Basolateral Amygdala Inactivation Reduces Sexual Motivation in Male Rats during Performance of a T-Maze Task with a Sexual Reward

Abstract

This study was aimed to determine the effect of amygdaline inactivation on the sexual motivation of male rats during a T-maze task with a sexual reward. Subjects were chronically implanted with two stainless-steel cannulae that enabled the infusion of tetrodotoxin, a sodium channel blocker, into the left and right basolateral amygdala (BLA). Animals were divided into 3 groups: saline (SS); TTX1 (tetrodotoxin at 2.5 ng); and TTX2 (tetrodotoxin at 5.0 ng). To induce a sexually-motivated state, all male rats were allowed to have an intromission with a receptive female before performing the T-maze task, after which their sexual motivation was evaluated during seven trials in which a receptive female was placed in one goal-box of the T-maze, and a non-receptive one in the other. Subjects were allowed an intromission as a sexual reward whenever they reached the goal-box containing the receptive female, but were returned to the start-box if they did not. At the end of the experiment, copulation until ejaculation was permitted. Both doses of TTX increased the time rats required to cross the maze stem during the final trials. In terms of sexual interaction, the high dose of TTX increased more markedly mount, intromission and ejaculation latencies and the number of mounts and intromissions. Overall, these results indicate that the BLA may play an important role in modulating sexual behavior, particularly in maintaining sexual motivation in successive trials in a T-maze task and during sexual interaction per se.