Dromedary vimentin hypothalamo - neurohypophysal system expression may help adapt to severe arid environment

The dromedary comparing to the other mammals, presents a great capacity of adaptation to dehydration; essentially by reducing diuresis; which is due to vasopressin action on kidney. We have hypothesized that the hypothalamo-neurohypophysal system (HNS) of this animal witch is the site of production and release of vasopressine; may present some peculiarities. During times of high vasopressin demand, important alterations occur in the architecture of magnocellular neurons and glial cells of the HNS. To enhance neurosecretion, this phenomenon induces a coordinated astrocytic withdrawal from between the magnocellular somata and release of engulfed axons in the nervous lobe of hypophysis. Different cytoskeletal proteins are implicated in this cell plasticity, namely intermediate filaments (IF) like vimentin that helps cells tolerate different forms of stresses such as the mechanical one. Immunoperoxydase labeling was performed to investigate the antigenicity of dromedary hypothalamo-neurohypophysal system for vimentin. Vimentin expression was observed at the different HNS levels. It was present in granulated cytoplasmic structures of MCN cell bodies and between them, in what may correspond to glial cells processes. In neurohypophysis, vimentin was highly concentrated as filamentous structures, mostly outside the specialized islets of blood vessels. These results strongly suggest a significant role of vimentin in the dromedary HNS adaptation to vasopressin secretion that will enable dromedary to better deal with arid long-lasting stimulations.