Combination of tea catechins and ornithine effectively activates the urea cycle: an in vitro and human pilot study.

PURPOSE: Accumulation of ammonia causes central and peripheral fatigue. This study aimed to investigate the synergistic effect of tea catechins and low-dose ornithine in activating the urea cycle to reduce blood ammonia levels during exercise. METHODS: We used hepatocyte-like cells derived from human-induced pluripotent stem (iPS) cells to assess the effect of tea catechins combined with ornithine on urea cycle activity. The urea production and expression of key genes involved in the metabolism of urea were investigated. We then examined the synergistic improvement in ammonia metabolism by tea catechins in combination with ornithine in a human pilot study. RESULTS: Tea catechins combined with ornithine increased urea cycle activity in hepatocyte-like cells derived from human iPS cells. Intake of 538.6 mg of tea catechins with 1592 mg of ornithine for 2 consecutive days during exercise loading suppressed the exercise-induced increase in the blood ammonia concentration as well as stabilized blood glucose levels. CONCLUSION: Controlling the levels of ammonia, a toxic waste produced in the body, is important in a variety of situations, including exercise. The present study suggests that a heterogeneous combination of polyphenols and amino acids efficiently suppresses elevated ammonia during exercise in humans by a mechanism that includes urea cycle activation. TRIAL REGISTRATION: This study was registered in the University Hospital Medical Information Network Clinical Trial Registry (No. UMIN000035484, dated January 8, 2019).

Assessment of Multidimensional Health Care Parameters Among Adults in Japan for Developing a Virtual Human Generative Model: Protocol for a Cross-sectional Study.

BACKGROUND: Human health status can be measured on the basis of many different parameters. Statistical relationships among these different health parameters will enable several possible health care applications and an approximation of the current health status of individuals, which will allow for more personalized and preventive health care by informing the potential risks and developing personalized interventions. Furthermore, a better understanding of the modifiable risk factors related to lifestyle, diet, and physical activity will facilitate the design of optimal treatment approaches for individuals. OBJECTIVE: This study aims to provide a high-dimensional, cross-sectional data set of comprehensive health care information to construct a combined statistical model as a single joint probability distribution and enable further studies on individual relationships among the multidimensional data obtained. METHODS: In this cross-sectional observational study, data were collected from a population of 1000 adult men and women (aged ≥20 years) matching the age ratio of the typical adult Japanese population. Data include biochemical and metabolic profiles from blood, urine, saliva, and oral glucose tolerance tests; bacterial profiles from feces, facial skin, scalp skin, and saliva; messenger RNA, proteome, and metabolite analyses of facial and scalp skin surface lipids; lifestyle surveys and questionnaires; physical, motor, cognitive, and vascular function analyses; alopecia analysis; and comprehensive analyses of body odor components. Statistical analyses will be performed in 2 modes: one to train a joint probability distribution by combining a commercially available health care data set containing large amounts of relatively low-dimensional data with the cross-sectional data set described in this paper and another to individually investigate the relationships among the variables obtained in this study. RESULTS: Recruitment for this study started in October 2021 and ended in February 2022, with a total of 997 participants enrolled. The collected data will be used to build a joint probability distribution called a Virtual Human Generative Model. Both the model and the collected data are expected to provide information on the relationships between various health statuses. CONCLUSIONS: As different degrees of health status correlations are expected to differentially affect individual health status, this study will contribute to the development of empirically justified interventions based on the population. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/47024.

Tyrosine Is a Booster of Leucine-Induced Muscle Anabolic Response.

