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1.
Effect of intracerebroventricular orexin-B on food intake in sheep.   总被引：6，自引：0，他引：6  
Orexin is a hypothalamic neuropeptide that regulates feeding behavior in rats. Orexin-B has recently been cloned in pigs and was shown to stimulate food intake after intramuscular injection. This study was designed to determine whether intracerebroventricular (ICV) and intravenous injections of orexin could regulate appetite in sheep. Suffolk wethers were moved to indoor facilities, adapted to diets for 6 wk, and trained to stand in stanchions for 3 to 6 h each day for 2 wk before indwelling ICV cannulas were installed. These sheep were provided water and they consumed feed ad libitum. On the day before an experiment, each sheep was cannulated in a jugular vein. On the day of an experiment, sheep were placed in stanchions and allowed to stand for 1 h before use. Sheep were then monitored over a 2-h control period before i.v. injection with saline or porcine orexin-B (3 micrograms/kg BW) or ICV injection with artificial cerebrospinal fluid (CSF), orexin (0.03, 0.3, or 3 micrograms/kg BW) or in a second experiment with either orexin B (0.03, 0.3, 3 micrograms/kg BW), neuropeptide-Y (NPY; 0.3 microgram/kg BW), or orexin plus NPY. Food intake was monitored for consecutive 2-h periods. The i.v. injections of orexin did not affect food intake or metabolite or hormone concentrations. In ICV sheep, orexin increased food intake at 2 (P < 0.04) and at 4 h (P < 0.02). Food intake was greatest with the 0.3 microgram/kg BW dosage of orexin (P < 0.05). In the first 2 h after injection, orexin had an effect similar to that of NPY (0.23 kg for orexin and 0.2 kg for NPY). The combination of NPY and orexin had a greater effect on food intake (to 0.34 kg) than did either orexin (P < 0.05) or NPY (P < 0.008) alone. Differences were not apparent in the subsequent 2-h interval. No differences were noted in free fatty acid, glucose, growth hormone, luteinizing hormone, or insulin concentrations following orexin injection. There was an effect of ICV orexin treatment on plasma cortisol concentrations (P < 0.002). Cortisol was increased by orexin at the 0- to 2-h (P < 0.008) and in the 2- to 4-h (P < 0.009) intervals after orexin injection. These data indicate that central administration of orexin stimulates feed intake in sheep.  相似文献   

2.
We studied effects of protein intake at two protein-free energy intake levels on plasma glucose and insulin concentrations, urinary glucose excretion and on liver and intestinal fat content in milk-fed veal calves. Two experiments were performed at body weights (BW) of 80-160 kg (mean 120 kg; Exp. 1) and 160-240 kg (mean 200 kg; Exp. 2). In each experiment, 36 calves were allocated to one of six protein intake levels, at each of two energy intake levels. Digestible protein intakes ranged between 0.90 and 2.72 g nitrogen (N)/(kg BW(0.75) x d) in Exp. 1 and between 0.54 and 2.22 g N/(kg BW(0.75)x d) in Exp. 2. The two energy intake levels were kept constant on a protein-free basis and were 663 and 851 kJ/(kg BW(0.75) x d) in Exp. 1 and 564 and 752 kJ/(kg BW(0.75)x d) in Exp. 2. Blood samples were taken between 5 and 6h post-feeding at 14-d intervals until calves reached target BW, and liver fat mass was determined at slaughter. Urinary glucose excretion was quantified at 120 and 200 kg BW in Exps. 1 and 2, respectively. Increased protein-free energy intake increased plasma glucose concentrations and urinary glucose losses in 200 kg calves, but not in 120 kg calves. Increasing protein intake decreased plasma glucose, urinary glucose and plasma insulin in both experiments. Liver fat content decreased with increasing protein intake. In conclusion, long-term low-dietary protein intake increased hyperglycemia, hyperinsulinemia, glucosuria and hepatic steatosis in heavy milk-fed calves, likely associated with increased insulin resistance.  相似文献   

