Melanocortin 4 receptor signals at the neuronal primary cilium to control food intake and body weight

The melanocortin 4 receptor (MC4R) plays a critical role in the long-term regulation of energy homeostasis, and mutations in the MC4R are the most common cause of monogenic obesity. However, the precise molecular and cellular mechanisms underlying the maintenance of energy balance within MC4R-expressing neurons are unknown. We recently reported that the MC4R localizes to the primary cilium, a cellular organelle that allows for partitioning of incoming cellular signals, raising the question of whether the MC4R functions in this organelle. Here, using mouse genetic approaches, we found that cilia were required specifically on MC4R-expressing neurons for the control of energy homeostasis. Moreover, these cilia were critical for pharmacological activators of the MC4R to exert an anorexigenic effect. The MC4R is expressed in multiple brain regions. Using targeted deletion of primary cilia, we found that cilia in the paraventricular nucleus of the hypothalamus (PVN) were essential to restrict food intake. MC4R activation increased adenylyl cyclase (AC) activity. As with the removal of cilia, inhibition of AC activity in the cilia of MC4R-expressing neurons of the PVN caused hyperphagia and obesity. Thus, the MC4R signaled via PVN neuron cilia to control food intake and body weight. We propose that defects in ciliary localization of the MC4R cause obesity in human inherited obesity syndromes and ciliopathies.     

GIPR agonism mediates weight-independent insulin sensitization by tirzepatide in obese mice

Tirzepatide (LY3298176), a dual GIP and GLP-1 receptor (GLP-1R) agonist, delivered superior glycemic control and weight loss compared with GLP-1R agonism in patients with type 2 diabetes. However, the mechanism by which tirzepatide improves efficacy and how GIP receptor (GIPR) agonism contributes is not fully understood. Here, we show that tirzepatide is an effective insulin sensitizer, improving insulin sensitivity in obese mice to a greater extent than GLP-1R agonism. To determine whether GIPR agonism contributes, we compared the effect of tirzepatide in obese WT and Glp-1r–null mice. In the absence of GLP-1R–induced weight loss, tirzepatide improved insulin sensitivity by enhancing glucose disposal in white adipose tissue (WAT). In support of this, a long-acting GIPR agonist (LAGIPRA) was found to enhance insulin sensitivity by augmenting glucose disposal in WAT. Interestingly, the effect of tirzepatide and LAGIPRA on insulin sensitivity was associated with reduced branched-chain amino acids (BCAAs) and ketoacids in the circulation. Insulin sensitization was associated with upregulation of genes associated with the catabolism of glucose, lipid, and BCAAs in brown adipose tissue. Together, our studies show that tirzepatide improved insulin sensitivity in a weight-dependent and -independent manner. These results highlight how GIPR agonism contributes to the therapeutic profile of dual-receptor agonism, offering mechanistic insights into the clinical efficacy of tirzepatide.     

Early programming of weight gain in mice prevents the induction of obesity by a highly palatable diet

Poor early growth is associated with Type II diabetes, hypertension and other features of the metabolic syndrome in adulthood. It has been suggested that this results from the development of a thrifty phenotype by a malnourished fetus. Such a phenotype would predispose the offspring to the development of obesity if born into conditions of over-nutrition. The present study aimed to determine if early nutrition affected subsequent development of obesity. Mice were established as follows: (a) controls (offspring of control dams), (b) recuperated (offspring of dams fed a low-protein diet during pregnancy, but nursed by control dams) and (c) postnatal low-protein (offspring of control dams nursed by low-protein-fed dams). Mice were weaned on to standard laboratory chow or a cafeteria diet. Recuperated offspring, although smaller at birth ( P <0.01), caught up and exceeded the weight of control offspring by 7 days of age ( P <0.001). Postnatal low-protein offspring were smaller than controls by 7 days of age ( P <0.001). Recuperated animals gained more weight than controls when given free access to a highly palatable diet ( P <0.01). Postnatal low-protein animals showed no additional weight gain when given a highly palatable diet compared with chow-fed litter-mates. These results suggest that the early environment has long-term consequences for weight gain. These programmed responses are powerful enough to block excess weight gain from a highly palatable diet and, thus, have major implications for the drug-free regulation of food intake and obesity.     

