共查询到20条相似文献，搜索用时 31 毫秒
1.
K. KITA 《British poultry science》1998,39(5):679-682
1. We examined the influence of refeeding after 2 d of fasting on plasma insulin-like growth factor-I (IGF-I) concentration and hepatic IGF-I gene expression in chickens at 6 weeks of age. 2. Hepatic IGF-I mRNA was measured by ribonuclease protection assay and plasma IGF-I concentration was determined by radioimmunoassay. 3. Plasma IGF-I concentration decreased following fasting, increased to the level of fed controls after 2 h of refeeding but then fell back to the level of fasted chickens after 6 h of refeeding. 4. Fasting reduced hepatic IGF-I mRNA concentrations to less than half of those in the fed controls. Refeeding increased IGF-I mRNA sharply at 2 h after refeeding, but by 6 h after refeeding they had taller back again to levels significantly lower than at 2 h. 5. A significant correlation between plasma IGF-I concentration and hepatic IGF-I gene expression was found, suggesting that when chicks are refed after 2 d of fasting, the short-term increase in plasma IGF-I concentration may be partly regulated by the alteration in hepatic IGF-I mRNA. 相似文献
2.
Glucocorticoids are known to hinder somatic growth in a number of vertebrate species. In order to better understand the mechanisms through which they may act in channel catfish, we examined the effects of feeding cortisol on the growth hormone (GH)/insulin-like growth factor-I (IGF-I)/IGF-binding protein (IGFBP) network. Fish (30.6 ± 3.0 g) were fed once daily for 4 weeks and treatments included: (1) High-cortisol (dietary cortisol provided at 400 mg/kg feed), (2) Low-cortisol (dietary cortisol provided at 200 mg/kg feed), and (3) Control (commercial catfish feed). Fish fed diets with cortisol weighed approximately 50% less than Controls. Feed intake was reduced by approximately 30% in both treatments of cortisol fed fish compared to Controls. A 20-kDa IGFBP was observed in plasma from High- and Low-treated fish while it was not detected in Control fish plasma. High-cortisol treatment increased pituitary GH mRNA expression approximately 10-fold while liver IGF-I mRNA expression was not different between cortisol-treated fish and Controls. Cortisol treatments decreased plasma levels of IGF-I. These data indicate that feeding cortisol for 4 weeks reduces weight gain, feed intake, and plasma levels of IGF-I and induces a 20-kDa IGFBP. One mechanism through which cortisol may impede growth of catfish is through an increase in a low molecular weight IGFBP which may lead to inhibitory effects on the action of IGF-I. 相似文献
3.
The effects of fasting on insulin-like growth factor (IGF)-I, IGF-II, and IGF-binding protein (IGFBPs) mRNA in channel catfish were examined. Fed control fish (Fed) were compared to fish that had been fasted for 30 d followed by 15 d of additional feeding (Restricted). Sequence alignment and similarity to orthologous proteins in other vertebrates provided structural evidence that the 3 catfish sequences identified in the present research were IGFBP-1, -2, and -3. Prolonged fasting (30 d) reduced body weight approximately 60% (P < 0.001) and decreased IGF-I mRNA in the liver and muscle (P < 0.01). Fifteen days of re-feeding restored concentrations of hepatic and muscle IGF-I mRNA. Liver IGF-II mRNA was not affected by fasting but was increased 2.2-fold after 15 d of re-feeding (P < 0.05). Abundance of muscle IGF-II mRNA was similar between the fed control group and the restricted group throughout the experimental period. Fasting also increased liver IGFBP-1 mRNA (P < 0.05) and decreased IGFBP-3 mRNA (P < 0.01), whereas abundance of IGFBP-2 mRNA was not significantly affected. Interestingly, re-feeding for 15 d did not restore concentrations of IGFBP-1 and IGFBP-3 mRNA relative to fed control concentrations. The IGF results suggest that IGF-I and IGF-II are differently regulated by nutritional status and probably have a differential effect in promoting muscle growth during recovery from fasting. Similar to mammals, IGFBP-1 mRNA in catfish is increased during catabolism, whereas IGFBP-3 mRNA is decreased during inhibited somatic growth. The IGFBP results provide additional evidence of the conserved nature of the IGF-IGFBP-growth axis in catfish. 相似文献
4.
