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...

We studied the influence of imipramine on the duration of immobility in chronic forced-swim-stressed rats. Both single and chronic administration of imipramine potently shortened immobility in naive rats during forced-swim testing. However, chronic, 14-day forced-swim stress testing blocked the immobility-decreasing effect induced by a single administration of imipramine. When imipramine was ad...

The effect of 90 minute supine restraint or forced swim stress, on weights of various organs in sixty adult male albino rats was studied. One group of twenty rats served as control; second group of twenty was immobilized and third group of twenty was forced to swim in water at room temperature. The animals were studied for a period of 15 days. During this period, they were subjected to 90 minut...

Introduction: Sub-chronic swim stress is known to induce a prolonged hyperalgesia, which is mediated through NMDA and opioid systems. Nitric oxide is a soluble gas, which acts as a retrograde messenger that modulates the release of mentioned neurotransmitters. It is also involved in nociception and memory. The aim of this study was to evaluate the role of NO pathway in nociception and memory...

The opiate-receptor antagonist naloxone was administered to rats after passive-avoidance training either alone or in combination with forced-swim stress. A retention test revealed that while naloxone enhanced retention when administered alone, it impaired retention when administered in combination with forced-swim stress. The findings provide evidence for a "protective" endogenous opioid-based ...

Objective(s): Stress alters sensory and cognitive function in humans and animals. Angiotensin (AT) receptors have demonstrated well-established interactions in sets of physiological phenomena. AT1 receptors can play a part in stress-induced activation of hypothalamic-pituitary-adrenal (HPA) axis; besides angiotensinergic neurotransmission plays a pivotal role in stress-evoked physiological resp...

Background Stress constitutes a risk factor across several psychiatric disorders. Moreover, females are more susceptible to stress-related disorders, such as depression, than males. Although dopamine system underactivation is implicated in the pathophysiology of depression, little is known about the female dopamine system at baseline and post-stress. Methods The effects of chronic mild stress...

objective(s): intracerebroventricular injection of orexin-a (hypocretin-1) antagonist has been shown to inhibit stress-induced analgesia. however the locations of central sites that may mediate these effects have not been totally demonstrated. this study was performed to investigate the role of rostral ventromedial medulla (rvm) orexin receptor 1 in stress-induced analgesia (sia). materials and...

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...

The inability to learn an adaptive coping strategy in a novel stressful condition leads to dysfunctional stress coping, a marker of mental disturbances. This study tested the involvement of dorsal striatal dopamine receptors in the dysfunctional coping with the Forced Swim test fostered by a previous experience of reduced food availability. Adult male mice were submitted to a temporary (12 days...