FARRELL, W.J.*; HAYES, K.A.; WILCZYNSKI, W.; The University of Texas at Austin: Arginine Vasotocin Alters Mirror-Elicited Aggressive Behavior in Green Anolis Lizards (Anolis carolinensis).

The neuropeptide arginine vasopressin and its non-mammalian homologue, arginine vasotocin (AVT) have been implicated in the regulation of a variety of species-typical social behaviors including male aggression. Prior reports suggest that the effects of AVT on aggressive behavior are species-specific. In the present study, we sought to determine whether AVT administration would alter mirror-elicited aggressive behavior in the green anolis lizard (Anolis carolinensis). Male green anoles are territorial, arboreal lizards that readily engage in aggressive behavior in a laboratory setting. Following the introduction of a male conspecific into its home cage, or exposure to a mirror, resident male anoles typically respond with species-typical pushup displays (PU) and sagital expansion of the body surface. To assess the effects of AVT on male aggressive behavior, the number of PU was recorded during two (once daily) 30 min exposures to a mirror. 35 min prior to the initial baseline exposure all animals were injected with saline (10 ul/g, i.p.). Prior to the subsequent test period, half of the animals (n=7) received a second saline injection while the remaining animals received AVT (1ug/g BW) in an equivalent volume of saline. Lizards that received saline injections prior to the test exposure exhibited an average of 67 � 89 additional PU relative to baseline. In contrast, AVT treated animals exhibited an average of 298 � 91 fewer PU. An unpaired t-test indicates a significant difference between these means (t=2.87, p<.02 two-tailed). These results suggest a regulatory role for AVT in reptilian aggressive behavior similar to those previously reported in mammals, birds and fish. Supported by NSF 0090739.