The Nervous System of Delphinidae: Neurochenical Studies on Different Central and Peripheral Regions

During the evolutionary path, cetaceans experienced a return to waters and hence had to adapt many of their anatomical and physiological features to this new life. Many organs and systems present several modifications and specialisations and the nervous system either displays peculiar features. Despite a strong interest in studying these peculiarities, many areas of the cetaceans nervous system lack a detailed anatomical, histological and neurochemical description. The aim of the present research is to investigate the neurochemistry of different central and peripheral regions of the Delphinidae nervous system, including anatomical and histological features. We developed four anatomical studies on the central and peripheral nervous system of dolphins under healthy and pathological conditions. We investigated the architecture and distribution of calretinin-immunoreactivity in the lateral nucleus of the bottlenose dolphin (Tursiops truncatus) amygdala, and the Calcitonin Gene-Related Peptide (CGRP) expression in the spinal cord and spinal ganglia of the bottlenose dolphin. Subsequently, we focused on nitrergic and substance P immunoreactive (SP) neurons in the enteric nervous system of the bottlenose dolphin intestine. Finally, we designed a preliminary study on the expression of calcium binding proteins and neuronal nitric oxide synthase (nNOS) in the cortex and cerebellum of striped dolphins (Stenella Coeruleoalba) affected by morbillivirus. In each of these studies, interesting and unreported peculiarities have been described, together with features that are more conserved across mammalian species. This collection of studies is a little contribution to the current knowledge on cetaceans’ nervous system. We believe that anatomy and other basic sciences represent the necessary way that leads to a better knowledge and understanding of these peculiar animals, with a view to planning proper and effective conservation strategies.