Three TRH-Like Molecules Are Released from Rat Hypothalamus In Vitro |
| |
Authors: | Méndez Milagros Cisneros Miguel Baez Armida Joseph-Bravo Patricia Charli Jean-Louis |
| |
Institution: | (1) Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, MEXICO, 62271;(2) División de Investigaciones Clínicas, Instituto Mexicano de Psiquiatría, México, D.F., MEXICO;(3) Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., Mexico;(4) Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, A. P. 510-3, Cuernavaca, 62271, Mor, Mexico |
| |
Abstract: | TRH-like immunoreactivity distinct from TRH is present in various tissues and fluids. In order to determine whether TRH-like molecules are secreted by the hypothalamus, we analyzed tissues and media from hypothalamic slices incubated in Krebs Ringer bicarbonate. Media from basal or high KCl conditions contained 3 TRH-like molecules evidenced by reverse phase high performance liquid chromatography followed by TRH radioimmunoassay. Peak I corresponded to authentic TRH (73% of total immunoreactivity) and peaks II and III had a higher retention time. These additional TRH-like forms were neither detected in hypothalamic tissue nor in tissue or medium from olfactory bulb. Gel filtration analysis of hypothalamic media revealed only one TRH-like peak eluting as TRH, suggesting that the molecular weights of peaks II and III are similar to that of TRH. Peak II retention time was similar to that of pglu-phe-proNH2. We analysed if they could be produced by post secretory metabolism of TRH. Incubation of hypothalamic slices with 3H-Pro]-TRH did not produce radioactive species comigrating with peaks II or III. However, it induced rapid degradation to 3H-Pro]-his-prodiketopiperazine (3H]-HPDKP). Inhibitor profile suggested that pyroglutamyl aminopeptidase II, but not pyroglutamyl aminopeptidase I, is responsible for 3H]-HPDKP production. These data are consistent with the hypothesis that pyroglutamyl aminopeptidase II is the main aminopeptidase degrading TRH in hypothalamic extracellular fluid. Furthermore, we suggest that the hypothalamus releases additional TRH-like molecules, one of them possibly pglu-phe-proNH2, which may participate in control of adenohypophyseal secretions. |
| |
Keywords: | TRH pglu-phe-proNH2 high performance liquid chromatography hypothalamus release pyroglutamyl aminopeptidase II |
本文献已被 SpringerLink 等数据库收录! |
|