3.
Chronic elevation of glucocorticoid concentrations is detrimental to health. We investigated effects of chronic increase in plasma cortisol concentrations on energy balance and endocrine function in sheep. Because food intake and reproduction are regulated by photoperiod, we performed experiments in January (JAN) and August (AUG), when appetite drive is either high or low, respectively. Ovariectomized ewes were treated (intramuscularly) daily with 0.5 mg Synacthen Depot® (synthetic adrenocorticotropin: ACTH) or saline for 4 wk. Blood samples were taken to measure plasma concentrations of cortisol, luteinising hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), leptin, insulin, and glucose. Adrenocorticotropin treatment increased concentrations of cortisol. During JAN, treatment reduced food intake transiently, but increased food intake in AUG. Leptin concentrations were reduced and glucose concentrations were greater in AUG, and insulin concentrations were similar throughout the year. Treatment with ACTH increased leptin concentrations in AUG only, whereas insulin concentrations increased in JAN only. Synacthen treatment increased glucose concentrations, with a greater effect in JAN. Changes in truncal adiposity and ACTH-induced cortisol secretion were positively correlated in JAN and negatively correlated in AUG. Treatment reduced the plasma LH pulse frequency in JAN and AUG, with an effect on pulse amplitude in JAN only. Treatment did not affect plasma GH or FSH concentrations. We conclude that chronically elevated cortisol concentrations can affect food intake, adiposity, and reproductive function. In sheep, effects of chronically elevated cortisol concentrations on energy balance and metabolism depend upon metabolic setpoint, determined by circannual rhythms.  相似文献   

4.
The effects of zinc–methionine (Zn‐Met) supplementation on growth, blood metabolites and gastrointestinal development were investigated in two experiments with sheep. The objective of Experiment 1 was to determine the effects of Zn‐Met supplementation on hormones and metabolites involved in growth and energy balance regulation, while Experiment 2 aimed to determine the effects of Zn‐Met on feed intake, body weight, gastrointestinal development and liver glycogen concentration in lamb. The animals were assigned to groups with different concentrations of dietary Zn‐Met (0, 0.4, 0.8 and 1.2 g/day) in both experiments. In Experiment 1, feeding different doses of Zn‐Met increased plasma insulin‐like growth factor 1 (IGF‐1) concentration, but it linearly decreased plasma growth hormone (GH). No differences were observed in blood cortisol, insulin and glucose concentrations among the treatments. In Experiment 2, addition of Zn‐Met to the diets did not lead to changes in the body weights of the lambs. Both average daily gain and dry matter intake (DMI) increased linearly with increasing concentrations of dietary Zn‐Met. Lambs receiving Zn‐Met showed higher liver glycogen concentrations than the control. While significant increases were observed in the villus height and crypt depth in the duodenum and jejunum as a result of Zn‐Met supplementation, no change was detected in blood glucose concentrations (p > 0.05). Our findings suggest that dietary Zn‐Met may improve growth, energy balance and gastrointestinal development in sheep.  相似文献   

5.
Seventeen Thoroughbred and Quarter Horse yearlings were used in a 2×2 factorial experiment to determine 1) whether adding fat (5% corn oil) to the concentrate would influence feed intake, growth and development and 2) whether time of hay feeding would influence energy metabolism on the basal and added fat diets. Yearlings were assigned at random, within breed and gender subgroups, to one of four diets: B-I, basal concentrate with Coastal Bermuda grass (Cynodon dactylon) hay fed immediately after the concentrate; B-D, basal with hay fed 3.5 hr after the concentrate; F-I, basal + fat with the hay fed immediately; and F-D, basal + fat with the hay fed 3.5 hr after the concentrate. The basal concentrate was formulated to meet or exceed NRC (1989) recommendations when fed with the hay. The basal + fat concentrate was formulated at 9.7% higher digestible energy than the basal concentrate and all of the other nutrients were increased proportionately so if the intake was reduced, the yearlings would still meet nutrient needs. The concentrates were fed individually to appetite for two 1.5-hr feeding periods daily in 1.5×3.0 m slip stalls. Hay was group fed in the paddocks at a rate of 1.0 kg/100 kg BW daily divided into two equal feedings. Animals were housed in four 9.1×34.9-m drylot paddocks with three, four, or five animals in each paddock. The mean age at the start of the experiment was 377±8 days. Weight and body measurements for withers height, heart girth, body length, and hip height were taken at the start of the experiment and at 28-day intervals for 84 days. Radiographs for bone mineral estimates were made at the start and completion of the experiment. During the final 28-day period of the feeding trial, three animals from each experimental group were randomly selected for a 24-h period of blood sampling to evaluate the effects of the diets on blood glucose and insulin.Fat addition to the concentrate reduced the daily concentrate DM (P=0.0187) and total feed DM (P=0.0021) intake. When feed intake was expressed as a function of BW, concentrate and total feed intakes were 1.33 and 2.14 kg/100 kg BW daily and were not influenced by diet (P>0.1). Colts consumed more concentrate DM (P=0.0039) and total feed DM (P=0.0022) than fillies. The yearlings gained an average of 0.60 kg/d for the 84 days. Weight gain, body measurements and bone mineral deposition were not influenced by gender or diet. Mean plasma glucose concentrations were higher (P=0.05) in yearlings consuming the basal concentrate with hay fed immediately than when hay feeding was delayed. When fat was fed, the time of hay feeding had no effect on plasma glucose concentrations (P>0.05). Plasma glucose and insulin were lowest just prior to the morning feeding and peaked two to three hours after both morning and afternoon feedings. Fat supplementation reduced plasma insulin (P=0.001). Results suggest that the addition of 5% corn oil to a yearling concentrate may reduce feed intake but will not reduce growth and development of the animal if other nutrients are supplied at concentrations that provide for the animal's daily needs. Delaying hay feeding may be advantageous to growing horses as it may allow the concentrate to move down the tract at a slower rate reducing the glucose peaks.  相似文献   

6.
This study was conducted to investigate effects of glucagon intracerebroventricularly administered on feed intake and endocrine changes in sheep. Four male sheep (48–55 kg BW) were used. The animals were acclimatized to be fed alfalfa hay cubes at 12.00 hour. Human glucagon (40 and 80 µg/0.5 mL) was injected into the lateral ventricle at 12.00 hour. Blood samples were taken every 10 min from 30 min before to 180 min after the glucagon injection. Soon after the injection, the animals were given alfalfa hay cubes, and the amounts of the feed eaten within 2 h were measured. Feed intakes were significantly (P < 0.05) suppressed by 80 µg of glucagon. Plasma glucose levels in control animals were gradually decreased after the feeding, whilst those in glucagon‐treated animals were temporarily elevated just after the feeding and then kept higher than control levels. Plasma insulin was abruptly elevated after the feeding and was maintained at higher levels than before the feeding in all treatments. Plasma NEFA concentrations were decreased after the feeding in all treatments. A tendency of increase in plasma cortisol levels occurred in glucagon‐injected animals. The present study provides the first evidence that glucagon directly acts on the brain, then inhibiting feeding behavior and inducing endocrine responses in ruminants.  相似文献   

7.
Prolonged infusions of bacterial lipopolysaccharides (LPS) are known to model gram-negative bacterial infections, but the basic mechanisms of the LPS effects on feed intake and metabolism and their potential interdependence are largely unknown. The aim of the present study was to distinguish and to better characterize the feeding suppressive and metabolic effects of LPS. Six heifers were infused intravenously for 100 min with either 1) LPS (2 microg/kg BW) with free access to feed, 2) saline with free access to feed, or 3) saline with feeding restricted to the amount of feed consumed after LPS infusion. Feed intake, body temperature, plasma concentrations of various metabolites and hormones, and the respiratory quotient and heat production were measured. The LPS reduced feed intake and induced pronounced changes in metabolic energy turnover and fat and carbohydrate metabolism that were largely independent of the concomitant feed intake reduction. Some of the metabolic changes were biphasic; the first phase resembled a stress response with increases in plasma glucose and cortisol, and the second phase reflected a beginning energy deficit with low plasma glucose and enhanced lipolysis. The coincidence of a short-term surge of plasma insulin with marked transient decreases in plasma FFA, glycerol, and beta-hydroxybutyrate as well as with the transition from hyper- to hypoglycemia indicates that insulin plays a role in some of the metabolic responses to LPS. The failure of LPS to clearly increase energy expenditure despite the increase in body temperature suggests that anaerobic mechanisms of heat production and, perhaps, a reduced peripheral blood flow contributed to the fever. Many of the initial metabolic responses occurred before and, therefore, independent of, an increase in circulating tumor necrosis factor-alpha.  相似文献   

8.
OBJECTIVE: To determine the effect of continuous IV administration of 50% dextrose solution on phosphorus homeostasis in lactating dairy cows. DESIGN: Clinical trial. ANIMALS: 4 multiparous Jersey cows. PROCEDURES: Cows were administered 50% dextrose solution IV (0.3 g/kg/h [0.14 g/lb/h]) for 5 days. Plasma concentrations of glucose, immune-reactive insulin (IRI), and phosphorus were determined before, during, and for 72 hours after dextrose infusion. Phosphorus intake and losses of phosphorus in urine, feces, and milk were determined. Each cow received a sham treatment that included instrumentation and sampling but not administration of dextrose. RESULTS: Plasma glucose, IRI, and phosphorus concentrations were stable during sham treatment. Plasma phosphorus concentration decreased rapidly after onset of dextrose infusion, reaching a nadir in 24 hours and remaining less than baseline value for 36 hours. Plasma phosphorus concentration increased after dextrose infusion was stopped, peaking in 6 hours. Urinary phosphorus excretion did not change during dextrose infusion, but phosphorus intake decreased because of reduced feed intake, followed by decreased fecal phosphorus loss and milk yield. Rapid changes in plasma phosphorus concentration at the start and end of dextrose infusion were temporally associated with changes in plasma glucose and IRI concentrations and most likely caused by compartmental shifts of phosphorus. CONCLUSIONS AND CLINICAL RELEVANCE: Hypophosphatemia developed in response to hyperglycemia or hyperinsulinemia in dairy cows administered dextrose via continuous IV infusion. Veterinarians should monitor plasma phosphorus concentration when administering dextrose in this manner, particularly in cows with decreased appetite or preexisting hypophosphatemia.  相似文献   

9.
The objective of this study was to examine the relationship between mitochondrial function and residual feed intake in Angus steers. Individual feed intakes were recorded for a contemporary group of 40 steers via the GrowSafe feed intake system. Intakes were then used to calculate residual feed intake (RFI), a measure of efficiency. Based on these calculations, 9 low (RFI = -0.83) and 8 high (RFI = 0.78) RFI animals were selected for further study. Blood samples were collected via jugular venipuncture 1 wk before slaughter for the determination of plasma glucose and insulin concentrations. Tissue samples were taken from the LM from both the high and low RFI animals and mitochondria were isolated for measurement of oxygen consumption and hydrogen peroxide production. Average daily gain and carcass composition were not different between the high and low RFI steers; however, ADFI by the high RFI animals was 1.54 kg/d greater (P < 0.001) than for the low RFI animals. Low RFI steers exhibited a greater (P < 0.05) rate of state 2 and 3 respiration, respiratory control ratio, and hydrogen peroxide production than high RFI steers when provided with glutamate or succinate as a respiratory substrate. The acceptor control and adenosine diphosphate:oxygen ratios were not different between the 2 groups for either substrate. When hydrogen peroxide production was expressed as a ratio to respiration rate there was no difference between groups, signifying that electron leak was similar for both groups. Plasma glucose concentration was greater (P < 0.05) in the high RFI steers than in the low RFI steers; however, plasma insulin concentration was not different (P = 0.22) between the 2 groups. The ratio between plasma glucose and insulin concentration was similar (P = 0.88) between the 2 groups indicating no difference in glucose metabolism. The increased plasma glucose concentration observed in the high RFI steers was presumed to be the result of a greater feed intake by these animals. It seems that mitochondrial function is not different between the high and low RFI groups but rather the rate of mitochondrial respiration is increased in low RFI steers compared with high RFI steers.  相似文献   

10.
These studies were conducted to determine whether ghrelin, a 28-amino acid peptide produced mainly by the stomach, was involved in tryptophan-mediated appetite stimulation in swine. In experiment 1, 36 crossbred (Long WhitexLarge White) barrows were used in a 2x3 factorial design to determine the effects of food intake (ad libitum versus limit fed) and tryptophan level (0.12%, 0.19% and 0.26%) on growth performance as well as ghrelin expression, plasma insulin, ghrelin and leptin levels. Ad libitum fed pigs gained more weight, but had poorer feed conversion than limit fed pigs. Weight gain, food intake and feed conversion all improved with increased ingestion of dietary tryptophan. Ad libitum feeding increased plasma insulin. Plasma insulin was unaffected by the level of dietary tryptophan. However, plasma leptin was significantly lower in pigs fed 0.19% tryptophan compared to those fed 0.12% tryptophan. Plasma ghrelin levels and ghrelin mRNA level in gastric fundus and duodenun was significantly higher in pigs fed 0.19% and 0.26% tryptophan diet compared with pigs fed 0.12%. In the second experiment, 18 crossbred barrows were divided into three treatments involving oral infusion of saline, tryptophan (40mg/kg BW) or 5-hydroxytryptophan (40mg/kg BW). Plasma ghrelin levels at 20, 40 and 60min after infusion of tryptophan were higher than after saline and 5-hydroxytryptophan infusion, 5-hydroxytryptophan infusion induced lower food intake than saline infusion, and tryptophan infusion increased food intake 2, 8 and 24h after infusion. In conclusion, oral tryptophan ingestion increased ghrelin expression in gastric fundus and plasma ghrelin level.  相似文献   