氯丙嗪、氯氮平和舒必利所致体重增加的对照研究

目的　比较氯丙嗪、氯氮平与舒必利治疗对精神分裂症患者体重的影响。方法　对 90例住院男性精神分裂症患者单独服用氯丙嗪、氯氮平或舒必利的体重采用自身对照及组间对照前瞻性研究方法 ,进行为期 12w的观察 ,并对其相关因素进行分析。结果　治疗 12w末平均体重与治疗前比 ,氯丙嗪和氯氮平组均有显著性差异 (P <0 .0 5 ) ,舒必利组有极显著性差异 (P <0 .0 1) ,平均增加体重舒必利组大于其他两组。体重增加与精神症状改善有关 ,与药物剂量及睡眠时间无明显关系。结论　氯丙嗪、氯氮平和舒必利均能导致体重增加 ,尤以舒必利为甚     

Hepatocyte-specific suppression of ANGPTL4 improves obesity-associated diabetes and mitigates atherosclerosis in mice

Hepatic uptake and biosynthesis of fatty acids (FAs), as well as the partitioning of FAs into oxidative, storage, and secretory pathways, are tightly regulated processes. Dysregulation of one or more of these processes can promote excess hepatic lipid accumulation, ultimately leading to systemic metabolic dysfunction. Angiopoietin-like-4 (ANGPTL4) is a secretory protein that inhibits lipoprotein lipase (LPL) and modulates triacylglycerol (TAG) homeostasis. To understand the role of ANGPTL4 in liver lipid metabolism under normal and high-fat–fed conditions, we generated hepatocyte-specific Angptl4 mutant mice (Hmut). Using metabolic turnover studies, we demonstrate that hepatic Angptl4 deficiency facilitates catabolism of TAG-rich lipoprotein (TRL) remnants in the liver via increased hepatic lipase (HL) activity, which results in a significant reduction in circulating TAG and cholesterol levels. Consequently, depletion of hepatocyte Angptl4 protects against diet-induced obesity, glucose intolerance, liver steatosis, and atherogenesis. Mechanistically, we demonstrate that loss of Angptl4 in hepatocytes promotes FA uptake, which results in increased FA oxidation, ROS production, and AMPK activation. Finally, we demonstrate the utility of a targeted pharmacologic therapy that specifically inhibits Angptl4 gene expression in the liver and protects against diet-induced obesity, dyslipidemia, glucose intolerance, and liver damage, which likely occur via increased HL activity. Notably, this inhibition strategy does not cause any of the deleterious effects previously observed with neutralizing antibodies.     

Selective stimulation of IL-4 receptor on smooth muscle induces airway hyperresponsiveness in mice

Production of the cytokines IL-4 and IL-13 is increased in both human asthma and mouse asthma models, and Stat6 activation by the common IL-4/IL-13R drives most mouse model pathophysiology, including airway hyperresponsiveness (AHR). However, the precise cellular mechanisms through which IL-4Rα induces AHR remain unclear. Overzealous bronchial smooth muscle constriction is thought to underlie AHR in human asthma, but the smooth muscle contribution to AHR has never been directly assessed. Furthermore, differences in mouse versus human airway anatomy and observations that selective IL-13 stimulation of Stat6 in airway epithelium induces murine AHR raise questions about the importance of direct IL-4R effects on smooth muscle in murine asthma models and the relevance of these models to human asthma. Using transgenic mice in which smooth muscle is the only cell type that expresses or fails to express IL-4Rα, we demonstrate that direct smooth muscle activation by IL-4, IL-13, or allergen is sufficient but not necessary to induce AHR. Five genes known to promote smooth muscle migration, proliferation, and contractility are activated by IL-13 in smooth muscle in vivo. These observations demonstrate that IL-4Rα promotes AHR through multiple mechanisms and provide a model for testing smooth muscle-directed asthma therapeutics.     

