Effects of castration and replacement therapy on sexual behavior of adult male rhesuses.

Abstract

The sexual behavior of 10 male rhesus monkeys was observed before and after castration and during replacement therapy with testosterone propionate. In 10 tests before castration, all of the males ejaculated at least once, and in Weeks 21-25 and 51-55 after castration, 50% and 30%, respectively, ejaculated at least once. In the 35 postcastration tests given over a 55-wk. period, 2 males did not ejaculate. Fifty percent of the males achieved intromission 1 yr. after castration. The percentage of castrated animals showing intromission and ejaculation and the frequency of these responses were higher than those reported for most nonprimate species but did not differ greatly from those reported for the dog. Within 1 wk. testosterone propionate restored whatever aspects of behavior were affecled to precastration levels.

Annual plasma testosterone cycle and ejaculatory ability in the laboratory-housed crab-eating macaque (Macaca fascicularis)

“…Likewise, injecting an intact male rhesus macaque with testosterone does not enhance its sexual performance (Phoenix, Dixson and Resko, 1977 (Vandenbergh, 1969). We do not know if the constant ovulatory menstrual cycles are due to the permanent round-the-year sexual activity of our males, but copulation cannot initiate ovarian activity in the female rhesus in seasonal rest (Vandenbergh and Post, 1976 (Resko et Phoenix, 1972 ;Phoenix et al, 1973 ; Wilson, 1974Wilson, , 1975 amène à penser qu'au-dessus d'un niveau minimum, la variation du taux de cette hormone n'affecte plus le comportement sexuel mâle, tout au moins en ce qui concerne l'activité éjaculatoire. De plus, au cours de cette étude, nous avons aperçu qu'au-dessus d'un taux maximum de testostérone, variable suivant la saison, on assisterait à une diminution de la rapidité à l'éjaculation ( fig.…”

“…In the second period ( fig. 3b) (Resko and Phoenix, 1972 ;Phoenix, Slob and Goy, 1973 ;Michael and NVilson, 1974). Likewise, injecting an intact male rhesus macaque with testosterone does not enhance its sexual performance (Phoenix, Dixson and Resko, 1977 (Vandenbergh, 1969).…”

“…After studying ejaculatory ability and plasma testosterone level in the intact macaque throughout the year and comparing it to the results obtained by Resko and Phoenix (1972), Phoenix et al (1973) and bVilson (1974, 1975) studying castrated males, we believe that above a minimal level, variation in the plasma testosterone level does not affect male sexual behavior, at least as far as ejaculatory ability is concerned. Moreover, du ring this study we noted that above a maximal plasma testosterone level, varying with the season, the ejaculation rate may be depressed ( fig.…”

Influence of gonadal hormones on odours emitted by male meadow voles (Microtus pennsylvanicus)

“…In male rats and hamsters, the activation of sexual behaviour and olfactory investigation appear to involve aromatization of testosterone to oestrogen (Baum & Vreeburg, 1973;Christensen et al, 1973;Södersten et al, 1986). Yet, in some male primates, guinea-pigs and rabbits, testosterone acts on androgen receptors and conversion to oestradiol is not part of the process by which these behav¬ iours are affected (Strauss & Ebling, 1970;Phoenix et al, 1973;Alsum & Goy, 1974;Michael et al, 1990). …”

Mating Seasonality in Castrated Male Rhesus Monkeys

“…Thus, both males and females were subjected to constant hormonal stimulation. Behavioural tests were conducted from behind one-way vision mirrors in special observation cages to which first the male and then the female of the pair was introduced (Michael, Saayman & Zumpe, 1968 (Michael, 1972;Phoenix, Slob & Goy, 1973) …”