The objective of this study was to assess the effects of food deprivation and exogenous cortisol administration on somatic growth of channel catfish, Ictalurus punctatus, and examine the resultant changes in circulating insulin-like growth factor-I (IGF-I) concentrations and growth hormone receptor (GHR) gene expression. Integral to this objective, we report the isolation, sequence, and characterization of channel catfish GHR. Sequence analysis and characterization results indicate sequence identity and tissue distribution similar to GHRs in other teleost fish and several functional characteristics conserved in known vertebrate GHRs. The effects of food deprivation and dietary exogenous cortisol administration were assessed as part of a 4-week study. Growth was significantly reduced after 4 weeks in cortisol-fed fish compared to fed-control fish, and fasting resulted in weight loss. At the end of the 4-week study, both IGF-I plasma concentrations and hepatic GHR mRNA abundance were significantly reduced in fasted and cortisol-fed catfish. Levels of hepatic GHR mRNA were positively correlated to circulating IGF-I levels. These results suggest that a reduction in hepatic GHR gene expression might serve as a mechanism for the reduction of circulating IGF-I and growth in channel catfish during periods of food deprivation and stress. 相似文献
5.
Research was conducted to examine growth rates, circulating concentrations of IGF-I, and mRNA abundance levels of IGF-I and IGF-II in channel catfish (Ictalurus punctatus) given recombinant bovine ST (rbST; Posilac, Monsanto Co., St. Louis MO). In the first study, juvenile catfish (5.5 +/- 0.5 g) were randomly assigned to one of three treatments: 1) sham-injected control (one needle puncture per week); 2) rbST (30 microg x g BW(-1) x wk(-1); Posilac); and 3) nonhandled control (control). At the end of the 6-wk study, the fish were weighed, measured for length, and G:F was determined. Compared with sham and control treatments, rbST-treated fish had 48% greater final BW, 14% greater total length, and 52% greater G:F (P < 0.001). In the second study, juvenile catfish (41.1 +/- 1.5 g) were assigned randomly to one of two treatments: 1) sham or 2) rbST. Eight fish per treatment were sampled on d 0, 1, 2, 7, 14, and 21 for blood, muscle, and liver. Relative expression of IGF-I and IGF-II mRNA was determined by real-time PCR and plasma concentrations of IGF-I were measured using a validated fluoroimmunoassay. Circulating concentrations of IGF-I were increased (37.9 +/- 5.5 vs. 22.0 +/- 6.6 ng/mL; P < 0.05) in rbST-injected fish compared with sham-injected controls by d 14. Liver IGF-I and IGF-II mRNA was increased 4.3-and 14.4-fold, respectively, by d 1 in rbST-injected fish compared with controls (P < 0.05); however, abundance of liver IGF-I and IGF-II mRNA did not differ from controls on d 0, 2, 7, 14, and 21. Abundance of muscle IGF-I and IGF-II mRNA did not differ in rbST-injected fish compared with controls throughout the study. Results of the first study demonstrated that rbST improves growth performance of channel catfish. Results of the second study showed that the growth-promoting effects of rbST were not mediated by the expression of IGF-I or IGF-II mRNA in the muscle. Instead, the results suggest that rbST promotes growth by stimulating plasma IGF-I release, possibly through its direct effect on the liver or on local tissues to synthesize IGF-I. The changes in mRNA abundance and plasma concentrations of IGF-I support the role of IGF-I in growth regulation of channel catfish. 相似文献
6.
