Fig. 3. Grn-/- male mice were not hyperaggressive but showed evidence of altered social interactions.

(A) Grn-/- male mice were significantly less reactive to handling on average across three daily test sessions compared to Grn+/+ controls (**p = 0.009), with differences being significant during session 3 (*p = 0.013) and during session 2 (†p = 0.020). (B) However, no reliable differences were observed between the Grn-/- and Grn+/+ male groups on an aggression index (duration of fighting + biting) derived from data collected during the resident-intruder test. (C) In contrast, the Grn-/­male mice displayed a significantly decreased duration of pawing during nonaggressive interactions (**p=0.005), with differences being significant during session 3 (*p = 0.004), and very large during sessions 1 and 2 (†p < 0.025). (D) Male Grn-/- mice also spent a significantly decreased duration of time following the intruder mouse compared to the Grn+/+ group across test sessions (**p = 0.018) with differences being significant during session 3 (*p = 0.004). (E) The Grn-/- mice spent significantly more time alone compared to the Grn+/+ group (**p = 0.004) with significant differences being observed during sessions 1 (*p = 0.006) and 2 (*p = 0.012) and substantial differences also being found for session 3 (†p = 0.026).