The pouched mouse, Saccostomus campestris (Cricetidae), is an African rodent, known to lead a solitary life, where the female is overtly aggressive towards all conspecifics, except during the very short time of sexual receptivity, when she will tolerate the presence of a male and mate with him. In the present study, males were introduced to sexually receptive females to study their behaviour after mating and correlate that to the endocrine status of the female at that time.
The present paper demonstrates that c. 12 hours after mating (and ovulation), the behaviour of female pouched mice reflects whether conception has occurred or not; conceived females became aggressive towards the male at that time, while non-conceived females continued to be amicable towards the male during the subsequent phases of that and the following cycle(s), until conception occurred.
Aggressive behaviour was not associated with measurable plasma levels of testosterone, and owing to large intra- and inter-individual differences, no relationship was confirmed between plasma levels of oestradiol-17β and levels of aggression during the oestrous cycle.
Approximately 12 hours after mating, plasma concentration of progesterone was significantly higher in females that had conceived than in those that had not. This could not be correlated with the occurrence of aggression in these females, however, as there were no differences in progesterone levels between single, cycling females and mated non-pregnant females at any stage during the cycle.
The presence of a male, vaginal stimulation, and prolactin are not presumed to be involved in suppression of aggression in female pouched mice.