The role of serotonin in analgesia elicited by morphine in the periaqueductal gray matter (PAG).
The serotonergic antagonist, methysergide, administered into the periaqueductal gray matter (PAG), inhibited the antinociceptive effect of morphine, but not of glutamate, also administered into the PAG. At this dose methysergide did not alter the pain threshold when administered by itself. The implications for serotonin's role in the modulation of nociception in the PAG are discussed.
Department of Psychology, Tel Aviv University, Ramat Aviv, Israel.
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D000698:Analgesia; D000704:Analysis of Variance; D000818:Animals; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D008845:Microinjections; D008959:Models, Neurological; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000502:physiology; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*; D013238:Stereotaxic Techniques
D005971:Glutamates; D018377:Neurotransmitter Agents; D012701:Serotonin; D018698:Glutamic Acid; D009020:Morphine; D008784:Methysergide