacy varies depending on the pain syndrome being treated. One reason for this may be a differential effect of individual pain syndromes on the function of the endogenous pain control circuits at which these drugs act to produce analgesia. To test this hypothesis, we examined the effects of diverse (i.e., ongoing inflammatory, neuropathic, or chronic widespread) pain syndromes on a...

Previous studies have demonstrated that stress may increase prodynorphin gene expression, and kappa opioid agonists suppress drug reward. Therefore, we tested the hypothesis that stress-induced release of endogenous dynorphin may mediate behavioral responses to stress and oppose the rewarding effects of cocaine. C57Bl/6 mice subjected to repeated forced swim testing (FST) using a modified Porso...

Orexin is produced exclusively in the lateral hypothalamus, where it is known to be involved in pain modulation through brain stem. Due to the important role of this peptide in functions such as eating, sleeping and awaking, addiction, it attracted the attention of researchers in medical sciences specially neuroscientists. These hypothalamic peptides play a critical role in arousal in s...

Introduction: Different mechanisms are involved in stress induced analgesia (SIA) and hyperalgesia (SIH). Repeated stress induces development of tolerance to SIA. The role of HPA axis and Gs signaling pathway in these effects are investigated in the current study. Methods: Forced swim stress (5 min/day) in water (20±1 ºC) was employed to adult male Wistar rats (200-250 g). The nociceptive t...

introduction: several researches have reported that stress is able to inhibit the development of morphine tolerance via activating of hypothalamic-pituitary-adrenal (hpa) axis. in the present study we tried to examine the effect of epinephrine, the product of adrenal medulla, on the development of morphine tolerance. methods: analgesic tolerance was induced by intrathecal (i.t.) injection of mo...