TY - JOUR
T1 - Regulation of brain aromatase activity in rats
AU - Roselli, Charles E.
AU - Ellinwood, William E.
AU - Resko, John A.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1984
Y1 - 1984
N2 - We studied the distribution and regulation of aromatase activity in the adult rat brain with a sensitive in vitro assay that measures the amount of 3H2O formed during the conversion of [1β-3H]androstenedione to estrone. The rate of aromatase activity in the hypothalamus-preoptic area (HPOA) was linear with time up to 1 h, and with tissue concentrations up to 5 mgeq/200 µl incubation mixture. The enzyme demonstrated a pH optimum of 7.4 and an apparent Michaelis-Menten constant (Km) of 0.04 µM. We found the greatest amount of aromatase activity in amygdala and HPOA from intact male rats. The hippocampus, midbrain tegmentum, cerebral cortex, cerebellum, and anterior pituitary all contained negligible enzymatic activity. Castration produced a significant decrease in aromatase activity in the HPOA (P < 0.001), but not in the amygdala or cerebral cortex (P > 0.05). The HPOAs of male rats contained significantly greater aromatase activity than the HPOAs of female rats. In females, this enzyme activity did not change during the estrous cycle or after ovariectomy. Administration of testosterone to gonadectomized male and female rats significantly enhanced HPOA aromatase activities (P < 0.05) to levels approximating those found in HPOA from intact males. Therefore, our results suggest that testosterone, or one of its metabolites, is a major steroidal regulator of HPOA aromatase activity in rats.
AB - We studied the distribution and regulation of aromatase activity in the adult rat brain with a sensitive in vitro assay that measures the amount of 3H2O formed during the conversion of [1β-3H]androstenedione to estrone. The rate of aromatase activity in the hypothalamus-preoptic area (HPOA) was linear with time up to 1 h, and with tissue concentrations up to 5 mgeq/200 µl incubation mixture. The enzyme demonstrated a pH optimum of 7.4 and an apparent Michaelis-Menten constant (Km) of 0.04 µM. We found the greatest amount of aromatase activity in amygdala and HPOA from intact male rats. The hippocampus, midbrain tegmentum, cerebral cortex, cerebellum, and anterior pituitary all contained negligible enzymatic activity. Castration produced a significant decrease in aromatase activity in the HPOA (P < 0.001), but not in the amygdala or cerebral cortex (P > 0.05). The HPOAs of male rats contained significantly greater aromatase activity than the HPOAs of female rats. In females, this enzyme activity did not change during the estrous cycle or after ovariectomy. Administration of testosterone to gonadectomized male and female rats significantly enhanced HPOA aromatase activities (P < 0.05) to levels approximating those found in HPOA from intact males. Therefore, our results suggest that testosterone, or one of its metabolites, is a major steroidal regulator of HPOA aromatase activity in rats.
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U2 - 10.1210/endo-114-1-192
DO - 10.1210/endo-114-1-192
M3 - Article
C2 - 6537806
AN - SCOPUS:0021335635
SN - 0013-7227
VL - 114
SP - 192
EP - 200
JO - Endocrinology
JF - Endocrinology
IS - 1
ER -