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1.
We investigated the effects of electrical foot shock stress on the melanocortin signaling cascade and the hypothalamus-pituitary-adrenal (HPA) system by observing levels of mRNA expression of corticotropin releasing factor (CRF), pro-opiomelanocortin (POMC), and melanocortin receptor subtype 4 (MC4R) in the rat amygdala and hypothalamus. When rats were exposed to electrical shock for 0.5 hr or 1 hr, plasma ACTH and corticosterone concentrations increased, indicating stress. The rats were then sacrificed to obtain RNA preparations from the brain tissue. In the amygdala, the expression of MC4R and POMC mRNA as well as CRF mRNA was significantly increased by electrical foot shock stress. In the hypothalamus, MC4R and POMC mRNA increased, but CRF mRNA remained unchanged. The duration of increased gene expression of MC4R and POMC in the amygdala was more sustained than in the hypothalamus. These results have provided the first evidence that exposure to stress increases expression of the MC4R system in the amygdala and hypothalamus.  相似文献   

2.
Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the IL-6 family that activates the hypothalamic-pituitary-adrenal axis and promotes corticotrope cell differentiation during development. The aim of this study was to investigate the expression of LIF and its receptor (LIFR) in the canine pituitary gland and in corticotrope adenomas, and to perform a mutation analysis of LIFR. Using immunohistochemistry, immunofluorescence, and quantitative expression analysis, LIF and LIFR expression were studied in pituitary glands of control dogs and in specimens of corticotrope adenoma tissue collected through hypophysectomy in dogs with pituitary-dependent hypercortisolism (PDH, Cushing's disease). Using sequence analysis, cDNA was screened for mutations in the LIFR. In the control pituitary tissues and corticotrope adenomas, there was a low magnitude of LIF expression. The LIFR, however, was highly expressed and co-localized with ACTH1-24 expression. Cytoplasmatic immunoreactivity of LIFR was preserved in corticotrope adenomas and adjacent nontumorous cells of pars intermedia. No mutation was found on mutation analysis of the complete LIFR cDNA. Surprisingly, nuclear to perinuclear immunoreactivity for LIFR was present in nontumorous pituitary cells of the pars distalis in 10 of 12 tissue specimens from PDH dogs. These data show that LIFR is highly co-expressed with adrenocorticotropic hormone (ACTH) and α-melanocyte-stimulating hormone (α-MSH) in the canine pituitary gland and in corticotrope adenomas. Nuclear immunoreactivity for LIFR in nontumorous cells of the pars distalis may indicate the presence of a corticotrope adenoma.  相似文献   

3.
The melanocortin-4 receptor (MC4R), a G protein-coupled seven-transmembrane receptor, which is expressed in the brain, plays an important role in the control of mammalian energy homeostasis. A missense mutation (Asp298Asn) was identified in the porcine MC4R gene, which is associated with growth and food intake traits. The Asn298 mutation occurs within a highly conserved motif, NPLIY, of all members of G protein-coupled receptors; whereas, Asp298 is conserved in all five melanocortin receptor subtypes. Functional analysis of the porcine MC4R variant was performed with an in vitro gene expression system in 293 cells. Ligand binding (NDP-alphaMSH) did not differ between Asp298 and Asn298 MC4R proteins. However, the Asn298 MC4R variant was unable to stimulate cAMP production in response to NDP-alphaMSH stimulation; whereas, the Asp298 variant could stimulate cAMP accumulation. These results demonstrate that the Asp298 is required for normal MC4R signaling to the adenylyl cyclase. Sequencing of the MC4R gene of seven diverse genera within the Suiformes that include Hippopotamidae (hippos), Tayassuidae (peccaries) and Suidae (pigs), revealed 62 nucleotide variations in MC4R. Phylogenetic relationships of MC4R variations are consistent with those previously described from morphological and physiological data among the subfamilies of the Suiformes. These findings revealed that a single missense mutation (Asp298Asn) of aspartic acid (Asp) to asparagine (Asn) in MC4R gene decreased cAMP content and MC4R signaling, but with no difference in the ligand binding was associated with growth and feed intake traits in domestic pigs.  相似文献   