Leucine (Leu), an essential amino acid, is known to stimulate protein synthesis in the skeletal muscle via mTOR complex 1 (mTORC1) activation. However, the intrinsic contribution of other amino acids to Leu-mediated activation of mTORC1 signaling remains unexplored. This study aimed to identify amino acids that can promote mTORC1 activity in combination with Leu and to assess the effectiveness of these combinations in vitro and in vivo. We found that tyrosine (Tyr) enhanced Leu-induced phosphorylation of S6 kinase (S6K), an indicator of mTORC1 activity, although it exerted no such effect individually. This booster effect was observed in C2C12 cells, isolated murine muscle, and the skeletal muscles of mice orally administered the amino acids. To explore the molecular mechanisms underlying this Tyr-mediated booster effect, the expression of the intracellular Leu sensors, Sestrin1 and 2, was suppressed, and the cells were treated with Leu and Tyr. This suppression enabled Tyr alone to induce S6K phosphorylation and enhanced the booster effect, suggesting that Tyr possibly contributes to mTORC1 activation when Sestrin-GAP activity toward Rags 2 (GATOR2) is dissociated through Sestrin knockdown or the binding of Sestrins to Leu. Collectively, these results indicate that Tyr is a key regulator of Leu-mediated protein synthesis.

The Impact of Milk Fat Globule Membrane with Exercise on Age-Related Degeneration of Neuromuscular Junctions.

Morphological changes in neuromuscular junctions (NMJs), which are synapses formed between α-motor neurons and skeletal muscle fibers, are considered to be important in age-related motor dysfunction. We have previously shown that the intake of dietary milk fat globule membrane (MFGM) combined with exercise attenuates age-related NMJ alterations in the early phase of aging. However, it is unclear whether the effect of MFGM with exercise on age-related NMJ alterations persists into old age, and whether intervention from old age is still effective when age-related changes in NMJs have already occurred. In this study, 6- or 18-month-old mice were treated with a 1% MFGM diet and daily running wheel exercise until 23 or 24 months of age, respectively. MFGM treatment with exercise was effective in suppressing the progression of age-related NMJ alterations in old age, and even after age-related changes in NMJs had already occurred. Moreover, the effect of MFGM intake with exercise was not restricted to NMJs but extended to the structure and function of peripheral nerves. This study demonstrates that MFGM intake with exercise may be a novel approach for improving motor function in the elderly by suppressing age-related NMJ alterations.

DOK7 Gene Therapy Enhances Neuromuscular Junction Innervation and Motor Function in Aged Mice.

Muscle denervation at the neuromuscular junction (NMJ), the essential synapse between motor neuron and skeletal muscle, is associated with age-related motor impairment. Therefore, improving muscle innervation at aged NMJs may be an effective therapeutic strategy for treating the impairment. We previously demonstrated that the muscle protein Dok-7 plays an essential role in NMJ formation, and, indeed, its forced expression in muscle enlarges NMJs. Moreover, therapeutic administration of an adeno-associated virus vector encoding human Dok-7 (DOK7 gene therapy) suppressed muscle denervation and enhanced motor activity in a mouse model of amyotrophic lateral sclerosis (ALS). Here, we show that DOK7 gene therapy significantly enhances motor function and muscle strength together with NMJ innervation in aged mice. Furthermore, the treated mice showed greatly increased compound muscle action potential (CMAP) amplitudes compared with the controls, suggesting enhanced neuromuscular transmission. Thus, therapies aimed at enhancing NMJ innervation have potential for treating age-related motor impairment.

Involvement of ammonia metabolism in the improvement of endurance performance by tea catechins in mice.

Blood ammonia increases during exercise, and it has been suggested that this increase is both a central and peripheral fatigue factor. Although green tea catechins (GTCs) are known to improve exercise endurance by enhancing lipid metabolism in skeletal muscle, little is known about the relationship between ammonia metabolism and the endurance-improving effect of GTCs. Here, we examined how ammonia affects endurance capacity and how GTCs affect ammonia metabolism in vivo in mice and how GTCs affect mouse skeletal muscle and liver in vitro. In mice, blood ammonia concentration was significantly negatively correlated with exercise endurance capacity, and hyperammonaemia was found to decrease whole-body fat expenditure and fatty acid oxidation-related gene expression in skeletal muscle. Repeated ingestion of GTCs combined with regular exercise training improved endurance capacity and the expression of urea cycle-related genes in liver. In C2C12 myotubes, hyperammonaemia suppressed mitochondrial respiration; however, pre-incubation with GTCs rescued this suppression. Together, our results demonstrate that hyperammonaemia decreases both mitochondrial respiration in myotubes and whole-body aerobic metabolism. Thus, GTC-mediated increases in ammonia metabolism in liver and resistance to ammonia-induced suppression of mitochondrial respiration in skeletal muscle may underlie the endurance-improving effect of GTCs.

