Estrous Cycle, Folliculogenesis, and Brain Catecholamines after Stimulation of the Sexual System by Choriogonadotropin in Female Minks Selected for Behavior

The content of hypothalamic dopamine (DA) and noradrenaline (NA) is determined and ovary function (folliculogenesis) in various states of estrous cycle is studied in non-selected (control) immature (7-month old) standard female minks and in similar females of aggressive and quiet behavioral types (the 18th generation of selection) in norm and at the 7th day after single intramuscular injections of chorionic gonadotropin (CG). At the 7th day after the CG administrations, the control females were distributed by their estrous cycle state as follows: anestrus (A)-- 47.2%, anestrus-proestrus (AP)--10.0%, proestrus (P)--8.5%, proestrus-estrus (PE)--14.3%, and estrus (E)-- 20.0%. In the female minks selected for behavior, there was a significant increase of percentage of estrous females: to 84.6% in the aggressive ( p < 0.001) and to 58.4% in the quiet type animals ( p < 0.01). The number of growing and maturing (at the early stage) follicles in intact females of aggressive behavior was lower than in control and in females of the quiet type. However, the number of Graafian vesicles in ovaries of aggressive and quiet females did not differ and exceeded control. The stimulation by CG enhanced the differences between the ovaries of selected animals. In control females at the 7th day after CG injections there was a tendency for a decrease of the DA and NA content with development of estrus (A[arrow right]AP[arrow right]P). The hypothalamic DA concentration was higher in intact females of the aggressive type than in the quiet females ( p < 0.05). In animals of the aggressive type, stimulation of the sex system decreased the DA level. No correlation between sexual function and DA and NA levels was found in females of the quiet type. However, differential analysis of NA in these females with different reactions of vaginal epithelium to CG stimulation (A, AP vs P, PE, E) indicates correlation of catecholamine level with sexual function. Thus, selection of minks for aggressive behavioral type produces an increase of the hypothalamic catecholamine level, which, in turn, is one of factors inhibiting sexual function.[PUBLICATION ABSTRACT]