Serotonergic regulation of the brain and gut beta-endorphin and dynorphin content in the rat.
A specific radioimmunoassay was used to measure immunoreactive dynorphin (ir-DYN) and beta-endorphin (ir-BE) in the brain, pituitary and gut, following a pharmacological manipulation of the serotonin system. Administration of the serotonin receptor agonist m-chlorophenylpiperazine (m-CPP, 2.5-5 mg/kg ip) or the serotonin releasing agent fenfluramine (20-40 mg/kg ip) induced a significant increase in the hypothalamic ir-BE content and a decrease in its anterior pituitary level. These effects were antagonized by cyproheptadine (1 mg/kg ip). Similar results were obtained after fluvoxamine (15 mg/kg ip), femoxetine (10 mg/kg ip) and 5-hydroxytryptophan (5-HTP 40-160 mg/kg ip). None of the above treatments altered significantly the ir-DYN content in the brain and pituitary. However, the gut ir-DYN level was dramatically decreased after m-CPP, fenfluramine, fluvoxamine, femoxetine and 5-HTP. The latter effect was antagonized by cyproheptadine. The obtained results suggest that serotonergic activation stimulates the release of beta-endorphin from the anterior pituitary and dynorphin from the gut, while the cerebral beta-endorphin system appears to be inhibited by activation of serotonin neurons.
Majeed
N H
NH
Lasoń
W
W
Przewłocka
B
B
Przewłocki
R
R
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002850:Chromatography, Gel; D004386:Duodenum / Q000378:metabolism*; D004399:Dynorphins / Q000378:metabolism*; D004723:Endorphins / Q000378:metabolism*; D005277:Fenfluramine / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D010902:Pituitary Gland / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*; D001615:beta-Endorphin
D004723:Endorphins; D010879:Piperazines; D005277:Fenfluramine; D012701:Serotonin; D001615:beta-Endorphin; D004399:Dynorphins; C015068:1-(3-chlorophenyl)piperazine