The effect of constant light on the concentration of catecholamines of the hypothalamus and adrenal glands, circulatory hadrenocorticotropin hormone and progesterone

The participation of adrenocorticotropic hormone (ACTH) in the control of adrenal glands and the regulation of ACTH secretion in female rats exposed to constant light for six weeks were studied. A significant increase of plasma ACTH (p < 0.05) in rats exposed to constant light is in correlation with an increase of epinephrine (E) synthesis in adrenal gland (p < 0.05) when compared to intact controls. On the other hand, ACTH secretion is in inverse relation with a significantly reduced concentration of dopamine (DA) and norepinephrine (NE) in hypothalamus (p < 0.05). In addition, higher concentration of plasma ACTH in rats exposed to constant light through its effect on the adrenal cortex is responsible for the appearance of polycystic ovaries. As a contribution to this assumption is the result showing an increased concentration of serum progesterone in rats exposed to constant light when compared to corresponding controls which is probably of adrenal origin. These results indicate an inverse relationship between plasma ACTH concentrations and DA and NE concentrations in hypothalamus and that the hypothalamo-pituitary-adrenal axis has a significant role in the regulation of ovarian function.