11.
These experiments were conducted to determine if 1) syndyphalin-33 (SD33), a mu-opioid receptor ligand, affects feed intake; 2) SD33 effects on feed intake are mediated by actions on opioid receptors; and 3) its activity can counteract the reduction in feed intake associated with administration of bacterial endotoxin. In Exp. 1, 5 mixed-breed, castrate male sheep were housed indoors in individual pens. Animals had ad libitum access to water and concentrate feed. Saline (SAL; 0.9% NaCl) or SD33 (0.05 or 0.1 micromol/kg of BW) was injected i.v., and feed intake was determined at 2, 4, 6, 8, 24, and 48 h after the i.v. injections. Both doses of SD33 increased (at least P < 0.01) feed intake at 48 h relative to saline. In Exp. 2, SAL + SAL, SAL + SD33 (0.1 micromol/kg of BW), naloxone (NAL; 1 mg/kg of BW) + SAL, and NAL + SD33 were injected i.v. Food intake was determined as in Exp. 1. The SAL + SD33 treatment increased (P = 0.022) feed intake at 48 h relative to SAL + SAL. The NAL + SAL treatment reduced (at least P < 0.01) feed intake at 4, 6, 8, 24, and 48 h, whereas the combination of NAL and SD33 did not reduce feed intake at 24 (P = 0.969) or 48 h (P = 0.076) relative to the saline-treated sheep. In Exp. 3, sheep received 1 of 4 treatments: SAL + SAL, SAL + 0.1 micromol of SD33/kg of BW, 0.1 microg of lipopolysaccharide (LPS)/kg of BW + SAL, or LPS + SD33, and feed intake was monitored as in Exp. 1. Lipopolysaccharide suppressed cumulative feed intake for 48 h (P < 0.01) relative to saline control, but SD33 failed to reverse the reduction in feed intake during this period. These data indicate that SD33 increases feed intake in sheep after i.v. injection, and its effects are mediated via opioid receptors. However, the LPS-induced suppression in feed intake cannot be overcome by the opioid receptor ligand, SD33.  相似文献   

12.
The association between feed intake and lipogenic activity in adipose tissue was investigated in growing cattle. Twenty-five 300-kg steers were allotted by BW to one of five levels of intake of a single high-energy corn-corn silage-based diet. Steers were adapted to diets over 4 wk and intakes were adjusted weekly to achieve steady but varying rates of growth. Daily intakes (% of BW) averaged .92, 1.15, 1.64, 2.28 and 2.69 and resulted in growth rates over the final 3 wk of -.28, .07, .71, 1.67 and 1.69 kg/d, respectively. Lipogenic activities in biopsied tissue and circulating concentrations of glucose and insulin were lowest at maintenance feeding and below but increased linearly (P less than .01 for lipogenesis; P less than .1 for glucose and insulin) as intake increased above maintenance. Mean minimal and maximal rates (mumoles.-min(-1).10(6) cells(-1)) or concentrations were fatty acids synthesis ([14C]acetate---fatty acid)), .065 and .723; fatty acid synthetase (NADPH oxidized), .266 and 2.97; lipoprotein lipase (fatty acid released), .048 and .359; glucose (mg/dl), 60.4 and 70.7 and insulin (ng/ml), .70 and 1.66. In a preliminary study with the same 25 steers fed ad libitum, nearly 25% of the variability in adipose tissue lipogenesis was accounted for by variation in feed intake. Results indicate that activities of lipogenic enzymes and lipogenic capacity in growing steers coordinately adapt to the level of feed consumed and that nutrient availability and(or) insulin concentrations may participate in this adaptation.  相似文献   

