Neuromedin U (NMU) and neuromedin S (NMS) are structurally related neuropeptides that have been reported to modulate energy homeostasis. Pharmacological data have shown that NMU and NMS inhibit food intake when administered centrally and that NMU increases energy expenditure. Additionally, NMU-deficient mice develop obesity, whereas transgenic mice overexpressing NMU are lean and hypophagic. Two high-affinity NMU/NMS receptors, NMUR1 and NMUR2, have been identified. NMUR1 is predominantly expressed in the periphery, whereas NMUR2 is predominantly expressed in the brain, suggesting that the effects of centrally administered NMU and NMS are mediated by NMUR2. To evaluate the role of NMUR2 in the regulation of energy homeostasis, we characterized NMUR2-deficient (Nmur2(-/-)) mice. Nmur2(-/-) mice exhibited a modest resistance to diet-induced obesity that was at least in part due to reduced food intake. Acute central administration of NMU and NMS reduced food intake in wild-type but not in Nmur2(-/-) mice. The effects on activity and core temperature induced by centrally administered NMU were also absent in Nmur2(-/-) mice. Moreover, chronic central administration of NMU and NMS evoked significant reductions in body weight and sustained reductions in food intake in mice. In contrast, Nmur2(-/-) mice were largely resistant to these effects. Collectively, these data demonstrate that the anorectic and weight-reducing actions of centrally administered NMU and NMS are mediated predominantly by NMUR2, suggesting that NMUR2-selective agonists may be useful for the treatment of obesity.
These data suggest that Fuzhuan tea protects against liver and adipose tissue stress induced by a high SAT diet and positively influences intestinal function. Further investigation of the molecular targets of Fuzhuan tea is warranted.
The increased risk for cardiometabolic disease with the onset of menopause is widely studied and likely precipitated by the decline in endogenous estradiol (E2), yet the precise mechanisms are unknown. The gut microbiome is involved in estrogen metabolism and has been linked to metabolic disease, suggesting its potential involvement in the postmenopausal phenotype. Furthermore, menopause-associated risk factors, as well as gut ecology, are altered with exercise. Therefore, we studied microbial changes in an ovariectomized (OVX vs. Sham) rat model of high (HCR) and low (LCR) intrinsic aerobic capacity (n = 8–10/group) in relation to changes in body weight/composition, glucose tolerance, and liver triglycerides (TG). Nine weeks after OVX, HCR rats were moderately protected against regional adipose tissue gain and liver TG accumulation (P < 0.05 for both). Microbial diversity and number of the Bacteroidetes phylum were significantly increased in LCR with OVX, but unchanged in HCR OVX relative to Sham. Plasma short-chain fatty acids (SCFA), produced by bacteria in the gut and recognized as metabolic signaling molecules, were significantly greater in HCR Sham relative to LCR Sham rats (P = 0.05) and were decreased with OVX in both groups. These results suggest that increased aerobic capacity may be protective against menopause-associated cardiometabolic risk and that gut ecology, and production of signaling molecules such as SCFA, may contribute to the mediation.
MT Foster (2015) Lower body adipose tissue removal decreases glucose tolerance and insulin sensitivity in mice with exposure to high fat diet, Adipocyte, 4:1, 32-43, DOI: 10.4161/21623945.2014 It has been postulated that the protective effects of lower body subcutaneous adipose tissue (LBSAT) occur via its ability to sequester surplus lipid and thus serve as a "metabolic sink." However, the mechanisms that mediate this protective function are unknown thus this study addresses this postulate. Ad libitum, chow-fed mice underwent Shamsurgery or LBSAT removal (IngX, inguinal depot removal) and were subsequently provided chow (Chow; typical adipocyte expansion) or high fat diet (HFD; enhanced adipocyte expansion) for 5 weeks. Primary outcome measures included glucose tolerance and subsequent insulin response, muscle insulin sensitivity, liver and muscle triglycerides, adipose tissue gene expression, and circulating lipids and adipokines. In a follow up study the consequences of extended experiment length post-surgery (13 wks) or pre-existing glucose intolerance were examined. At 5 wks postsurgery IngX in HFD-fed mice reduced glucose tolerance and muscle insulin sensitivity and increased circulating insulin compared with HFD Sham. In Chow-fed mice, muscle insulin sensitivity was the only measurement reduced following IngX. At 13 wks circulating insulin concentration of HFD IngX mice continued to be higher than HFD Sham. Surgery did not induce changes in mice with pre-existing glucose intolerance. IngX also increased muscle, but not liver, triglyceride concentration in Chow-and HFD-fed mice 5 wks post-surgery, but chow group only at 13 wks. These data suggest that the presence of LBSAT protects against triglyceride accumulation in the muscle and HFD-induced glucose intolerance and muscle insulin resistance. These data suggest that lower body subcutaneous adipose tissue can function as a "metabolic sink."
Objective Postprandial lipemia worsens after menopause, but the mechanism remains unknown. We hypothesized menopause-related postprandial lipemia would be: 1) associated with reduced storage of dietary fatty acids (FA) as triglyceride (TG) in subcutaneous adipose tissue (SAT); and 2) improved by short-term estradiol (E2). Design and Methods We studied 23 pre- (mean±SD; 42±4yr) and 22 postmenopausal (55±4yr) women with similar total adiposity. A subset of postmenopausal women (n=12) were studied following 2 weeks of E2 (0.15mg) and matching placebo in a random, cross-over design. A liquid meal containing 14C-oleic acid traced appearance of dietary FA in: serum (postprandial TG), breath (oxidation), and abdominal and femoral SAT (TG storage). Results Compared to premenopausal, healthy lean postmenopausal women had increased postprandial glucose and insulin and trend for higher TG, but similar dietary FA oxidation and storage. Adipocytes were larger in post- compared to premenopausal women, particularly in femoral SAT. Short-term E2 reduced postprandial TG and insulin, but had no effect on oxidation or storage of dietary FA. E2 increased the proportion of small adipocytes in femoral (but not abdominal) SAT. Conclusions Short-term E2 attenuated menopause-related increases in postprandial TG and increased femoral adipocyte hyperplasia, but not through increased net storage of dietary FA.
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