Steers were made hyperthyroid or hypothyroid to study the effects of physiological alterations in thyroid hormone status on plasma growth hormone (GH) profiles, plasma insulin-like growth factor-I (IGF-I) concentrations, and relative abundance of IGF-I mRNA in skeletal muscle and liver. Eighteen yearling crossbred steers (360 to 420 kg) were randomly allotted to hyperthyroid (subcutaneous injection 0.6 μg/kg BW L-thyroxine for 10 d), hypothyroid (oral thiouracil; 0.25% diet plus 12.5 g capsule/d for 17 d), or control (subcutaneous injection 0.9% NaCl) treatment groups. Blood samples were taken for measurement of GH, IGF-I, thyroxine (T4) and triiodothyronine (T3) by RIA. Samples of liver and skeletal muscle were taken by biopsy for measurement of IGF-I mRNA by solution hybridization. Steers receiving thiouracil had 57 and 53% (P<.05) lower T4 and T3, respectively, than control steers (84.1 and 1.7 ng/ml). The hyperthyroid steers had 228 and 65% greater (P<.05) T4 and T3 than control steers. Neither increased nor decreased thyroid status had any significant effects on plasma GH profiles, liver IGF-I mRNA, or plasma concentration of IGF-I. There was no effect of thyroid hormone alteration on skeletal muscle IGF-I mRNA concentrations. The results of this study suggest that short-term changes in thyroid status of cattle had no major impact on the GH-IGF-I axis or skeletal muscle IGF-I mRNA. 相似文献
7.
The effects of fasting on IGF-binding proteins (IGFBPs), glucose, and cortisol in channel catfish were examined. Fed fish (controls) were compared to 14-, 30-, and 45-day fasted fish and 45-day fasted fish refed for 15 additional days. Body length and weight changes, condition factor (CF), hepatosomatic index (HSI), and plasma glucose and cortisol were assessed to determine growth and metabolic status. Body length and growth rates were inhibited (P<0.05) after 14, 30, and 45 days of fasting. The 14-, 30-, and 45-day fasted fish exhibited hypoglycemia and reduced CF and HSI. Cortisol levels were increased (22.8 +/- 15.2 ng/ml versus 4.7 +/- 3.9 ng/ml) in 30-day fasted fish compared to fed controls (P<0.05). Associated with the increase in cortisol in fasted fish was a concomitant increase in plasma levels of a 20-kDa IGFBP through day 45. A 35- and a 45-kDa IGFBP were also identified but were similar between fed and unfed fish throughout the experiment. At the end of 15 days of refeeding, 20-kDa IGFBP, glucose, and cortisol levels were similar to fed controls. Refeeding also caused an increase in growth rates. These results suggest the existence of a catfish counter part to mammalian IGFBP-1, similar to lower molecular mass IGFBPs reported in other species of fish. These results also suggest that a 20-kDa IGFBP is upregulated during fasting-induced growth inhibition of channel catfish and provide additional evidence of the conserved nature of the IGF-IGFBP-growth axis in fish. 相似文献
8.
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
9.
We determined the effects of short-term fasting and refeeding on temporal changes in plasma concentrations of leptin, insulin, insulin-like growth factor- 1 (IGF-1), growth hormone (GH), glucose, and nonesterified fatty acids (NEFA), in early lactating cows, non-lactating pregnant cows, and postpubertal heifers. In experiment 1, Holstein cows in early lactation were either fed ad libitum (Control, n=5) or feed deprived for 48 h (Fasted, n=6). Plasma leptin, insulin, and glucose concentrations rapidly declined (P<0.05) within 6h, and IGF-1 by 12h, but all these variables sharply returned to control levels (P>0.10) within 2h of refeeding. Plasma NEFA and GH concentrations were elevated (P<0.05) by 4 and 36 h of fasting and returned to control levels (P>0.10) by 8 and 24h after refeeding, respectively. In experiment 2, four ruminally cannulated pregnant non-lactating Holstein cows were used in a cross-over design and were fasted for 48 h (Fasted) or fasted with partial evacuation of rumen contents (Fasted-Evac). The plasma variables measured did not differ (P>0.10) between Fasted and Fasted-Evac cows. Plasma leptin, insulin, and IGF-1 concentrations were reduced by 10, 6, and 24h of fasting, respectively, in Fasted-Evac cows; and these variables were reduced by 24h in Fasted cows (P<0.05). Plasma glucose levels were reduced (P<0.05) by 48 h of fasting in both groups of fasted animals. Plasma NEFA and GH levels were increased (P<0.05) by 12 and 48 h of fasting, respectively. In experiment 3, postpubertal Holstein heifers were either fed ad libitum (Control, n=4) or feed deprived for 72 h (Fasted, n=5). Concentrations of leptin, insulin, IGF-1, and glucose in plasma were reduced (P<0.05) by 24, 10, 24, and 48 h of fasting, respectively. Plasma NEFA concentrations increased (P<0.05) by 4h, of fasting while GH levels were not significantly (P>0.10) affected by fasting. Collectively, our data provide evidence that plasma leptin concentrations are reduced with short-term fasting and rebound on refeeding in dairy cattle with the response dependent on the physiological state of the animals. Compared to the rapid induction of hypoleptinemia with fasting of early lactation cows, the fasting-induced hypoleptinemia was delayed in non-lactating cows and postpubertal heifers. 相似文献
10.
