Function of the hypothalamo-pituitary-adrenal system in mice with ectopic overexpression of agouti protein

Agouti protein (AP) is known to antagonise the effects of melanocortins (ACTH, MSH) on the melanocortin receptors which participate in regulation of central and peripheral HPA links. This study aimed at estimation of effects of dominant mutation Agouti yellow (Ay-ectopic overexpression Agouti protein) on the HPA axis function in mice. Male mice of C57B1/6J strain of Ay/a- and a/a genotypes (control animals, lack of AP), were used. We demonstrated that basal corticosterone level in the Ay mice matched those of control animals. Stress-activated corticosterone level (p < 0.02) and sensitivity of adrenal to low doses ACTH in vitro and in vivo were higher in Ay mice compared with control mice. Dexamethazone-inhibition of stress-reactivity was more intensive in Ay/a than in a/a mice (p < 0.0007).