Sodium 4-phenylbutyrate prevents murine dietary steatohepatitis caused by trans-fatty acid plus fructose

Excess consumption of trans-fatty acid could increase the risk of non-alcoholic steatohepatitis (NASH); however, treatment targeting trans-fatty acid-induced NASH has not been examined. Here we focused on the influence of trans-fatty acid intake on endoplasmic reticulum (ER) stress in hepatocytes, so we investigated the effect of the chemical chaperone 4-phenylbutyric acid (PBA), on trans-fatty acid-caused steatohepatitis using diabetic KK-A^y mice. Elaidic acid (EA, trans-fatty acid) alone did not cause definitive liver injury. In contrast, EA plus low-dose fructose induced extensive apoptosis in hepatocytes with severe fat accumulation. EA plus fructose significantly increased ER stress markers such as glucose-regulated protein 78 (GRP78), eukaryotic initiation factor 2α (eIF2α) and phosphorylated c-jun N-terminal kinase (JNK), while PBA significantly reduced this response. In vitro, EA promoted expression of GRP78 and phosphorylation of eIF2α in primary-cultured hepatocytes. EA also increased hepatocellular susceptibility to low-dose tert-butyl hydroperoxide. Treatment with PBA significantly reduced these responses. In conclusion, EA potentiates susceptibly to non-hazardous dose of fructose, and increases ER and oxidative stress. PBA improved steatohepatitis induced by EA plus fructose through amelioration of ER stress. Therefore, ER stress-targeted therapy using a chemical chaperone is a promising novel strategy for trans-fatty acid-induced steatohepatitis.     

Toll 样受体4参与鲍曼不动杆菌肺炎发病机制的研究进展

Toll受体4(Toll like receptors,TLR4)可迅速识别鲍曼不动杆菌释放的脂多糖(LPS),是鲍曼不动杆菌肺部炎症反应的启动闸门,当其过度表达时则可引起相关的瀑布级联的炎症性疾病,从而增加病死率。抑制TLR4能应用于治疗鲍曼不动杆菌肺炎。     

长期吸入低浓度七氟醚对雌性小鼠排卵的影响

目的:评价长期吸入低浓度七氟醚对雌性小鼠排卵功能的影响。方法:雌性昆明种小鼠40只,6周龄,体重(20±2)g,随机分为5组(n=8):实验组(ABCD组)分别吸入0.003%、0.03%、0.06%、0.1%七氟醚,每天6h,E组吸空气。于30d后,孕马血清促性腺激素(PMSG)、人体绒膜促性腺激素(HCG)促超排卵后处死动物,压片法计数卵母细胞,光学显微镜观察卵母细胞形态学。结果:与对照组相比,ABCD四个实验组小鼠卵母细胞数相近(P>0.05)、形态相似。结论:长期吸入≤0.1%七氟醚后,小鼠排卵功能未见明显影响。     

Apoptosis mediated by Fas but not tumor necrosis factor receptor 1 prevents chronic disease in mice infected with murine cytomegalovirus.

The role of Fas- and TNF-receptor 1 (TNF-R1)-mediated apoptosis in the clearance of virally infected cells and in the regulation of the immune response was analyzed after murine cytomegalovirus (MCMV) infection of C57BL/6 (B6)-+/+ mice, Fas-mutant B6-lpr/lpr mice, TNF-R1 knockout B6-tnfr0/0 mice, and double-deficient B6-tnfr0/0 lpr/lpr mice. There was approximately equivalent clearance of MCMV in B6-+/+, B6-tnfr0/0, and B6-lpr/lpr mice, and by day 28 no infectious virus could be detected in the liver, kidney, lung, or peritoneal exudate. However, delayed virus clearance was observed in B6-tnfr0/0 lpr/lpr mice. An acute inflammatory response occurred in the liver, lung, and kidney of all mice, which was most severe 7 d after MCMV infection, but resolved by day 28 in B6-+/+ and B6-tnfr0/0 mice, but not in B6-lpr/lpr or B6-tnfr0/0 lpr/lpr mice. These results indicate that apoptosis mediated by either Fas or TNF-R1 is sufficient for rapid clearance of the virus. However, apoptosis induced by Fas, but not TNF-R1, is required for the downmodulation of the immune response to the virus and prevention of a chronic inflammatory reaction.     