Nutrient supply may control muscle growth directly and indirectly through its influence on regulatory factors. The present study focuses on its effects on muscle insulin-like growth factors (IGF-I and -II) and myostatin (MSTN). Their mRNA levels were quantified by real time RT-PCR in pectoralis major (PM) and sartorius (SART) muscles from broiler chickens submitted to different feeding regimens (fed or fasted for 48 h) between hatch and 2 days of age and at 4 weeks of age. In the PM of 4 weeks old broilers, mRNA levels were also evaluated after a 16 h-fast and a refeeding period (refed 24 or 48 h after a 48 h-fast). In the PM muscle, both IGF-I and MSTN mRNA levels increased between 0 and 2 days of age in the fed group, while they remained low in the unfed one. A comparable trend was observed in the SART, but with lesser amplitude. In both muscles of 4 weeks old chickens, a 48 h-fast induced a significant reduction in MSTN mRNA levels (20% of fed state). In the PM, this effect required more than 16 h of fasting to occur and was fully reversed by only 24h of refeeding. IGF-I mRNA levels also varied with nutritional state. They decreased significantly with fasting in the SART muscle. By contrast, IGF-II mRNA levels did not vary significantly. Our data shows for the first time that two major paracrine regulators of muscle growth, IGF-I and MSTN, are sensitive to nutrient supply in hatching chicks, and also that fasting reduced IGF-I and MSTN mRNA levels in muscles of older chickens. 相似文献
11.
Galeati G Forni M Govoni N Spinaci M Zannoni A De Ambrogi M Volpe S Seren E Tamanini C 《Domestic animal endocrinology》2007,33(3):281-293
The aims of this study were to study the effects of fasting on progesterone (P4) production in the pig and to verify whether fasting influences luteal expression of PGF(2alpha) receptor (FPr) and prostaglandin secretion. Superovulated prepubertal gilts were used; half of them were fasted for 72h starting on day 2 (F2) or 9 (F9) of the induced estrous cycle, respectively, while two groups (C2 and C9) served as respective controls. Plasma P4 and PGFM concentrations were determined by RIA while FPr mRNA expression in CLs collected at the end of fasting period was measured by real-time PCR. In experiment 1, plasma P4 concentrations in fasted gilts were significantly (P<0.01) higher than in controls starting from day 3 (F2; n=6) and 10 (F9; n=6). FPr mRNA expression was similar in F2 and C2 (n=6) CLs while it was significantly (P<0.05) higher in F9 than in C9 (n=6) CLs. In experiment 2, cloprostenol administered on day 12 significantly (P<0.05) increased FPr mRNA expression in CLs from both F9 (n=6) and C9 (n=6) gilts. At the time of cloprostenol injection PGFM levels were significantly higher (P<0.05) in the fasted group and cloprostenol-induced luteolysis in fasted but not in normally fed gilts. Results from this study indicate that fasting in prepubertal gilts induced to ovulate stimulates luteal P4 and PGFM production as well as FPr mRNA expression, thus increasing luteolytic susceptibility. 相似文献
12.
Nagao K Aman Yaman M Murai A Sasaki T Saito N Okumura J Kita K 《British poultry science》2001,42(4):501-504
1. We examined the changes in plasma IGF-I concentration and tissue IGFBP-2 gene expression of young fasted chickens refed a commercial diet or administered bovine insulin intravenously. 2. Plasma IGF-I concentration was decreased by fasting for 2 d. Although plasma IGF-I concentration was increased by refeeding, it didn't recover to the level of chickens fed a commercial diet ad libitum. 3. Insulin administration lowered plasma IGF-I concentration compared to other groups. 4. Hepatic IGFBP-2 mRNA was increased by fasting for 2 d and decreased by refeeding for 6 h. Insulin administration also decreased hepatic IGFBP-2 gene expression stimulated by fasting to the level of refed chickens. 5. IGFBP-2 mRNA in the gizzard was increased by fasting for 2 d and tended to decrease after refeeding for 6 h. Insulin administration decreased gizzard IGFBP-2 gene expression to less than that in refed chickens. 6. There was no between-treatment difference in IGFBP-2 mRNA in the brain and kidney. 7. These results suggest that the changes in IGFBP-2 gene expression in the liver and gizzard by fasting and refeeding might be partly regulated by the alteration in plasma insulin concentration. 相似文献
13.
