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1.
Ghrelin is a gut peptide which participates in growth regulation through its somatotropic, lipogenic and orexigenic effects. Synergism of ghrelin and growth hormone-releasing hormone (GHRH) on growth hormone (GH) secretion has been reported in humans and rats, but not in domestic animals in vivo. In this study, effects of a combination of ghrelin and GHRH on plasma GH and other metabolic parameters, and changes in plasma active and total ghrelin levels were studied in Holstein bull calves before and after weaning. Six calves were intravenously injected with vehicle (0.1% BSA-saline), ghrelin (1 microg/kg BW), GHRH (0.25 microg/kg BW) or a combination of ghrelin plus GHRH at the age of 5 weeks and 10 weeks (weaning at 6 weeks of age). Ghrelin stimulated GH release with similar potency as GHRH and their combined administration synergistically stimulated GH release in preweaning calves. After weaning, GH responses to ghrelin and GHRH became greater compared with the values of preweaning calves, but a synergistic effect of ghrelin and GHRH was not observed. The GH areas under the concentration curves for 2h post-injection were greater in weaned than in preweaning calves (P<0.05) if ghrelin or GHRH were injected alone, but were similar if ghrelin and GHRH were injected together. Basal plasma active and total ghrelin levels did not change around weaning, but transiently increased after ghrelin injection. Basal plasma insulin, glucose and non-esterified fatty acid levels were reduced after weaning, but no changes by treatments were observed. In conclusion, ghrelin and GHRH synergistically stimulated GH release in preweaning calves, but this effect was lost after weaning.  相似文献   

2.
The objectives were to determine relative ADG, ADFI, behavior, and endocrine responses in weaned pigs receiving exogenous ghrelin. Twenty-four barrows weaned at 18 d of age (d 0 of the experiment) were catheterized via the jugular vein, weighed, and assigned to either a ghrelin (n = 12) or saline (control; n = 12) infusion group. Initial pig BW did not differ between treatments (7.87+/-0.39 vs. 7.92+/-0.35 kg for ghrelin and control treatments, respectively). Pig BW and feed intakes were measured once daily throughout the experiment. Starting on d 1, the ghrelin pigs were intravenously infused three times daily for 5 d with 2 microg/kg BW of human ghrelin, and the control pigs were similarly infused with saline. Activity observations and blood samples were taken at -15, 0, 15, 30, 60, 90, 120, 240, and 480 min relative to the first infusion and then three times daily (0800, 1600, and 2400) for 8 d. Weight gain during the 5-d infusion period was greater by the ghrelin than by control pigs (0.57+/-0.10 vs. 0.21+/-0.13 kg, respectively; P < 0.04); however, there was no increase in feed intake. During two behavioral observation periods, more pigs in the ghrelin treatment were observed eating compared with control pigs (P < 0.05). The initial infusion of exogenous ghrelin increased serum ghrelin, GH, insulin, and cortisol concentrations (P < 0.05). Endogenous serum ghrelin increased from d 1 to 8 of the experiment in control animals (P < 0.05). Serum IGF-I initially fell in both treatment groups from d 1 to 2 (P < 0.05) but then increased from d 5 to 8 (P < 0.05). Peripheral concentrations of glucose in the ghrelin pigs were greater on d 2, 3, 7, and 8 than on d 1 (P < or = 0.05). In both treatment groups, peripheral concentrations of leptin increased from d 7 to 8, and cortisol decreased from d 1 to 5 of the experiment. These observations provide evidence that ghrelin may positively influence weight gain and concomitantly increase GH, insulin, and cortisol secretion in weaned pigs.  相似文献   

3.
试验选用体重(12.6±0.7)kg的健康莱芜猪、鲁莱和大约克夏仔猪各12头,每个品种随机分对照组和试验组,每组6头。试验组腹膜注射200μg/kg体重的脂多糖(LPS),对照组注射等量生理盐水。于注射前、后采血,测定血浆中白介素-1β(IL-1β)、皮质醇和生长激素(GH)含量。结果表明:用LPS刺激后2、4h和7h每个品种的试验组与对照组相比,血浆中IL-1β和皮质醇含量均显著提高(P0.05),GH含量均降低,且LPS刺激后2h的GH水平显著降低(P0.05)。3个品种猪相比,莱芜猪在LPS刺激后2h时IL-1β、皮质醇的升高幅度和GH降低幅度均最小,与大约克夏猪相比差异均显著(P0.05)。结果显示,用LPS进行免疫应激,不同品种猪抗应激能力不同,莱芜猪相对于引进品种、地方品种有较强的抗免疫应激能力。  相似文献   

