Role of the neuronal histaminergic system in the regulation of somatotropic function: comparison between the neonatal and the adult rat.

摘要: To study possible age-related differences in the role of neuronal histaminergic pathways control GH secretion, effects alpha-fluoromethylhistidine (alpha-FMH), an irreversible inhibitor histamine (HA) synthesis, were examined on basal and opioid-induced release neonatal adult rats. The mechanisms involved such evaluated by measuring pituitary mRNA levels hypothalamic GH-releasing hormone (GHRH) somatostatin (SRIF) mRNAs. Daily injection alpha-FMH (20 mg/kg, s.c.) pups either sex, from birth until 10 days age, caused a significant increase baseline plasma potentiated response to [Met5]-enkephalin analog FK 33-824 (1 administered 3 h after last injection. SRIF significantly higher alpha-FMH-treated than controls, whereas no difference was observed GHRH levels. In young male rats, acute administration (100 s.c., before) did not change but (0.3 intracarotid)-induced stimulation secretion. Repeated (200 micrograms/rat, i.c.v., for days) failed modify 33-824-induced reduction left mRNAs unchanged. These findings indicate that HA exerts inhibitory effect secretion both different short-term depletion indices somatotropic function at two age periods may be ascribed immaturity system early postnatal life functional GH-regulatory factors during ontogeny.