Influence of diet on basal and growth hormone-stimulated plasma concentrations of IGF-I in beef cattle 总被引：2，自引：0，他引：2
The effects of nutrition on plasma concentrations of insulin-like growth factor-I (IGF-I) were characterized in steers under basal conditions and following single i.m. injection of bovine growth hormone (bGH, .1 mg/kg BW). Nutritional effects on IGF-I were studied in three trials. In all trials steers were individually fed and penned Angus or Hereford x Angus (280 kg). In the first trial, two diets (LPLE1: 8% CP and 1.96 Mcal ME/kg, 4.5 kg.hd-1.d-1; MPHE1: 11% CP, 2.67 Mcal ME/kg, 6.5 kg.hd-1.d-1) were fed (n = 5/diet). Plasma IGF-I concentrations averaged 74 (LPLE1) and 152 (MPHE1) ng/ml (P less than .02). Following bGH injection, IGF-I increased to peak concentrations between 12 and 24 h (averaging 105 and 208 ng/ml at peak for LPLE and MPLE, respectively, P less than .01). In the second trial, steers were fed diets composed of 8, 11 or 14% CP and 1.96 or 2.67 Mcal ME/kg dry matter (6.35 kg.hd-1.d-1 in a factorial arrangement for 84 d, n = 4/diet). Within the low ME diet groups, plasma IGF-I was similar in steers fed 11 and 14% CP but greater at these two CP levels than in steers fed 8% CP (P less than .05). Within the high ME diet groups, plasma IGF-I increased linearly with CP (P less than .01). In the third trial, steers were fed diets to result in a negative N status. Insulin-like growth factor-I was lower (P less than .02) during feed restriction than when steers were full-fed. The IGF-I response to bGH was diminished or absent in underfed steers (P less than .01). These data are interpreted to suggest that diet composition and intake affect plasma concentrations of IGF-I in steers. In cattle, CP may be the primary nutritional determinant of basal IGF-I, but the IGF-I response to CP may be affected by the available ME. Undernutrition can attenuate the IGF-I response to GH and uncouple the regulation of IGF-I normally ascribed to GH. 相似文献
14.
Nonaka S Hashizume T Horiuchi M Mikami U Osawa T Miyake Y Hara S 《The Journal of reproduction and development》2003,49(3):253-258
The objective of this study was to clarify the origin of the increase in plasma insulin-like growth factor-I (IGF-I) during estrus in goats. Focusing on the uterus, the effect of estradiol-17 beta (E2) on the secretion of IGF-I was examined using ovariectomized and hysterectomized animals. A single 5 microg/kg BW of E2 was injected intramuscularly into ovariectomized and hysterectomized goats for 3 consecutive days, and plasma IGF-I concentrations in the two groups were compared. The concentrations of IGF-I rose after the treatments in both groups. The concentrations were significantly higher from 3 to 8 days after the treatment than before the treatment in ovariectomized goats (P<0.05), and from 1 to 3 days after the treatment than before in hysterectomized goats (P<0.05). Thus higher concentrations of plasma IGF-I tended to last longer in ovariectomized than hysterectomized goats. The area under the IGF-I response curve for the 8-day period after the first injection of E2 tended to be greater in ovariectomized than in hysterectomized goats. The results show that E2 increases plasma IGF-I concentrations in goats, and suggest that E2-stimulated IGF-I in plasma may originate mainly from the uterus. 相似文献
15.