Epidural Spinal Cord Stimulation Improves Motor Function in Rats With Chemically Induced Parkinsonism.

Background. Epidural stimulation of the spinal cord can reorganize and change the excitability of the neural circuitry to facilitate stepping in rats with a complete spinal cord injury. Parkinson's disease results in abnormal supraspinal signals from the brain to the spinal cord that affect the functional capacity of the spinal networks. Objective. The objective was to determine whether epidural stimulation (electrical enabling motor control, eEmc) of the lumbosacral spinal cord can reorganize the spinal networks to facilitate hindlimb stepping of rats with parkinsonism. Methods. A unilateral 6-OHDA (6-hydroxydopamine) lesion of the nigrostriatal pathway was used to induce parkinsonism. Sham rats (N = 4) were injected in the same region with 0.1% of ascorbic acid. Stimulation electrodes were implanted epidurally at the L2 and S1 (N = 5) or L2 (N = 5) spinal levels. Results. The 6-OHDA rats showed severe parkinsonism in cylinder and adjusting step tests and were unable to initiate stepping when placed in a running wheel and dragged their toes on the affected side during treadmill stepping. During eEmc, the 6-OHDA rats initiated stepping in the running wheel and demonstrated improved stepping quality. Conclusion. Stepping was facilitated in rats with parkinsonism with spinal cord stimulation. The underlying assumption is that the normal functional capacity of spinal networks is affected by supraspinal pathology associated with Parkinson's disease, which either generates insufficient or abnormal descending input to spinal networks and that eEmc can appropriately modulate spinal and supraspinal networks to improve the motor deficits.

Continuous Supplementation of Milk Fat Globule Membrane with Habitual Exercise from a Young Age Improves Motor Coordination and Skeletal Muscle Function in Aged Mice.

Since the decline of physical performance gradually progresses with aging, continuous exercise with nutritional supplementation from a young age is a feasible and effective way to maintain a comfortable life until late old age. We examined the effects of continuous milk fat globule membrane (MFGM) supplementation combined with voluntary running exercise (VR) for prevention of aging-associated declines in physical performance in naturally aging mice. The MFGM with VR group showed a significantly attenuated age-related decline in motor coordination and suppression of the loss of muscle mass and strength. Compared with the control group, the MFGM with VR group showed significantly higher mRNA and protein expression for docking protein 7, which maintains neuromuscular junction (NMJ) integrity, in the quadriceps muscles. These results suggest that dietary MFGM and VR attenuate natural aging-related decline in motor coordination and muscle function by regulating NMJ integrity.

TRPM8-mediated cutaneous stimulation modulates motor neuron activity during treadmill stepping in mice.

Motor units are generally recruited from the smallest to the largest following the size principle, while cutaneous stimulation has the potential to affect spinal motor control. We aimed to examine the effects of stimulating transient receptor potential channel sub-family M8 (TRPM8) combined with exercise on the modulation of spinal motor neuron (MN) excitability. Mice were topically administrated 1.5% icilin on the hindlimbs, followed by treadmill stepping. Spinal cord sections were immunostained with antibodies against c-fos and choline acetyltransferase. Icilin stimulation did not change the number of c-fos+ MNs, but increased the average soma size of the c-fos+ MNs during low-speed treadmill stepping. Furthermore, icilin stimulation combined with stepping increased c-fos+ cholinergic interneurons near the central canal, which are thought to modulate MN excitability. These findings suggest that TRPM8-mediated cutaneous stimulation with low-load exercise promotes preferential recruitment of large MNs and is potentially useful as a new training method for rehabilitation.

Combined Supplementation of Pre-Exercise Carbohydrate, Alanine, and Proline and Continuous Intake of Green Tea Catechins Effectively Boost Endurance Performance in Mice.

Continuous intake of green tea catechins (GTC) increases fatty acid utilization as an energy source and improves endurance capacity. Conversely, the single pre-exercise intake of maltodextrin (MD) as a carbohydrate source and the gluconeogenic amino acids alanine (Ala) and proline (Pro) effectively maintain blood glucose levels and increase endurance performance. In this study, we investigated the synergistic combinational effect of these interventions on endurance performance in mice. Male BALB/c mice were fed a 0.5% GTC diet or Control diet for 8 weeks. Maximum running time was measured every 2 weeks. MD (2 g/kg body weight (B.W.)), MD (1 g/kg B.W.) + AlaPro (9:1, 1 g/kg B.W.), and vehicle were orally administrated 60 mins before measurements in each diet group. The GTC + MD + AlaPro group showed significantly higher endurance performance than the Control-Vehicle group at all measurements. Indirect calorimetry analysis during running exercise at 4 weeks in the Control and GTC groups supplemented with pre-exercise MD + AlaPro administration revealed significantly higher fat oxidation in the GTC groups compared to the Control group. The combined increase in fatty acid utilization through continuous GTC intake and pre-exercise MD + AlaPro carbohydrate energy supplementation synergistically improves endurance capacity.

Milk fat globule membrane supplementation with voluntary running exercise attenuates age-related motor dysfunction by suppressing neuromuscular junction abnormalities in mice.

Age-related loss of skeletal muscle mass and function attenuates physical performance, and maintaining fine muscle innervation is known to play an important role in its prevention. We had previously shown that consumption of milk fat globule membrane (MFGM) with habitual exercise improves the muscle mass and motor function in humans and mice. Improvement of neuromuscular junction (NMJ) was suggested as one of the mechanisms underlying these effects. In this study, we evaluated the effect of MFGM intake combined with voluntary running (MFGM-VR) on morphological changes of NMJ and motor function in aging mice. Seven months following the intervention, the MFGM-VR group showed a significantly improved motor coordination in the rotarod test and muscle force in the grip strength test compared with the control group at 13 and 14months of age, respectively. In 14-month old control mice, the extensor digitorum longus muscle showed increased abnormal NMJs, such as fragmentation and denervation, compared with 6-month old young mice. However, such age-related deteriorations of NMJs were significantly suppressed in the MFGM-VR group. Increase in the expression of NMJ formation-related genes, such as agrin and LDL Receptor Related Protein 4 (LRP4), might contribute to this beneficial effect. Rotarod performance and grip strength showed significant negative correlation with the status of denervation and fragmentation of NMJs. These results suggest that MFGM intake with voluntary running exercise effectively suppresses age-related morphological deterioration of NMJ, thus contributing to improvement of motor function.

Effects of Nutritional Supplementation with Milk Fat Globule Membrane on Physical and Muscle Function in Healthy Adults Aged 60 and Over with Semiweekly Light Exercise: A Randomized Double-Blind, Placebo-Controlled Pilot Trial.

This study aimed to demonstrate the beneficial effects of nutritional supplementation with dietary milk fat globule membrane (MFGM) on physical performance and skeletal muscle function in healthy adults aged 60 and over with semiweekly light exercise. The study was designed as a randomized double-blind controlled trial. Twenty-two Japanese participants (10 men, 12 women) aged 60-73 y were assigned to one of two groups (11 [5 men, 6 women] in each). One group received MFGM tablets (1 g MFGM/d), and the other received placebo tablets daily for 10 wk. Both groups participated in a twice-weekly light exercise program. Physical function tests and surface electromyography (EMG) were conducted at the baseline and after 5 and 10 wk. Chair stand time significantly shortened in both groups after 10 wk compared with that at the baseline. The average time shortened more considerably in the MFGM group than in the placebo group, although the change was not statistically significant. Both knee extension strength and the cross-sectional area of the quadriceps muscles significantly increased from baseline in the MFGM group but not in the placebo group. Surface EMG showed that muscle fiber conduction velocity increased significantly after 10 wk from the baseline only in the MFGM group. The increase from the baseline was significantly greater in the MFGM group than in the placebo group. Daily supplementation with MFGM increased motor unit action potential conduction and improved muscle strength and physical performance in healthy Japanese adults aged 60 y and over paired with semiweekly light exercise.

Deletion of nuclear factor-κB p50 upregulates fatty acid utilization and contributes to an anti-obesity and high-endurance phenotype in mice.

