The effect of intracerebroventricular 5,7-dihydroxytryptamine on morphine analgesia is time-dependent.
The analgesic effect of morphine in the tail immersion test was studied in rats three and ten days after intracerebroventricular 5,7-dihydroxytryptamine (5,7-DHT) given to selectively destroy serotonergic neurons. Morphine analgesia was reduced three but not ten days after the neurotoxin. Ten days after 5,7-DHT, the inhibiting effect of metergoline, a serotonin antagonist, on morphine analgesia was still present, suggesting that functional recovery of the serotonergic system may partly explain the different results.
D015116:5,7-Dihydroxytryptamine / Q000008:administration & dosage / Q000494:pharmacology*; D000698:Analgesia; D000818:Animals; D004102:Dihydroxytryptamines / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007700:Kinetics; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D009020:Morphine / Q000037:antagonists & inhibitors*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000502:physiology; D012702:Serotonin Antagonists
D004102:Dihydroxytryptamines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D008711:Metergoline; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D009020:Morphine