Effects of copulatory experience on mating behavior in the male rat.

Abstract

According to Beach (1942), the male rat's tendency to initiate coitus is controlled by a central excitatory mechanism (CEM) which reacts to sexual stimuli when selectively sensitized by an appropriate hormone (androgen). At a threshold excitatory level, the CEM discharges into motor centers which mediate copulation. The CEM may become reactive to normally inadequate stimuli after their repeated association, during copulation, with adequate sexual stimuli. The level of excitement is assumed to increase more rapidly and to reach a higher point when more stimulation acts upon the CEM. Finally, Beach slates that the motor centers for copulation remain relatively unaffected by this type of experience.It follows from this analysis that experienced males should reach excitatory threshold sooner and therefore require less time to make the first sexual contact after the female has been introduced. Moreover, in a time-limited test, a greater percentage of experienced than inexperienced males should become sufficiently aroused to achieve coitus. Other measures of sexual performance which are presumably controlled by motor centers, that is, the frequency and spacing of mounts, intromissions, and ejaculations, should be about the same for experienced and naive 5s which copulate at all.Before one would expect to observe the predicted differences, 5s must be of sufliciently low arousability at the time of testing for improvement to be measured. It is obvious that males which always copulate cannot improve in terms of percentage copulating. Also, males which initiate coitus within 10 or 15 sec. (the usual average) are not likely to show any great decrease in latency. Clearly, then, the most direct procedure of pairing

Development of sexual behaviour in the male hamster.

“…The effects of sexual experience on mount and intromission latencies found in the present study are in agreement with results obtained with the male rat (Larsson, 1956;Rabedeau & Whalen, 1959). Differences in the frequency of ejaculation have not been reported for the rat, but die time-limited test employed in the rat studies make the number of ejaculations dependent upon the ICI and PEI (that is, the rate of ejaculation) which are relatively unaffected by sexual experience (Rabedeau & Whalen, 1959). Because of differences in the mating pattern and in testing procedures of the guinea pig, it is difficult to make quantitative comparisons between hamster and guinea pig.…”

Sexual motivation.

“…Behavior is not simply a function of motivational state; behavior is a function of some interaction between motivation and habit (Wittenborn, 1957). In species such as the rat where habits usually contribute little to sexual behavior (Rabedeau & Whalen, 1959), measures of the behavior may allow relatively direct inferences about motivation. In carnivores and primates, habits greatly influence the expression of sexual behavior (Harlow, 1962;Rosenblatt & Aronson, 1958;Whalen, 1963a).…”

Sexual experience changes sex hormones but not hypothalamic steroid hormone receptor expression in young and middle-aged male rats

“…A role for previous sexual experience has been shown for both motivational (Kelliher and Baum, 2002; Matuszczyk and Larsson, 1994) and consummatory components of behavior [cats (Rosenblatt and Aronson, 1958) and hamsters (Lisk and Heimann, 1980)]. Although conflicting results were found for the effect of experience in the timing of the loss of mating behaviors in rats (Bloch and Davidson, 1968; Rabedeau and Whalen, 1959; Retana-Marquez and Velazquez-Moctezuma, 1997), it was shown that male rat copulatory behavior is more efficient after sexual experience. Compared to naïve animals, sexually experienced rats could achieve an ejaculation with fewer mounts and intromissions; those males with prior sexual experience had lower mount, intromission and ejaculation latencies (Bialy et al, 2000; Dahlof and Larsson, 1978; Dewsbury, 1969; Frankel, 1981; Pfaus and Wilkins, 1995) and lower post-ejaculatory interval (Larsson, 1959).…”