Postpartum follicular and luteal activity in Holstein-Friesian cows genetically selected for high or low mature bodyweight: Relationships with follicle stimulating hormone,insulin, insulin-like growth factor-1 and growth hormone

AIM: To investigate ovarian follicular and luteal activity during the postpartum period of cows genetically selected for high or low mature bodyweight, in relation to metabolic and reproductive endocrine parameters, to determine whether there are differences between strains that could affect fertility outcomes.

METHODS: The presence of follicles ≥5 mm diameter and luteal structures was mapped in the ovaries of 12 high (heavystrain) and 12 low (light-strain) mature bodyweight cows by daily trans-rectal ultrasonography from Day 7 postpartum until the end of their first normal oestrous cycle. Blood samples were collected daily, for measurement of concentrations of follicle stimulating hormone (FSH), progesterone, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin. Intervals to first ovulation were calculated from ultrasonography data.

RESULTS: Heavy-strain cows had shorter intervals than light-strain cows from calving to the emergence of the first (9.0 (SE 0.9) vs 12.4 (SE 1.3) days) and second (16.4 (SE 1.8) vs 20.6 (SE 1.6) days) dominant follicles (p<0.05). Concentrations of FSH in heavy-strain cows prior to the emergence of the second, third and fourth dominant follicles were higher than in light-strain cows (p<0.05). Heavy-strain cows were more likely to have a large (>15 mm diameter) follicle earlier than light-strain cows (p<0.01). Concentrations of insulin and IGF-1, but not those of GH, were higher in heavy- than light-strain cows during the postpartum period (p=0.01 and p=0.02, respectively), and concentrations of both on Day 6 were inversely related to the time of emergence of the first dominant follicle (p>0.01).

Concentrations of progesterone were similar in both strains of cow until Day 10 of the first oestrous cycle, but thereafter were higher in light- than heavy-strain cows until Day 16. Progesterone concentrations in heavy-strain cows declined earlier and more rapidly than in their lighter counterparts.

CONCLUSION: These results indicate that there is a rapid postpartum resumption of follicular activity in both heavy-and light-strain cows, but that there is an earlier emergence of dominant follicles and ovulation in the former. Differences in luteal function, in terms of lower dioestrus progesterone concentrations and an earlier onset of luteolysis, in heavy- than light-strain cows might be sufficient to impair the fertility of the former.     

Relationship between receptors for insulin-like growth factor- I, steroid hormones and apoptosis-associated proteins in canine mammary tumors

In the veterinary literature there are few data concerning the expression of insulin-like growth factor type I (IGF-IR) in the canine mammary gland tumors. The aim of the present study was the evaluation of IGF-IR expression and its correlation to the expression of estrogen receptor alpha (ERalpha) and progesterone receptor (PR), proteins: Bcl-2, Bax, p53 in canine mammary gland tumors, and also a correlation with other features: bitch's age, tumor diameter, histologic type of tumor, degree of histologic malignancy, proliferate activity. The study was done on 112 epithelial neoplasms: 21 (19%) were adenoma, 38 (34%) complex carcinoma (adenocarcinoma), 47 (42%) simple carcinoma (adenocarcinoma) and 6 (5%) solid carcinoma. Histochemistry and immunohistochemistry methods were employed. It was shown that more common and/or higher IGF-IR expression in cells of canine mammary gland tumors was related to the histologic type of cancer of worse prognostic (solid and simple carcinoma), high histologic degree of malignancy (III degrees) but the statistical analysis did not reveal any significant differences. We observed the high degree of IGF-IR expression in tumors which displayed the high ERalpha and PR expression. These results suggest the involvement of IGF-IR in the development of hormonosensitive canine mammary tumors. Additionally, the significant positive correlation between expression of IGF-IR and p53, Bax was found. Our study provides some evidence that interactions exist between the IGF-IR and these apoptosis-associated proteins may contribute to the development and progression of canine mammary gland tumors. These results require further investigations.     

Serum growth hormone and insulin-like growth factor-1 concentrations in Japanese black cattle with growth retardation

Serum concentrations of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were determined in 5 calves in the same lineage with growth retardation. They had normal appetites, activities, body proportion, and laboratory test results. Calves with growth retardation had higher serum GH concentrations and lower serum IGF-I concentrations. These findings suggested defects in the GH-IGF-1 axis, such as in the GH-receptor.     

