Detection and distribution of aromatase in hypothalamus of the male rat.
Conversion of androgen to estrogen in the rat brain is catalyzed by aromatase. An in vitro assay for aromatase activity, which quantitates the production of 3H2O during the conversion of 1 beta-3H-androstenedione to estrone, was developed and validated in the present study. The distribution of aromatase activity in discrete hypothalamic nuclei was also explored. Individual hypothalamic nuclei were microdissected from 200-micron frozen sections. Tissues from 3 animals were pooled and assayed for aromatase activity. It was found that the rate of aromatase activity was linear with time up to 1 hour, and with protein concentrations up to 900 micrograms/ml tissue homogenate. A maximal rate was obtained with a substrate concentration of 0.3 microM. The aromatase activity was heterogeneously distributed within the rat brain. The greatest amount of aromatase activity was found in the preoptic area. The suprachiasmatic nucleus also contained a high level of aromatase activity. The aromatase activities in the anterior hypothalamus, ventromedial nucleus, arcuate nucleus and dorsomedial nucleus were less than half that found in the preoptic area.
Department of Physiology, College of Medicine, National Taiwan University, Taipei, R.O.C.
T J
TJ
Chen
M W
MW
Tsai
D000818:Animals; D001141:Aromatase / Q000032:analysis*; D007032:Hypothalamus, Anterior / Q000201:enzymology*; D007033:Hypothalamus, Middle / Q000201:enzymology*; D008297:Male; D011874:Radiometry / Q000379:methods; D051381:Rats; D011919:Rats, Inbred Strains
D001141:Aromatase