Influence of maternal testosterone on the strategies in the open field behaviour of rats.

OBJECTIVES The purpose of the present study was to characterize the influence of testosterone administered to pregnant females on offsprings postnatal behavioral strategies in the open field. METHODS The influence of maternal testosterone on behaviour of 23 day old male and female offsprings was studied in a 20-minute open field test. A total of 9 behavioural events were compared between a control (male n=12, female n=8) and a testosterone group (male n=9, female n=9). Dynamics and patterns of association of these behavioural events were analyzed. The testosterone group was prenatally exposed to testosterone (a single intramuscular injection of 2.5 mg testosteroni isobutyras on gestation day 14). RESULTS Male offsprings exposed prenatally to testosterone displayed significantly high levels of ambulation (P<0.05), sniffing (P<0.01), sniffing the air (P<0.05), urination (P<0.05) and significantly lower level of vocalization (P<0.05) than control. Female offsprings exposed prenatally to testosterone displayed significantly higher level of sniffing the air (P<0.05) than control. Significant differences in the dynamics of habituation process were registered only in the group of male. They were from 5 to 10 min in ambulation (P<0.05), from 10 to 15 min in sniffing (P<0.05) and vocalization (P<0.05), from 10 to 15 min and from 15 to 20 min in sniffing the air (P<0.05) and from 0 to 5 min in defecation (P<0.05) and urination (P<0.01). CONCLUSION Our results suggest that maternal testosterone may influence especially male postnatal open field strategies.