THE INFLUENCE OF EXTEROCEPTIVE STIMULI AND PHEROMONAL FACILITATION OF OVULATION IN DIFFERENT STRAINS OF MICE

Abstract

SUMMARY Pheromonal facilitation of pregnant mare serum gonadotrophin (PMSG)-induced ovulation was compared in four strains of immature mice after exposure to adult intact males, castrated males, castrated males after treatment with testosterone propionate, or exposure to adult females. Psychobehavioural modification of their response was studied after transferring PMSG-injected females between cages, or after their exposure to either electric foot shock or adverse auditory stimuli. Significant facilitation of the average number of ova released and percentage of mice ovulating was found in females of the strains C3HeB/FeJ and BALB/cJ, but not in strains DBA/2J and C57BL/6J after exposure to adult males. Exposure to castrated males treated with testosterone propionate resulted in a response essentially the same as that to intact males, whereas exposure to adult females inhibited ovulation uniformly in all the strains studied except BALB/cJ. Auditory stimuli prevented this phenomenon in strains C3HeB/FeJ and C57BL/6J, but an obvious facilitation was observed in strains BALB/cJ and DBA/2J. Electric shock facilitated ovulation in strain DBA/2J but not in the other three strains.