Colak M Shimizu T Matsunaga N Murayama C Nagashima S Kataoka M Kawashima C Matsui M van Dorland HA Bruckmaier RM Miyamoto A 《Reproduction in domestic animals》2011,46(5):854-861
Many metabolic hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin affect ovarian functions. However, whether ovarian steroid hormones affect metabolic hormones in cattle remains unknown. This study aimed to determine the effect of sex steroids on the plasma profiles of GH, IGF-I and insulin and their receptors in the liver and adipose tissues of dairy cows. Ovariectomized cows (n = 14) were randomly divided into four groups: control group (n = 3) was treated with saline on Day 0; oestradiol (E2) group (n = 3), with saline and 1 mg oestradiol benzoate (EB) on Day 0 and 5, respectively; progesterone (P4) group (n = 4) with two CIDRs (Pfizer Inc., Tokyo, Japan) from Day 0; and E2 + P4 group (n = 4) with two CIDRs on Day 0 that were removed on Day 6 and were immediately injected with 1 mg EB. The animals were euthanized after the experiment, and liver and adipose tissues samples were quantitatively analysed using real-time PCR for the expression of mRNA for the GH (GHR), IGF-I (IGFR-I) and insulin (IR) receptor mRNAs. Oestradiol benzoate significantly increased the number of peaks (p < 0.05), pulse amplitude (p < 0.05) and area under the curve (AUC; p < 0.01) for plasma GH; moreover, it increased plasma IGF-I concentration (p < 0.05), but it had no effect on the plasma insulin profile. P4 significantly decreased the AUC (p < 0.01), compared with the control group, whereas it did not affect the number of peaks and the amplitude of GH pulses. P4 + E2 did not affect the GH pulse profile. E2 increased the mRNA expression of GHR, IGFR-I and IR in the liver (p < 0.05), whereas both P4 and E2 + P4 did not change their expressions. Our results provide evidence that the metabolic and reproductive endocrine axes may regulate each other to ensure optimal reproductive and metabolic function. 相似文献
16.
Kosior-Korzecka U Bobowiec R Lipecka C 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2006,53(1):5-11
The aim of this experiment was to study the changes in the hormonal status and ovulation rate (OR) evoked by starvation during the follicular phase of the oestrous cycle in ewes. To achieve this goal, 12 female crossbreed sheep were synchronized and then half of them were fasted from the 12th to the 16th day of the oestrous cycle. On the 16th day, analysis of hormones and insulin-like growth factor-I (IGF-I) were performed in 10-min intervals. Then, on the 6th day of the following oestrous cycle, the OR in all ewes was determined by laparoscopy. Fasting reduced significantly (P < 0.05) the OR in ewes (1.25 +/- 0.50) in comparison with control (1.75 +/- 0.50). The drop in the OR was coincident with a significant (P < 0.001) decrease in the plasma concentration and pulse amplitude of leptin (0.29 +/- 0.08 ng/ml versus control 0.53 +/- 0.14 ng/ml), the plasma level of luteinizing hormone (LH) (0.19 +/- 0.06 IU/l versus 0.25 +/- 0.09 IU/l in control; P < 0.05) and the mean frequency of LH pulses (2.0/h versus 2.5/h in control). Fasting resulted also in a significant (P < 0.05) decrease in the plasma concentration and pulse amplitude of follicle stimulating hormone (FSH) in comparison with the control. Simultaneously, a significant (P < 0.001) drop in the IGF-I concentration in the fasted ewes (4.78 +/- 0.91 ng/ml) was found in comparison with control (7.63 +/- 1.85 ng/ml). Also the level of insulin were significantly (P < 0.001) lower in the fasted (178.99 +/- 39.08 pM/l respectively) than in the control sheep (302.66 +/- 49.01 pM/l respectively). Meanwhile, a double increase in the growth hormone (GH) pulses frequency and an augmentation in its plasma concentrations as a result of starvation was found. The obtained results shows that the acute fasting exerts an inhibitory effect on the ovulation rate in ewes coincident with suppression in leptin, FSH and LH secretion and changes in signalization mediated by GH. 相似文献
17.
