Caloric Restriction Effect on MAPK and MMP-1 Levels in the Skin of Male Wistar Rats (Rattus norvegicus) Exposed to Ultraviolet B Radiation

Abstract

ABSTRACT:
Introduction: Skin aging is greatly caused by prolonged exposure to ultraviolet (UV) radiation, reflected in the increased production of various molecular products, including mitogen-activated protein kinase (MAPK). This is followed by the activation of the activator protein-1 (AP-1) complex, leading to increased production of one type of collagenase matrix metalloproteinase (MMP) enzymes, MMP-1. MAPK and MMP-1 pathway contributes to the photo-aging process, manifests in formation of wrinkles and loss of skin elasticity. Caloric restriction is a method of limiting energy intake from the diet while ensuring sufficient energy for metabolic homeostasis. By suppressing the MAPK pathway and reducing MMP-1 production, caloric restriction is expected to enhance proteostasis and autophagy in skin cells, thereby mitigating damage caused by UVB exposure.

Objectives: This study aimed to evaluate the role of caloric restriction in supressing MAPK and MMP-1 levels on skin exposed to UVB radiation.

Methods: Experimental study was conducted on 30 Wistar rats, which were further divided into five groups: K1 (normal), K2 (UVB radiation + normal diet), P1 (UVB radiation + 20% caloric restriction), P2 (UVB radiation + 30% caloric restriction), and P3 (UVB radiation + 40% caloric restriction). Caloric restriction was given for 2 weeks before and throughout UVB exposure. UVB irradiation was conducted for 4 weeks with a total dose of 480 mJ/cm². ELISA analysis of MAPK and MMP-1 levels in skin tissue was done at 48 hours after last irradiation.

Results: Statistical analysis test showed no significant differences in MAPK and MMP-1 levels among the groups (p > 0.05; 0.164 and 0.139, respectively).

Conclusions: Caloric restriction does not prevent the increase in MAPK and MMP-1 levels in the skin of Wistar rats exposed to UVB radiation.