Expression of c-fos as an index of functional interaction of the frontal cortex and limbic cerebral structures in the course of food-procuring stereotyped movements in rats

Abstract

We estimated expression of the c-fos gene (a marker of increase in neuronal activity) and manifestations of the histochemical reaction to NADPH-diaphorase (a marker of NO-generating neurons) in the medial prefrontal cortex (MPFC) and forebrain limbic structures of rats in the norm, in the state of starvation, and during realization of long-lasting (60 min) periodic (several times per minute) food-procuring movements of the forelimb. The starvation state or realization of motivated stereotyped forelimb movements were related to significant bilateral increases (P < 0.05) in the levels of c-fos expression in the anterior olfactory (AOP) and cortical (ACo) nuclei and the central (Ce) and basolateral (BLA) nuclei of the amygdala, and also in the pyriform (Pyr), prelimbic (PrL), and inferior limbic (IL) cortices. The described findings demonstrate that the high Fos immunoreactivity in the MPFC and amygdalar structures is related to the motivation state in animals and reflects the active involvement of limbic cerebral structures in the formation of motor programs and also in the stabilization and realization of operant reflexes.