Castration alters the circadian clock and Ucp1 expression in subcutaneous white adipose tissue of mice

Castration increases the risk of metabolic syndromes in mammals. In addition, recent studies have demonstrated that castration increases the expression of Ucp1 in subcutaneous white adipose tissue (scWAT). However, how castration leads to thermogenic aberration remains poorly understood. Here, we found that castrated mice showed elevated Ucp1 expression in scWAT in response to cold exposure with an increase in body temperature in the light phase and a reduction in body weight gain with fat reduction despite showing no alterations in food intake, locomotor activity in a novel environment, and gastrocnemius muscle weight. We also analyzed the circadian behavioral rhythm and the expression rhythm of clock genes in the suprachiasmatic nucleus (SCN) and scWAT. We found that castrated mice showed fluctuations in circadian locomotor activity and a decrease in the expression rhythm of clock genes in the SCN ( clock ) and scWAT ( Bmal1 and Per2 ). Moreover, the expression of Ucp1 in scWAT was rhythmic, and it was increased in castrated mice, while the expression of clock genes was decreased. These results indicate that castration may impact browning in scWAT through variations in the circadian clock and Ucp1 expression.