Studies on the role of catecholamines in the regulation of the developmental pattern of hypothalamic aromatase

Experiments were conducted to study the regulation of the developmental pattern of aromatase in the forebrain of the perinatal rat. Two experimental designs were used: aromatase measured in primary cultures of fetal hypothalamic cells and in cell-free preparations of forebrain tissue excised at varying ages. In cultured cells, aromatase decreased logarithmically at a slow rate (t1/2 = 7.8 days). Norepinephrine caused a pronounced dose (4 x 10(-6) M) and time-dependent (2-6 days) drop in aromatase without affecting the levels of 5 alpha-reductase or substance P. In isolated tissue, aromatase activity was compared with the concentrations of norepinephrine and dopamine in the forebrain of males vs females at different perinatal ages and in discrete forebrain areas at postnatal day 4. In no case was a sex difference in catecholamines seen. An overall developmental decline in aromatase was associated with developmental increases in catecholamine levels. Acute treatment with the beta-agonist, isoproterenol, had no effect on brain aromatase activity.