Proliferogenic effect of neurotensin (NT) and neuromedin-N (NMN) on the rat adrenal cortex: evidence that angiotensin-II mediates the effect of NMN, but not of NT.
NT and NMN, two biologically active peptides acting via the same specific receptor, are both able to stimulate in vivo the proliferative activity of rat adrenocortical cells. The present study aimed to investigate whether the mechanism underlying this effect of NT and NMN may involve an enhanced production of angiotensin-II (ANG-II), a potent adrenocortical proliferogenic factor. Metaphases per adrenal section were counted 120 min after vincristine injection. A bolus administration of ANG-II resulted in a marked increase in the number of metaphase-arrested cells 12, 24 and 48 h after the beginning of the experiment; the concomitant administration of saralasin (SAR), a competitive antagonist of ANG-II, completely blocked the proliferogenic effect of ANG-II. NT-evoked rise in the number of metaphases occurred 48 h after administration and was not influenced by the simultaneous SAR injection. On the contrary, NMN injection induced a burst of adrenocortical cell proliferation within 12 h, and this effect was prevented by SAR. These data suggest that ANG-II mediates the proliferogenic effect of NMN, but not that of NT.
Markowska
A
A
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
Nussdorfer
G G
GG
Malendowicz
L K
LK
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects*; D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D005260:Female; D009496:Neurotensin / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D010446:Peptide Fragments; C042090:neuromedin N; D000804:Angiotensin II; D009496:Neurotensin