Elevation of Met5-enkephalin and beta-endorphin hypothalamic content in rats receiving anorectic drugs: differences between D-fenfluramine and D-amphetamine.
D-Fenfluramine, an anorectic that releases serotonin (5-HT), repeatedly injected in rats (15 mg/kg per day) enhanced the met5-enkephalin and beta-endorphin content of the hyhpothalamus. The onset of this effect was slow, reaching a peak at 5 days; the increase in beta-endorphin gradually declined toward control level while the drug was still being administered although that of met-enkephalin persisted for 15 days. The elevation of the opioid peptide content of the hypothalamus was temporally associated with a slowing in the rate of body weight increase. A transient, small, increase in striatal met-enkephalin content was also induced by repeated D-fenfluramine injections; however the met-enkephalin content of frontal cortex, hippocampus and brainstem was not affected. A modification of the beta-endorphin content of hypothalamus was not seen after acute injection of D-fenfluramine or D-amphetamine but an increase was observed during repeated treatment with D-fenfluramine. Repeated injections of D-amphetamine for 5 days (4.5 mg/kg per day) failed to increase either the met-enkephalin or the beta-endorphin content of the hypothalamus. These data suggest that the anorexia elicited by repeated injections of D-fenfluramine but not that elicited by D-amphetamine, includes a participation by hypothalamic and beta-endorphin stores.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D003913:Dextroamphetamine / Q000494:pharmacology*; D004723:Endorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine; D004745:Enkephalins / Q000378:metabolism*; D005277:Fenfluramine / Q000494:pharmacology*; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013997:Time Factors; D001615:beta-Endorphin
D004723:Endorphins; D004745:Enkephalins; D005277:Fenfluramine; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; D003913:Dextroamphetamine