4.
We measured changes in plasma ghrelin and GH concentrations in mature Holstein cows and 3-mo-old female Holstein calves fed at scheduled times. Our objective was to determine the characteristics of ghrelin secretion in dairy cattle and its influence on GH. Animals were fed at 0800 and 1600 for 2 wk before and during experiments. Plasma was sampled for 24 h at 2-h intervals in Exp. 1. In mature cows, plasma ghrelin concentrations decreased (P < 0.01) just after 0800 but not at the 1600 feeding. Ghrelin concentrations were lower (P < 0.01) in calves than in mature cows and they did not decrease after feeding in calves. The temporal relationship between ghrelin and GH remained unclear. In Exp. 2, plasma was sampled 2 h before and after both morning and evening feedings at 20-min intervals. Plasma ghrelin concentrations decreased (P < 0.05) 40 min after 0800 feeding and 60 min after 1600 feeding in mature cows. These results indicate that in mature cows, plasma ghrelin concentration decreased after feeding, but this decrease was not evident in 3-mo-old calves. Further studies are required to define the relationship between plasma ghrelin and GH concentrations.  相似文献   

5.
Ghrelin and growth hormone (GH) play a key role in regulating energy balance, metabolic hormone secretion and food intake. Ghrelin and GH responses to dietary compositions have not yet been fully clarified, although there may be significant relationships between dietary compositions and ghrelin and GH responses. In the present study, therefore, we assessed whether dietary compositions influence postprandial plasma ghrelin and GH levels in wethers. Four wethers were respectively fed concentrate (C) or timothy hay (R) for 14 days. The levels of total digestive nutrients (TDN) and crude protein (CP) were adjusted to be at the same level. The basal ghrelin in both groups was rapidly and significantly decreased after feeding. Although the decline of ghrelin levels in C was greater and shorter than that in R, no significant difference was observed in the area under the curve (AUC) or in the incremental area. The plasma GH levels were also rapidly and significantly decreased after feeding in both groups and a significant difference was observed between the two groups for AUC of GH. Interestingly, the circadian changes in the plasma ghrelin levels were close to those in the GH levels in C, but this was not the case in R. These data suggest that dietary compositions influence postprandial plasma ghrelin and GH levels, and that these differences may be caused by several factors, including nutrients and ruminal fermentation.  相似文献   

6.
Ghrelin, the endogenous ligand of the growth hormone (GH) secretagogue receptor, is considered a pleiotropic regulator involved in a large array of functions, including control of energy balance, regulation of food intake and, more recently, modulation of the reproductive axis. The present study was aimed at determining the changes in plasma concentrations of acyl-ghrelin in pregnant and lactating sows, with special emphasis on the relationship with the levels of GH, leptin, non-esterified fatty acids (NEFA) and insulin-like growth factor (IGF-1). Blood samples were collected via jugular venipuncture from 22 multiparous sow 30, 60 and 90 days after artificial insemination, 7 and 21 days after farrowing and at first oestrus post-weaning. Plasma concentrations of acyl-ghrelin, leptin, GH and IGF-1 were quantified by validated radioimmunoassay; NEFA were determined using a colorimetric procedure. Plasma acyl ghrelin levels were highest at 30 days of pregnancy and decreased thereafter and during lactation. At the beginning of lactation, GH, IGF-1 and NEFA concentrations significantly increased, while a significant reduction occurred in leptin. In conclusion, ghrelin concentrations in sow maternal circulation does not seem to play an important role in maintaining circulating GH levels during lactation; moreover, ghrelin is not associated with leptin, NEFA and IGF-1 levels.  相似文献   

