Gonadal steroids influence the involvement of arginine vasopressin in social recognition in mice.

Gonadal steroids have been shown to modulate the involvement of vasopressinergic neurotransmission in social recognition in rats. To assess whether the same phenomenon occurs in another species showing sexual dimorphism of vasopressinergic neurons, social recognition was studied in DBA2 male mice. Social recognition was inferred from the reduction in investigation time of a juvenile conspecific when this social stimulus was presented for the second time at different intervening intervals after the initial exposure. Such a reduction occurred when the interval was 20 min or 1 hr but not 2 hr. This effect was stimulus-specific, because it did not occur when a different juvenile was presented on the second exposure. AVP (0.4 micrograms/mouse, SC) injected immediately after the first exposure to the juvenile prolonged social recognition, whereas SC injection of an antagonist of the vasopressor receptors of AVP, dPTyr(Me)AVP (2 micrograms/mouse) impaired it. Compared with intact males, castrated mice spent less time investigating juveniles but were still able to recognize them after a 2-hr interval. However, this recognition was no longer sensitive to dPTyr(Me)AVP. These results confirm that androgen-dependent vasopressinergic transmission modulates social recognition in mice.