13.
The effects of feed restriction, cold exposure, and the initiation of feeding on blood glucose metabolism, other blood metabolites, hormones, and tissue responsiveness and sensitivity to insulin were measured in sheep. The sheep consumed orchardgrass hay ad libitum (AL) or were restricted to 82% of the ME requirement for maintenance (RE) and were exposed to a thermoneutral (20 degrees C) or a cold environment (2 degrees C). An isotope dilution method and a glucose clamp approach were applied to determine blood glucose metabolism and insulin action, respectively. Plasma NEFA and insulin concentrations were influenced by feed restriction. Concentrations of plasma glucose, NEFA, insulin, and glucagon were influenced by cold exposure. Plasma NEFA concentration for RE decreased after the initiation of feeding and plasma insulin concentration increased transiently for all treatments. [U-13C]Glucose was continuously infused for 8 or 7 h after a priming injection starting 3 h before the initiation of either feeding or insulin infusion, respectively. When responses to feeding were studied, blood glucose turnover rate was less (P < .001) for RE than for AL, and it was greater (P < .001) during cold exposure than in the thermoneutral environment. The rate changed little after the initiation of feeding. For the glucose clamp approach, insulin was infused over four sequential 1-h periods at rates from .64 to 10 mU x kg BW(-1) x min(-1), with concomitant glucose infusion to maintain preinfusion plasma glucose concentrations. The rates of glucose infusion and blood glucose turnover increased (P < .001) dose-dependently with insulin infusion rate. The maximal glucose infusion rate was greater (P < .05) for RE than for AL and was greater (P < .001) during cold exposure than in the thermoneutral environment. The plasma insulin concentration at half-maximal glucose infusion rate was lower (P < .1) during cold exposure. Blood glucose turnover rate tended to be greater (P = .10) for RE than for AL, and it was greater (P < .001) during cold exposure than in the thermoneutral environment. The ratio of endogenous production to utilization of glucose was suppressed by insulin infusion. In sheep fed a roughage diet, blood glucose turnover rate seems to be influenced by both intake level and environmental temperature, but not by the act of feeding. Moreover, the action of insulin on glucose metabolism is enhanced during cold exposure, and the effect of feed restriction is somewhat enhanced.  相似文献   

14.
Plasma concentrations of prolactin (PRL), growth hormone (GH), insulin, glucagon, glucose, urea and free fatty acids (FFA) were measured in Holstein calves, yearlings, bred heifers and primiparous cows, either sired by bulls with high predicted differences (PD) for milk (selection group) or by bulls from an unselected random bred control population (control group; n = 6). Serial blood samples were collected before and after feeding for an 8-h period from 0900 to 1700 h. All animals were fed a complete feed at 1100 h and administered insulin (.6 IU/100 kg body weight) at 1400 h. Mean plasma PRL was greater in control animals after feeding and insulin administration, while GH was greater overall in selection cattle. Insulin remained elevated longer in selection animals after exogenous administration, and plasma glucagon was increased in the control group. While plasma glucose and urea were unaffected by genetic group, plasma FFA were elevated in selection group calves and primiparous cows compared with the control group. All hormones and metabolites differed among the pre- and post-feeding and insulin administration periods and also with age. Mean PRL and GH increased after feeding, while glucagon decreased after exogenous insulin. Plasma FFA declined after feeding, while urea and glucose were similar before and after feeding. Mean PRL increased and glucagon decreased with advancing age and plasma GH and insulin showed inverse relationships at different ages. Plasma FFA changes closely followed GH changes with age, while plasma glucose more closely followed insulin changes with age. Results indicate that all hormones measured and FFA responded to genetic selection for milk, and increases in GH are uniformly associated with increased genetic potential for milk yield.  相似文献   

15.
The effect of xylazine and xylazine followed 20 minutes later by insulin upon glucose metabolism and plasma insulin concentrations was examined in three cows. After doses of 0.18 mg per kg xylazine given intramuscularly (IM) or 0.15 mg per kg given intravenously (IV) hepatic glucose production increased, plasma insulin concentrations decreased to 25 to 33 per cent of control values, and there was a prolonged hyperglycaemia. When 200 units of soluble insulin were given 20 minutes after similar doses of xylazine there was a rapid fall in blood glucose and a reduction in the rate of glucose production by the liver. Xylazine-induced hyperglycaemia arose from a combination of increased hepatic glucose production and reduced plasma insulin concentrations. Peripheral tissues were still responsive to insulin and when adequate insulin was available blood glucose concentrations rapidly decreased.  相似文献   

16.
1. The effects of exogenous corticosterone administration and glucose supplementation on energy intake, lipid metabolism and fat deposition of broiler chickens were investigated. 2. A total of 144 three-d-old male chickens were randomly assigned to one of the following 4 treatments for 7 d: a low energy diet (10.9 MJ ME/kg, 200 g/kg CP) with or without corticosterone (30 mg/kg diet) and drinking water supplemented with glucose (80 g/l) or saccharine (2 g/l, control). 3. Body weight (BW) gain and breast and thigh muscle yields (% body mass) were all significantly decreased by corticosterone treatment. The relative cumulative feed intake (RCFI) and relative ME intake (RMEI), rather than the feed (FI) or ME intake (MEI) were increased by corticosterone administration. Both feed efficiency (FE) and caloric efficiency (CE) were decreased by corticosterone administration. Corticosterone administration had no obvious effect on water consumption. 4. Glucose supplementation had no influence on BW gain and breast and thigh muscle yield (as % of body mass). FI or RCFI was decreased while MEI or RMEI was increased by glucose supplementation. FE was improved by glucose treatment, whereas CE was reduced. 5. Liver weight and abdominal, cervical and thigh fat deposits were all significantly increased by either corticosterone or glucose treatment. 6. Plasma concentrations of glucose, urate, triglyceride, non-esterified fatty acids (NEFA), very low density lipoprotein and insulin were all significantly increased by corticosterone treatment. Glucose supplementation had no obvious influence on any of the measured plasma parameters except for NEFA, which were significantly increased. 7. Lipoprotein lipase activities in either cervical or abdominal adipose tissues, rather than in thigh fat tissue, were significantly elevated by either glucose or corticosterone treatment.  相似文献   