The transcription factor nuclear factor-κB (NF-κB) plays an important role in regulating physiological processes such as immunity and inflammation. In addition to this primary role, NF-κB interacts physically with peroxisome proliferator-activated receptors regulating lipid metabolism-related gene expression and inhibits their transcriptional activity. Therefore, inhibition of NF-κB may promote fatty acid utilization, which could ameliorate obesity and improve endurance capacity. To test this hypothesis, we attempted to elucidate the energy metabolic status of mice lacking the p50 subunit of NF-κB (p50 KO mice) from the tissue to whole body level. p50 KO mice showed a significantly lower respiratory quotient throughout the day than did wild-type (WT) mice; this decrease was associated with increased fatty acid oxidation activity in liver and gastrocnemius muscle of p50 KO mice. p50 KO mice that were fed a high-fat diet were also resistant to fat accumulation and adipose tissue inflammation. Furthermore, p50 KO mice showed a significantly longer maximum running time compared with WT mice, with a lower respiratory exchange ratio during exercise as well as higher residual muscle glycogen content and lower blood lactate levels after exercise. These results suggest that p50 deletion facilitates fatty acid catabolism, leading to an anti-obesity and high-endurance phenotype of mice and supporting the idea that NF-κB is an important regulator of energy metabolism.

Ginger extract prevents high-fat diet-induced obesity in mice via activation of the peroxisome proliferator-activated receptor δ pathway.

The initiation of obesity entails an imbalance wherein energy intake exceeds expenditure. Obesity is increasing in prevalence and is now a worldwide health problem. Food-derived peroxisome proliferator-activated receptor δ (PPARδ) stimulators represent potential treatment options for obesity. Ginger (Zingiber officinale Roscoe) was previously shown to regulate the PPARγ signaling pathway in adipocytes. In this study, we investigated the antiobesity effects of ginger in vivo and the mechanism of action in vitro. Energy expenditure was increased, and diet-induced obesity was attenuated in C57BL/6J mice treated with dietary ginger extract (GE). GE also increased the number of Type I muscle fibers, improved running endurance capacity and upregulated PPARδ-targeted gene expression in skeletal muscle and the liver. 6-Shogaol and 6-gingerol acted as specific PPARδ ligands and stimulated PPARδ-dependent gene expression in cultured human skeletal muscle myotubes. An analysis of cellular respiration revealed that pretreating cultured skeletal muscle myotubes with GE increased palmitate-induced oxygen consumption rate, which suggested an increase in cellular fatty acid catabolism. These results demonstrated that sustained activation of the PPARδ pathway with GE attenuated diet-induced obesity and improved exercise endurance capacity by increasing skeletal muscle fat catabolism. 6-Shogaol and 6-gingerol may be responsible for the regulatory effects of dietary ginger on PPARδ signaling.

Menaquinone-4 enhances testosterone production in rats and testis-derived tumor cells.

BACKGROUND: Vitamin K is essential for the posttranslational modification of various Gla proteins. Although it is widespread in several organs, including the testis, the function of vitamin K in these organs is not well characterized. In this study, we investigated the function of vitamin K in the testis and analyzed its role in steroidogenesis. METHODS: Eight-week-old male Wistar rats were fed a diet supplemented with menaquinone-4 (MK-4, 75 mg/kg diet), one of the predominant K2 vitamins present in the testis, for 5 weeks. In vivo testosterone levels of the rats' plasma and testes were measured by enzyme-linked immunosorbent assay, and in vitro testosterone levels of testis-derived tumor cells (I-10 cells) maintained in Ham's F-10 medium with 10% fetal bovine serum were measured following treatment with MK-4 (0 to 100 µM) at several time points. Testosterone and cellular protein levels were analyzed with respect to their effects on steroidogenesis. RESULTS: Testosterone levels in the plasma and testes of MK-4-fed rats were significantly increased compared to those of control rats, with no obvious differences in plasma luteinizing hormone levels. Secreted testosterone levels from I-10 cells were elevated by MK-4, but not by vitamin K1, in a dose-dependent manner independent of cAMP treatment. Western blot analysis revealed that expression of CYP11A, the rate-limiting enzyme in steroidogenesis, and phosphorylation levels of protein kinase A (PKA) and the cAMP response element-binding protein were all stimulated by the presence of MK-4. Enhancement of testosterone production was inhibited by H89, a specific inhibitor of PKA, but not by warfarin, an inhibitor of γ-glutamylcarboxylation. CONCLUSIONS: MK-4 stimulates testosterone production in rats and testis-derived tumor cells via activation of PKA. MK-4 may be involved in steroidogenesis in the testis, and its supplementation could reverse the downregulation of testosterone production in elders.

