The combination of nicotinamide mononucleotide and lycopene prevents cognitive impairment and attenuates oxidative damage in D-galactose induced aging models via Keap1-Nrf2 signaling

Aging is referred to progressive dysfunction of body organs, including the brain. This study aims to explore the anti-aging effect of combing nicotinamide mononucleotide (NMN) and lycopene (Lyco) (NMN + Lyco) on aging rats and senescent PC12 cells. Both in vivo and in vitro aging models were established using D-galactose (D-gal). The combination showed a trend to superiority over monotherapy in preventing aging in vivo and in vitro. Morris water maze test showed that NMN + Lyco effectively improved the ability of spatial location learning and memory of aging model rats. NMN + Lyco mitigated the oxidative stress of rat brains, livers, and PC12 cells by elevating the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), GSH, as well as total antioxidant capacity (T-AOC), and reducing malondialdehyde (MDA) content. CCK-8 assay, senescence-associated β-galactosidase staining, and flow cytometer confirmed the cellular senescence of PC12 cells after exposing D-gal, and indicated the anti-senescence effect of NMN + Lyco in vitro. Moreover, NMN + Lyco effectively down-regulated the expressions of p53, p21, and p16 (senescence-related genes), and activated Keap1-Nrf2 signaling in both in vivo and in vitro aging models. In total, NMN + Lyco protected rats and PC12 cells from cognitive impairment and cellular senescence induced by D-gal, of which effects might be linked to the reduction of oxidative stress and the activation of Keap1-Nrf2 signaling.