Decreased hypothalamic epinephrine concentration by quipazine and other serotonin agonists in rats.
Epinephrine concentrations in rat hypothalamus were decreased after the injection of quipazine, a direct-acting serotonin (5-HT) agonist. The decrease was statistically significant and dose-dependent from 0.1 to 10 mg/kg, s.c., was apparent within 1 hr, and persisted for 8 hr but not 24 hr. There was no decrease in epinephrine concentrations in rat medulla oblongata, a region containing epinephrine cell bodies. Epinephrine concentrations in rat hypothalamus were also decreased by 1-(m-trifluoromethylphenyl)-piperazine (TFMPP) and by 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), other direct-acting 5-HT agonists, and by d-fenfluramine, a 5-HT-releasing drug. The decrease evoked by quipazine was prevented by pretreatment with metergoline, ketanserin or LY53857 (6-methyl-1-[methylethyl]-ergoline-8-carboxylic acid 2-hydroxy-1-methyl-propyl ester), centrally acting 5-HT antagonists. The lowering of rat hypothalamic epinephrine concentrations by 8-OH-DPAT was prevented by pretreatment with pindolol, a centrally acting 5-HT1A receptor antagonist. These data suggest that serotonergic drugs affect epinephrine concentrations in rat hypothalamus.
Hemrick-Luecke
S K
SK
Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285.
Fuller
R W
RW
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004837:Epinephrine / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D011814:Quipazine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D010879:Piperazines; D017366:Serotonin Receptor Agonists; C018406:1-(3-trifluoromethylphenyl)piperazine; D011814:Quipazine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D004837:Epinephrine