Effects of neurotensin and bombesin on the secretory and proliferative activity of regenerating rat adrenal cortex

A. Hochol1, A. Markowska1, V. Meneghelli2, N. Jedrzejczak1, M. Majchrzak1, M. Nowak1, G.G. Nussdorfer2 and L.K. Malendowicz1

1Department of Histology and Embryology, School of Medicine, Poznan, Poland and
2Department of Human Anatomy and Physiology, Section of Anatomy, University of Padua, Padua, Italy

Offprint requests to: Prof. Gastone G. Nussdorfer, Department of Anatomy, Via Gabelli 65, I-35121 Padova, Italy. Fax: +39 049 827 2319. e-mail: ggnanat@ipdunidx.unipd.it

Summary. Neurotensin (NT) and bombesin (BM)-like peptides are known to be involved in the regulation of the rat hypothalamo-pituitary-adrenal axis. By using selective NT- and BM-receptor antagonists (NT-A and BM-A, respectively) we investigated whether endo-genous NT and BM-like peptides play a role in the control of rat adrenal secretion and growth during enucleation-induced regeneration. At day 5 of regeneration, NT-A did not affect the plasma concentrations of aldosterone (PAC) and corticosterone (PBC), but at day 8, it raised both PAC and PBC over the respective baseline value; the simultaneous administration of NT abolished this effect of NT-A. BM-A did not alter PAC and PBC at day 5 of regeneration, while at day 8 it enhanced PBC, an effect reversed by BM. NT-A did not alter mitotic index, and BM-A lowered it at both day 5 and day 8 of regeneration, an effect suppressed by the simultaneous administration of BM. Collectively, these findings allow us to draw the following conclusions: 1) endogenous NT and BM-like peptides influence adrenocortical regeneration in rats; 2) NT exerts a tonic inhibitory action on both aldosterone and corticosterone secretion, without affecting cell-proliferation rate; and 3) BM-like peptides exert a tonic suppressive effect on corticosterone production, coupled with a clear-cut stimulating effect on cell proliferation. Histol. Histopathol. 14, 1073-1078 (1999)

Key words: Neurotensin, Bombesin-like peptides, Steroid-hormone secretion, Adrenocortical-cell proliferation, Adrenal regeneration, Rat

DOI: 10.14670/HH-14.1073