Central actions of arginine vasopressin and a V1a receptor antagonist on maternal aggression, maternal behavior, and grooming in lactating rats

Abstract

Maternal aggression is a robust type of aggression displayed by lactating female rats. Although arginine vasopressin (AVP) has been implicated in the control of male aggression, its involvement in maternal aggression has not been thoroughly investigated. Previous neuroanatomical studies suggest that AVP may mediate the display of aggression during lactation. In the current study, AVP and an AVP V1a receptor antagonist were centrally administered to primiparous rats on days 5 and 15 of lactation, and aggression, maternal behavior, and grooming were recorded. Although AVP did not affect the number of attacks or duration of aggression, it increased the latency to initiate aggression on day 5, in addition to decreasing maternal behavior and increasing grooming. Conversely, V1a antagonist treatment increased maternal aggression on both days of lactation, decreased maternal behavior on day 15, and decreased grooming on day 5. Thus, it appears that central AVP activity modulates maternal aggression, as well as maternal behavior and grooming behavior during lactation.

Figure 1

Figure 1A–C. Mean (+SEM) seconds(s) for attack latency, number of attacks, and cumulative seconds spent attacking during 15 minute maternal aggression trials on days 5 and 15 of lactation following icv injections of saline (n = 9), an AVP V1a receptor antagonist (n = 26), or AVP (n = 20). * indicates a significant difference when compared to same day saline controls following ANOVA (p < 0.05). # indicates a significant difference when compared to day 5 saline controls following ANOVA (p < 0.05).

Figure 2

Figure 2. A–B. Mean (+SEM) cumulative seconds (s) of grooming and maternal behavior during 15 minute maternal aggression trials on days 5 and 15 of lactation following icv injections of saline (n = 9), an AVP V1a receptor antagonist (n = 26), or AVP (n = 20). * indicates a significant difference when compared to saline controls following ANOVA (p < 0.05). # indicates a significant difference when compared to day 5 saline controls following ANOVA (p < 0.05).

Figure 3

Mean (+SEM) elevation in body temperature (°C) during 15 minute maternal aggression trials on days 5 and 15 of lactation following icv injections of saline (n = 9), an AVP V1a receptor antagonist (n = 26), or AVP (n = 20). * indicates a significant difference when compared to saline controls following ANOVA (p < 0.05).