Red grape leaf extract improves endurance capacity by facilitating fatty acid utilization in skeletal muscle in mice.

Improving endurance capacity leads to increased athletic performance and active lifestyles. The aim of this study was to investigate the effect of the intake of red grape leaf extract (RGLE), used as a traditional herbal medicine in the Mediterranean area, on endurance capacity in mice. Male BALB/c mice were divided into three experimental groups with similar swimming times and body weights; control group, 0.2% (w/w) and 0.5% RGLE group. Swimming times were measured for evaluation of endurance capacity once a week during the 10-week experimental period. Blood and tissues were collected from anesthetized mice immediately after 30 min of swimming exercise, and analyzed blood component and fatty acid oxidation enzyme activity, and gene expression in soleus muscle and mesenteric adipose tissue. Endurance capacity was improved by RGLE in a dose-related manner, and was significantly longer in the 0.5% RGLE group than in the control group at week 10. Plasma lactate levels after exercise in the 0.5% RGLE group were significantly lower than that in the control group. RGLE induced the upregulation of hormone-sensitive lipase mRNA in mesenteric adipose tissue, increased the plasma free fatty acid concentration after exercise, and enhanced fatty acid oxidation enzyme activity in the soleus muscle. Furthermore, peroxisome proliferator-activated receptor-gamma coactivator 1α (Pgc1α) and its downstream target genes were also significantly upregulated in the soleus muscle in the 0.5% RGLE group. Intake of RGLE upregulated Pgc1α expression and facilitated fatty acid oxidation in skeletal muscle, and these effects contributed, in part, to improve endurance capacity.

Coffee polyphenols suppress diet-induced body fat accumulation by downregulating SREBP-1c and related molecules in C57BL/6J mice.

The prevalence of obesity is increasing globally, and obesity is a major risk factor for type 2 diabetes and cardiovascular disease. We investigated the effects of coffee polyphenols (CPP), which are abundant in coffee and consumed worldwide, on diet-induced body fat accumulation. C57BL/6J mice were fed either a control diet, a high-fat diet, or a high-fat diet supplemented with 0.5 to 1.0% CPP for 2-15 wk. Supplementation with CPP significantly reduced body weight gain, abdominal and liver fat accumulation, and infiltration of macrophages into adipose tissues. Energy expenditure evaluated by indirect calorimetry was significantly increased in CPP-fed mice. The mRNA levels of sterol regulatory element-binding protein (SREBP)-1c, acetyl-CoA carboxylase-1 and -2, stearoyl-CoA desaturase-1, and pyruvate dehydrogenase kinase-4 in the liver were significantly lower in CPP-fed mice than in high-fat control mice. Similarly, CPP suppressed the expression of these molecules in Hepa 1-6 cells, concomitant with an increase in microRNA-122. Structure-activity relationship studies of nine quinic acid derivatives isolated from CPP in Hepa 1-6 cells suggested that mono- or di-caffeoyl quinic acids (CQA) are active substances in the beneficial effects of CPP. Furthermore, CPP and 5-CQA decreased the nuclear active form of SREBP-1, acetyl-CoA carboxylase activity, and cellular malonyl-CoA levels. These findings indicate that CPP enhances energy metabolism and reduces lipogenesis by downregulating SREBP-1c and related molecules, which leads to the suppression of body fat accumulation.

Nootkatone, a characteristic constituent of grapefruit, stimulates energy metabolism and prevents diet-induced obesity by activating AMPK.

