title: Effects of opioid peptides on thyrotropin-releasing hormone release from the rat caecum in vitro.
abstract: Effects of opioid peptides (beta-endorphin, dynorphin (1-13). alpha-neoendorphin, beta-neoendorphin, leucine-enkephalin, methionine-enkephalin) on the release of thyrotropin-releasing hormone (TRH) from the rat caecum were studied in vitro. The rat caecum was incubated in medium 199 with 1.0 mg/ml of bacitracin (pH 7.4) (medium). The amount of TRH release from the rat caecum into the medium was measured by radioimmunoassay. The immunoreactive TRH (ir-TRH) release from the rat caecum was inhibited significantly in a dose-related manner with the addition of opioid peptides. The inhibitory effects of opioid peptides on ir-TRH release from the rat caecum were blocked with an addition of naloxone. The elution profile of acid-methanol-extracts of rat caecum on Sephadex G-10 was identical to that of synthetic TRH. The findings suggest that opioid peptides inhibit TRH release from the rat caecum in vitro.
authors.affiliation: Fourth Department of Internal Medicine, Aichi Medical University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Mitsuma
authors.forename: Y
authors.initials: Y
authors.lastname: Hirooka
authors.forename: K
authors.initials: K
authors.lastname: Nakata
authors.forename: T
authors.initials: T
authors.lastname: Nogimori
mesh_terms: D000818:Animals; D002432:Cecum / Q000378:metabolism*; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
chemical_list: D004723:Endorphins; D013973:Thyrotropin-Releasing Hormone