Serum growth hormone and insulin-like growth factor-1 concentrations in Japanese black cattle with renal tubular dysplasia

To elucidate the cause of growth retardation, 14 cattle with renal tubular dysplasia (RTD) were investigated by determining serum growth hormone (GH) and insulin-like growth factor (IGF)-1 concentrations. Compared with 6 healthy cattle, the baseline, maximum, area under the curve and peak amplitude of serum GH concentrations were higher or tended to be higher. Serum IGF-1 concentrations were lower normal or lower in cattle with RTD than in healthy cattle. Serum IGF-1 concentrations correlated significantly with body weight and chest girth, but not with serum GH and creatinine concentrations. Growth retardation in RTD might be associated partially with GH resistance.     

Effects of peroral insulin and glucose on circulating insulin-like growth factor-I, its binding proteins and thyroid hormones in neonatal calves

There is disagreement in the literature about the ability of neonatal calves to absorb perorally administered insulin. This study evaluated the absorption of a bolus of insulin administered alone or with an energy souce and its effects on the circulating insulin-like growth factor system and thyroid hormones in newborn Holstein-Friesian calves. Within 1 h of dosing, mean serum insulin and triiodothyronine (T3) concentrations had increased considerably, whether the insulin was applied alone (n = 4) or together with glucose (n = 4), accompanied by marked hypoglycemia. No significant changes were observed in control calves (n = 4) given the vehicle solution. Increased serum glucose and T3 concentrations with no change in insulinemia occurred in a 4th group of calves given glucose alone. At 32 h of age and after 3 meals of colostrum there were no differences in glycemia, insulinemia, or proteinemia among the 4 groups of calves examined. Mean serum insulin-like growth factor-I (IGF-I) tended to decrease over this period in the control group. The decrease was more pronounced in the insulin-treated group but absent in both groups that received glucose. These differences were associated with equivalent differences in abundance of the 40-45K IGF-binding protein-3 (IGFBP-3); however, lower molecular mass IGFBPs were not affected. The results show that a pharmacological peroral dose of insulin can lead to rapid systemic alterations in the IGF/IGFBP system in neonatal calves that can be modified by simultaneous administration of a small energy supply in the form of glucose.     

Relationships between the thyroid and somatotropic axes in steers I: Effects of propylthiouracil-induced hypothyroidism on growth hormone, thyroid stimulating hormone and insulin-like growth factor I

The effects of propylthiouracil (PTU)-induced thyroid hormone imbalance on GH, TSH and IGF-I status in cattle were examined. In the first study, four crossbred steers (avg wt 350 kg) were fed a diet dressed with PTU (0, 1, 2 or 4 mg/kg/d BW) in a Latin square design with four 35-d periods. On day 29 in each period, steers were challenged with an intrajugular bolus of thyrotropin releasing hormone (TRH, 1.0 μg/kg). Blood samples were obtained to assess the change in plasma GH and TSH as affected by PTU. Plasma IGF-I was measured from blood samples obtained before and after (every 6 hr for 24 hr) intramuscular injection of bovine GH (0.1 mg/kg, day 31). Doses of 1 and 2 mg/kg PTU increased plasma T₄ (P<.01). At 4 mg/kg, PTU depressed T₄ concentrations to 30% of control (P<.01). Plasma T₃ linearly decreased with increasing doses of PTU (P<.01). Plasma TSH increased when PTU was fed at 4 mg/kg (P<.05) while the TSH response to TRH declined with increasing PTU (P<.02). Neither basal nor TRH-stimulated plasma concentration of GH was affected by PTU; the IGF-I response to GH tended to increase at the 1 and 2 mg/kg PTU (P<.01). In a second study 24 crossbred steers were fed PTU (1.5 mg/kg) for 119 d in a 2 × 2 factorial design with implantation of the steroid growth effector, Synovex-S (200 mg progesterone + 20 mg estradiol), as the other main effect. Basal plasma GH and IGF-I were not affected by PTU treatment. Synovex increased plasma concentration (P<.01) of IGF-I without an effect on plasma GH. The data suggest that mild changes in thyroid status associated with PTU affects regulation of T₃, T₄ and TSH more than GH or IGF-I in steers.     