AMP-activated protein kinase (AMPK) is a serine/threonine kinase that is implicated in the control of energy metabolism and is considered to be a molecular target for the suppression of obesity and the treatment of metabolic syndrome. Here, we identified and characterized nootkatone, a constituent of grapefruit, as a naturally occurring AMPK activator. Nootkatone induced an increase in AMPKalpha1 and -alpha2 activity along with an increase in the AMP/ATP ratio and an increase the phosphorylation of AMPKalpha and the downstream target acetyl-CoA carboxylase (ACC), in C(2)C(12) cells. Nootkatone-induced activation of AMPK was possibly mediated both by LKB1 and Ca(2+)/calmodulin-dependent protein kinase kinase. Nootkatone also upregulated PPARgamma coactivator-1alpha in C(2)C(12) cells and C57BL/6J mouse muscle. In addition, administration of nootkatone (200 mg/kg body wt) significantly enhanced AMPK activity, accompanied by LKB1, AMPK, and ACC phosphorylation in the liver and muscle of mice. Whole body energy expenditure evaluated by indirect calorimetry was also increased by nootkatone administration. Long-term intake of diets containing 0.1% to 0.3% (wt/wt) nootkatone significantly reduced high-fat and high-sucrose diet-induced body weight gain, abdominal fat accumulation, and the development of hyperglycemia, hyperinsulinemia, and hyperleptinemia in C57BL/6J mice. Furthermore, endurance capacity, evaluated as swimming time to exhaustion in BALB/c mice, was 21% longer in mice fed 0.2% nootkatone than in control mice. These findings indicate that long-term intake of nootkatone is beneficial toward preventing obesity and improving physical performance and that these effects are due, at least in part, to enhanced energy metabolism through AMPK activation in skeletal muscle and liver.

Differential regulation of intestinal lipid metabolism-related genes in obesity-resistant A/J vs. obesity-prone C57BL/6J mice.

The effects of high-fat (HF) feeding on gene expression in the small intestine were examined using obesity-resistant A/J mice and obesity-prone C57BL/6J (B6) mice. Both strains of mice were maintained on low-fat (LF; 5% fat) or HF (30% fat) diets for 2 wk. Quantitative reverse transcription-PCR analysis revealed that lipid metabolism-related genes, including carnitine palmitoyltransferase (CPT) I, liver fatty acid binding protein, pyruvate dehydrogenase kinase-4, and NADP(+)-dependent cytosolic malic enzyme, were upregulated by HF feeding in both strains of mice. The upregulated gene expression levels were higher in A/J mice than in B6 mice, suggesting more active lipid metabolism in the small intestine of A/J mice. The prominent upregulation of the lipid metabolism-related genes were specific to the small intestine; the expression levels were little or unchanged in the liver, muscle, and white adipose tissue. The increase by HF feeding and predominant expression of the intestinal lipid metabolism-related genes in A/J mice were reflected in the enzyme activities; malic enzyme, CPT, and beta-oxidation activities were increased by HF feeding, and the upregulated malic enzyme and CPT activities were significantly higher in obesity-resistant A/J mice compared with those in obesity-prone B6 mice. These findings suggest that intestinal lipid metabolism is associated with susceptibility to obesity.

Vitamin K deficiency reduces testosterone production in the testis through down-regulation of the Cyp11a a cholesterol side chain cleavage enzyme in rats.

Vitamin K (K) is an essential factor for the posttranslational modification of blood coagulation factors as well as proteins in the bone matrix (Gla proteins). It is known that K is not only distributed in the liver and bones but also abundantly distributed in the brain, kidney, and gonadal tissues. However, the role of K in these tissues is not well clarified. In this study, we used DNA microarray and identified the genes whose expression was affected in the testis under the K-deficient (K-def) state. The expression of genes involved in the biosynthesis of cholesterol and steroid hormones was decreased in the K-def group. The mRNA levels of Cyp11a - a rate-limiting enzyme in testosterone synthesis - positively correlated with the menaquinone-4 (MK-4) concentration in the testis. Moreover, as compared to the control (Cont) and K-supplemented (K-sup) groups, the K-def group had decreased testosterone concentrations in the plasma and testis. These results suggested that K is involved in steroid production in the testis through the regulation of Cyp11a.