study of apomorphine effects and heterogeneity in the medial prefrontal cortex on the dopaminergic behaviors of rats

ABSTRACT

While the nucleus accumbens and the striatum have received much attention regarding their roles in stereotyped behaviors, the role of the medial prefrontal cortex [mPFC] has not been investigated to the same degree. Few studies have reported the role of the mPFC in dopaminergic induction of locomotor hyperactivity. The mPFC is a heterogeneous area [the anterior cingulated, prelimbic, and the infralimbic] with particular inputs and outputs to subcortical regions that may have different effects on stereotyped behaviors. In this work, apomorphine, a non-specific dopamine agonist, was microinjected into the three different subregions of the mPFC for induction of stereotyped behaviors to show the role of the three subareas of the mPFC on behaviors and its heterogeneity. Cannulas implanted in the infralimbic, the prelimbic or the anterior cingulated areas of the mPFC. Apomorphine microinjected at five doses and then behaviors recorded. There were significant differences among three areas. The rats receiving apomorphine in the anterior cingulated showed less sniffing and climbing but more chewing behaviors. Yawning observed more significantly in the rats given apomorphine in the prelimbic area. The rats getting apomorphine in the infralimbic of the mPFC showed more climbing behavior. It was indicated that manipulation of the dopaminergic system in mPFC alters behaviors and with regard to this, there may be heterogeneity among its three subregions