Regulation of brain aromatase activity in rats

Journal Article · Sun Jan 01 00:00:00 EST 1984 · Endocrinology; (United States)

DOI:https://doi.org/10.1210/endo-114-1-192· OSTI ID:6729103

Roselli, C E; Ellinwood, W E; Resko, J A

The distribution and regulation of aromatase activity in the adult rat brain with a sensitive in vitro assay that measures the amount of /sup 3/H/sub 2/O formed during the conversion of (1 beta-/sup 3/H)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 microliters incubation mixture. The enzyme demonstrated a pH optimum of 7.4 and an apparent Michaelis-Menten constant (Km) of 0.04 microns. The greatest amount of aromatase activity was found 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, but not in the amygdala or cerebral cortex. 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 to levels approximating those found in HPOA from intact males. Therefore, the results suggest that testosterone, or one of its metabolites, is a major steroidal regulator of HPOA aromatase activity in rats.

• Research Organization: Oregon Health Sciences Univ., Portland
• OSTI ID: 6729103
• Journal Information: Endocrinology; (United States), Vol. 114:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ANDROSTENEDIONE
BIOCHEMICAL REACTION KINETICS
BRAIN
ENZYME ACTIVITY
ESTRONE
OXIDOREDUCTASES
RATS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANDROGENS
ANDROSTANES
ANIMALS
BODY
CENTRAL NERVOUS SYSTEM
ENZYMES
ESTRANES
ESTROGENS
HORMONES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
MAMMALS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
REACTION KINETICS
RODENTS
STEROID HORMONES
STEROIDS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques