SIRT1 Controls Enteroendocrine Progenitor Cell Proliferation in High-Fat Diet-Fed Mice.

Background & Aims: We aimed to investigate how sirtuin 1 (SIRT1), a conserved mammalian Nicotinamide adenine dinucleotide-dependent protein deacetylase, regulates the number of enteroendocrine cells (EECs). EECs benefit metabolism, and their increase potentially could treat type 2 diabetes and obesity.

Methods: We used mice with specific Sirt1 disruption in the intestinal epithelium (VilKO, villin-Cre, and Sirt1 mice) or enteroendocrine progenitor cells (EEPCs) (NgnKO, neurogenin 3-Cre, Sirt1 mice) and mice with increased SIRT1 activity owing to overexpression (Sir2d mice) or 24-hour fasting.

Blood levels of nicotinic acid negatively correlate with hearing ability in healthy older men.

Background: Age-related hearing loss (ARHL) is a common phenomenon observed during aging. On the other hand, the decrease in Nicotinamide adenine dinucleotide (NAD +) levels is reported to be closely related to the age-related declines in physiological functions such as ARHL in animal studies. Moreover, preclinical studies confirmed NAD + replenishment effectively prevents the onset of age-related diseases.

Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men.

Preclinical studies have revealed that the elevation of nicotinamide adenine dinucleotide (NAD + ) upon the administration of nicotinamide mononucleotide (NMN), an NAD + precursor, can mitigate aging-related disorders; however, human data on this are limited. We investigated whether the chronic oral supplementation of NMN can elevate blood NAD + levels and alter physiological dysfunctions in healthy older participants. We administered 250 mg NMN per day to aged men for 6 or 12 weeks in a placebo-controlled, randomized, double-blind, parallel-group trial.