[Sexual motivation in male mice induced by the presence of the female].

Receptive female mouse placed in a cage behind a partition which prevented physical contacts but allowed the female to be smelt and seen produced in CBA and A/He males an elevation of plasma testosterone level and increase in time spent near the partition (TSNP) in attempts to reach the female. Both in CBA and A/He males the TSNP was much higher than in controls with empty adjacent compartment or with a male in it. The number of approaches to the partition was also increased but not sex-depended reflecting the general motor excitement of animals. A 3-4-fold increase in the TSNP preceding blood testosterone elevation was found within the first 10 min of female exposure. It was suggested that sexual motivation in males induced by female exposure was not caused by testosterone increase. The TSNP in male mice produced by female exposure can be used as an adequate index of sexual motivation.