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1.
Reasons for performing study: Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C‐peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Hypothesis: A human double antibody radioimmunoassay (RIA) detects C‐peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatostatin administered i.v. as a primed continuous rate infusion, followed by 50 nmol human C‐peptide i.v. Insulin and C‐peptide concentrations were measured in horses (n = 6) undergoing an insulin‐modified frequently sampled i.v. glucose tolerance test, and in horses with insulin resistance (n = 10) or normal insulin sensitivity (n = 20). Results: A human RIA was validated for use with equine sera. Endogenous C‐peptide secretion was suppressed by somatostatin and median (range) clearance rate was 0.83 (0.15–1.61) ml/min/kg bwt. Mean ± s.d. C‐peptide‐to‐insulin ratio significantly (P = 0.004) decreased during the glucose tolerance test from 3.60 ± 1.95 prior to infusion to 1.03 ± 0.18 during the first 20 min following dextrose administration. Median C‐peptide and insulin concentrations were 1.5‐ and 9.5‐fold higher, respectively in horses with IR, compared with healthy horses. Conclusions: Endogenous C‐peptide secretion decreases in response to somatostatin and increases after dextrose infusion. Results suggest that relative insulin clearance decreases as pancreatic secretion increases in response to dextrose infusion. Hyperinsulinaemia in insulin resistant horses may be associated with both increased insulin secretion and decreased insulin clearance. Potential relevance: Both C‐peptide and insulin concentrations should be measured to assess pancreatic secretion and insulin clearance in horses.  相似文献   

2.
This study aimed to characterize the relationship between the growth of rumen papillae in calves and the mRNA expression of insulin‐like growth factor‐binding proteins (IGFBPs) in the rumen papillae. The length of rumen papillae, the mRNA expression of IGFBPs in rumen papillae by quantitative real‐time PCR, and the presence of insulin‐like growth factors I and II (IGF‐I and II) by immunohistochemistry (IHC) were analyzed in nine Holstein calves divided into three groups: suckling (2 weeks, n = 3), milk‐continued (8 weeks, n = 3), and weaned (8 weeks, n = 3). The length of rumen papillae was greater (p < 0.01) in weaned calves than in suckling and milk‐continued calves, whereas the expressions of IGFBP2, IGFBP3, and IGFBP6 genes were lower (p < 0.05) in the rumen papillae of weaned calves than in milk‐continued calves. Thus, rumen papillae length and IGFBP2, 3, and 6 expressions were negatively correlated. The IHC analysis showed that IGF‐I and IGF‐II were present in the rumen epithelium of calves. These results suggested that the growth of rumen papillae after weaning is associated with the induction of IGFs by the low levels of IGFBP2, IGFBP3, and IGFBP6.  相似文献   

3.
Effects of different carbohydrate sources on plasma glucose, insulin and insulin-like growth factor-I (IGF-I) levels were compared to subsequently be able to study effects of insulin-stimulating diets on follicle development in sows. The following feed components were tested in 12 sows during six consecutive test periods of 9.5 days: dextrose (DEX), sucrose (SUC), lactose (LAC), dextrose plus lactose (DL), sucrose plus lactose (SL), dextrose plus sugarbeet pulp (DSBP) and control (CON). On day 2, 5 and 9 of each test period, plasma glucose (only at day 9), insulin and IGF-I profiles were determined. Despite similar glucose profiles for all diets, the postprandial insulin response was higher for DL and SL compared with CON and LAC; the other diets were intermediate. Plasma IGF-I levels were higher in CON, LAC and SL compared with DSBP, but differences were only marginal. It was concluded that dextrose and sucrose have the potential to stimulate fast and high insulin peaks, especially when combined with additional lactose. Despite the high dextrose in the DSBP diet, the insulin response was flattened, probably due to the viscosity of sugarbeet pulp. The results show that modulation of plasma insulin levels by dietary carbohydrates seems possible in anabolic sows, but IGF-I levels are less easily modified.  相似文献   

4.
The aim of this study was to examine the effect of administering an anti‐gonadotropin‐releasing hormone vaccine (Improvac®, developed for pigs) on the performance, temperament, testicular development, and hormone and metabolite profiles of feral bulls (Bos taurus) vaccinated at two different live weights (LW). In all, 16 Serrana de Teruel animals were involved in this 2 x 2 factorial design using the factors LW (LIGHT vs. HEAVY) and vaccine treatment (control, C vs. vaccinated, VA). All animals received the same diet (ad libitum concentrate plus straw) over a 164‐day fattening period. Temperament was assessed using chute and flight speed tests. Testicular diameter and subcutaneous fat thickness were recorded. Testosterone, IGF‐1, urea, NEFA, and creatinine profiles were analyzed. Bull weight gain was reduced in VA compared to C animals, regardless of the initial LW. The vaccine did not affect the temperament tests, subcutaneous fat thickness or NEFA and creatinine concentrations and had minor effects on linear body measures. The vaccine inhibited testicular growth, reduced plasma testosterone to residual levels, and increased urea concentrations. LIGHT‐C animals exhibited increased mean plasma IGF‐1 concentrations compared to LIGHT‐VA animals. In conclusion, vaccination reduced bull growth and sexual development irrespective of LW at immunization.  相似文献   

5.
The aim of this study was to identify factors that regulate ruminal epithelial insulin‐like growth factor‐binding protein (IGFBP) expression and determine its role in rumen epithelial cell proliferation. Primary bovine rumen epithelial cells (BREC) were incubated with short‐chain fatty acids (SCFAs) at pH 7.4 or 5.6, lactate, lipopolysaccharide (LPS), insulin‐like growth factor‐I (IGF‐I), ‐II (IGF‐II), or recombinant bovine IGFBP2 (rbIGFBP2). The mRNA expression levels of IGFBP in BREC were analyzed using quantitative real‐time polymerase chain reaction (qRT‐PCR). The proliferation rate of BREC was analyzed using a WST‐1 assay. IGFBP2 gene expression tended to be lower with SCFA treatment (p < .1), and IGFBP6 gene expression was significantly lower with SCFA treatment (p < .05). IGFBP3 and IGFBP6 gene expression tended to be higher with d ‐Lactate treatment (p < .1). IGFBP3 gene expression was significantly higher (p < .05) with LPS treatment. BREC treated with IGF‐I grew more rapidly than vehicle control‐treated cells (p < .01); however, recombinant bovine rbIGFBP2 inhibited IGF‐I‐induced proliferation. IGF‐II and/or rbIGFBP2 did not affect BREC proliferation. Taken together, SCFA treatment decreased IGFBP2 and IGFBP6 expression in rumen epithelial cells, and lower expression of these IGFBP might promote rumen epithelial cell proliferation by facilitating IGF‐I.  相似文献   

6.
We investigated the effects of gonadotropin releasing hormone (GnRH) agonist on expressions of GnRH receptor (GnRHR), follicle‐stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) proteins in the ovaries and follicular development in the ewes. Forty‐two pre‐pubertal ewes were assigned to experimental groups 1 to 5 (EG‐I to EG‐V) and control group (CG). Ewes in EG‐I, EG‐II and EG‐III were subcutaneously injected with 200, 300 or 400 μg alarelin antigens twice (on days 0 and 14), respectively. Ewes in EG‐IV and EG‐V were subcutaneously injected with 200 μg and 300 μg alarelin antigen four times (on days 0, 7, 14 and 21). Ewes in CG were subcutaneously injected with a solvent twice (on days 0 and 14). Serum concentrations of GnRH antibody in the EGs increased and were higher than (P < 0.05) that of CG from day 14 to day 60. GnRH antibody concentrations in EG‐IV and EG‐V were higher than that in EG‐I, EG‐II and EG‐III from days 35 to 45. Expressions of GnRHR protein in EG‐IV and EG‐V were lower than that in CG (P < 0. 01). Expressions of FSHR and LHR proteins in EGs increased. Levels of FSHR and LHR proteins in EG‐IV and EG‐V (P < 0.05) were higher than CG. Ovarian weights in EGs increased. Values of follicle vertical diameter, follicle transverse diameter, follicle wall thickness, follicle externatheca thickness and follicle internatheca thickness in EG‐III and EG‐V were greater than other groups. Primordial follicles and primary follicles developed quickly in alarelin‐immunized animals. Secondary follicles and mature follicles became more abundant. Mitochondria, mitochondrial cristaes and cortical granules increased. Serum FSH concentrations of EGs remained higher than that in CG from days 28 to 70 (P < 0.05). Alarelin immunization stimulated GnRH antibody production, suppressed expression of GnRHR protein, enhanced expressions of FSHR and LHR proteins in ovaries, promoted FSH secretion and thereby accelerated the development of ovaries and follicles in ewes.  相似文献   

