Morphological signatures of neurogenesis and neuronal migration in hypothalamic vasopressinergic magnocellular nuclei of the adult rat

Arginine vasopressin (AVP)-magnocellular neurosecretory system (AVPMNS) in the hypothalamus plays a critical role in homeostatic regulation as well as in allostatic motivational behaviors. However, it remains unclear whether adult neurogenesis exists in the AVPMNS. By using immunoreaction against AVP, neurophysin II, glial fibrillar acidic protein (GFAP), cell division marker (Ki67), migrating neuroblast markers (doublecortin, DCX), microglial marker Iba1, and 5′-bromo-2′-deoxyuridine (BrdU), we report morphological evidence that low rate neurogenesis and migration occur in adult AVPMNS in rat hypothalamus. Tangential AVP/GFAP migration routes and AVP/DCX neuronal chains as well as ascending AVP axonal scaffolds were observed. Chronic water deprivation significantly increased the BrdU+ nuclei within both the SON and PVN. These findings raise new questions about AVPMNS’s potential hormonal role for brain physiological adaptation across the lifespan, with possible involvement in coping with homeostatic adversities.