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We studied the capability of hypothalamic tissue from young (3-4 months) and old (22-24 months) male rats to aromatize androgens to estrogens. Aromatase activity was measured in homogenates of brain tissue by using a radiometric assay that quantifies the stereospecific production of 3H2O from [1 beta-3H]androstenedione as an index of estrogen formation. Despite the 40% drop in circulating testosterone (T) levels associated with aging in males, we found that hypothalamic aromatase activity was unaffected by age. This finding suggested that chronic exposure to low levels of circulating T can maintain brain aromatase activity in aged male rats. In an experiment designed to examine the acute response of hypothalamic aromatase activity to induction by T, we found a significant positive correlation between circulating T levels and hypothalamic aromatase activity in both age groups. These results demonstrate that T remains an effective regulator of hypothalamic aromatase in old male rats.
C E Roselli, and
L W Kaler, and
J A Resko
April 1990,
Neuroendocrinology,
C E Roselli, and
L W Kaler, and
J A Resko
February 1982,
Physiology & behavior,
C E Roselli, and
L W Kaler, and
J A Resko
March 1979,
Biology of reproduction,
C E Roselli, and
L W Kaler, and
J A Resko
January 1999,
Endocrinology,
C E Roselli, and
L W Kaler, and
J A Resko
October 1986,
Nihon Naibunpi Gakkai zasshi,
C E Roselli, and
L W Kaler, and
J A Resko
September 1987,
Brain research,
C E Roselli, and
L W Kaler, and
J A Resko
February 2007,
Journal of neuroendocrinology,
C E Roselli, and
L W Kaler, and
J A Resko
June 2001,
Molecular and cellular endocrinology,
C E Roselli, and
L W Kaler, and
J A Resko
January 1980,
Neurobiology of aging,
C E Roselli, and
L W Kaler, and
J A Resko
December 1982,
Experimental neurology,
