P23 | CALRETININ IMMUNOREACTIVE NON-TRADITIONAL LARGE NEURONS IN THE GRANULAR LAYER OF THE HUMAN CEREBELLAR CORTEX

P. Flace¹, M. E. Caringella², D. Galletta³, G. Santangelo³, C. Caporusso², M. Stolfa², A. Cacciola⁴, J.J.V. Branca⁵, G. Agazzino², R. Gradini⁶, P. Livrea⁷, A. Marzullo² | ¹Medical School, University of Bari ‘Aldo Moro’, Bari, Italy; ²Section of Molecular Pathology, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University of Bari ‘Aldo Moro’, Italy; ³Department of Psychology, Specialization School of Neuropsychology. University of Campania ‘Luigi Vanvitelli’, Caserta, Italy; ⁴Brain Mapping Lab, Department of Biomedical, Dental Sciences and Morphological and Functional Imaging, University of Messina, Messina, Italy; ⁵Department of Experimental and Clinical Medicine, University of Firenze, Firenze, Italy; ⁶Department of Experimental Medicine, Sapienza University, Roma, Italy; ⁷University of Bari ‘Aldo Moro’, Bari, Italy

Calretinin (CR) is a calcium binding protein of the EF-hand family. CR and Calbindin D28k present 58% of identical amino acids residues. CR is widely expressed in the neuronal cell bodies and processes and form asymmetrical and symmetrical synaptic specializations. CR is a modulator neuronal excitability. Although several studies suggest a role of the CR and of the cerebellum in neurological and psychiatric disorders (e.g. Alzheimer’s disease, Parkinson’s disease, schizophrenia, spinocerebellar ataxias). In the cerebellar cortex, few studies suggest CR expression in the granules and in two non-traditional large neuron types (unipolar brush neuron, Lugaro neuron). Currently, in the granular layer of the human cerebellum does not exist a detailed morphofunctional description of CR immunoreactive non-traditional large neuron types. Therefore, the aim of this study is to carry out, using an immunohistochemical approach, a detailed analysis of CR in the non-traditional large neurons of the human cerebellar granular layer^1-3. The study was carried out on postmortem fragments of human cerebellar cortex fixed in neutral buffered formalin, embedded in paraffin, cut into 5 μm sections and subjected to light microscopic immunohistochemistry with mouse polyclonal antibody for CR. In the granular layer of the cerebellar cortex the CR immunoreactivity (ir) in cell bodies and processes of different nontraditional large neuron types (e.g. perivascular neurons, synarmotic neurons) and in the sites of cerebellar glomeruli have been detected. These results indicate in the cerebellar granular layer a widely presence of CR-ir in different non-traditional large neuron types and suggest in these neurons a role of CR in calcium homeostasis and in neurotransmission mechanisms. Although, further research is needed, CR dysregulation and non-traditional large neuron types may be impaired in brain psychiatric and neurologic diseases in which the cerebellum is involved, and in specific cerebellar diseases.