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...

UNLABELLED Restraint stress exposures evoke progressively larger increases in 2-arachidonoylglycerol (2-AG) in limbic brain regions as the number of repetitions increases. The Porsolt swim test usually involves two swim exposures separated by 24 h, and we asked whether the 2-AG response differed between the first and second exposures. METHODS Four groups of male C57/Bl6N mice were studied: co...

Flavone, dextrose and long swim stress exhibited antinociception. Degree of antinociception was greater with long swim stress as compared to flavone or dextrose. Combination of these treatments resulted in potentiation of antinociception. Naloxone (opioid antagonist; 5 mg/kg i.p.) antagonised flavone or long stress induced antinociception showing opioid medicated mechanism, however, failed to r...

Inappropriate recollections and responses in stressful conditions are hallmarks of post-traumatic stress disorder and other anxiety and mood disorders, but how stress contributes to the disorders is unclear. Here we show that stress itself reactivates memories even if the memory is unrelated to the stressful experience. Forced-swim stress one day after learning enhanced memory recall. One-day p...

We discover a new contribution to the pressure (or stress) exerted by a suspension of self-propelled bodies. Through their self-motion, all active matter systems generate a unique swim pressure that is entirely athermal in origin. The origin of the swim pressure is based upon the notion that an active body would swim away in space unless confined by boundaries-this confinement pressure is preci...

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 The formalin test is the most accepted chemical test for evaluation of nociception. It requires the injection of an adequate amount of formalin into the surface of the hindpaw. Formalin test consists of phase 1 (0-7 min) and phase 2 (15-60) in which the animal shows painful behaviors. These phases are separated with a quiet phase named interphase, in which the nociceptive responses...

A common feature of post-traumatic stress disorder and various mood and anxiety disorders is the formation of negative associations with neutral stimuli, or the recall of negative memories stimulated by unrelated, neutral circumstances. However, the contribution of stress itself to these phenomena is unclear. Now, Fenton and colleagues have shown that in rats stress can reactivate memories that...

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 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 ...