7.
Background: Three experiments were conducted to examine the overall hypothesis that addition of medium chain triglycerides(MCT) and cysteamine hydrochloride(CSH) into the diets of young and growing pigs would stimulate the endogenous somatotropic axis to improve growth and performance.Results: In Experiment 1, weaner pigs were given either a 5 d dietary supplement of 5 % MCT(n = 8) or a control diet(n = 8). MCT increased the plasma concentration of growth hormone(GH; P 0.05) and the GH secretagogue,ghrelin(P 0.05). Additionally, the MCT treatment reduced scouring(P 0.05), maintained villous height in the small intestine(P 0.05) and stabilised daily weight gain(P 0.05), compared to the controls. Experiment 2compared the effects of 4 levels(0, 1, 3 and 6 % v/v) of MCT supplementation in grower-finisher male pigs, of approximately 35 kg live weight(n = 15 per treatment). Blood samples taken after 7 wk of treatment showed that the MCT supplementation increased circulating ghrelin(P 0.001), GH(P 0.01) and insulin(P 0.05)concentrations in a dose-dependent manner. Daily weight gain, feed intake and feed conversion ratio were not affected by the MCT diets. In Experiment 3, 64 female pigs of approximately 60 kg live weight were allocated to one of three dietary treatments: control(n = 20); 6 % MCT(n = 21); and 70 mg/kg CSH(n = 21). After 3 wk of supplementation, the MCT treated pigs had a higher plasma concentration of ghrelin compared to the control and CSH pigs(P 0.05). Plasma concentrations of GH and weight were not affected by any of the dietary treatments.Conclusions: Evidence is provided in Experiment 1 to support the use of dietary MCT supplements, perhaps acting via stimulation of somatotropic endocrine pathways, to minimise weaning-associated disorders such as slowing of growth and diarrhoea. In Experiments 2 and 3, although there was no effect on weight gain or feed conversion ratio in either experiment, MCT and CSH increased endocrine components of the somatotropic axis.  相似文献   

8.
The effects of GHRP-2 (also named KP102), a new growth hormone-releasing peptide, on the release of growth hormone (GH) and growth performance were examined in swine. The single intravenous (i. v.) injection of GHRP-2 at doses of 2, 10, 30 and 100 microg/kg body weight (BW) to cross-bred castrated male swine stimulated GH release in a dose-dependent manner, with a return to the baseline by 120 min. The peak GH concentrations and GH areas under the response curves (GH AUCs) for 180 min after the injections of GHRP-2 were higher (P < 0.05) than those after the injection of saline. The GH responses to repeated i.v. injections of GHRP-2 (30 microg/kg BW) at 2-h intervals for 6 h were decreased after each injection. The chronic subcutaneous (s.c.) administration of GHRP-2 (30 microg/kg BW) once daily for 30 days consistently stimulated GH release. The GH AUCs for 300 min after the injections on d 1, 10 and 30 of treatment in GHRP-2-treated swine were higher than those in saline-treated swine. However, chronic administration of GHRP-2 caused a partial attenuation of GH response between d 1 and 10 of treatment. The chronic s.c. administration of GHRP-2 also increased average daily gain for the entire treatment period by 22.35% (P < 0.05) and feed efficiency (feed/gain) by 20.64% (P < 0.01) over the saline control values, but did not significantly affect daily feed intake. These results indicate that GHRP-2 stimulates GH release and enhancing growth performance in swine.  相似文献   

9.
Ghrelin is a highly conserved peptide hormone secreted by the stomach, which is involved in the regulation of food intake and energy expenditure. Ghrelin stimulates growth hormone (GH) release, and increases appetite in a variety of mammalian and non-mammalian vertebrates, including several fish species. Studies were conducted to investigate the effect of feeding and fasting on plasma and stomach ghrelin, and the growth hormone/insulin-like growth factor I (IGF-I) axis in the Mozambique tilapia, a euryhaline teleost. No postprandial changes in plasma and stomach ghrelin levels or stomach ghrelin mRNA levels were observed. Plasma levels of GH, IGF-I and glucose all increased postprandially which agrees with the anabolic roles of these factors. Fasting for 4 and 8 d did not affect ghrelin levels in plasma or stomach. Plasma GH was elevated significantly after 4 and 8 d of fasting, while plasma IGF-I levels were reduced. Plasma ghrelin levels were elevated significantly after 2 and 4 wk of fasting, but no change was detected in stomach ghrelin mRNA levels. Four weeks of fasting did not affect plasma GH levels, although plasma IGF-I and glucose were reduced significantly, indicating that GH resistance exists during a prolonged nutrient deficit (catabolic state). These results indicate that ghrelin may not be acting as a meal-initiated signal in tilapia, although it may be acting as a long-term indicator of negative energy balance.  相似文献   

