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Alzheimer’s disease (AD) is the most prevalent human neurodegenerative disease. Disturbances of brain glucose uptake, glucose tolerance, glucose utilization and of the insulin/insulin receptor signaling cascade are thought to be key features of the pathophysiology of AD. Changes in energy homeostasis in the brain and in the periphery dramatically influence the proliferation of adult neural stem cells and neurogenesis in the hippocampus. Recent findings suggest that adult neurogenesis is altered in the hippocampus of AD patients and in various animal models of AD. Several factors associated with the pathogenesis of AD are also known to be involved in the regulation of adult neurogenesis. Understanding the mechanisms underlying these changes at different stages of AD could provide insights into its pathogenesis, contribute to identifying biomarkers of early AD, and supply fundamental knowledge that will allow novel therapeutic approaches to treating AD by intervening in adult neurogenesis. In this review we provide an overview of the connections between energy metabolism, adult neurogenesis and AD.

Altered adult hippocampal neurogenesis (AN) plays a role in the etiopathology of Alzheimer’s disease (AD), a disorder characterized by a progressive loss of memory and spatial orientation impairment. Diabetes is shown to be one risk factor for the development of the sporadic form of AD (sAD), which affects >95% of AD patients. Streptozotocin intracerebroventricularily (STZ icv) treated rats, which develop an insulin-resistant brain state and learning and memory deficits preceding amyloid beta and tau pathology, may act as an appropriate animal model for sAD. The goal of our quantitative immunohistochemistry study was to compare short-term (1 month) and long-term (3 months) effects of STZ icv treatment on different AN stages. Applying MCM2 antibodies we quantified cell (e.g. stem cell) proliferation, by the use of NeuroD and DCX antibodies we analyzed immature neurons. BrdU incorporation with approximately 27 days of survival before sacrifice allowed us to quantify and identify surviving newborn cells. Performing co-localization studies with antibodies detecting BrdU and cell-type specific markers we could confirm that STZ treatment does not affect the differentiation fate of newly generated cells. Whereas STZ icv treatment does not seem to considerably influence cell proliferation over a shortterm period (1 month), in the long-term (3 months) it significantly decreased generation of immature and mature neurons. This reduction seen after 3 months was specific for the septal hippocampus, discussed to be important for spatial learning. Moreover, AN changes display the same timeline as the development of amyloid beta pathology in this animal model of sAD.