Aggressive behaviour and locomotor activity in male Sprague Dawley rats with serotoninergic depletion

M. MULLE BERNEDO; GARCÍA S.; CABRERA, R

Mar del Plata

Congreso; LXI reunión anual de la SAIC; 2016

SAIC

The serotoninergic system modulates appetitive, motivational and aggressive behaviors. The last one is particularly associated with territorial defense and the increase of aggressiveness. The reduction of 5-HT synthesis by the drug has proven effective in increasing aggressive behavior, in strains and species prone to it, and locomotion activity. The aims were: 1- to describe the aggressive behavior induced by the tryptophan hydroxylase inhibition by parachlorophenylalanine (pCPA) in a strain characterized by low aggressiveness and 2- to examine dose/day response on aggressive behavior and locomotor activity. Male Sprague-Dawley rats 60 days old were used. The animals were divided into 5 groups naïve, saline control and pCPA treated rats (300 mg/kg, i.p) evaluated on the 3rd and 6th day after. We evaluated intermale aggression with smaller males test and 5 minutes before in the arena to tested locomotor activity. The aggressive behavior was measured as the persecution latency time (PL) and presence of tromping, bites, attempted mounts and lateral threats (AB). We also measured non-social interaction (freezing, lying, and sitting), social interaction (sniffing and grooming) and locomotor activity. The test was recorded and the videos were analyzed with the Kinovea 0.8.15 software. The data were analyzed by ANOVA I and II and Tukey post hoc test. We observed a significant decrease in PL (p≤ 0.001) and a significant increase (p≤ 0.001) in non- social interaction between the treated, control and naïve groups. There was a significant increase (p≤ 0.05) in AB between the treated group tested on the 3rd and 6th day. There were no significant differences in social interaction and locomotor activity. The depletion of 5-HT affects PL, AB, and non-social exploration. AB is related to the day/dose-response even in a strain with low aggressiveness. Aggressive behavior, as we describe, is related both to serotonergic depletion and to dose/day response, while there is no incidence in locomotion activity.