Effect of variations in pituitary-adrenal activity on dopamine-beta-hydroxylase activity in various regions of rat...

Since noradrenergic neurons in the brain appear to inhibit ACTH secretion and dopamine-beta-hydroxylase (DBH) is found in noradrenergic neurons, the effect of variations in pituitary-adrenal activity on the activity of DBH in the brain stem, hypothalamus and hippocampus was determined. There was no significant circadian fluctuation in hypothalamic or brain stem DBH, as measured by the coupled radioenzymatic method of MOLINOFF et. al. [1971]. Pentobarbital and ether anesthesia, injection stress and surgical stress also had no acute effect. There was a decrease in anterior hypothalamic DBH 30 min after immobilization stress. Two days after adrenalectomy, there was a decrease in DBH in the hypothalamus and brain stem. A large dose of corticosterone (B) caused an increase in hypothalamic DBH. However, a smaller dose of B which increased plasma B to values comparable to those produced by endogenous secretion failed to have this effect. The data demonstrate an effect of the adrenal glands on brain DBH activity, but it is as yet uncertain whether this effect is mediated by glucocorticoids.