Opioid involvement in the adaptive change of 5-HT1 receptors induced by chronic restraint.
Rats immobilized for 2 h daily for 7 days showed an increased behavioral response (forepaw treading and hind-limb abduction) to 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) 24 h after the last stress session. An injection of naloxone before each stress session fully antagonized the increased behavioral reactivity to 5-MeODMT. Treatment with morphine or beta-endorphin associated with each immobilization session for 3 days produced a response to 5-MeODMT higher than that of animals subjected to immobilization only. Chronic immobilization for 7 days did not affect the shaking behavior induced by 5-hydroxytryptophan (5-HTP) 24 h after the last restraint session. These findings suggest that chronic stress may induce a selective adaptive change of the 5-HT1 site and activate an opioid mechanism that is most likely to be involved in the development of this adaptive change.
Cancela
L
L
Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Volosin
M
M
Molina
V A
VA
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D008297:Male; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000502:physiology*; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology* / Q000523:psychology; D001615:beta-Endorphin / Q000494:pharmacology
D008732:Methoxydimethyltryptamines; D009294:Narcotics; D011985:Receptors, Serotonin; D009270:Naloxone; D001615:beta-Endorphin; D009020:Morphine; D006916:5-Hydroxytryptophan