Nobiletin (NOB), a naturally occurring small-molecule compound abundant in citrus peels, has displayed potential lipid-lowering and circadian-enhancing properties in preclinical studies. However, the requirement of specific clock genes for the beneficial effects of NOB is not well understood. In the current study, mice with a liver-specific deletion of the core clock component, Bmal1—Bmal1LKO—were fed a high-fat diet (HFD) ad libitum for eight weeks, while NOB (200 mg/kg) was administered by daily oral gavage from the fifth week and throughout the last four weeks. NOB decreased liver triglyceride (TG) alongside the decreasing mRNA levels of de novo lipogenesis (DNL) genes in both Bmal1^flox/flox and Bmal1LKO mice. NOB increased serum very low-density lipoprotein (VLDL) levels in Bmal1LKO mice, which was consistent with higher liver Shp and lower Mttp mRNA expression levels, the key genes that facilitate VLDL assembly and secretion. NOB decreased liver and serum cholesterol levels in the Bmal1^flox/flox mice, consistent with lower Hmgcr and higher Cyp7a1, Cyp8b1, Gata4 and Abcg5 mRNA levels in the liver. In contrast, in the Bmal1LKO mice, NOB increased Hmgcr mRNA levels and had no effect on the above-mentioned genes related to bile acid synthesis and cholesterol excretion, which might contribute to the elevation of liver and serum cholesterol levels in NOB-treated Bmal1LKO mice. NOB inhibited hepatic DNL and decreased liver TG levels in HFD-fed mice independently of liver Bmal1, whereas liver-specific Bmal1 depletion reversed the beneficial effects of NOB on liver cholesterol homeostasis. The complex interactions between NOB, the circadian clock and lipid metabolism in the liver warrant further research.

Background/Objectives: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic hepatic condition marked by lipid buildup, lipotoxicity, and inflammation. Prior research indicates that 3,3′-Diindolemethane (DIM), a natural indole-type phytochemical that is abundant in brassicaceae vegetables, has been reported to reduce body weight and improve lipid metabolism in mice subjected to a high-fat diet (HFD). The aryl hydrocarbon receptor (AhR), a nuclear receptor implicated in lipid metabolism and immune regulation, serves as a functional receptor for DIM. However, the underlying signaling pathways that regulate MAFLD remain elusive. Our objective is to ascertain the beneficial impact of DIM on MAFLD and the associated mechanisms. Methods: Hematoxylin and eosin staining, together with Oil Red O staining, were utilized to assess the pathological changes and lipid deposition in the liver. Biochemical analysis was employed to measure levels of triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), aspartate transaminase (AST), alanine transaminase (ALT), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). The cell survival rate of HepG2 cells treated with palmitic acid (PA) and DIM was assessed using the CCK-8 assay. Flow cytometry was employed to measure the fluorescence intensity emitted by lipid droplets within cells. Western blotting analysis was performed to assess AhR pathway and fatty acid transporter expression levels in hepatic tissue. Results: Our results showed that DIM significantly attenuated body weight gain and hepatic injury brought on by HFD, decreased lipid droplet accumulation in HepG2 cells, and effectively suppressed the phosphorylation of p38 MAPK and the protein expression levels of fatty acid transporters CD36 and FATP4. Conclusions: DIM reduced lipid accumulation by activating AhR and suppressing p38 MAPK phosphorylation, thereby inhibiting fatty acid transport and inflammatory responses. These findings suggest that DIM may represent a promising therapeutic candidate for MAFLD, warranting further exploration for clinical applications.

Caffeine intake can have numerous effects on neurological and cognitive impairments. However, its influences on offspring still need to be evaluated. This study aimed to investigate the effects of caffeine exposure during gestation on behavioral development, metabolic function, and circadian rhythms in offspring. A total of 96 Sprague–Dawley rats were included, with an equal number of males and females. After confirming pregnancy, the female rats were randomly divided into four groups on average and administered caffeine at three distinct doses (5, 20, and 80 mg/kg/day) or equivalent volumes of normal saline throughout the gestational period. The health status and weight gain of pregnant rats, as well as the litter size and body weight of offspring, were continuously monitored. Open field test, Morris water maze, intraperitoneal glucose tolerance tests (IPGTT) and intraperitoneal insulin tolerance tests (IPITTs) were performed. The expression levels of 7 circadian clock genes (Bmal1, Clock, Cry1, Cry2, Per1, Per2, and Rev-erbα) were quantified. This revealed a significant reduction in maternal weight gain in the 80 mg/kg caffeine group compared to controls. Although the birth weight of offspring was not significantly affected, the postnatal weight gain of offspring was slower in caffeine groups. Behavioral assessments demonstrated elevated spontaneous activity and increased anxiety-like behaviors in caffeine-exposed offspring. Metabolic evaluations indicated impaired glucose tolerance specifically in female offspring, though no significant alterations were observed in insulin sensitivity, spatial learning and memory performance. Maternal caffeine exposure during gestation also disrupted the rhythmicity of hepatic circadian clock gene expression in offspring rats. These findings suggest that gestational caffeine exposure exerts selective adverse effects on offspring development, behavior, glucose metabolism and circadian rhythm. Caffeine consumption during pregnancy necessitates careful consideration.