In vitro TRH release from hypothalamus slices varies during the diurnal cycle
Por:
Covarrubias L., Redondo J.L., Vargas M.A., Uribe R.M., Méndez M., Joseph-Bravo P., Charli J.L.
Publicada:
1 ene 1994
Resumen:
We have previously described a daily rhythm in thyrotropin releasing hormone (TRH) and TRH mRNA in the rat hypothalamus. To determine whether TRH release fluctuates in a diurnal manner, we have measured basal and potassium stimulated release from hypothalamic slices, and compared it to release from olfactory bulb slices, during the diurnal cycle. Basal TRH release was higher at 7:00 h than at any other time (1:00, 13:00 or 19:00 h) in either hypothalamus or olfactory bulb. The ratio of stimulated over basal release was higher in the hypothalamus at 19:00 h, when TRH content was highest. Potassium stimulated TRH release from olfactory bulb was not different from basal release at any time. TRH release fluctuations were not due to a rhythm of extracellular inactivation: the activity of pyroglutamyl aminopeptidase II, an ectoenzyme responsible for TRH inactivation, was constant throughout the cycle. Our data demonstrate that diurnal variations of TRH release occur in vitro and that the enhanced responsiveness to potassium stimulation in hypothalamus is correlated with increased levels of peptide. © 1994 Plenum Publishing Corporation.
Filiaciones:
Covarrubias L.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Redondo J.L.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Vargas M.A.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Uribe R.M.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Méndez M.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Joseph-Bravo P.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
Charli J.L.:
Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, A.P. 510-3, Cuernavaca, 62271, Morelos, Mexico
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