DCX‐expressing cells in the vicinity of the hypothalamic neurogenic niche: A comparative study between mouse, sheep, and human tissues

Abstract

Neural stem and precursor cells persist postnatally throughout adulthood and are capable of responding to numerous endogenous and exogenous signals by modifying their proliferation and differentiation. Whereas adult neurogenesis has been extensively studied in the dentate gyrus of the hippocampal formation and in the subventricular zone adjacent to the wall of the lateral ventricles, we and others have recently reported constitutive adult neurogenesis in other brain structures, including the hypothalamus. In this study, we used immunohistochemistry to study the expression of the neuroblast marker doublecortin (DCX), and compared its expression pattern in adult ovine, mouse, and human hypothalamic tissues. Our results indicate that DCX-positive cells resembling immature and developing neurons occur in a wide range of hypothalamic nuclei in all three species, although with different distribution patterns. In addition, the morphology of DCX-positive cells varied depending on their location. DCX-positive cells near the third ventricle had the morphology of very immature neuroblasts, a round shape with no processes, whereas those located deeper in the parenchyma such as in the ventromedial nucleus were fusiform and showed a bipolar morphology. Extending this observation, we showed that among the cohort of immature neurons entering the ventromedial nucleus, some appeared to undergo maturation, as revealed by the partial colocalization of DCX with markers of more mature neurons, e.g., human neuronal protein C and D (HuC/D). This study provides further confirmation of the existence of an adult hypothalamic neurogenic niche and argues for the potential existence of a migratory path within the hypothalamus.

Heterogeneous vascular permeability and alternative diffusion barrier in sensory circumventricular organs of adult mouse brain

“…GFAP is expressed by not only astrocytes but also tanycytes in the CVOs (Robins et al 2013;Batailler et al 2014). The density of the GFAP-positive astrocytes/tanycytes was apparently higher at distal subdivisions of the sensory CVOs as compared with central subdivisions; the lateral zone (vs capillary plexus) in the OVLT (Fig.…”

Changes in hippocampal neurogenesis throughout early development

“…Here, dentate DCX expression was used as surrogate marker of neurogenesis (Couillard-Despres et al, 2005), to examine the impact of increasing age on total numbers of late progenitor cells (neuroblasts) and immature postmitotic newborn neurons. It should be mentioned however that DCX expression is not limited to the "canonical" neurogenic regions (hippocampus and SVZ/olfactory bulb) as DCXþ cells have been described in the adult striatum, corpus callosum, piriform cortex, amygdala, and hypothalamus (Batailler et al, 2014;Klempin et al, 2011;Marlatt et al, 2011;Martí-Mengual et al, 2013;Saaltink et al, 2012;Zhang et al, 2009).…”

Increasing Adult Hippocampal Neurogenesis is Sufficient to Reduce Anxiety and Depression-Like Behaviors

“…Recently, studies have suggested the presence of adultneurogenesis in the hypothalamus (Batailler et al, 2014;Saaltink et al, 2012), involved in maintaining weight and metabolism (Lee and Blackshaw, 2012). To determine Figure 1 In the absence of stress, genetically increasing adult hippocampal neurogenesis in iBax mice increases adult hippocampal neurogenesis, but does not affect anxiety-and antidepressant-responsive behavior.…”