Nighttime light exposure enhances Rev-erbα-targeting microRNAs and contributes to hepatic steatosis

Abstract

Thus, altered miRNAs profile is an important mechanism underlying the disruption of the peripheral clock caused by exposure to ALAN, which could lead to hepatic steatosis.

Differential Effects of Constant Light and Dim Light at Night on the Circadian Control of Metabolism and Behavior

“…Constant light did not influence total 24 h food intake [51,61,62,[73][74][75], but the daily variation was suppressed mostly due to increased food consumption in mice during the subjective day [51,61,62,73,74]. On the other hand, total food intake was reduced in mice fed a high-fat diet [61].…”

“…In mice, most studies have shown the loss of daily variation in metabolic measures due to LL conditions (Table 1). Insulin sensitivity was diminished during the subjective night, causing the loss of diurnal variation [51,61], which is in line with changes in insulin and glucose levels [51], as well as endogenous glucose production [61]. Glucose tolerance was impaired during the subjective day [62,74].…”

“…On the other hand, total food intake was reduced in mice fed a high-fat diet [61]. These results suggest that the abnormal distribution of food intake can initiate elevated body weight gain [51,61,73,74] together with fat mass (Table 1) [51,72,74]. Even if the body mass is equal to the control group, the increase in fat mass and adipocyte size is observed [72].…”

“…Melatonin levels in mice vary greatly and many strains do not even produce this hormone [50], therefore, there are not much data on how LL influences melatonin levels. However, urinary 6-sulfatoxymelatonin is suppressed in melatonin-producing mice (CH3-HePas mice) during the subjective night in LL [51]. Unlike mice, rats produce melatonin, and its synthesis is highly sensitive to light exposure [52,53] (Table 1).…”

“…The inefficient activity of brown adipose tissue and its lowered nutrient uptake can result in the lipid accumulation in the white adipose tissue [72]. After LL exposure, lost rhythmicity between subjective day and night was described in hepatic lipogenesis enzymes, fatty acid synthase and ATP citrate lyase, due to their elevated expression during the subjective day [51]. All these alterations lead to increased fat mass [51,62,72,74] and ectopic accumulation of lipids observed after exposure to LL [51,74].…”