Prediction of body weight changes caused by changes in energy balance

BACKGROUND: Experimental difficulties have so far restricted knowledge of the effects of energy imbalance on change in body weight. Direct measurement requires that the subjects are kept under dietary supervision for several months while the activity is being measured. MATERIALS AND METHODS: The effects of energy balance can be calculated using a combination of fundamental principles and directly measurable data: the law of energy conservation (increase in combustible energy equals the difference between energy intake and energy expenditure); data on energy expenditure of fat and lean tissues; and data on the composition of added/removed tissue during weight change. RESULTS AND CONCLUSIONS: We obtained an explicit differential equation describing the development of body weight over time, with energy intake and energy expenditure as control variables. Using this model it is possible to isolate and analyse the measured effects of parameters not included in the model, such as age or 'adaptivity' of the body.     

Selective long-term elimination of natural killer cells in vivo by an anti-interleukin 2 receptor beta chain monoclonal antibody in mice

The interleukin 2 receptor beta chain (IL-2R beta) is preferentially expressed in natural killer (NK) cells, but is not detected in a majority of resting T and B cells. We recently established a novel monoclonal antibody (mAb) to murine IL-2R beta and examined in vivo the effect of the mAb in mice. We found that intraperitoneal injection of the anti-IL-2R beta mAb into adult mice resulted in a selective in vivo elimination of splenic NK function in various mouse strains. The reduction of NK cell function is associated with complete disappearance of NK1.1+ cells in C57BL/6 mice. Other lymphocyte subsets in the thymus and spleen were uncompromised. T cell function was not affected by the mAb treatment as judged by allogeneic cytotoxic T cell induction. The single injection of anti-IL-2R beta mAb caused a long-term elimination of splenic NK cells, lasting for at least 5 wk. We also found that NK and/or NK precursor cells become susceptible to the mAb treatment only after birth, suggesting that functional maturation of NK cells in terms of IL-2R beta expression is a later event in the course of NK cell development. The use of the anti-IL-2R beta mAb will be useful in defining the physiological role of NK cells in host defense as well as dissecting their developmental pathway in vivo.     

The effects of combined modalities of prefeeding stimulation on feeding progression,length of stay and weight gain in early preterm babies

Study purposeSensorimotor interventions in preterm neonates help to tackle feeding problems. This study was aimed to find out whether combined modalities of prefeeding stimulation were better than the conventional methods of kangaroo mother care and non-nutritive sucking, with regards to transition time, duration of hospital stay and feeding behavior in early preterm babies.MethodsSixty new-born babies in the gestational age of 28–32 weeks, were randomized to receive either combined methods of stimulation (n = 30) or conventional methods alone (n = 30).ResultsThere was a significant reduction in the duration of hospital stay in the interventional group compared to the control group (p = 0.008). There were no significant differences in the time duration taken to attain full oral feeds, mean weight gain per day, the mean number of sucks in the initial 5 min of feeding and mean amount of milk spillage per feed.ConclusionCombined methods of prefeeding stimulation resulted in earlier discharge and shorter duration of hospital stay in early preterm babies.     

