Senescence Effect on Gastric Parietal Cells in Male Albino Rats and the Impact of Nicotinamide Riboside (a NAD+ Precursor): Histological Study.

Introduction: Senescence is a normal succession in time and cell maturity with progressive structural and functional cellular changes. Its influence predisposes numerous non-communicable diseases such as neurodegenerative, metabolic and cardiovascular diseases, as well as cancers with subsequent high morbidities and mortalities. Gastrointestinal tract (GIT) manifestations are commonly associated with ageing starting from stomatitis to maldigestion and malabsorption. Nicotinamide adenine dinucleotide [NAD+], a co-enzyme in oxidative-phosphorylation and redox reactions in metabolism and energy production, is decreased in multiple ageing-associated pathological conditions and its replenishment reveals marked improvement in these conditions. Aim of the Work: This study aimed at evaluating the senescence sequelae on gastric parietal cells of male albino rats, the probable role of NAD+ and the potential protecting influence of nicotinamide riboside (NR) [a NAD+ precursor]. Materials and Methods: 18 male albino rats were grouped equally into the non-aged group [~3 months, group I], aged group [~24 months, group II] and aged/NR group [~24 months, group III] that received daily single oral dose of 200mg/kg NR for 3 weeks. Just before sacrifice, serum NAD+, gastrin and pepsinogen-I levels were assessed for all animals. Then, biochemical, histological, immunohistochemical [for H+/K+ ATPase & B-cell lymphoma-2 (Bcl-2)] and morphometric studies were done. Results: The senescence features demonstrated in the parietal cells of the aged rats were markedly ameliorated with 3 weeks oral intake of NR [a NAD+ precursor]. Conclusion: Ageing is a systemic process of NAD+ reduction and consequent oxidative stress, inflammageing, DNA damage and altered apoptosis. Parietal cells ageing results in GIT disturbances that may exacerbate ageing sequelae through induction of anaemia, and continuous NAD+ reduction. Most manifestations can be blocked by oral supplementation of a NAD+ precursor, especially NR as it has many advantages over the others. [ABSTRACT FROM AUTHOR]