Adrenal and hypothalamic dopamine-beta-hydroxylase activity in the hamster: evidence for species-distinctive...

Dopamine-beta-hydroxylase (DBH) activities were measured in the adrenal gland and hypothalamus of the golden hamster (Mesocricetus auratus) by means of a sensitive radioenzymatic method. Groups of unoperated control (C), sham pinealectomized (SPX), and pinealectomized (PX) adult males were sacrificed shortly before (09:00 h) and after (11:00 h) the onset of darkness of the daily photoperiod of LD 12:12 (lights on 22:00 h to 10:00 h). In neither adrenal gland nor the hypothalamus were there any day-night changes in the C groups. Pinealectomy led to no significant differences in hypothalamic DBH activity either in light or in dark. However, intracranial surgery resulted in increased DBH activity in the adrenal gland, evident in both light and dark. Although this increase was greatest in the PX groups, intracranial surgery in SPX groups also showed a trend of increase in adrenal DBH, evident even one month after surgery. Such an increase, however, was not found in hypothalamic DBH in the same SPX groups. In both the adrenal gland and the hypothalamus, copper-sensitive endogenous inhibitors of DBH did not show any notable change in concentration, either in relation to the daily light-to-dark change or as a consequence of intracranial surgery. These and related results suggest that important interspecies variations exist in DBH activities in relation to diurnal changes, and also in control or modulation by pineal and other factors.