Differential modulation of the beta-endorphin and dynorphin systems by serotonergic stimulation in the rat.
The serotonergic modulation of the brain, pituitary and gut beta-endorphin and dynorphin systems in the rat was determined pharmacologically. Acute administration of fenfluramine (20 mg/kg), m-chlorophenylpiperazine (m-CPP 2.5 mg/kg), fluvoxamine (15 mg/kg) and 5-hydroxytryptophan (5-HTP 160 mg/kg) increased immunoreactive (ir)beta-endorphin (beta E) in the hypothalamus and decreased it in the anterior lobe of the pituitary. That effect was antagonized by cyproheptadine (1 mg/kg). None of the treatments altered significantly ir-dynorphin (DYN) level in the hypothalamus and pituitary, however, ir-DYN in the gut was dramatically decreased after fenfluramine, m-CPP, fluvoxamine, femoxetine and 5-HTP, the latter effects being antagonized by cyproheptadine. The obtained results suggest that the serotonin system might stimulate the release of the anterior pituitary beta-endorphin and gut dynorphin pools, while the brain beta-endorphin system appears to be inhibited by activation of serotonin neurons.
Majeed
N H
NH
Lason
W
W
Przewłocka
B
B
Przewłocki
R
R
D000818:Animals; D004386:Duodenum / Q000502:physiology; D004399:Dynorphins / Q000378:metabolism*; D004723:Endorphins / Q000378:metabolism*; D007031:Hypothalamus / Q000502:physiology; D008297:Male; D009424:Nervous System Physiological Phenomena; D010903:Pituitary Gland, Anterior / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*; D009435:Synaptic Transmission; D001615:beta-Endorphin
D004723:Endorphins; D012701:Serotonin; D001615:beta-Endorphin; D004399:Dynorphins