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8.
The objective of this study was to determine the effects of high and moderate non-structural carbohydrates (NSC) hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings. Eight adult overweight (average BCS 7 [9-point scale]) Arabian geldings were fed each of two orchardgrass hays, high NSC (18% DM) and moderate NSC (12% DM), in a cross over design during two 28-day periods. Body weight and body condition score assessment along with blood sampling to measure insulin, glucose, leptin, and triglyceride concentrations were performed on days 0, 7, 14, 21 and 28 of each period. Effects of hay, period, day, and day*hay on plasma glucose and serum leptin were not detected. Serum insulin was influenced by hay (p = 0.001), day (p = 0.03), and day*hay (p = 0.04). Insulin concentrations were higher on day 7 in the high NSC group (15.6 μIU/ml) than the moderate NSC group (9.5 μIU/ml), but not by day 14 (p = 0.0007). Plasma triglyceride was influenced by period (p = 0.0003), day*period (p < 0.0001), and day*hay (p = 0.02). Hyperinsulinaemia was not observed in the overweight Arabian geldings fed either a moderate or high NSC hay.  相似文献   

9.
Some evidence suggests that there might be a species difference in the effect of intracerebroventricularly administered (ICV) prolactin‐releasing peptide (PrRP) between rodents and sheep. We compared the levels of cortisol (CORT) and prolactin (PRL), rectal temperature (RT) and behavioral responses to ICV bovine PrRP (bPrRP) in steers. ICV bPrRP (0.2, 2 and 20 nmol/200 µL) tended to evoke a dose‐related increase in CORT concentrations and 0.2 nmol of bPrRP induced transient increase in PRL concentrations. A significant time–treatment interaction was observed for the percent change of CORT (P < 0.05) and PRL (P < 0.05) from pre‐injection value. The time–treatment interaction for changes in RT was not significant (P = 0.50). There tended to be a difference among the four treatments in terms of maximum change in RT from the pre‐injection value between 0 and 90 min (P < 0.1). Stress‐related behavioral signs were not observed in the present experiment. These findings indicate that ICV bPrRP increased CORT and PRL levels, suggesting that central PrRP might participate in controlling the hypothalamo‐pituitary‐adrenal axis and PRL release in cattle, unlike sheep. In contrast, central PrRP is unlikely to be involved in controlling the behavior of this species because ICV bPrRP did not induce marked changes in their behavior.  相似文献   

10.
It is well established that tumour cells have metabolic differences when compared with normal cells. This is particularly true for energy metabolism in which dogs with cancer have been reported to have higher blood insulin and lactate concentrations than control dogs. Moreover, some human and animal studies suggest that the insulin‐like growth factor 1 (IGF‐1) signalling pathway may play a role in tumorigenesis and tumour progression. At present, IGF‐1 has not been evaluated in dogs with multicentric lymphoma. In this prospective, cross‐sectional study, blood levels of IGF‐1, as well as other markers of energy metabolism—insulin, glucose, lactate, and β‐hydroxybutyrate—were measured in 16 dogs with histologically or cytologically confirmed treatment‐naïve lymphoma. These results were compared with 16 age‐, sex‐ and weight‐matched healthy controls. Dietary histories were collected, and protein, fat and carbohydrate intake were compared between groups. Results demonstrated that IGF‐1, insulin, glucose and insulin:glucose ratio were not different between groups. However, lactate and β‐hydroxybutyrate were higher in the dogs with lymphoma than that in the control dogs (1.74 ± 0.83 mmoL/L vs 1.08 ± 0.27 and 2.59 ± 0.59 mmol/L vs 0.77 ± 0.38 mmol/L, respectively). Median dietary protein, fat and carbohydrates did not differ between the groups. This preliminary study suggests that higher insulin and IGF‐1 levels relative to controls may not be a consistent finding in dogs with lymphoma. The significance of increased β‐hydroxybutyrate in dogs with lymphoma warrants further investigation in a larger prospective study.  相似文献   

11.
Insulin receptor (INSR) or insulin-like growth factor (IGF) signalling is speculated to be involved in mammary tumour development. Expression levels of members of the insulin receptor family (INSR, IGF1R, IGF2R, GHR) and their ligands IGF1and IGF2 were quantified in macro- and microdissected tissue samples of normal canine mammary gland, adenomas, carcinomas and their lymph node metastases to evaluate their potential impact on the carcinogenesis of canine mammary tumours. Normal mammary gland and adenomas had strong INSR expression, while carcinomas and metastases had significantly decreased expression. No differences were observed for IGF1R expression. IGF1, IGF2 and GHR mRNA expressions were strongly decreased in adenomas, carcinomas and metastases. INSR and IGF1R are therefore expressed in normal gland and adenomas and an increased stimulus by their ligands may be a proliferative stimulus in those tissues. However, decreased INSR expression carcinomas and their metastases render questionable its impact at late stages of carcinogenesis.  相似文献   

