A ketogenic diet containing medium-chain triglycerides reduces REM sleep duration without significant influence on mouse circadian phenotypes.

Ketogenic diets (KDs) affect the circadian rhythms of behavior and clock gene expression in experimental animals. However, these diets were designed to simulate a fasting state; thus, whether these effects are caused by diet-induced ketogenesis or persistent starvation is difficult to distinguish. The present study aimed to define the effects of a KD containing medium-chain triglycerides (MCT-KD) that increase blood ketone levels without inducing carbohydrate starvation, on circadian rhythms and sleep regulation. Mice were fed with a normal diet (CTRL) or MCT-KD for 2 weeks. Blood ß-hydroxybutyrate levels were significantly increased up to 2 mM by the MCT-KD, whereas body weight gain and blood glucose levels were identical between the groups, suggesting that ketosis accumulated without carbohydrate starvation in the MCT-KD mice. Circadian rhythms of wheel-running activity and core body temperature were almost identical, although wheel-running was slightly reduced in the MCT-KD mice. The circadian expression of the core clock genes, Per1, Per2, Bmal1, and Dbp in the hypothalamus, heart, liver, epididymal adipose tissues, and skeletal muscle were almost identical between the CTRL and MCT-KD mice, whereas the amplitude of hepatic Per2 and adipose Per1 expression was increased in MCT-KD mice. The MCT-KD reduced the duration of rapid-eye-movement (REM) sleep without affecting the duration of non-REM sleep and the duration of wakefulness. These findings suggested that the impact of ketone bodies on circadian systems are limited, although they might reduce locomotor activity and REM sleep duration.

Identification of salivary microRNA profiles in male mouse model of chronic sleep disorder.

Chronic sleep disorders (CSD) comprise a potential risk factor for metabolic and cardiovascular diseases, obesity and stroke. Thus, the identification of biomarkers for CSD is an important step in the early prevention of metabolic dysfunctions induced by sleep dysfunction. Diagnostic saliva samples can be easily and noninvasively collected. Thus, we aimed to identify whole microRNA (miRNA) profiles of saliva in control and psychophysiologically stressed CSD mouse models and compare them at Zeitgeber time (ZT) 0 (lights on) and ZT12 (lights off). The findings of two-way ANOVA revealed that the expression of 342 and 109 salivary miRNAs was affected by CSD and the time of day, respectively. Interactions were found in 122 miRNAs among which, we identified 197 (ZT0) and 62 (ZT12) upregulated, and 40 (ZT0) and seven (ZT12) downregulated miRNAs in CSD mice. We showed that miR-30c-5p, which is elevated in the plasma of patients with hypersomnia, was upregulated in the saliva of CSD mice collected at ZT0. The miRNAs, miR-10a-5p, miR-146b-5p, miR-150-5p, and miR-25-3p are upregulated in the serum of humans with poor sleep quality, and these were also upregulated in the saliva of CSD mice collected at ZT0. The miRNAs miR-30c, miR146b-5p, miR150, and miR-25-5p are associated with cardiovascular diseases, and we found that plasma concentrations of brain natriuretic peptides were significantly increased in CSD mice. The present findings showed that salivary miRNA profiles could serve as useful biomarkers for predicting CSD.

