Effects of neuropeptides B and W on the rat pituitary-adrenocortical axis: in vivo and in vitro studies.
Neuropeptides (NP) B and W are hypothalamic peptides involved in the regulation of feeding and neuro-endocrine axes. Evidence has been provided that NPB and NPW act on both the central and the peripheral branches of the rat hypothalamic-pituitary-adrenocortical axis, and we carried out in vivo and in vitro studies to gain insight into this topic. Reverse transcription-polymerase chain reaction showed the expression of NPB, NPW and their receptors in both adrenal cortex (zonae glomerulosa and fasciculata-reticularis) and adrenal medulla, where immunocytochemistry also detected the presence of abundant NPB- and NPW-immunoreactivity. The acute subcutaneous administration of NPB (0.5 or 1.5 nmol/100 g) did not alter ACTH plasma concentration, while that of NPW (1.5 nmol/100 g) decreased it. Neither NPB nor NPW affected the blood level of aldosterone, while both peptides (0.5 nmol/100 g) raised that of corticosterone. NPB (10(-6) M) lowered ACTH-stimulated aldosterone secretion, and basal and ACTH-stimulated corticosterone production from adrenal quarters containing both cortical and medullary tissues. NPW (10(-6) M) enhanced basal aldosterone secretion from adrenal quarters, and the effect was suppressed by the beta-adrenoceptor antagonist l-alprenolol (10(-5) M). NPW did not affect corticosterone production. Collectively, our findings allow us to draw the following tentative conclusions: i) ACTH-independent extra-adrenal mechanism(s) are operative in vivo, by which NPB and NPW stimulate adrenal glucocorticoid, but not mineralocorticoid secretion; ii) in vitro the interaction of NPB with adrenal medulla activates unknown mechanism(s) hampering adrenocortical steroidogenic machinery; and iii) NPW stimulates in vitro aldosterone secretion by enhancing the release of medullary catecholamines, which in turn activate beta-adrenoceptors located on zona glomerulosa cells.
Hochol
Anna
A
Department of Histology and Embryology, Poznan School of Medicine, PL-60781 Poznan, Poland.
Tortorella
Cinzia
C
Ricinski
Marcin
M
Ziolkowska
Agnieszka
A
Nussdorfer
Gastone G
GG
Malendowicz
Ludwik K
LK
D000302:Adrenal Cortex / Q000187:drug effects* / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000096:biosynthesis / Q000097:blood; D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D003345:Corticosterone / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D009479:Neuropeptides / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar
D018076:DNA, Complementary; D009479:Neuropeptides; D012333:RNA, Messenger; C495188:neuropeptide B; C496874:neuropeptide W, rat; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone