Propagation of the pseudorabies virus particles to the amygdaloid complex after inoculation into rat's insular cortex

Amygdaloid complex (AC) is a heterogeneous group of subcortical nuclei and cortical structures which has a crucial role in the limbic system functions, and which is interconnected with many brain regions. The projections from the AC to the posterior insular cortex, were studied in 5 male adult rats by retrograde marking of neurons with pseudorabies virus (PRV). After inoculation of PRV into the insular cortex, rats were sacrificed after 51, 57 or 72 hours. The serial sections of AC were examined by using immunohistochemistry, with an antibody against PRV. The goal of this study was to identify the nuclei of rat AC with the presence of PRV, to estimate the density of PRV, and also to note the speed of PRV propagation from the posterior insular cortex to AC. Clear distribution of PRV particles in amygdaloid nucleus was observed in the rat brain after 72 hours while in earlier sacrificed animals (51 and 57 hours) there was no positive reaction. The high density of PRV-immunoreactive neurons was in the ipsilateral lateral and basolateral nucleus, as well as in the amygdalohippocampal area. The lower density was in the ipsilateral basomedial, central, medial, posterior cortical nucleus, and nuclei of lateral olfactory tracts, as well as in the contralateral basomedial nucleus. In conclusion, by PRV retrograde tracing was found that the main projections of AC to posterior insular cortex originate from lateral and basolateral nucleus which are known as important regions of sensory convergence of AC, and from the amygdalohyppocampal area, as well.