The hippocampus, a brain region critical for learning, memory and emotional processing, maintains its capacity to undergo structural plasticity throughout life. Hippocampal structural plasticity can be modulated by a number of intrinsic and extrinsic factors. This study investigated the effects of adiponectin, an adipocyte-derived hormone, on dendritic growth, arborization, and spinogenesis in mature granule neurons of the hippocampal dentate gyrus generated during embryonic (early-born) or early postnatal (late-born) stages. We found that adiponectin deficiency reduced dendritic length, branching and spine density of granule neurons. The reduction was more evident in early-born granule neurons than in late-born granule neurons. Intracerebroventricular infusion of adiponectin for 1 week increased of dendritic spines and arbor complexity in late-born granule neurons. Moreover, adiponectin deficiency decreased the production of adult-born new granule neurons through suppressing neural progenitor cell proliferation and differentiation, whereas intracerebroventricular adiponectin infusion increased the proliferation of neural progenitor cells in adult dentate gyrus. These results suggest that adiponectin plays an important role in dendritic spine remodeling and neurogenesis in the dentate gyrus.
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