内毒素血症小鼠骨骼Toll样受体4基因的变化

目的 通过检测内毒素血症模型动物骨骼相关基因表达变化,进一步明确内毒素对机体的损害机制,为下一步研究骨骼变化对脏器产生何种影响奠定基础.方法 腹腔注射内毒素脂多糖(LPS)制作内毒素血症小鼠模型.将48只小鼠随机分为正常组和LPS处理4、6、8、12、24、48和72 h组,每组6只.采尾血计数全血白细胞;取眼眶血检测肝、肾功能;用逆转录-聚合酶链反应(RT-PCR)检测骨骼中TLR4 mRNA表达;苏木素-伊红(HE)染色,镜下观察骨骼病理学变化.结果 与正常组比较,LPS 4 h组白细胞计数显著下降(P＜0.01),之后逐渐升高,于72 h时显著高于正常组(P＜0.05);LPS 4 h和6 h组丙氨酸转氨酶(ALT)水平显著升高(P均＜0.05),于8 h降至正常水平(P＞0.05);LPS 6 h组血尿素氮(BUN)水平逐渐升高(P＜0.05),于8 h达峰值(P＜0.05),然后下降,12 h趋于正常(P＞0.05);LPS 6 h组TLR4 mRNA表达增加(P＜0.01),24 h达峰值(P＜0.01),然后逐渐下降,72 h仍处在较高水平(P＜0.05).LPS作用于骨骼后,HE染色显示骨骼无明显改变.结论 内毒素血症中骨骼TLR4 mRNA表达量显著增加.     

Tocotrienols reach the brain and play roles in the attenuation of body weight gain and improvement of cognitive function in high-fat diet-treated mice

Obesity induces severe disorders such as type 2 diabetes and cardiovascular events, and the number of people with obesity is increasing all over the world. Furthermore, it is possible that obesity increases the risk of cognitive dysfunction via the acceleration of oxidative damage. Tocotrienols, which are part of the vitamin E family, have antioxidant and anti-obesity effects. However, the effects of tocotrienols on high-fat diet-treated mice have not been completely elucidated. In this study, we assessed changes in body weight, spatial reference memory acquisition, liver lipid droplet size, blood brain barrier-related protein expressions and antioxidative defense systems in high-fat diet-treated mice in the presence or absence of tocotrienols. The results showed that tocotrienols significantly inhibited body weight gain and lipid droplet synthesis. Although the amount was very small, it was confirmed that tocotrienols surely reached the brain in the perfused brain. Treatment with tocotrienols was tended to improve cognitive function in the control mice. However, tocotrienols did not modulate blood brain barrier-related protein expressions or antioxidative defense systems. These results indicate that treatment with tocotrienols could be effective for the prevention of obesity and cognitive dysfunction. Further extended research is needed to elucidate the relationship between anti-obesity and antioxidant effects of tocotrienols, especially in the brain.     

Lipid-induced insulin resistance mediated by the proinflammatory receptor TLR4 requires saturated fatty acid-induced ceramide biosynthesis in mice

Obesity is associated with an enhanced inflammatory response that exacerbates insulin resistance and contributes to diabetes, atherosclerosis, and cardiovascular disease. One mechanism accounting for the increased inflammation associated with obesity is activation of the innate immune signaling pathway triggered by TLR4 recognition of saturated fatty acids, an event that is essential for lipid-induced insulin resistance. Using in vitro and in vivo systems to model lipid induction of TLR4-dependent inflammatory events in rodents, we show here that TLR4 is an upstream signaling component required for saturated fatty acid-induced ceramide biosynthesis. This increase in ceramide production was associated with the upregulation of genes driving ceramide biosynthesis, an event dependent of the activity of the proinflammatory kinase IKKβ. Importantly, increased ceramide production was not required for TLR4-dependent induction of inflammatory cytokines, but it was essential for TLR4-dependent insulin resistance. These findings suggest that sphingolipids such as ceramide might be key components of the signaling networks that link lipid-induced inflammatory pathways to the antagonism of insulin action that contributes to diabetes.     

中子辐射对小鼠肝细胞损伤的实验研究

[目的]用2．5Gy90％的中子射线照射BALB／C小鼠，研究小鼠血清中反映肝功能损伤程度的血清丙氨酸氨基转移酶（ALT）、血清总胆汁酸（TBA）、总蛋白（TP）、白蛋白（Alb）和球蛋白（Glo）的变化情况，以确定2．5Gy中子辐射对小鼠肝功能损伤的情况。[方法]采用二级BALB／C雄性小鼠作为实验动物，共计78只。实验期间在军事医学科学院实验动物中心统一饲养。将上述小鼠分为2组，包括1个对照组和1个实验组。采用北京清华大学的中子源分别对各动物组进行90％中子照射，照射剂量为2．5Gy（66只），对照组12只。分别在照射动物之后的6h、12h、1d．3d．5d．7d、10d、14d、21d、28d和41d采取静脉血，进行ALT、TBA、TP、Alb和Glo的浓度测定。采用Microcal Origin软件包进行数理统计分析。[结果]小鼠血清ALT于照射后6h～3d无显著变化，照射后第5d开始升高，直至第21d血清ALT仍维持在较高的水平，其中第10d血清ALT达到最高值，与对照组相比，有显著差别。照射后第28d后出现下降趋势，照后第28d～41d的血清ALT活力与对照组相比，无显著差别。小鼠血清TBA于照射后6h～28d持续升高。血清总蛋白和白蛋白浓度在5d显著降低，之后逐渐恢复至正常水平。血清球蛋白在照射前后无显著变化。[结论]2．5Gy中子辐射可以引起肝细胞不同程度的破坏，进而引起血清ALT活力和TBA浓度的增高；肝功能损伤后，肝脏蛋白质的合成代谢减少，进而引起血清TP、Alb浓度不同程度的下降。     

Effects of fluoroquinolones on experimental pneumonia caused by penicillin-resistantStreptococcus pneumoniae in mice

The in vitro and in vivo activities of several fluoroquinolones, ampicillin and cefteram-pivoxil were investigated against penicillin-resistantStreptococcus pneumoniae (PRSP). The MIC₉₀s of sparfloxacin, levofloxacin, tosufloxacin, AM-1155, ampicillin, and cefteram-pivoxil for 13 PRSP strains were 0.78, 3.13, 0.39, 1.56, 3.13, and 3.13 μg/mL, respectively. An experimental fatal pneumonia was induced by intranasal inoculation of PRSP No. 65 in CBA/J mice. The fluoroquinolones were effective against the experimental pneumonia, but ampicillin and cefteram-pivoxil were not sufficiently effective. The oral 50% effective doses (ED₅₀) of sparfloxacin, levofloxacin, tosufloxacin, and AM-1155 on the experimental pneumonia were 6.09, 49.3, 5.07, and 8.59 mg/kg/dose, respectively, when treatment was initiated 3 hours after infection and were 30.0, >50, 17.7, and 45.9 mg/kg/dose, respectively, when treatment was initiated 24 hours after infection. These results suggest that some fluoroquinolones such as sparfloxacin, tosufloxacin and AM-1155 may be effective in the treatment of pneumonia due to PRSP in humans.     

Changes in GABA(A) receptor gene expression induced by withdrawal of,but not by long-term exposure to,ganaxolone in cultured rat cerebellar granule cells

The effects of ganaxolone, a synthetic analog of the endogenous neuroactive steroid allopregnanolone, on the function and expression of GABA(A) receptors were determined. Electrophysiological recordings demonstrated that ganaxolone potentiated with a potency and efficacy similar to those of allopregnanolone the Cl- currents evoked by GABA at recombinant human GABA(A) receptors (comprising alpha1beta2gamma2L or alpha2beta2gamma2L subunit assemblies) expressed in Xenopus oocytes. Exposure of cultured rat cerebellar granule cells to 1 microM ganaxolone for 5 days had no effect on the abundance of mRNAs encoding the alpha1, alpha2, alpha3, alpha4, alpha5, gamma2L, or gamma2S subunits of the GABA(A) receptor. Withdrawal of ganaxolone after such long-term treatment, however, induced an increase in the abundance of alpha2, alpha4, and alpha5 subunit mRNAs and a decrease in the amounts of alpha1, gamma2L, and gamma2S subunit mRNAs. These changes were maximal 3 to 6 h after drug withdrawal and were reversible, being no longer apparent after 24 h. These results suggest that long-term exposure of cerebellar granule cells to ganaxolone does not affect the sensitivity of the GABA(A) receptor to several positive modulators. Nevertheless, the reduction in the amounts of the alpha1 and gamma2 subunit mRNAs together with the increase in the abundance of the alpha4 subunit mRNA induced by abrupt discontinuation of long-term treatment with ganaxolone suggest that withdrawal of this drug might result in a reduced response to classic benzodiazepines.