Exogenous pituitary and recombinant growth hormones induce insulin and insulin-like growth factor 1 resistance in pig adipose tissue

In the present study, pigs were treated daily for 7 days with exogenous porcine growth hormone (pGH; 70 micrograms/kg BW) in order to determine whether pGH induced insulin and insulin-like growth factor 1 (1GF-1) resistance in pig adipose tissue. In the first experiment, pituitary-derived pGH (ppGH) decreased basal and insulin-stimulated lipogenesis by 50%. Insulin sensitivity decreased more than 90% as the result of pGH treatment. Sensitivity and responsiveness to IGF-1 were decreased 50% by ppGH. In a second experiment, pigs were treated daily (70 micrograms/kg BW) with exogenous pituitary pGH (ppGH) or recombinant pGH (rpGH) for 7 days in order to determine if the effects of pGH were intrinsic properties of the hormone. Both rpGH and ppGH caused similar decreases in basal rates of lipogenesis, insulin- and IGF-1-stimulated lipogenesis, and insulin and IGF-1 responsiveness in pig adipose tissue. In summary, the decrease in adipose tissue growth of pigs treated chronically with pGH is due in large part to the suppression of fatty acid synthesis and a decrease in the ability of insulin to stimulate lipid synthesis in pig adipocytes. These responses are intrinsic properties of pGH since the effects of rpGH mimicked those of ppGH. The role and importance of a decrease in IGF-1 responsiveness remains to be resolved.     

Effects of field bean (Vicia faba L. var. minor) dietary supplementation on plasma thyroid hormones, insulin, insulin-like growth factor-1 concentrations and mohair characteristics in growing Angora goat kids

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

The relationship between endogenous insulin-like growth factors and growth in pigs.

Previous studies have reported conflicting data on gender differences in plasma IGF-I in postnatal pigs. There is also debate over the role of IGF-II in regulation of postnatal growth. We have, therefore, determined the concentrations of plasma IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) in boars, barrows, and gilts and related these to postnatal growth characteristics. Plasma concentrations of IGF-I were higher in boars than in gilts or barrows from 13 wk. of age, and plasma IGF-II levels were generally higher in barrows than in boars or gilts. Plasma IGFBP-3 levels were higher in boars than in gilts or barrows at most ages. Between 15 and 23 wk. of age, IGF-I and IGFBP-3, but not IGF-II, were positively associated with growth rate, voluntary feed intake, and gain:feed ratio. Plasma IGF-II, but not IGF-I or IGFBP-3, was positively associated with backfat depth during this period. These results support the hypothesis that circulating IGF-I and IGF-II are regulators of lean and adipose tissue growth, respectively.     

Effects of in ovo administration of L-carnitine on hatchability performance,glycogen status and insulin-like growth factor-1 of broiler chickens

1.?Eggs from a meat-type breeder flock (Ross) were used in two trials to study the effects of in ovo administration of L-carnitine (carnitine) on hatchability traits (hatchability percentage, embryo deaths, pipped with live or dead embryo), chick weight at hatch as an absolute value (CWT) or expressed as a percentage of egg weight (CWT%), hatching period, glycogen status (liver and pectoral muscle) and plasma insulin-like growth factor-1 (IGF-1) of hatched chicks were investigated. There were 9 treatments with three replicates of each. Treatments were non-injected control (negative control), or injection with sterilised saline (0?9%, positive control), or sterilised saline with carnitine at 25, 50, 100, 200, 300, 400, and 500 µg/egg.

2.?In ovo carnitine treatment increased CWT, CWT%, glycogen in the liver and pectoral muscle, glycogen index and plasma IGF-1 of hatched chicks, and did not influence hatchability traits and hatching period. The glycogen index of hatched chicks of the in ovo carnitine treatments with values (500 > 400 = 300 > 200) was higher than that of the control and in ovo carnitine at 25, 50, and 100 µg/egg treatments. The nature of response to carnitine was cubic for CWT and CWT%, and linear for glycogen in the liver and pectoral muscle, glycogen index of hatched chicks when the negative control or positive control treatment was used as base line.