12.
To provide new insights into the neural mechanisms of physiological and behavioral responses to stressors in sheep, acute changes in endocrine, autonomic and behavioral functions following 30 min infusions of ovine‐corticotropin‐releasing hormone (oCRH; 0, 0.5, 5 or 50 µg/0.5 mL of artificial cerebrospinal fluid/30 min) into the third ventricle of sheep (n = 7–8) were examined. Serial blood samples were collected through indwelling jugular catheters to determine plasma cortisol concentrations (CORT). Heart rate (HR) and rectal temperature (RT) were obtained via telemetry systems. The behaviors of the animal were monitored simultaneously. Intracerebroventricular infusions of CRH dose‐dependently induced an increase in CORT; there was a time–treatment interaction in CORT (P < 0.001). There was not a time–treatment interaction either in HR (P = 0.29) or in RT (P = 0.28). That RT showed a tendency to decrease with higher doses of CRH in sheep was in contradiction to previous reports in rats and pigs. As to changes in behavioral function, only the induction of bleating was marked. These results suggest that in physiological and behavioral responses of sheep to stressors, CRH regulates the increase in CORT and the induction of bleating. However, CRH might have little function in sympathetic nervous activation during physiological responses to stressors in sheep.  相似文献   

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14.
Increased fructose consumption is linked to insulin resistance, weight gain, hyperlipidemia and hypertension. Although the advantages of several dietary restriction regimens have been demonstrated, the effects of alternate‐day fasting (ADF) on fructose‐induced insulin resistance have not yet been studied. This study is based on a new modification on ADF by combining the fructose‐rich solution (10% w/v) and regular mice diet. Mice were randomly allocated into four groups: ADF50% (50% restriction in chow food intake but ad libitum fructose drink), ADF100% (100% restriction for chow food but ad libitum fructose drink), control (ad libitum chow food intake plus tap water) and daily food and fructose (DFF) (had free access to both chow and fructose solution). Biweekly fasting blood sugar (FBS), glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted. All groups gained weight during the study (p < 0.05). Body weights of DFF and control groups did not differ from that of ADF groups, but ADF50% gained more (p < 0.01) weights than ADF100% through the study. Total calorie intake (feed + fast days) of ADF50% was higher than that of ADF100% (p < 0.001) and control (p < 0.03). In addition, ADF groups consumed more energy than the control and DFF groups in feed (ad libitum) days (p < 0.05). At the end of the study, the mean FBS levels in the control and ADF100% groups were similar and significantly lower in relation to that of DFF and ADF50% groups (p < 0.01). Measurements of area under the curve in GTT and ITT revealed that the ADF100% group was more insulin‐sensitive than the DFF and ADF50% groups. In conclusion, these data suggest that the ADF100% improves fructose‐induced insulin resistance in mice.  相似文献   

15.
Growth hormone (GH) secretion regularity and the effects of lighting condition and GH‐releasing hormone (GHRH) on GH release were determined in steers. First, steers were kept under 12:12 L : D conditions (light: 06.00–18.00 hours). The animals were then subjected to a 1‐h advancement in lighting on/off conditions (05.00 and 17.00 hours, respectively). Blood was sampled for 24 h at 1‐h interval on the seventh day of each condition. Second, GHRH was injected intravenously (IV) at 12.00 and 00.00 hours under 12:12 L : D and blood was sampled at 15‐min interval for 4‐h (1 h before and 3 h after the injection). Plasma GH concentrations were measured by a radioimmunoassay. Periodicity of GH secretory profile was calculated by power spectrum analysis using the maximum entropy method. Plasma GH concentrations showed a characteristic pattern consisting of four distinct peaks. Mean periodicity of GH secretory profile was 5.7 h, and it was not altered by any change in lighting conditions. IV injection of GHRH increased GH secretion during the day and night. The increase in GH secretory volume after GHRH injection during the night was equal to that during the day. The present results suggest that GH secreted from the anterior pituitary have regularity in steers.  相似文献   

16.
Elevated ambient temperatures affect animal production and welfare. Animal's reduced production performances during heat stress were traditionally thought to result from the decreased feed intake. However, it has recently been shown that heat stress disturbs the steady state concentrations of free radicals, resulting in both cellular and mitochondrial oxidative damage. Indeed, heat stress reorganizes the use of the body resources including fat, protein and energy. Heat stress reduces the metabolic rates and alters post‐absorptive metabolism, regardless of the decreased feed intake. Consequently, growth, production, reproduction and health are not priorities any more in the metabolism of heat‐stressed animals. The drastic effects of heat stress depend on its duration and severity. This review clearly describes about biochemical, cellular and metabolic changes that occur during thermal stress in farm animals.  相似文献   