10.
To clarify the direct effects of Ghrelin on growth hormone (GH) release from anterior pituitary (AP) cells in pigs, GH-releasing effects of human Ghrelin (hGhrelin) and rat Ghrelin (rGhrelin) on porcine AP cells were compared with GHRH in vitro. The AP cells were obtained from 6-month-old pigs and the cells (2 x 10(5) cells per well) were incubated for 2 h with the peptides after incubating in DMEM for 3 days. hGhrelin and rGhrelin significantly stimulated GH release from the cultured cells at doses of 10(-8) and 10(-7)M (P < 0.05). The rates of increase in GH at 10(-8) and 10(-7)M of hGhrelin were 82.7 and 131.9%, while those with rGhrelin were 43.9 and 79.5%, respectively. GHRH significantly stimulated GH release from the cells at a dose as low as 10(-11)M (P < 0.05), and the response to GHRH was greater than that induced by Ghrelins. In time-course experiments, GHRH continued to increase GH concentrations in media until 120 min after incubation; however, those in media treated with hGhrelin reached a plateau 60 min after incubation, and the maximal value was approximately one third that obtained with GHRH. When hGhrelin (10(-8)M) and GHRH (10(-8)M) were added together, additive effects of both peptides on the release of GH were observed (P < 0.05). Somatostatin (SS, 10(-7)M) significantly blunted GH release induced by hGhrelin (10(-8)M) and GHRH (10(-8)M) (P < 0.05). In the presence of SS, additive effects of hGhrelin and GHRH on the release of GH were observed (P < 0.05). These results show that Ghrelin directly stimulates GH release from anterior pituitary cells in pigs; however, the GH-releasing effect is weaker than that of GHRH in vitro. The present results also show that Ghrelin interacts with GHRH and SS to in the release of GH from porcine adenohypophysial cells.  相似文献   

11.
Gastric-derived peptide hormone ghrelin is known for its potent growth hormone (GH) stimulatory effects. The acyl-modification on N-terminal Ser(3) residue is reported to be important to stimulate the ghrelin receptor, GH secretagogue-receptor type1a (GHS-R1a). However, major portion of circulating ghrelin lacks in acylation, and some biological properties of des-acyl ghrelin have been reported in monogastric animals. In the present study, the responsiveness of plasma hormones and metabolites to ghrelin in steers was characterized, and role for des-acyl ghrelin in these changes was investigated. The repeated intravenous administrations of bovine ghrelin (1.0 microg/kg BW) every 2h for 8h to Holstein steers significantly increased the plasma acylated ghrelin, total ghrelin, GH, insulin and NEFA levels. The GH responses in peak values and area under the curves (AUCs) were attenuated by repeated injections of ghrelin, however, the responses of plasma total ghrelin were similar. Plasma insulin AUC decreased after fourth injection of ghrelin while plasma NEFA AUCs gradually increased by repeated injections of ghrelin. Pretreatment of des-acyl ghrelin (10.0 microg/kg BW) 5 min prior to the single injection of ghrelin (1.0 microg/kg BW) did not affect the ghrelin-induced hormonal changes. Moreover, the responses of plasma GH to bovine and porcine ghrelin, which differ in C-terminal amino acid residues, were similar in calves. These data show that (1) GH release was attenuated by repeated administration of ghrelin, (2) ghrelin regulates glucose and fatty acid metabolism probably via different pathway, and (3) des-acyl ghrelin is unlikely the antagonist for ghrelin to induce endocrine effects in Holstein steers.  相似文献   

12.
The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 μg ghrelin/kg body weight (BW), with and without GHRH at 0.25 μg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3 h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 μg/kg BW) and high (6.6 μg/kg BW) doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P < .05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P < .01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals.  相似文献   

13.
The study was performed to determine whether orally administered KP102 (also known as GHRP-2) stimulates GH release in adult goats, and how the orally administered KP102 passes through the digestive tract and stimulates GH release in ruminant animals. Five mg/kg body weight (BW) of KP102 dissolved in 9 ml of saline were administered into the oral cavity, rumen, omasum and duodenum of adult goats, and GH release after administration of KP102 was examined. The GH levels were significantly elevated at 20 min after administration of KP102 into the oral cavity, and plasma concentrations of GH remained significantly elevated until 60 min (P < 0.05). The GH levels after administration of KP102 into the abomasum were variable. However, the GH level tended to increase within 30 min after administration, and were significantly higher than those of controls after 120 to 150 min (P < 0.05). The GH levels after administration of KP102 into the duodenum were significantly elevated at 40 min after administration, and plasma concentrations of GH remained significantly elevated until 140 min (P < 0.05). The administration of KP102 into the rumen failed to stimulate GH release. The GH response curves (AUC) produced after administration of KP102 into the abomasum or duodenum were 2.2-fold greater than those for after administration into the oral cavity (P < 0.05). The oral administration of 5 mg/kg BW of KP102 in the powder state, not dissolved in 9 ml of saline, failed to stimulate GH release. These results suggested that orally administered KP102 dissolved in saline transiently stimulates GH release in adult goats, and this phenomenon might be due to small amounts of the peptides entering directly into the abomasum with liquid bypassing the rumen.  相似文献   

