Sweet cherries modulate thyroid hormones and hepatic glucose metabolism in F344 rats in a photoperiod-dependent manner

Abstract

Sweet cherry intake affects oxidative stress and hepatic lipid metabolism, depending on composition, mainly (poly)phenol profile and daylight length. Thyroid hormones (TH) respond to daylight changes and regulate the hepatic glucose metabolism. This study investigated whether cherries with different phenolic hallmarks exhibit seasonal responses to TH and hepatic glucose metabolism. Fischer 344 rats fed a standard diet were chronically exposed to L6 (6 h light), L12 (12 h light), and L18 (18 h light) photoperiods and were supplemented with two sweet cherries (Ch1 and Ch2). Serum TH levels and glucose metabolism-related metabolites were affected by both the cherry composition and photoperiod. Thus, Ch1 and Ch2 reduced serum T3 levels in L6, whereas Ch2 increased it in L18, nullifying the photoperiod effect. Moreover, although photoperiod was the main factor affecting the hepatic expression of gluconeogenesis-related genes, Ch1 exerted effects mainly on L6 photoperiod and Ch2 on L18, tending to cancel out the photoperiod effects.