Unusual effect of prolonged vasoactive intestinal peptide (VIP) administration on the adrenal growth and corticosterone secretion in the rat.
VIP is widely distributed in the body, and among others is present within the hypothalamo-pituitary-adrenal axis. The aim of this study was to investigate the effect of prolonged VIP administration on the structure and function of the rat adrenal cortex. Adult female rats were treated for 7 or 14 days with VIP (1.5 micrograms/100 g/day). This treatment did not change adrenal weight and evoked only slight changes in the stereologic parameters of adrenal cortex (volume of adrenocortical zones, average cell volume and number of cells in the gland). On the contrary, basal plasma corticosterone levels were markedly lowered (44% and 26% of control values in 7- and 14-day experiments, respectively), an effect accompanied by a significant decrease in corticosterone output by adrenal slices. After standardized ether stress, blood corticosterone concentration was similar in control and 14-day VIP-treated rats, while corticosterone secretion by adrenal quarters was higher in VIP-administered animals. Thus, prolonged VIP administration results in an unusual inhibition of corticosterone secretion in the rat, which is not coupled with a compensatory hypertrophy of the rat adrenal cortex. Such changes may depend on a modulatory action of VIP on the hypothalamo-pituitary-adrenal axis, and its possible mechanism is discussed.
Malendowicz
L K
LK
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
Nussdorfer
G G
GG
D000302:Adrenal Cortex / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003345:Corticosterone / Q000097:blood / Q000378:metabolism*; D004986:Ether; D005260:Female; D066298:In Vitro Techniques; D009929:Organ Size / Q000187:drug effects; D010903:Pituitary Gland, Anterior / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000503:physiopathology; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000008:administration & dosage / Q000494:pharmacology*
D004986:Ether; D014660:Vasoactive Intestinal Peptide; D003345:Corticosterone