14.
The growth hormone (GH) secretagogue activity of variable dosages of clonidine (16.5, 50, 150, and 450 micrograms/kg of body weight), given orally mixed with the daily food ration, was evaluated in young and old dogs. Significant (P less than 0.05) increase in plasma GH concentration was detected at all dosages tested in young dogs and in response to all but the lowest dose tested in the old dogs fed the clonidine-containing diet. Old dogs had plasma GH concentration that exceeded that of young dogs when higher doses of clonidine were used. A clonidine (100 micrograms/kg)-supplemented diet was fed to middle-aged dogs twice daily for 30 days. Significant (P less than 0.01) increase of plasma GH concentration was observed on the first day of the feeding trial, but was undetectable by day 30. After feeding the clonidine-enhanced diet for 30 days, the effects on thymic morphology were variable, and there was no effect on plasma thymulin titer. Clonidine-fed dogs had significantly increased lymphocyte blastogenic responsiveness to mitogens, compared with that of control dogs, when evaluated as stimulation index.  相似文献   

15.
To improve culture system for in vitro maturation (IVM) of porcine oocytes, ghrelin, leptin or growth hormone (GH), at concentration of 0, 0.5, 5, 50 and 500 ng/ml were added to the porcine follicular fluid (pFF)‐supplemented medium NCSU23, and their effects on the maturation and cytoskeletal distribution of the oocytes with or without cumulus cells were compared. In the cumulus‐denuded oocytes, no significant changes were noted in the maturation rate by different hormone treatments due to a marked decline in the controls. Maturation of the cumulus intact oocytes was moderately interfered by ghrelin (0.5–50 ng/ml, p < 0.01), but not significantly affected by leptin and GH. Distribution density of the cytoplasmic microtubules was decreased significantly by addition of ghrelin (by approximately 30% in 50–500 ng/ml, p < 0.01), whereas no remarkable effect was noted by leptin supplementation. High concentration (500 ng/ml) of ghrelin or leptin decreased significantly the cytoplasmic microfilaments in density (by 43% and 38%, p < 0.01, respectively). GH did not affect cytoskeletal distribution. The results suggest, in the culture system using pFF‐supplemented medium that (i) ghrelin may have some inhibitory effect on the organization of microtubules and microfilaments, probably being a factor in lowered maturation rate and (ii) the addition of higher concentration of leptin may decrease microfilaments in density with no effect on meiotic maturation of the porcine oocytes.  相似文献   

16.
Our objective was to determine the effects of the administration of growth hormone (GH) alone or plus teverelix, a gonadotrophin releasing hormone antagonist (GnRHa), on follicle development in sheep. Ewes were treated daily for 6 days by the intramuscular route with 15 mg of GH alone (GH group; n = 6) or combined with two subcutaneous doses of GnRHa (1.5 mg) on days 0 and 3 of GH treatment (GH/GnRHa group; n = 6); the control group (n = 6) received similar treatment with saline solution. Plasma follicle stimulating hormone levels were significantly lower in the GH/GnRHa group than in the control (P < 0.001) and GH groups (P < 0.05). The number of follicles > or =2 mm increased to reach significant differences with control (18.7 +/- 0.6) on day 4 in GH/GnRHa group (22.7 +/- 0.5, P < 0.001) and on day 5 in GH group (20.3 +/- 0.4 vs. 17.0 +/- 0.6, P < 0.05). These results indicate that GH and GnRHa may be useful for increasing the number of gonadotrophin-responsive follicles in the ovary. However, follicle function could be affected as both GH and GH/GnRHa groups showed lower plasma inhibin A concentrations than control sheep (90-110 pg/mL vs. 170-185 pg/mL, P < 0.005).  相似文献   

