Dopamine-B-hydroxylase activity in rat hypothalamus during the estrus cycle.

This experiment provides a direct test of our previous suggestion that estradiol regulates dopamine-B-hydroxylase (DBH) activity in hypothalamic loci. Anterior, medial and posterior hypothalamic slices from triplets of rats were taken during estrus and diestus and assayed for DBH activity using the technique of Molinoff et al. [15]. DBH activity was measured in hypothalamic slices on three different occasions from three triplets during the estrous phase of the cycle and also from separate triplets during the diestrous stage of the cycle. Results showed a significant increase in DBH activity during the estrous phase of the cycle. Increased activity did not appear to be anatomically localized within the tissue slices. Explanation of the results has been discussed in terms of possible mechanisms of action.