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Gonadal Influences on the Sexual Differentiation of Monoamine Oxidase Type A and B Activities in the Rat Brain
Author(s) -
Vaccari A.,
Caviglia A.,
Sparatore A.,
Biassoni R.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb12535.x
Subject(s) - clorgyline , endocrinology , monoamine oxidase , medicine , sexual differentiation , monoamine oxidase b , monoamine oxidase a , monoamine neurotransmitter , hypothalamus , biology , hormone , chemistry , enzyme , serotonin , biochemistry , receptor , gene
The sex‐dependent differentiation of monoamine oxidase (MAO) in the hypothalamus of 60‐day‐old, Charles River rats was found to involve only type A (MAO‐A), and not type B (MAO‐B) enzyme. In vivo inhibition of type A by clorgyline, and type B by (−)deprenyl, however, tended to decrease the specific activity of both types of MAO to a smaller extent in the female than in the male hypothalamus. When masculinization was prevented by neonatal administration of estradiol (E) to males, hypothalamic MAO‐A and MAO‐B activities increased in both control and MAO‐inhibited rats. Androgenization of females, however, had little effect on the MAO activity. Whereas the effects of neonatal estrogenization were attributable neither to a direct influence of E nor to a sexual difference in the peripheral clearance of the MAO‐inhibitor used, single, high doses of steroids to adult, but not to newborn rats, did acutely affect the kinetics of MAO‐A. The activity of MAO‐A was also decreased by high concentrations of E or TS in vitro. The imprinting for patterns of hypothalamic MAO‐A and MAO‐B in the two sexes results, probably, from genetic predetermination. Neonatal changes in the homeostasis of gonadal hormones may result in type‐MAO nonspecific effects in adulthood, whereas the short‐term effects of high concentrations of steroids may be selective for the A form.