Ketogenic diet containing medium-chain triglyceride ameliorates transcriptome disruption in skeletal muscles of rat models of duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a myopathy characterized by progressive muscle weakness caused by a mutation in the dystrophin gene on the X chromosome. We recently showed that a medium-chain triglyceride-containing ketogenic diet (MCTKD) improves skeletal muscle myopathy in a CRISPR/Cas9 gene-edited rat model of DMD. We examined the effects of the MCTKD on transcription profiles in skeletal muscles of the model rats to assess the underlying mechanism of the MCTKD-induced improvement in DMD. DMD rats were fed MCTKD or normal diet (ND) from weaning to 9 months, and wild-type rats were fed with the ND, then tibialis anterior muscles were sampled for mRNA-seq analysis. Pearson correlation heatmaps revealed a one-node transition in the expression profile between DMD and wild-type rats. A total of 10,440, 11,555 and 11,348 genes were expressed in the skeletal muscles of wild-type and ND-fed DMD rats the MCTKD-fed DMD rats, respectively. The MCTKD reduced the number of DMD-specific mRNAs from 1624 to 1350 and increased the number of mRNAs in common with wild-type rats from 9931 to 9998. Among 2660 genes were differentially expressed in response to MCTKD intake, the mRNA expression of 1411 and 1249 of them was respectively increased and decreased. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses suggested that the MCTKD significantly suppressed the mRNA expression of genes associated with extracellular matrix organization and inflammation. This suggestion was consistent with our previous findings that the MCTKD significantly suppressed fibrosis and inflammation in DMD rats. In contrast, the MCTKD significantly increased the mRNA expression of genes associated with oxidative phosphorylation and ATP production pathways, suggesting altered energy metabolism. The decreased and increased mRNA expression of Sln and Atp2a1 respectively suggested that Sarco/endoplasmic reticulum Ca2+-ATPase activation is involved in the MCTKD-induced improvement of skeletal muscle myopathy in DMD rats. This is the first report to examine transcription profiles in the skeletal muscle of CRISPR/Cas9 gene-edited DMD model rats and the effect of MCTKD feeding on it.

A medium-chain triglyceride containing ketogenic diet exacerbates cardiomyopathy in a CRISPR/Cas9 gene-edited rat model with Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked recessive myopathy caused by dystrophin mutations. Although respiratory management has improved the prognosis of patients with DMD, inevitable progressive cardiomyopathy is a current leading cause of premature death. Recently, we showed that a medium-chain triglyceride containing ketogenic diet (MCTKD) improves skeletal muscle function and pathology in a CRISPR/Cas9 gene-edited rat model with DMD. In this study, we sought to clarify whether MCTKD also improves the cardiomyopathy in these rats. DMD rats were fed either the MCTKD or normal diet (ND) from ages of 3 weeks to 9 months old. Compared with the ND-fed rats, MCTKD-fed rats showed significantly prolonged QRS duration, decreased left ventricular fractional shortening, an increased heart weight/body weight ratio, and progression of cardiac fibrosis. In contrast to our previous study which found that MCTKD improved skeletal myopathy, the current study showed unexpected exacerbation of the cardiomyopathy. Further studies are needed to explore the underlying mechanisms for these differences and to explore modified dietary options that improve skeletal and cardiac muscles simultaneously.

Ketogenic diet with medium-chain triglycerides restores skeletal muscle function and pathology in a rat model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an intractable genetic disease associated with progressive skeletal muscle weakness and degeneration. Recently, it was reported that intraperitoneal injections of ketone bodies partially ameliorated muscular dystrophy by increasing satellite cell (SC) proliferation. Here, we evaluated whether a ketogenic diet (KD) with medium-chain triglycerides (MCT-KD) could alter genetically mutated DMD in model rats. We found that the MCT-KD significantly increased muscle strength and fiber diameter in these rats. The MCT-KD significantly suppressed the key features of DMD, namely, muscle necrosis, inflammation, and subsequent fibrosis. Immunocytochemical analysis revealed that the MCT-KD promoted the proliferation of muscle SCs, suggesting enhanced muscle regeneration. The muscle strength of DMD model rats fed with MCT-KD was significantly improved even at the age of 9 months. Our findings suggested that the MCT-KD ameliorates muscular dystrophy by inhibiting myonecrosis and promoting the proliferation of muscle SCs. As far as we can ascertain, this is the first study to apply a functional diet as therapy for DMD in experimental animals. Further studies are needed to elucidate the underlying mechanisms of the MCT-KD-induced improvement of DMD.