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

Marisela Hernández-González,Gina Lorena Quirarte,Francisco Abelardo Robles Aguirre,Paulina Haro Magallanes,Miguel Ángel Guevara

doi:10.4236/jbbs.2014.45024

Marisela Hernández-González, Gina Lorena Quirarte + Show 3 more

Open Access

https://doi.org/10.4236/jbbs.2014.45024

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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.

Highlights

It has been suggested that the amygdala plays an important role in the regulation of several primary motivational states, including sexual, aggression, ingestion- and fear-motivated behaviors
Bearing in mind the major role that has been attributed to the BLA in incentive motivation, and considering that copulation is a motivated behavior that depends on the male’s ability to process sexual stimuli, the aim of this study was to determine whether inactivation of the BLA in male rats affects the maintenance of sexual motivation during the performance of a T-maze task using a sexual reward
Motor Activity Test The number of squares that the male rats from the three groups crossed in the open field test previous to the T-maze task was similar (F = 0.32; p = 0.73). 3.3

Summary

Introduction

It has been suggested that the amygdala plays an important role in the regulation of several primary motivational states, including sexual-, aggression-, ingestion- and fear-motivated behaviors. Rich inputs from the neocortex are directed to the BLA, and most olfactory (allocortical) inputs are directed to the CMA, while autonomic regulatory centers in the brainstem are reciprocally connected to the central nuclei [4]. In light of these connections, it has been proposed that the BLA may represent a polymodal, cortical-like area that receives information from the visual, taste, olfactory and auditory cortices [5] [6], while the CMA is a more traditional limbic-like area [6] [7]. Primates with ablation of the BLA show a significant deficit in the associative learning of visual stimuli when presented with a reinforcer from different sensorial modalities [11], while after suffering lesions in the amygdala, monkeys showed impairments in reinforcer devaluation [12] in reversal learning tasks, and in emotional responses to threatening stimuli [13]

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