Hippocampal cholineacetyltransferase activity, agonistic behaviour and social stress in male rabbits.

Agonistic behaviour was observed in pairs of unfamiliar male rabbits living in an outdoor enclosure. Attack, Chase, Follow and Cross-over were scored. On the basis of their frequencies the subjects in the pair were assigned a first or second rank-position. Hippocampal cholineacetyltransferase (ChAT) and plasma levels of corticosterone were considered in relation to rank. ChAT levels in the dorsal hippocampus varied in relation to agonistic behaviour. Second-ranking subjects had significantly higher levels of ChAT than the first-ranking animals and had levels of corticosterone which were markedly higher at the end of the experimental period than at the beginning. A negative correlation was found between Attack and ChAT levels in the dorsal hippocampus. These results suggest the presence of social stress in the second-ranking animals and indicate a state of activation of the hippocampus in relation to agonistic behaviour.

Immune and endocrine aspects of social and territorial behavior in male rabbits.

Although there have been some studies of the relation between behavior and mitogen-induced lymphocyte proliferation and immunoglobulin synthesis, few data are available about the effect of behavior on specific lymphokine production. In this study, we describe the effect of social and territorial behaviors on interferon-gamma (IFN-gamma) production by concanavalin A-stimulated peripheral blood mononuclear cells (PBMCs) in pairs of socially naive male rabbits living in a seminatural open-air environment. We also assayed PBMC glucocorticoid receptors (GcRs) and plasma corticosterone (C). Three groups of behaviors were identified: agonistic (Mount and Follow), affiliative (Groom) and territorial (Mark and Dig). Mount was correlated with Follow, while Mark was correlated with Dig. Groom was correlated with all the other behaviors. Groom, Mark, Mount and Follow were all positively correlated with PBMC GcRs. Groom and PBMC GcRs were each negatively correlated with plasma C. The two rabbits in each pair could be distinguished in terms of territorial behavior, since one animal always had a higher score. The animals with the higher level of territorial behavior within the pairs exhibited a significant increase in IFN-gamma production at the end of the experimental period. They also showed a positive correlation between the percentage variations of IFN-gamma production and PBMC GcRs. It is suggested that social factors, especially territorial behavior, affect adrenocortical activity and IFN-gamma production.

Experimental assessments of behavioral and anatomical components of female chacma baboon (Papio ursinus) sexual attractiveness.

Two experiments were carried out in order to separate the effects of the behavioral and the anatomical components of female sexual attractiveness in baboons. In the first experiment, two ovariectomized females were given increasing dosages of exogenous estradiol benzoate, and data were collected on their behavior as well as on male sexual arousal as assessed by the occurrence of coagulated seminal emissions of the type that result from masturbation. Male sexual arousal levels increased positively with the females' perineal swellings and appeared relatively unrelated to the females' behavior. In the second experiment, data were collected from five different groups of males in a systematic fashion across the period of a full menstrual cycle for their varied stimulus female partners. Behavior observations were carried out on the five different stimulus females, and ratings also were made of fluctuations in their perineal tumescence. The results of this experiment make it clear that male sexual arousal fluctuated across the study cycles in a fashion very similar to that of the perineal swellings of the stimulus females. Behavior was shown during all phases of the cycle, and, although it may have had a positive influence on male arousal during the follicular phase of the female's cycle, it had no apparent effect during the luteal phase. These results taken together establish for the first time that an estrogen stimulated female perineum per se has the potential to sexually arouse the male baboon. In addition, the data suggest that, although behavior may exert a positive effect on male arousal, in the absence of an estrogen stimulated perineum it is not sufficient to arouse males to masturbate. Finally the results establish that, although intact females appear to show behavior increases which may be arousing to males around the time of ovulation, these behaviors do not have to be shown by a female in order to arouse a male, provided she is swollen.

Steroid hormone influences on the mating behavior of vervet monkeys (Cercopithecus aethiops).

Eight ovariectomized female vervet monkeys (Cercopithecus aethiops) were tested in heterosexual and isosexual pairs, under estradiol and testosterone treatments. Pairs were tested under two different experimental situations in which the male was either restrained or left free. There were only small behavioral changes across the treatments, involving mainly male responses. Erection time, frequency of intromission, ejaculation, and olfactory investigation increased during estradiol treatment whereas during administration of testosterone erection time, the number of approaches, contacts, and olfactory investigations decreased. Female behaviors were relatively independent of hormone treatment showing only the disappearance of negative responses with estradiol and an increase of yawns with testosterone. Female behaviors were performed at a higher level with male partners than with other females, and the frequencies of spontaneous presents varied with the sex of partner. It is suggested that in vervet monkeys both estradiol and testosterone affect female attractivity, estradiol further influences receptivity, whereas proceptivity appears to be less directly involved in sexual interactions and more related to social context.