17.
A monoclonal antibody (mAb), PS-7.6, to porcine somatotropin (pST) significantly enhanced the growth responses to pST injections in hypophysectomized (hypox) rats but could not be tested in pigs because of the large quantity of antibody required for a growth trial. Because pST inhibits the hypoglycemic effects of insulin, an insulin tolerance test procedure was established to measure pST activity in jugular-catheterized pigs. Doses of 0, 30, 100, and 300 μg/kg per day of pST were split and administered subcutaneously (sc) in equal portions twice daily for 2 d. After a 17-hr fast, plasma samples were obtained at 10-min intervals for 30 min before an intravenous injection of insulin (0.08 IU/kg) and then for an additional 50 min. Because pST increased fasting plasma glucose concentrations, preinsulin glucose values were used as a covariate to adjust the postinsulin concentrations. pST caused a dose-dependent increase in resistance to the insulin injection in these pigs. The areas under the curves (AUC) for plasma glucose were 22.l, 29.0, 39.0, and 47.2 mg/dl per min for the 0, 30, 100, and 300 μg/kg pST doses, respectively. Because different doses of pST could be detected, the PS-7.6 enhancement of pST treatment was evaluated. In the first experiment, five pigs/group each received sc injections of either vehicle, pST (75 μg/kg; 3.0 mg/d), pST (75 μg/kg) + PS-7.6 at 3.75 mg/kg, or pST (75 μg/kg) + PS-7.6 at 15 mg/kg for 2 d before the insulin test. The pST and PS-7.6 were combined and incubated for at least 1 hr at room temperature before being injected. The injection of pST alone did not significantly change insulin tolerance activity (23.1 vs. 21.1, AUC, but insulin resistance was enhanced when this dose of pST also included PS-7.6 (27.4 and 29.5, AUC, respectively; P < 0.05). In a second experiment, the effects of PS-7.6 and PS-4.2, a mAb that did not potentiate the pST-stimulated growth of hypox rats, were compared. The five pigs/treatment received either vehicle, pST (75 μg/kg), pST (75 μg/kg) + PS-7.6 (3.75 mg/kg), or pST (75 μg/kg) + PS-4.2 (3.75 mg/kg) for 2 d. The administration of pST increased the resistance to insulin (26.7 vs. 18.8, AUC; P < 0.01), which was markedly potentiated by PS-7.6 (54.3, AUC, P < 0.001) but not affected by PS-4.2 (27.6 AUC. The injection of PS-7.6 at 7.5 mg/kg without exogenous pST did not alter the sensitivity to insulin. These results indicate that PS-7.6, but not PS-4.2, enhanced the insulin antagonistic activity of pST in swine, suggesting that an enhancement of pST-stimulated growth would also occur in PS-7.6-treated pigs.  相似文献   

18.
The fungal isolate myriocin inhibits serine palmitoyltransferase and de novo ceramide synthesis in rodents; however, the effects of myriocin on ceramide concentrations and metabolism have not been previously investigated in ruminants. In our study, 12 non-lactating crossbred ewes received an intravenous bolus of myriocin (0, 0.1, 0.3, or 1.0 mg/kg/body weight [BW]; CON, LOW, MOD, or HIGH) every 48 h for 17 d. Ewes consumed a high-energy diet from day 1 to 14 and were nutrient-restricted (straw only) from day 15 to 17. Blood was collected preprandial and at 1, 6, and 12 h relative to bolus and nutrient restriction. Tissues were collected following euthanasia on day 17. Plasma was analyzed for free fatty acids (FFAs), glucose, and insulin. Plasma and tissue ceramides were quantified using mass spectrometry. HIGH selectively decreased metabolizable energy intake, BW, and plasma insulin, and increased plasma FFA (Dose, P < 0.05). Myriocin linearly decreased plasma very-long-chain (VLC) ceramide and dihydroceramide (DHCer) by day 13 (Linear, P < 0.05). During nutrient restriction, fold-change in FFA was lower with increasing dose (P < 0.05). Nutrient restriction increased plasma C16:0-Cer, an effect suppressed by MOD and HIGH (Dose × Time, P < 0.05). Myriocin linearly decreased most ceramide and DHCer species in the liver and omental and mesenteric adipose, VLC ceramide and DHCer in the pancreas, and C18:0-Cer in skeletal muscle and subcutaneous adipose tissue (Linear, P ≤ 0.05). We conclude that the intravenous delivery of 0.3 mg of myriocin/kg of BW/48 h decreases circulating and tissue ceramide without modifying energy intake in ruminants.  相似文献   