4.
MC4R基因研究进展   总被引:2,自引:0,他引:2  
黑素皮质素受体-4(melanocortin-4 receptor,MC4R)是下丘脑腹内侧核分泌的一类肽类物质,为黑素皮质素受体家族5个亚型(MC1-5R)之一。在哺乳动物中,MC4R具有介导瘦蛋白(leptin)的功能,是一个调节能量平衡与能量动态平衡的重要信号分子,可与其内源性配体黑素皮质素激素(melanocortin,MC)或刺鼠色蛋白(agouti protein,agouti蛋白)和agouti相关蛋白(agouti related protein,AGRP)相结合,从而在控制食欲和体重稳态中起关键作用。因此,MC4R在人类肥胖研究中作为重要的调节因子倍受关注。最近有研究表明:MC4R的1232位点的G→A的突变与绵羊背膘厚度间存在关联,AG和AA型较GG型具有较高的背膘厚度。  相似文献   

5.
6.
Dogs have become one of the most important companion animals in modern society. However, it is estimated that 20% to 40% of owned dogs are obese, suggesting that obesity has become one of the most important canine health problem. In addition, obesity in dogs also leads to type II diabetes. Because the melanocortin-4 receptor (MC4R) has been shown to be essential in maintaining energy homeostasis in several different species, including rodents and humans, we initiated studies toward elucidating the roles of MC4R in obesity pathogenesis in dogs. Canine MC4R has been cloned, and a missense variant V213F was identified. We designed primers and successfully cloned canine MC4R and generated the variant V213F by site-directed mutagenesis. The objective of this study was to investigate the pharmacological properties of canine MC4R and its natural variant V213F. We measured ligand binding and signaling properties with the use of both natural and synthetic ligands. Human MC4R was also included in the experiments for comparison. Both wild-type canine MC4R and its natural variant V213F functioned normally in terms of binding and signaling. Of the ligands we used, [Nle4, D-Phe7]-α-melanocyte-stimulating hormone is the most potent ligand. We conclude that the cloned canine MC4R is a functional receptor, and the natural variant V213F does not have any functional defect and therefore is not likely to cause obesity in dogs.  相似文献   

7.
In the course of investigations on anorexia during infection, I found that B6-A(y) mice had significantly increased sensitivity to lipopolysaccharide (LPS)-induced lethality as compared with isogenic B6 mice. I also found that the sensitivity to the lethal effect of LPS dramatically increased in aged mice (age effect), both B6 and B6-A(y). However, the A(y) effect of enhancing sensitivity to LPS-induced lethality was still significant, suggesting that the A(y) effect is independent of age. In the absence of tumor necrosis factor alpha (TNFalpha), the A(y) effect was still significant, suggesting that the A(y) effect is independent of TNFalpha toxicity. A dose of LPS of 100 mug per mouse caused 15% lethality in B6, 65% in B6-A(y) (significantly higher than B6), and 100 % in leptin-deficient B6-ob/ob (significantly higher than B6 and B6-A(y)). The results support the hypothesis that endogenous leptin has a protective role against infection, and that a part of this leptin effect is mediated by alpha-melanocyte-stimulating hormone (alphaMSH). In contrast to the results of simple blockade at the melanocortin 4 receptor (MC4R), B6-A(y) suffered more severe LPS-induced anorexia than did B6; therefore, the pathway involving MC4R is not absolutely required for the LPS-induced anorexia, and the presence of pathways involving other melanocortin receptor types was suggested. Because alphaMSH is suggested to be an endogenous anti-inflammatory peptide, and because melanocortin 1 receptor (MC1R) is expressed in various cutaneous cell types, the A(y) effect might be caused via the pathway involving MC1R. Physiologic significance of alphaMSH-MC1R interaction in host defense against infection is discussed.  相似文献   

8.
为了调查兰尼定1型受体(RYR1)基因和黑素皮质素受体4(MC4R)基因[其目前公认的数量性状基因座(QTN)]在新组建的民猪群体内的分布情况,试验采用PCR-RFLP的方法,对黑龙江省农业科学院畜牧研究所收集整理的23头民猪的RYR1基因和MC4R基因进行检测,并与其他已报道的猪种进行比较。结果表明:RYR1基因的N等位基因频率为86.96%,n等位基因频率为13.04%;MC4R的A等位基因频率为76.19%,G等位基因频率为23.81%,与其他猪种相比,n等位基因频率偏高。  相似文献   

9.
Daytime variations in ACTH and plasma cortisol were studied in healthy dogs and in dogs with pituitary-dependent hypercortisolism (PDH), before and after treatment with retinoic acid. In control dogs ACTH showed a higher concentration at 8.00 AM and between 2.00 and 6.00 PM, with the lowest concentration registered at 10.00 AM (p < 0.05 vs. 8.00 AM and 2.00 PM and p < 0.01 vs. 4.00 PM). Cortisol did not show significant differences. In dogs with PDH, ACTH was lower at 8.00 AM (ACTH: p < 0.01 vs. 2.00 and 4.00 PM; and p < 0.05 vs. 6.00 PM). The lowest cortisol concentration was registered at 8.00 AM and 8.00 PM and the highest at 4.00 PM (p < 0.05 vs. 8.00 AM and p < 0.01 vs. 8.00 PM). After treatment, the lowest ACTH concentration was registered at 10.00 AM (p < 0.01 vs. 2.00 and 4.00 PM). To conclude, the adrenal is desensitized in PDH possibly showing negative in diagnostic tests.  相似文献   

10.
Studies of human adrenocortical tumors (ATs) causing Cushing's syndrome suggest that hypersecretion of cortisol is caused by altered expression of steroidogenic enzymes and that steroidogenesis can only be maintained when there is expression of the ACTH receptor (ACTH-R). Here we report the screening for the mRNA expression of the ACTH-R, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase, 21-hydroxylase (all in 38 cortisol-secreting ATs), 17α-hydroxylase, and 11β-hydroxylase (both in 28 cortisol-secreting ATs). Real-time PCR (RT-PCR) was applied in all samples and was compared with that in normal canine adrenal glands. Messenger-RNA encoding StAR, steroidogenic enzymes, and ACTH-R were present in both normal adrenal glands and cortisol-secreting ATs. The amounts of mRNA encoding StAR and enzymes of the steroidogenic cluster needed for cortisol production did not differ significantly between either adenomas or carcinomas and normal adrenal glands. The amount of mRNA encoding ACTH-R was significantly lower in carcinomas than in normal adrenal glands (P = 0.008). In conclusion, RT-PCR analysis revealed no overexpression of StAR and steroidogenic enzymes in canine cortisol-secreting ATs. Significant downregulation of ACTH-R in carcinomas might be associated with the malignant character of the AT.  相似文献   

11.
为检测黑色素受体1(melanocortin receptor 1,MC1R)基因型在不同毛色猪种中的分布,研究该基因在猪毛色决定中的地位和作用,本试验使用PCR-SSCP和PCR-RFLP方法对军牧1号白猪、杜洛克猪、西藏小型猪和大白猪的MC1R基因型进行了检测。结果显示,长白猪、大白猪存在nt894insCC和G1197A突变;杜洛克猪存在G668C、C1318T和G1554A突变;西藏小型猪存在C1318T和G1554A突变,而在nt894insCC位点则表现出其他基因型。通过对4个猪种的MC1R基因型的检测,为研究MC1R基因对毛色的作用机理奠定了基础。  相似文献   

12.
毛色作为家兔的一种遗传标记,在品种特征、纯度鉴定及品种选育中均具有重要的作用。MC1R基因作为控制动物毛色的重要基因之一,其核苷酸序列多态性与多种动物的毛色表型相关。本试验根据GenBank中已知的兔MC1R基因核苷酸序列(登录号:AM180881)设计引物RMCR1和RMCR2,采用PCR-末端加尾法获得了兔MC1R基因5'端930 bp的未知序列,该序列与GenBank数据库中的已知序列同源性为99%。  相似文献   

13.
To evaluate difference in the expression of skin color genes (melanocortin 1 receptor (MC1R) and premelanosome (PMEL)) in lymphocytes during winter and summer season and their correlation with tyrosinase enzyme and cortisol, ten Karan-Fries heifers were selected from National Dairy Research Institute (NDRI) cattle farm. Blood samples were collected from the animals during winter (THI?=?60) and summer (THI?=?83) season at weekly intervals. Relative MC1R and PMEL messenger RNA (mRNA) expression of Karan Fries cattle was found to be significantly (P?P?P?相似文献   

14.
为研究黑皮质素受体1(MC1R)基因对吐鲁番黑山羊毛色的影响,试验采用PCR扩增和测序技术,对吐鲁番黑羊MC1R基因编码区核苷酸序列及其与毛色的相关性进行了研究。结果表明:MC1R基因编码区核苷酸序列954 bp,编码317个氨基酸,编码区存在2个错义突变(c.218 T〉A,p.73 Met〉Lys;c.361 G〉A,p.121 Asp〉Asn)和3个同义突变(c.429 C〉T,p.143 Tyr〉Tyr;c.600 T〉G,p.200 Leu〉Leu;c.735 C〉T,p.245 Ile〉Ile)。SNPs分析表明,单倍型AATGT数量占62%。初步认为MC1R基因可以作为吐鲁番黑羊黑色被毛调控的候选基因。  相似文献   

15.
Acetylcholine interacts with endothelial muscarinic receptors releasing nitric oxide and causing vasodilatation. To identify the receptor subtype responsible for acetylcholine-induced relaxation in canine uterine artery, the usual organ bath method for in vitro investigation on isolated blood vessels was applied. Using a range of muscarinic receptor antagonists such as atropine (nonselective), pirenzepine (M1-selective), methoctramine (M2-selective) and p -fluoro-hexahydro-sila-difenidol ( p -FHHSiD) (M1/M3) and determining pA2 value of those antagonists through Shild analysis, we aimed at establishing a precise receptor mechanism underlying acetylcholine-induced relaxation in isolated canine uterine artery. The relaxation of uterine arterial rings in response to acetylcholine in the presence or absence of selective muscarinic receptors antagonists was calculated using concentration response curves. Acetylcholine induced concentration-dependent and endothelium-dependent relaxation of arterial rings precontracted with phenylephrine (pEC50 = 6.90 ± 0.02). Muscarinic receptors antagonists atropine, pirenzepine, methoctramine and p -FHHSiD competitively antagonized the response to acetylcholine and obtained pA2 values were 9.91 ± 0.06, 6.60 ± 0.04, 6.21 ± 0.08 and 8.05 ± 0.1, respectively. This study showed that acetylcholine induced endothelium-dependent relaxation of canine uterine artery by stimulation of muscarinic receptors localized on the endothelial cells. On the basis of differential antagonist affinity, we suggest that the muscarinic receptors involved in the acetylcholine-induced relaxation of canine uterine artery are predominantly of M3 subtype.  相似文献   

16.
The aim of the study was to investigate the association of two parts of melanocortin gene (MC4R‐1, MC4R‐2) and feed intake for V‐line rabbits. V‐line rabbits were grouped into high and low daily feed intake during the period from 30 to 63 days of age in order to identify MC4R SNPs useful for association study with feed intake. DNA from blood samples of each group was extracted to amplify the MC4R gene. The purified PCR products were sequenced in those had the highest and lowest feed intake. Alignment of sequence data from each group revealed that there is a variation detected in MC4R‐1 at nucleotide 35 (T‐G) (sense mutation) and another variation was detected in MC4R‐2 gene at nucleotide 19 (T‐C) (sense mutation) for high feed intake rabbits. These sense mutations lead to transform some amino acids and cause a significant change of the MC4R function. The results of average daily feed intake (ADFI) indicated that group (1) had significantly higher feed intake than group (2) of V‐line rabbits. The detected mutations and the analysis of daily feed intake means revealed a significant association between MC4R polymorphism and feed intake in rabbits.  相似文献   

17.
在欧洲马品种中,黑色素皮质激素受体1(melanocortin receptor 1,MC1R)基因第248位碱基有C/T多态性,纯合的T248位点决定欧洲马的栗毛色。针对MC1R基因的248位点设计了2对特异性引物,采用等位基因特异性PCR技术,研究3个中国马品种MC1R基因型与栗色毛之间的关系。经扩增获得两种DNA片段,克隆测序后证明,扩增片段确为MC1R基因,两种DNA片段序列在基因的248位点的确呈现C/T多态性,但检测126份贵州矮马、西南马和新疆伊犁马血液样本,全部为杂合基因型(Ee),其中包括栗毛、黑毛、骝毛3种单毛色及3种复毛色。这些研究结果提示,MC1R基因中248位点的多态性与国内3个马品种的栗色毛之间没有直接的相关性。  相似文献   

18.
19.
Oxytocin neurons have a physiological role in food intake and energy balance. Several studies have shown that central histaminergic and adrenergic systems synapse on oxytocin neurons but there is no information for their interaction on food intake regulation in birds. The purpose of this study was to examine the effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptors antagonist), famotidine (histamine H2 receptors antagonist), thioperamide (histamine H3 receptors antagonist), prazosin (α1 receptor antagonist), yohimbine (α2 receptor antagonist), metoprolol (β1 adrenergic receptor antagonist), ICI 118,551 (β2 adrenergic receptor antagonist) and SR59230R (β3 adrenergic receptor antagonist) on oxytocin-induced hypophagia in 3-h food-deprived (FD3) neonatal broiler chicken. In Experiment 1, 3 h-fasted chicks were given an ICV injection of saline, α-FMH (250 nmol), oxytocin (10 μg) and co-injection of α-FMH + oxytocin. Experiments 2–9 were similar to experiment 1 except birds were injected with chlorpheniramine (300 nmol), famotidine (82 nmol), thioperamide (300 nmol), prazosin (10 nmol), yohimbine (13 nmol), metoprolol (24 nmol), ICI 118,551(5 nmol) and SR59230R (20 nmol) instead of α-FMH, respectively. After injection cumulative food intake was measured until 120 min post injection. According to the results, ICV injection of oxytocin significantly decreased food intake in broiler chickens (P < 0.001). ICV injection of α-FMH significantly attenuated hypophagic effect of oxytocin (P < 0.001). Also, co-injection of chlorpheniramine plus oxytocin significantly decreased the effect of oxytocin on food intake (P < 0.001). Co-administration of thioperamide and oxytocin significantly amplified hypophagic effect of oxytocin in chickens (P < 0.001). In addition, ICI 118,551 attenuated hypophagic effect of oxytocin (P < 0.001); while famotidine, prazosin, yohimbine, metoprolol and SR59230R had no effect on oxytocin- induced food intake in FD3 broiler chickens. These results suggest that the effect of oxytocin on food intake is probably mediated by histaminergic (via H1 and H3 receptors) and noradrenergic (via β2 receptors) systems in broiler chickens.  相似文献   

20.
In order to evaluate the immune state of dogs suffering from pituitary-dependent hyperadrenocorticism (PDH), peripheral lymphocyte subsets were examined. Twenty seven PDH dogs and eight healthy control dogs were used in the current study. Eight healthy dogs served as the control group. Twenty seven PDH dogs were categorized into 4 groups based on their post serum cortisol concentrations by ACTH stimulation test: 2−5, excellent control (n = 8); 5−20, fair control (n = 7); >20, poor control (n = 4); and untreated (n = 8). Cell counts were executed with white blood cells (WBC), lymphocytes, CD3+ (T lymphocytes), CD4+ (Helper T lymphocytes), CD8+ (Cytotoxic T lymphocytes), CD21+ (B lymphocytes) cells in addition to calculating CD4+/CD8+ ratio. Results indicated a significant difference in lymphocyte numbers and lymphocyte subset populations (CD3+, CD4+, CD8+, and CD21+ cells) between PDH and control dogs. Moreover, comparison of the PDH groups (excellent control; fair control; poor control; untreated) demonstrated that all groups had a significant decrease in lymphocytes numbers (CD3+, CD4+ and CD21+ cell counts) as compared to control group. Meanwhile, no significant differences were observed in WBC counts and CD4+/CD8+ ratio between groups. Furthermore, lymphocyte subset distribution in excellent control PDH dogs without concurrent disease (n = 4) better resembled that of control dogs as compared to PDH dogs with concurrent disease (n = 4). PDH dogs may be suffering from an immuno-depressed state as evidenced by significant differences in lymphocyte subset populations. Furthermore, treatment of both PDH and concurrent disease might improve lymphocyte subset distribution.  相似文献   

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