Impaired endocannabinoid signalling in the rostral ventromedial medulla underpins genotype-dependent hyper-responsivity to noxious stimuli.

Administration of orexin receptor 1 antagonist into the rostral ventromedial medulla increased swim stress-induced antinociception in rat

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...

Permanent lesion in rostral ventromedial medulla potentiates swim stress-induced analgesia in formalin test

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...

Effect of transient inactivation of rostral ventromedial medulla on swim stress induced analgesia in formalin test in rats

Introduction: Despite significant progress in understanding pain control mechanism, there are numerous questions about central nervous mechanisms underlying stress-induced analgesia. The rostral ventromedial medulla (RVM) in the brainstem integrates a variety of functions, including pain modulation and pain perception. In the present study, we investigated the effect of temporary inactivatio...

Involvement of the caudal medulla in negative feedback mechanisms triggered by spatial summation of nociceptive inputs.

In the rat, applying noxious heat stimuli to the excitatory receptive fields and simultaneously to adjacent, much larger, areas of the body results in a surface-related reduction in the responses of lumbar dorsal horn convergent neurons. These inhibitory effects induced by spatial summation of nociceptive inputs have been shown to involve a supraspinally mediated negative feedback loop. The aim...

Activation of rostral ventromedial medulla neurons by noxious stimulation of cutaneous