17.
The presence of a receptor for calcitonin (CT) and the effect of chicken CT (cCT) on adrenocorticotropic hormone (ACTH) secretion stimulated by rat/human corticotropin‐releasing hormone (rhCRH) in the hen anterior pituitary were studied. The specific [125I]cCT binding component was present in the plasma membrane of hen anterior pituitary and this binding component had properties of a receptor which has binding specificity to cCT, reversibility, saturable binding, high affinity and limited capacity. When anterior pituitary cells were incubated in vitro, cCT increased the maximal secretion of chicken ACTH stimulated by rhCRH. These results suggest that CT may act directly on the anterior pituitary via its receptor binding and enhances the ACTH secretion by CRH.  相似文献   

18.
Twenty-two Angora kids were used to study the effect of a dietary supplementation with field bean (Vicia faba L. var. minor) on hair follicle activity, mohair characteristics and plasma total thyroxine (T4), triiodothyronine (T3), insulin (INS) and insulin-like growth factor-1 (IGF-1) concentrations. At birth, their mothers were divided in two groups (S: supplemented, C: control), the S group being supplemented with 300 g/head/day of whole field bean. At weaning, diet of kids from S group was supplemented with 80 g/head/day of whole field bean. At weaning, secondary hair follicle activity (S: 0.91 ± 0.01, C: 0.84 ± 0.02, p < 0.01) and staple length (S: 5.82 ± 0.13 cm, C: 5.16 ± 0.14 cm, p < 0.001) were greater in the S group. At 155 days of age, secondary fibre diameter (S: 16.54 ± 0.35 μm, C: 18.09 ± 0.31 μm, p < 0.01) was higher in the C kids. Concentrations of total plasma T4 and T3 were higher (p < 0.001) in S (120 ± 12 and 4.87 ± 0.92 ng/ml respectively) than in C kids (92 ± 8 and 2.97 ± 0.77 ng/ml respectively). At weaning, T4 values were negatively correlated (p < 0.05) with the secondary fibre diameter and the T3/T4 ratio was positively correlated (p < 0.05) with the secondary to primary hair follicle ratio. At 155 days of age, both T3 and T3/T4 values were positively correlated (p < 0.01) with staple length. Plasma INS (0.11 ± 0.03 ng/ml) and total IGF-1 concentrations (232 ± 13 ng/ml) were not affected by diet. Improvements of diet quality in kids positively affected fibre diameter and length and follicle activity rate. We suggest that increased circulating thyroid hormones concentrations, but not those of INS and IGF-1, may contribute to the beneficial actions of nutritional supplementation on anatomical growth and mohair production of kids.  相似文献   

19.
To determine the effect of supplemental feeding of Diamond V-XP yeast (XPY) alone or in combination with propionibacteria strain P169 on milk production, milk components, body weight, days to first and second ovulation, plasma insulin, and plasma and milk glucose, 31 primiparous and multiparous (MP) Holstein cows were fed one of three dietary treatments between 2 weeks prepartum to 30 weeks postpartum: (i) control (n = 10), fed a corn silage-based total mixed ration (TMR); (ii) XPY (n = 11), fed control TMR plus XPY (at 56 g/head/day); and (iii) P169+XPY (n = 10), received control TMR plus XPY plus P169 (at 6 x 10(11) cfu/head/day). After parturition, daily milk weights were recorded, and milk samples were collected twice weekly for milk component analyses. Daily uncorrected milk, solids-corrected milk, and 4% fat-corrected milk production for MP cows fed P169+XPY was 9-16% greater than control MP cows, but these increases were only evident during mid lactation (9-30 weeks). The percentage of milk fat was 8-18% greater in control than XPY and P169+XPY groups. Milk lactose percentage in MP cows fed P169+XPY was 3-5% greater than in control and XPY MP cows. Primiparous and MP cows fed P169+XPY had 28-32% greater milk glucose levels than control and XPY-fed cows. Diurnal plasma glucose concentration was not affected by diet in MP cows. Plasma insulin levels in MP cows fed P169+XPY were 30-34% greater than in other groups of MP cows. Milk glucose and plasma insulin responses to P169+XPY feeding suggest that P169+XPY might have enhanced gluconeogenesis and increased glucose uptake by the mammary gland in Holstein cows. Thus, a combined feed supplement of P169 and XPY may hold potential as a natural feed alternative to hormones and antibiotics to enhance lactational performance.  相似文献   

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