Effects of leptin on the response of rat pituitary-adrenocortical axis to ether and cold stresses.
Leptin is a hormone mainly secreted by the adipose tissue, which acts through specific receptors widely distributed in the body tissues, including hypothalamopituitary-adrenal axis. We have investigated the effects of a subcutaneous bolus injection of 5 nmol/kg leptin on the pituitary-adrenocortical function in both normal and ether- or cold-stressed rats. Blood concentrations of ACTH, aldosterone and corticosterone were measured by specific RIA 2 or 4 h after the leptin injection. Leptin administration to normal rats resulted in significant rises in the blood levels of ACTH, aldosterone and corticosterone at 2 h, but not at 4 h. Ether and cold stresses markedly increased hormonal blood concentrations at both 2 and 4 h. Leptin magnified ACTH response to ether stress at 2 h, but depressed it at 4 h, and enhanced aldosterone response at 2 h, without affecting corticosterone response. Leptin increased ACTH response to cold stress at both 2 and 4 h, without altering aldosterone and corticosterone responses. In light of these findings, we conclude that: (i) leptin evokes a middle transient activation of the pituitary-adrenocortical axis of rats under basal conditions; (ii) leptin inhibits the ACTH response to ether stress, but magnifies that to cold stress; and (iii) the leptin-evoked changes in the blood level of ACTH are not paralleled by significant modifications in the secretory activity of the adrenal cortex, which probably undergoes a maximal stimulation under stressful conditions.
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
A
A
Hochól
K W
KW
Nowak
A S
AS
Belloni
G G
GG
Nussdorfer
L K
LK
Malendowicz
D000302:Adrenal Cortex / Q000187:drug effects / Q000503:physiopathology*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000450:Aldosterone / Q000097:blood; D000818:Animals; D003080:Cold Temperature; D003345:Corticosterone / Q000097:blood; D004986:Ether; D005260:Female; D020738:Leptin / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000209:etiology / Q000503:physiopathology*
D020738:Leptin; D004986:Ether; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone