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Free access

Yuhui Liu, Le Zhang, Jing Li, Zhongyan Shan, and Weiping Teng

Marginal iodine deficiency is a major health problem in pregnant women, but its impact on nerve and intelligence development in offspring has been rarely reported. Our study aimed to investigate the effects of maternal marginal iodine deficiency on nerve and cognitive development in offspring and the related mechanisms. Marginal iodine-deficient rats were given 3 μg iodine per day, while normal control rats were given 4 μg iodine daily. Western blot was used to detect the amounts of brain-derived neurotropic factor (BDNF) and early growth response protein 1 (EGR1) in the hippocampus of each group. Immunohistochemistry was used to measure c-jun and c-fos expression in the hippocampal CA1 region. Finally, the water maze method was used to measure spatial performance. Free thyroxine (FT4) levels in marginal iodine-deficient rats decreased by about 30%. Seven days after birth, EGR1 and BDNF protein levels significantly decreased in the hippocampus of marginal iodine deficiency rats compared with the normal control group. In addition, c-jun and c-fos expression in the hippocampus of 40-day-old rats was decreased in marginal iodine-deficient rats, compared with control. The spatial learning and memory ability of 40-day-old marginal iodine-deficient rats had a downward trend compared with the normal control group. FT4 significantly decreased after pregnancy in rats with marginal iodine deficiency, affecting the expression of related proteins in the brain of offspring.

Free access

Jacob C Garza, Chung Sub Kim, Jing Liu, Wei Zhang, and Xin-Yun Lu

Pharmacological and genetic studies have suggested that melanocortin-4 receptor (MC4R) signaling in the paraventricular nucleus of hypothalamus (PVN) regulates appetite and energy balance. However, the specific role of MC4R signaling in PVN neurons in these processes remains to be further elucidated in normally developed animals. In the present study, we employed RNA interference to determine whether MC4R knockdown in the PVN modulates food intake and body weight in adult rats. Adeno-associated viral (AAV) vectors encoding short hairpin RNAs targeting MC4R (AAV-shRNA-MC4R) were generated to induce MC4R knockdown in the PVN. By in situ hybridization, we detected a high-level expression of Dicer, a key enzyme required for shRNA-mediated gene silencing, along the entire rostrocaudal extent of the PVN. Bilateral injection of AAV-shRNA-MC4R vectors into the PVN of the adult rat resulted in significant and specific reduction of MC4R mRNA expression. Animals with MC4R knockdown exhibited an increase in food intake and excessive body weight gain when exposed to a high-fat diet. Our results provide evidence that AAV-mediated silencing of MC4R on PVN neurons promotes hyperphagia and obesity in response to the dietary challenge in the adult animal.

Open access

Jianshu Chen, Jing Yu, Ruowen Yuan, Ningyin Li, Caie Li, and Xiaofang Zhang

Compelling evidence has described that the incidence of hypertension and left ventricular hypertrophy (LVH) in postmenopausal women is significantly increased worldwide. Our team’s previous research identified that androgen was an underlying factor contributing to increased blood pressure and LVH in postmenopausal women. However, little is known about how androgens affect LVH in postmenopausal hypertensive women. The purpose of this study was to evaluate the role of mammalian rapamycin receptor (mTOR) signaling pathway in myocardial hypertrophy in androgen-induced postmenopausal hypertension and whether mTOR inhibitors can protect the myocardium from androgen-induced interference to prevent and treat cardiac hypertrophy. For that, ovariectomized (OVX) spontaneously hypertensive rats (SHR) aged 12 weeks were used to study the effects of testosterone (T 2.85 mg/kg/weekly i.m.) on blood pressure and myocardial tissue. On the basis of antihypertensive therapy (chlorthalidone 8 mg/kg/day ig), the improvement of blood pressure and myocardial hypertrophy in rats treated with different dose gradients of rapamycin (0.8 mg/kg/day vs 1.5 mg/kg/day vs 2 mg/kg/day i.p.) in OVX + estrogen (E 9.6 mg/kg/day, ig) + testosterone group was further evaluated. After testosterone intervention, the OVX female rats exhibited significant increments in the heart weight/tibial length (TL), area of cardiomyocytes and the mRNA expressions of ANP, β-myosin heavy chain and matrix metalloproteinase 9 accompanied by a significant reduction in the uterine weight/TL and tissue inhibitor of metalloproteinase 1. mTOR, ribosomal protein S6 kinase (S6K1), 4E-binding protein 1 (4EBP1) and eukaryotic translation initiation factor 4E in myocardial tissue of OVX + estrogen + testosterone group were expressed at higher levels than those of the other four groups. On the other hand, rapamycin abolished the effects of testosterone-induced cardiac hypertrophy, decreased the systolic and diastolic blood pressure of SHR, and inhibited the activation of mTOR/S6K1/4EBP1 signaling pathway in a concentration-dependent manner. Collectively, these data suggest that the mTOR/S6K1/4EBP1 pathway is an important therapeutic target for the prevention of LVH in postmenopausal hypertensive female rats with high testosterone levels. Our findings also support the standpoint that the mTOR inhibitor, rapamycin, can eliminate testosterone-induced cardiomyocyte hypertrophy.

Free access

Li Ding, Yue Yin, Lingling Han, Yin Li, Jing Zhao, and Weizhen Zhang

Neurogenin3-driven deletion of tuberous sclerosis complex 1 (Tsc1) activated mechanistic target of rapamycin complex 1 (mTORC1) measured by the upregulation of mTOR and S6 phosphorylation in islet cells. Neurogenin3-Tsc1−/− mice demonstrated a significant increase in average islet size and mean area of individual islet cell. Insulin mRNA and plasma insulin levels increased significantly after weaning. Glucagon mRNA and plasma levels increased in neonate followed by modest reduction in adult. Somatostatin mRNA and plasma levels markedly increased. Neurogenin3-Tsc1−/− mice fed standard chow demonstrated a significant improvement in glucose tolerance and no alteration in insulin sensitivity. In Neurogenin3-Tsc1−/− mice fed 45% high-fat diets, both glucose tolerance and insulin sensitivity were significantly impaired. Rapamycin reversed the activation of mTORC1, attenuated β cells hypertrophy and abolished the improvement of glucose tolerance. TSC1-mTORC1 signaling plays an important role in the development of pancreatic endocrine cells and in the regulation of glucose metabolism.

Free access

Dan Li, Yan Ji, Chunlan Zhao, Yapeng Yao, Anlan Yang, Honghong Jin, Yang Chen, Mingjun San, Jing Zhang, Mingjiao Zhang, Luqing Zhang, Xuechao Feng, and Yaowu Zheng

Oxytocin receptor (OXTR) is a G-protein-coupled receptor and known for regulation of maternal and social behaviors. Null mutation (Oxtr−/−) leads to defects in lactation due to impaired milk ejection and maternal nurturing. Overexpression of OXTR has never been studied. To define the functions of OXTR overexpression, a transgenic mouse model that overexpresses mouse Oxtr under β-actin promoter was developed ( ++ Oxtr). ++ Oxtr mice displayed advanced development and maturation of mammary gland, including ductal distention, enhanced secretory differentiation and early milk production at non-pregnancy and early pregnancy. However, ++ Oxtr dams failed to produce adequate amount of milk and led to lethality of newborns due to early involution of mammary gland in lactation. Mammary gland transplantation results indicated the abnormal mammary gland development was mainly from hormonal changes in ++ Oxtr mice but not from OXTR overexpression in mammary gland. Elevated OXTR expression increased prolactin-induced phosphorylation and nuclear localization of STAT5 (p-STAT5), and decreased progesterone level, leading to early milk production in non-pregnant and early pregnant females, whereas low prolactin and STAT5 activation in lactation led to insufficient milk production. Progesterone treatment reversed the OXTR-induced accelerated mammary gland development by inhibition of prolactin/p-STAT5 pathway. Prolactin administration rescued lactation deficiency through STAT5 activation. Progesterone plays a negative role in OXTR-regulated prolactin/p-STAT5 pathways. The study provides evidence that OXTR overexpression induces abnormal mammary gland development through progesterone and prolactin-regulated p-STAT5 pathway.

Restricted access

Yang Chen, Xin Li, Jing Zhang, Mingjiao Zhang, Salah Adlat, Xiaodan Lu, Dan Li, Honghong Jin, Chenhao Wang, Zin Mar Oo, Farooq Hayel, Quangang Chen, Xufeng Han, Renjin Chen, Xuechao Feng, Luqing Zhang, and Yaowu Zheng

Obesity is caused by imbalanced energy intake and expenditure. The excessive energy intake and storage in adipose tissues is associated with many diseases. Several studies have demonstrated that VEGFB deficiency induces obese phenotypes. However, roles of VEGFB isoforms VEGFB167 and VEGFB186 in adipose tissue development and function are still not clear. In this study, genetic mouse models of adipose-specific VEGFB167 and VEGFB186 overexpression (aP2-Vegfb167tg/+ and aP2-Vegfb186tg/+) were generated and their biologic roles were investigated. On regular chow, adipose-specific VEGFB186 is negatively associated with white adipose tissues (WAT) and positively regulates brown adipose tissues (BAT). VEGFB186 up-regulates energy metabolism and metabolism-associated genes. In contrast, VEGFB167 has nominal roles in adipose development and function. On high fat diet, VEGFB186 expression can reverse the phenotypes of VEGFB deletion. VEGFB186 overexpression up-regulates BAT-associated genes and down-regulates WAT-associated genes. VEGFB186 and VEGFB167 have very distinct roles in regulation of adipose development and energy metabolism. As a key regulator of adipose tissue development and energy metabolism, VEGFB186 may be a target for obesity prevention and treatment.

Free access

Jiannan Zhang, Xin Li, Yawei Zhou, Lin Cui, Jing Li, Chenlei Wu, Yiping Wan, Juan Li, and Yajun Wang

The interaction of melanocortin-4 (MC4R) and melanocortin-3 (MC3R) receptors with proopiomelanocortin (POMC)-derived peptides (e.g. α-MSH), agouti-related protein (AgRP) and melanocortin-2 receptor accessory protein 2 (MRAP2) is suggested to play critical roles in energy balance of vertebrates. However, evidence on their interaction in birds remains scarce. Our study aims to reveal their interaction in chickens and the results showed that (1) chicken (c-)MC3R and cMC4R expressed in Chinese hamster ovary (CHO) cells can be activated by α-MSH and ACTH1–39 equipotently, monitored by a pGL3-CRE-luciferase reporter system; (2) cMC3R and cMC4R, when co-expressed with cMRAP2 (or cMRAP, a cMRAP2 homolog), show increased sensitivity to ACTH treatment and thus likely act as ACTH-preferring receptors, and the interaction between cMC3R/cMC4R and cMRAP2 was demonstrated by co-immunoprecipitation assay; (3) both cMC3R and cMC4R display constitutive activity when expressed in CHO cells, as monitored by dual-luciferase reporter assay, and cMRAP2 (and cMRAP) can modulate their constitutive activity; (4) AgRP inhibits the constitutive activity of cMC3R/cMC4R, and it also antagonizes ACTH/α-MSH action on cMC4R/cMC3R, indicating that AgRP functions as the inverse agonist and antagonist for both receptors. These findings, together with the co-expression of cMC4R, cMC3R, cMRAP2, cAgRP and cPOMC in chicken hypothalamus detected by quantitative real-time PCR, suggest that within the hypothalamus, α-MSH/ACTH, AgRP and MRAP2 may interact at the MC4R(/MC3R) interface to control energy balance. Furthermore, our data provide novel proof for the involvement of MRAP2 (and MRAP) in fine-tuning the constitutive activity and ligand sensitivity and selectivity of both MC3R and MC4R in vertebrates.

Open access

Bin Li, Jiming Yin, Jing Chang, Jia Zhang, Yangjia Wang, Haixia Huang, Wei Wang, and Xiangjun Zeng

Microcirculatory injuries had been reported to be involved in diabetic cardiomyopathy, which was mainly related to endothelial cell dysfunction. Apelin, an adipokine that is upregulated in diabetes mellitus, was reported to improve endothelial cell dysfunction and attenuate cardiac insufficiency induced by ischemia and reperfusion. Therefore, it is hypothesized that apelin might be involved in alleviating endothelial cell dysfunction and followed cardiomyopathy in diabetes mellitus. The results showed that apelin improved endothelial cell dysfunction via decreasing apoptosis and expression of adhesion molecules and increasing proliferation, angiogenesis, and expression of E-cadherin, VEGFR 2 and Tie-2 in endothelial cells, which resulted in the attenuation of the capillary permeability in cardiac tissues and following diabetic cardiomyopathy. Meanwhile, the results from endothelial cell-specific APJ knockout mice and cultured endothelial cells confirmed that the effects of apelin on endothelial cells were dependent on APJ and the downstream NFκB pathways. In conclusion, apelin might reduce microvascular dysfunction induced by diabetes mellitus via improving endothelial dysfunction dependent on APJ activated NFκB pathways.

Free access

Li Zhao, Chunfang Zhu, Meng Lu, Chi Chen, Xiaomin Nie, Buatikamu Abudukerimu, Kun Zhang, Zhiyuan Ning, Yi Chen, Jing Cheng, Fangzhen Xia, Ningjian Wang, Michael D Jensen, and Yingli Lu

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are an ideal therapy for type 2 diabetes and, as of recently, for obesity. In contrast to visceral fat, subcutaneous fat appears to be protective against metabolic diseases. Here, we aimed to explore whether liraglutide, a GLP-1RA, could redistribute body fat via regulating lipid metabolism in different fat depots. After being fed a high-fat diet for 8 weeks, 50 male Wistar and Goto-Kakizaki rats were randomly divided into a normal control group, a diabetic control group, low- and high-dose liraglutide-treated groups and a diet-control group. Different doses of liraglutide (400 μg/kg/day or 1200 μg/kg/day) or an equal volume of normal saline were administered to the rats subcutaneously once a day for 12 weeks. Body composition and body fat deposition were measured by dual-energy X-ray absorptiometry and MRI. Isotope tracers were infused to explore lipid metabolism in different fat depots. Quantitative real-time PCR and Western blot analyses were conducted to evaluate the expression of adipose-related genes. The results showed that liraglutide decreased visceral fat and relatively increased subcutaneous fat. Lipogenesis was reduced in visceral white adipose tissue (WAT) but was elevated in subcutaneous WAT. Lipolysis was also attenuated, and fatty acid oxidation was enhanced. The mRNA expression levels of adipose-related genes in different tissues displayed similar trends after liraglutide treatment. In addition, the expression of browning-related genes was upregulated in subcutaneous WAT. Taken together, the results suggested that liraglutide potentially redistributes body fat and promotes browning remodeling in subcutaneous WAT to improve metabolic disorders.