19.
OBJECTIVE: To assess the effects of prolonged feed deprivation on glucose tolerance, insulin secretion, and lipid homeostasis in llamas. ANIMALS: 9 adult female llamas. PROCEDURE: On each of 2 consecutive days, food was withheld from the llamas for 8 hours. Blood samples were collected before and 5, 15, 30, 45, 60, 120, and 240 minutes after IV injection of dextrose (0.5 g/kg) for determination of plasma insulin and serum glucose, triglyceride, and nonesterified fatty acid concentrations. Between experimental periods, the llamas received supplemental amino acids IV (185 mg/kg in solution). The llamas were then fed a limited diet (grass hay, 0.25% of body weight daily) for 23 days, after which the experimental procedures were repeated. RESULTS: Feed restriction decreased glucose tolerance and had slight effects on insulin secretion in llamas. Basal lipid fractions were higher after feed restriction, but dextrose administration resulted in similar reductions in serum lipid concentrations with and without feed restriction. Insulin secretion was decreased on the second day of each study period, which lessened reduction of serum lipid concentrations but did not affect glucose tolerance. CONCLUSIONS AND CLINICAL RELEVANCE: Despite having a comparatively competent pancreatic response, feed-restricted llamas assimilated dextrose via an IV bolus more slowly than did llamas on full rations. However, repeated administration of dextrose reduced insulin secretion and could promote hyperglycemia and fat mobilization. These findings suggested that veterinarians should use alternative methods of supplying energy to camelids with long-term reduced feed intake or consider administering agents to improve the assimilation of glucose.  相似文献   

20.
Thoroughbred and Quarter Horse yearlings (n = 24; 335+/-7 d of age) were used in a 112-d feeding trial to determine whether chromium (Cr) supplementation would alter growth, development, and energy metabolism of growing horses on high-concentrate diets. The horses were assigned at random within breed and gender subgroups to one of four treatment groups: A) basal concentrate; B) basal plus 175 microg of Cr/kg concentrate; C) basal plus 350 microg of Cr/kg concentrate; and D) basal plus 700 microg of Cr/kg concentrate. Chromium was provided via Cr tripicolinate (Prince Agri Products, Quincy, IL). The horses were weighed, measured for withers and hip height, heart girth, and body length and underwent ultrasound evaluation for croup fat thickness. The concentrate was fed for ad libitum consumption for two, 1.5-hr feeding periods daily. Coastal bermudagrass (Cynodon dactylon) hay was group-fed (six animals/group) at 1% of BW daily. Feed intake was 60% concentrate and 40% hay, resulting in a supplemental Cr intake of 0, 105, 210, and 420 microg/kg diet for groups A, B, C, and D, respectively. Colts consumed more concentrate and total feed than did fillies (P < .05), but no dietary effect on feed intake was detected. Colts weighed more than fillies at the completion of the experiment (P = .0754), but no dietary effects on weight, body measurements, or croup fat were detected. An i.v. glucose tolerance test (.2 g of glucose/kg BW) and an i.v. insulin sensitivity test (.1 IU of insulin/kg BW) were conducted on each animal during the third 28-d period of the experiment. Plasma glucose peaked immediately following injection and decreased more rapidly in animals consuming the high-Cr diet than in those consuming the control diet (P < .01). Mean glucose fractional turnover rate values increased (P = .0369) and mean half-life of glucose decreased (P = .0634) in response to the high Cr supplementation. Plasma glucose depletions in animals fed the other two diets were between and not different from (P > .10) the depletions in control animals or in those fed high-Cr diets. No difference in insulin sensitivity was detected (P > .10). Results indicate that Cr tripicolinate supplementation of yearling horses increases the rate at which glucose is metabolized and may lower the plasma glucose concentration. No effect of Cr supplementation on development of the animals was detected.  相似文献   

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