Neurogenesis and neuronal migration in hypothalamic vasopressinergic magnocellular nuclei of the adult rat

Abstract

AbstractIn restricted mammalian brain regions, cell proliferation and migration continue postnatally and throughout adulthood. Here we show, using immunohistochemical reaction (ir) against arginine vasopressin (AVP), neurophysin II, glial fibrillar acidic protein (GFAP), cell division and early neuronal markers Ki67 and doublecortin (DCX) respectively, and neuroanatomical analysis on the rat brain in serial sections of coronal, sagittal, horizontal and septo-temporal oblique orientations from adult rats, that neurons from hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei are dispersed along visible tangential routes to other subcortical regions, guided by AVP-ir cell chains and axon scaffolds. Using 5’-bromo-2’-deoxyuridine injection in adult rats followed by BrdU-ir, we observed numerous twin-nuclei within SON and PVN, with some double-labeled for AVP. Chronic water deprivation significantly increased the BrdU+ nuclei within both SON and PVN. Immunofluorescent reaction showed double labeling of AVP/DCX within SON and PVN. Interestingly, NeuN, a mature neuron marker, was largely absent in SON and PVN, but present in neurons within adjacent hypothalamic regions. These findings provide evidence that adult neurogenesis and migration occur in hypothalamic vasopressinergic nuclei and reveal tangential migration routes of AVP-ir neuronal chains and ascending axonal scaffolds in adult rats.