Immunocytochemical Analysis of Calretinin in the Frontal Cortex of Chinchilla

The aim of the study was to define morphology and distribution of calretinin (CR) positive neurons in the frontal cortex of adult chinchilla males and intracellular localisation of the protein in this area. The brains of 5 adult chinchilla males were used in the study. CR immunoreactive neurons were shown with peroxidase-antiperoxidase immunohistochemical reaction using a specific monoclonal antibody. Intensive CR immunoreactivity was demonstrated mainly in few polymorphic neurons of II, III, and V layers. Cytoplasmic and nuclear reaction product in most CR positive neurons was diffuse and in some neurons of layer V in the form of granules localised peripherally. In a few cells more intensive staining was observed in the nuclei than in the cytoplasm. The results indicate the presence of heteromorphic CR positive neurons in specific layers of the frontal cortex. Nuclear localisation of CR in neurons suggests passive transport of this protein, which may affect the nuclear genes. This protein is a neuroprotector maintaining appropriate level of calcium, modulating neuronal activity, and synaptic conduction in the frontal cortex of chinchilla.