Galeati G Forni M Spinaci M Zannoni A Govoni N Ribeiro LA Seren E Tamanini C 《Domestic animal endocrinology》2005,28(3):272-284
This study was designed to verify whether fasting influences vascular endothelial growth factor (VEGF) production and VEGF, VEGF receptor-2 (VEGFR-2) as well as endothelin (ET) system members (endothelin converting enzyme-1, ECE-1; ET-1; endothelin receptor type A, ET-A) mRNA expression in pig corpora lutea; furthermore, we wanted to assess whether fasting affects steroidogenesis in luteal cells. Eight prepubertal gilts were induced to ovulate and were randomly assigned to two groups: (A) n = 4, normally fed; and (B) n = 4, fasted for 72 h starting 3 days after ovulation. At the end of fasting, ovaries were removed from all the animals and corpora lutea (CLs) were collected. VEGF and steroid levels in luteal tissue were determined by ELISA and RIA, respectively; VEGF, VEGFR-2, ET-1, ET-A and ECE-1 mRNAs expression was measured by real-time PCR. VEGF protein levels were similar in the two groups, while all steroid (progesterone, testosterone, estradiol 17beta) concentrations were significantly (P < 0.001) higher in CLs collected from fasted animals compared with those from normally fed gilts. VEGF, VEGFR-2, ET-1 and ECE-1 (but not ET-A) mRNA expression was significantly lower (P < 0.05) in fasted versus normally fed animals. The overall conclusion is that all the parameters studied are affected by feed restriction, but the mechanisms activated at luteal level are possibly not fully adequate to compensate for nutrient shortage. 相似文献
18.
Z J Champion B H Breier W E Ewen T T Tobin P J Casey 《Veterinary journal (London, England : 1997)》2002,163(1):45-50
A survey of standardbred horses was conducted to build up a normal population profile for insulin like growth factor-I (IGF-I) concentrations in racing standardbreds and to ascertain how age, sex and geographic location affect IGF-I. Blood samples were drawn by jugular venepuncture from 202 racing standardbred horses aged one to eight years located in five different geographic regions of New Zealand. IGF-I concentrations were determined by insulin like growth factor-I binding protein (IGFBP)-blocked radioimmunoassay validated for the horse. As described in other species, age played a significant (P<0.05) role in IGF-I concentrations with the highest concentrations occurring in the younger horses. There was a significant (P<0.05) sex effect, intact males having significantly higher IGF-I concentrations compared of mares and/or geldings. Geographic location had a significant (P<0.05) influence on IGF-I. A significant (P<0.05) trainer effect also was noted both within and between geographic locations. We concluded that IGF-I concentrations in racing standardbred horses are affected by age, sex, trainer and geographic location. 相似文献
19.
20.
Georgieva TM Georgiev IP Ontsouka E Hammon HM Pfaffl MW Blum JW 《Journal of animal science》2003,81(9):2294-2300
The somatotropic axis and insulin are involved in pre- and postnatal development. In pre- and full-term calves (GrP0 and GrN0; born after 277 and 290 d of pregnancy, respectively) and in preterm calves on d 8 of life after being fed for 7 d (GrP8), we studied whether there are differences in the abundance of messenger RNA (mRNA) of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II, and insulin among different intestinal sites (duodenum, jejunum, ileum, and colon) and whether there are ontogenetic differences during the perinatal period in intestine and liver. Intestinal site differences (P < 0.05) existed in mRNA levels of IGF-I and IGF-II and receptors for GH, IGF-I, IGF-II, and insulin. Abundance of mRNA of IGF-I and -II and of receptors for IGF-I and GH was highest (P < 0.05) in the colon, abundance of the receptor for IGF-II was comparably high in the colon and ileum, and that of the receptor for insulin was similarly high in colon, ileum, and jejunum. Among GrP0, GrN0, and GrP8 groups, there were differences (P < 0.05) in mRNA levels of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II and insulin. Abundance of mRNA of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II and insulin was highest (P < 0.05) in GrP0 calves immediately after birth and was primarily seen in the ileum. In liver, the mRNA levels differed (P < 0.05) among groups for IGF-II and receptors for IGF-I, IGF-II, and insulin, and were highest (P < 0.05) for IGF-II in GrP0, for receptors of IGF-I in GrN0, and were higher (P < 0.05) in GrP0 than GrP8 for receptors of IGF-II. In conclusion, mRNA levels of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II, and insulin were different at different intestinal sites and in intestine and liver and changed during the perinatal period. 相似文献