Dietary restriction reduces hippocampal neurogenesis and granule cell neuron density without affecting the density of mossy fibers

Abstract

The hippocampal formation undergoes significant morphological and functional changes after prolonged caloric and dietary restriction (DR). In this study we tested whether prolonged DR results in deleterious alterations in hippocampal neurogenesis, density of granule cell neurons and mossy fibers, all of which support plasticity in the dentate gyrus. Young adult animals either experienced free access to food (control condition), or every-other-day feeding regimen (DR condition) for 3 months. The number of Ki-67 cells and 28-day old 5-bromo-2’-deoxyuridine (BrdU) cells were quantified in the dorsal and ventral dentate gyrus to determine the effect of DR on cellular proliferation and survival of neural progenitor cells in the anatomically defined regions of the dentate gyrus. The density of granule cell neurons and synaptoporin were also quantified to determine the effect of DR on granule cell neurons and mossy fiber projections in the dentate gyrus. Our results show that DR increases cellular proliferation and concurrently reduces survival of newly born neurons in the ventral dentate gyrus without effecting the number of cells in the dorsal dentate gyrus. DR reduced density of granule cell neurons in the dorsal dentate gyrus. These alterations in the number of granule cell neurons did not affect mossy fiber density in DR animals, which was visualized as no differences in synaptoporin expression. Our findings demonstrate that granule cell neurons in the dentate gyrus are vulnerable to chronic DR and that the reorganization of granule cells in the dentate gyrus subregions is not producing concomitant alterations in dentate gyrus neuronal circuitry with this type of dietary restriction.

Hippocampal neural progenitor cells play a distinct role in fear memory retrieval in male and female CIE rats

“…For morphometric analysis of the density of mossy fiber projections, dorsal hippocampal sections (representing −2.56 and −4.8mm from bregma, 4 sections per rat) were separately stained for synaptoporin (1:50, Rabbit polyclonal, SynapticSystems) followed by biotin-tagged secondary antibodies and visualized with DAB (Staples et al , 2017). For mossy fiber density, images were captured at 10x and synaptoporin in the hilus of the dorsal DG was evaluated by quantifying DAB stain (% area stained; (Galinato et al , 2018)) using ImageJ software (NIH).…”

Moderate Differences in Feeding Diets Largely Affect Motivation and Spatial Cognition in Adult and Aged but Less in Young Male Rats

“…Water maze experiments were performed at relatively cold water (21°C), which heavily affects water maze performance ( Salehi et al, 2010 ). Staples et al (2017) , however, found reduced dentate gyrus neurogenesis and granule cell density in forced food restricted rats, when restriction started at an age of 2 months, whereas Lee et al (2000) found increased neurogenesis after dietary restriction started at an age of 3 months and lasting for 3 months in rats.…”

Sex Differences in Context-Driven Reinstatement of Methamphetamine Seeking is Associated with Distinct Neuroadaptations in the Dentate Gyrus

“…For morphometric analysis of the density of mossy fiber projections, dorsal hippocampal sections (representing −2.56 and −4.8 mm from bregma, 4 sections per rat) were separately stained for synaptoporin [29]. For mossy fiber density, images were captured at 10× and the mossy fiber tracts were combined for density measures.…”