Hypothalamic nuclei catechol-O-methyl-transferase and the process of brain sexual differentiation.
The present review focuses on some aspects of the function of catechol-O-methyl-transferase (COMT) in the hypothalamic control of gonadotrophin release by the pituitary gland. The in situ influence of a catecholestrogen (2 OH.E2) on the amount of COMT in the hypothalamic nuclei involved in such control as well as on the process of sexual differentiation of the brain is also discussed. Catecholestrogens do not play a significant role in the induction of sexual differentiation and the observed action is probably a pharmacological one. It is difficult to understand why a substance whose structure is so closely related to that of estrogen is so much less active. Most probably the estrogen receptor in the cytosol at this stage of development is not able to recognize the catecholestrogen. Since catecholestrogens are not true virilizing substances they may be used to assess the critical levels of enzymes which are required to determine the sexual pattern of hypothalamic activity. The fact that the extent of the changes in COMT content of the hypothalamus is related to the amount of hormone used to induce virilization strengthens the view that sexual differentiation is the consequence of a genomic change during the critical period, which will induce an enzymatic pattern characteristic of the male acyclic pattern of gonadotrophin control. The finding that the COMT content of the hippocampus also changes in parallel to sexual differentiation leads us to speculate that perhaps sexual behavior may also be differentiated in the same way.
D000818:Animals; D002394:Catechol O-Methyltransferase / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D004967:Estrogens / Q000009:adverse effects; D005260:Female; D006062:Gonadotropins / Q000378:metabolism*; D007031:Hypothalamus / Q000201:enzymology*; D007247:Infertility, Female / Q000139:chemically induced; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010053:Ovary / Q000187:drug effects; D051381:Rats; D012733:Sex Differentiation; D012737:Sex Factors; D013739:Testosterone / Q000378:metabolism
D004967:Estrogens; D006062:Gonadotropins; D013739:Testosterone; D007986:Luteinizing Hormone; D002394:Catechol O-Methyltransferase; D004298:Dopamine