17.
The aim of the present study was to investigate the effect of cysteamine on growth performance of preweaning piglets and gastric expression of ghrelin mRNA in vivo and in vitro. Twelve litters of newborn piglets were allocated randomly to control and treatment groups. From 15 d of age, piglets in the control group were fed basal creep diet, whereas the treatment group received basal diet supplemented with 120 mg cysteamine per kg of diet until weaning on 35 d of age. Body weight gain, creep feed consumption, and diarrhea rates were recorded, and gastric mucosal tissues were collected for quantifying mRNA expression. To evaluate the direct effect of cysteamine on gastric ghrelin expression, primary cultures of gastric mucosal cells isolated from 35-d-old piglets were exposed to cysteamine for 20 h at 0, 1, 10, and 100 μg/mL, respectively. Dietary cysteamine increased (P < 0.05) average daily creep feed consumption and BW gain in preweaning pigs, which was accompanied by reduction in diarrhea rates. At 35 d of age, piglets treated with cysteamine showed increased (P < 0.05) ghrelin and gastrin and decreased (P < 0.05) somatostatin mRNA expression in gastric mucosa. Moreover, dietary cysteamine treatment increased serum concentration of gastrin (P < 0.05). In vitro, cysteamine significantly increased ghrelin mRNA expression in gastric mucosal cells at the concentration of 10 μg/mL. In conclusion, dietary cysteamine is effective in improving the growth performance and health condition of preweaning piglets, which is associated with its stimulatory effects on gastric ghrelin mRNA expression both in vivo and in vitro.  相似文献   

18.
The purpose of this study was to evaluate whether circulating ghrelin and growth hormone (GH) concentrations in cattle are regulated by endothelin-1 (ET-1), endothelin-3 (ET-3), and secretin. Six Holstein steers (242 ± 1 d old, 280.5 ± 4.4 kg body weight [BW]; mean ± SEM) were allocated randomly in an incomplete Latin square design to receive each of 4 treatment compounds (vehicle, ET-1, ET-3, and secretin) with 1-d intervals between successive treatments. The treatment compounds were injected intravenously via a catheter inserted into the external jugular vein of each steer. Blood was sampled from the indwelling catheter at -30, -15, 0, 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, and 180 min. Plasma ghrelin and GH responses to the treatment compounds were measured by a double-antibody radioimmunoassay system. Data were analyzed by using a MIXED procedure of SAS, version 9.1. Plasma acyl ghrelin, total ghrelin, and GH concentrations were increased by both ET-1 and ET-3 injection (ET-1 injection: 311 ± 15 pg/mL vs 245 ± 15 pg/mL, 2.4 ± 0.2 ng/mL vs 1.61 ± 0.05 ng/mL, 4.73 ± 0.92 ng/mL vs 1.17 ± 0.09 ng/mL for acyl ghrelin, total ghrelin, and GH, respectively; ET-3 injection: 337 ± 27 pg/mL vs 245 ± 15 pg/mL, 2.6 ± 0.1 ng/mL vs 1.61 ± 0.05 ng/mL, 5.56 ± 0.97 ng/mL vs 1.17 ± 0.09 ng/mL for acyl ghrelin, total ghrelin, and GH, respectively; P < 0.01). Ghrelin and GH concentrations were not changed by secretin injection throughout the experimental periods. These results indicate that ET-1 and ET-3 stimulate ghrelin and GH secretion in cattle and demonstrate for the first time that endogenous ghrelin released in response to endothelin injection stimulates GH secretion in vivo in cattle.  相似文献   

19.
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20.
Stimulation of swine growth by porcine growth hormone   总被引：7，自引：0，他引：7  
Highly purified porcine growth hormone (pGH; USDA-B1) was administered by im injection (22 micrograms X kg body weight-1 X d-1) to rapidly growing Yorkshire barrows for 30 d. Growth hormone significantly increased growth rate (10%), feed efficiency (4%), cartilage growth and muscle mass. However, pGH did not affect carcass adipose tissue mass. Intramuscular lipid content of the longissimus was increased 50% by pGH administration. Plasma pGH concentration was elevated (7- to 11-fold) for 3 to 5 h post-injection. Chronic administration of pGH depressed pituitary GH content and concentration approximately 45%. No GH antibodies were detected in the plasma of GH-treated swine. Plasma somatomedin-C concentration was increased 55% by GH treatment 3 h post-injection. Plasma glucose and insulin concentrations were both significantly increased in GH-treated swine, suggesting that the animals had developed a state of insulin resistance. Plasma-free fatty acid concentration tended to be higher in GH-treated animals. Treatment of swine with pGH significantly decreased plasma blood urea nitrogen. Assessment of animal health during the trial and postmortem indicated that pGH administration did not have any adverse effects. In summary, treatment of young, rapidly growing swine with pGH stimulated growth performance without affecting animal health or inducing the production of GH antibodies.  相似文献   

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