Aging, neurogenesis, and caloric restriction in different model organisms

Abstract

Brain aging is a multifactorial process that is occurring across multiple cognitive domains. A significant complaint that occurs in the elderly is a decrement in learning and memory ability. Both rodents and zebrafish exhibit a similar problem with memory during aging. The neurobiological changes that underlie this cognitive decline are complex and undoubtedly influenced by many factors. Alterations in the birth of new neurons and neuron turnover may contribute to age-related cognitive problems. Caloric restriction is the only non-genetic intervention that reliably increases life span and healthspan across multiple organisms although the molecular mechanisms are not well-understood. Recently the zebrafish has become a popular model organism for understanding the neurobiological consequences but to date very little work has been performed. Similarly, few studies have examined the effects of dietary restriction in zebrafish. Here we review the literature related to memory decline, neurogenesis, and caloric restriction across model organisms and suggest that zebrafish has the potential to be an important animal model for understanding the complex interactions between age, neurobiological changes in the brain, and dietary regimens or their mimetics as interventions.

Keywords: Age; Dietary Restriction; Neuron Turnover; Synapses; Zebrafish.

Figure 1:

Schematic diagram of the rodent hippocampus illustrating principal areas as well as main excitatory connectivity. CA1, CA3, dentate gyrus (DG), subgranular layer (SGL), perforant path (PP), entorhinal cortex (EC), mossy fiber (MF) and schafer collateral (SC) are shown.

Figure 2.

Schematic drawings of zebrafish brain anatomy showing the dorsal and ventral telencephalic regions. Drawing corresponds to the cross section 71 of the Wullimann atlas [83]. Medial pallium is shown with dashed lines which is the ventral division of the lateral zone of area dorsalis (Dlv) according to Wullimann and Mueller [84]. D, dorsal telencephalic area; Dc, central zone of D; Dl, lateral zone of D; Dm, medial zone of D; Dp, posterior zone of D; LOT, lateral olfactory tract; MOT, medial olfactory tract; V, ventral telencephalic area; Vc, central nucleus of V; Vd, dorsal nucleus of V; Vl, lateral nucleus of V; Vv, ventral nucleus of V.