Intermale aggression, GAD activity in the olfactory bulbs and Y chromosome effect in seven inbred mouse strains.

The capacity to attack a passive standard opponent in a resident-intruder test and the GAD activity in the olfactory bulbs were measured in 140 male mice from seven different inbred mouse strains. The effect of the non-pseudo autosomal region of the Y-chromosome (YNPAR) on these two phenotypes has also been investigated using a quartet of reciprocal strains congenic for the YNPAR. A strong negative correlation was found between the two variables but the YNPAR is not involved. This result suggests that males of more attacking strains have a lower olfactory threshold, making the olfactory discrimination of the opponent easier and its identification as a stranger more efficient.