DIFFERENTIAL REACTIVITY OF INDIVIDUALS AND THE RESPONSE OF THE MALE GUINEA PIG TO TESTOSTERONE PROPIONATE¹

Inhibition of Steroid Receptor Coactivator-1 Blocks Estrogen and Androgen Action on Male Sex Behavior and Associated Brain Plasticity

“…However, in several situations, variation in peripheral concentrations of steroid hormones do not explain variation in the behavioral response to hormones [e.g., individual and sex differences (Grunt and Young, 1952;Balthazart et al, 1996b)]. To understand the actions of sex steroid hormones on reproductive behaviors, one must take into account variation in the responsiveness of the target tissue to the hormone.…”

Effects of ewe proximity on peripheral plasma testosterone levels and behaviour in the ram

“…After androgen therapy, the social status of chimpanzees changes (Clark & Birch, 1945) ; rhesus mon¬ keys also show a correlation between hierarchal position and testosterone level (Rose et al, 1972 (Leuthold, 1966;Bramley, 1970). Established behavioural patterns in individual guineapigs and rats have been shown to persist when testosterone levels are artificially standardized by uniform replacement therapy following castration (Grunt & Young, 1952;Beach & Fowler, 1959 (Hulet, Ercanbrack, Blackwell, Price & Wilson, 1962;Lincoln et al, 1970;Geist, 1971). The present experiments suggest that the separation of male ungulates into bachelor herds and those exerting copulation rights through territorial or harem…”

Steinach and Young, Discoverers of the Effects of Estrogen on Male Sexual Behavior and the “Male Brain”

“…First of all, the concept of “tissue sensitivity” was introduced to account for the finding that individual differences in the display of sexual behavior by male guinea pigs cannot be overcome by the administration of large amounts of testosterone (Grunt and Young, 1952). Second, Beach (1948) had reviewed the evidence for the eight possible combinations among sex, gonadal hormone, and sexual behavior, and out of these combinations Young (1961) considered the “male sex–testosterone–masculine behavior” and the “female sex–estrogen–feminine behavior” relationships to be “typical.” Interestingly, while he regarded the “estrogen–masculine behavior” a “common relationship” in the female, he did not think that was a strong relationship in the male.…”

“…Steinach’s hypothesis that the behavioral sex of an animal is reversible by treatment with the hormones of the opposite sex was challenged in the 1950s, when it was discovered that the behavioral sensitivities to gonadal hormones are unequally distributed both within and between the sexes (Grunt and Young, 1952; Phoenix et al, 1959). Most important, these authors demonstrated that the sensitivities to gonadal hormones of adult animals are determined by exposure to testosterone in early development.…”