Gender-biased activity of the novel prolactin releasing peptides: comparison with thyrotropin releasing hormone reveals only pharmacologic effects.
The prolactin- (PRL) releasing activities of the newly described PRL-releasing peptides (PrRPs) were compared to that of thyrotropin-releasing hormone (TRH) in dispersed, rat anterior pituitary cell cultures. A dose-related stimulation of PRL release by TRH was observed in cells harvested from both intact male and random cycle female pituitary donors. The minimum effective dose of TRH ranged from 1 to 10 nM. Neither PrRP-20 nor PrRP-31 significantly altered PRL secretion in cells from male donors even at doses as high as 1 microM. In cells harvested from females, only the highest doses of PrRP-20 and PrRP-31 tested (0.1 and 1.0 microM) significantly stimulated PRL secretion. The PRL-releasing action of TRH was observed already at 15 min of incubation, whereas those of PrRP-20 and PrRP-31 appeared only after 1 and 2 h of incubation, and the magnitude of PRL release in the presence of 1 microM PrRPs was significantly less than that of a similar dose of TRH. These data do not suggest a physiologically relevant role for the PrRPs in the neuroendocrine regulation of PRL secretion in intact male and nonlactating, random-cycle female rats.
Samson
W K
WK
Department of Physiology, University of North Dakota School of Medicine, Grand Forks 58202, USA. wsamson@mail.med.und.nodak.edu
Resch
Z T
ZT
Murphy
T C
TC
Chang
J K
JK
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D007028:Hypothalamic Hormones / Q000494:pharmacology*; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D056690:Prolactin-Releasing Hormone; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D007028:Hypothalamic Hormones; D009479:Neuropeptides; C534379:Prlh protein, rat; D056690:Prolactin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin