Intraventricular administration of cyclo(His-Pro), a metabolite of thyrotropin-releasing hormone (TRH), decreases water intake in the rat.
We explored the effect of cyclo(His-Pro) on drinking in water-deprived rats. Intraventricular administration of cyclo(His-Pro) significantly reduced water intake in these rats in a dose-dependent fashion (3 X 10(-10) -3 X 10(-8) mole), whereas its intraperitoneal injection did not cause any effect on water intake. The inhibitory potency of cyclo(His-Pro) was found to be similar to that of thyrotropin-releasing hormone (TRH), but cyclo(His-Pro) did not significantly interfere with TRH binding in the rat brain. The data indicate that cyclo(His-Pro) action was not mediated through the TRH counterpart. These results suggest that cyclo(His-Pro) may play a potential role in the regulation of water intake in the rat brain.
D000818:Animals; D001921:Brain / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D004327:Drinking Behavior / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008297:Male; D010456:Peptides, Cyclic / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism* / Q000494:pharmacology
D010456:Peptides, Cyclic; D010879:Piperazines; D013973:Thyrotropin-Releasing Hormone; C015924:histidyl-proline diketopiperazine