Neurons in ventromedial medulla, including the nucleus raphe magnus, project to trigeminal nucleus caudalis and, via the dorsolateral funiculus, to spinal dorsal horn. The terminals of this descending system are in loci containing cells responsive to noxious stimuli. Electrical stimulation of nucleus raphe magnus selectively inhibits spinal dorsal horn neurons that respond to noxious stimuli. T...

Physiological studies of neurons in raphe magnus (RM) and the adjacent nucleus reticularis magnocellularis (NRMC) have demonstrated that the response to noxious cutaneous stimulation predicts the response to opioid administration and therefore a cell's functional role in nociceptive modulation. Although visceral stimulation, like opioids, elicits antinociception, little is known about how RM an...

Pharmacological studies have suggested that serotonergic cells in RM contribute to both the inhibition and facilitation of spinal nociceptive transmission. Physiological studies in the medullary nucleus raphe magnus (RM) and adjacent nucleus reticularis magnocellularis have identified putative nociceptive-inhibitory OFF cells and nociceptive-facilitatory neurons ON cells by their responses to n...

This study aimed to assess the effect of intra-habenular injection of morphine on acute trigeminal pain in rats. Also here, we examined the involvement of raphe nucleus opioid and 5HT3 receptors on the antinociceptive activity of intra habenular morphine to explore the possibility of existence of descending antinociceptive relay between the habenula and raphe nucleus. The numbers of eye wiping ...

Using two specific anti-peptide antibodies (WH-66 and WH-412) against tryptophan hydroxylase (TPH or WH), a single principle band from the midbrain raphe area was seen (approximately 49 kDa) in immunoblots. Densitometric comparison of the immunoreactivity of the 49 kDa band was greater (50-75%) in immunoblots of midbrain raphe samples from adrenalectomized (ADX) rats given dexamethasone (DEX) i...

Optogenetic stimulation of serotonin neurons in the dorsal raphe causes mice to move more slowly without causing any apparent motor deficits or anxiety-like effects.

The effects of stimulating locus coeruleus (LC) and nucleus raphe magnus (NRM) on lumbar dorsal horn cells that had been denervated by dorsal rhizotomy were studied. Both LC and NRM stimulation inhibited the responses of dorsal horn cells from the side of the cord with intact dorsal roots. However, when cells from the side of the spinal cord that had had prior rhizotomies were studied, half of ...

previous studies have shown that morphine addiction is caused by abnormality in neurotransmission system.serotonin is one of the most important neurotransmiters involved in addiction.the dorsal and median raphe nuclei are the important sites that synthesize and release this neurotransmiters in this study we have injected 5,7  dihyroxytryptamine a serotonergic neurotoxin into the dorsal and medi...