3.?It was concluded that in ovo administration of carnitine at 25–500 µg/egg increased chick weight at hatch and IGF-1, and did not influence hatchability traits and hatching period of eggs. The linear relationship between in ovo administration of carnitine and glycogen status of hatched chicks indicated that increasing in ovo doses improved glycogen status of hatched chicks.     

Leukocytes from heifers at different ages express insulin and insulin-like growth factor-1 (IGF-1) receptors

The objectives of this study were to investigate if insulin receptors (IR) and insulin-like growth factor-1 receptors (IGF-1R) could be detected on bovine leukocytes using fluorescence antibodies and flowcytometry, and use this method to investigate whether the amount of receptors differed among heifers at different ages. Twenty Danish Holstein heifers in the following three age groups were included in the investigation: (1) heifers aged 25-45 days (n = 8), (2) heifers aged 185-205 days (n = 7), and (3) heifers aged 780-900 days (approximately one month prepartum; n = 5). Antibodies against human IR and IGF-1R were used for indirect immunofluorescence staining of cells, and were found to cross-react with the bovine receptors. IR were found on lymphocytes, monocytes, and neutrophils in all animals, while IGF-1R were found only on monocytes and neutrophils. The percentage of IR+ lymphocytes was almost doubled from stage 1 to 3 (34% versus 57%) and IR expression on lymphocytes and monocytes increased significantly (P<0.01) from 6.80 and 13.60 to 8.24 and 17.50 in heifers aged 185-205 days and heifers aged 780-900 days, respectively. No differences were observed for neutrophil IR or IGF-1R expression. In conclusion, surface IR and IGF-1R can be detected on bovine leukocytes by flowcytometry. Interestingly, the highest numbers of IR were found in heifers one month prepartum. The regulation of IR and IGF-1R expression on bovine leukocytes, and their role in host immunity, needs further investigation.     

Effect of fat supplementation on leptin, insulin-like growth factor I, growth hormone, and insulin in cattle

We investigated the effect of fat supplementation on plasma levels of hormones related to metabolism, with special attention to leptin, in cows in early lactation and in feedlot steers. In experiment 1, 34 lactating cows received no fat or else 0.5 or 1.0 kg of partially hydrogenated oil per day in addition to their basal diet from day 20 before the expected calving date to day 70 postpartum. In experiment 2, part of the corn in the basal concentrate was replaced with 0.7 kg of the same oil such that the diets were isocaloric; 18 cows received the fat-substituted diet and 18 a control diet from day 20 before the expected calving date to day 75 postpartum. In experiment 3, calcium salts of fatty acids were added to the basal diet of 14 feedlot steers for 80 d; another 14 steers received a control diet. The basal plasma levels of leptin were higher in the cows than in the steers. Dietary fat supplementation did not affect the leptin levels in the lactating cows but lowered the levels in the feedlot steers despite greater energy intake and body fatness (body weight) in the steers receiving the supplement than in those receiving the control diet. The levels of insulin-like growth factor I and insulin were decreased with dietary fat supplementation in the lactating cows but were unaffected in the steers, suggesting that responses to fat ingestion depend on the physiological state of the animal, including age and sex. Finally, no effects of supplementary fat on the level of growth hormone were demonstrated in any of the models.     

Luteinizing hormone,growth hormone,insulin-like growth factor-i,insulin and metabolites before puberty in heifers fed to gain at two rates

Fall born Angus x Hereford heifers were allotted to treatments at 9 mo of age to achieve the following growth rates: 1) fed to gain 1.36 kg/d (n = 10; HGAIN); and 2) fed to gain 0.23 kg/d for 16 wk, then fed to gain 1.36 kg/d (n = 9; LHGAIN). Growth hormone (GH), insulin-like growth factor-1 (IGF-I), insulin, glucose, nonesterified fatty acids (NEFA), and progesterone were quantified in twice weekly blood samples until onset of puberty. Body weight, hip height, and pelvic area were recorded every 28 d. Frequent blood samples (n = 8 heifers/treatment) were collected every 14 d, commencing on day 29 of treatment until onset of puberty to evaluate secretion of luteinizing hormone (LH) and GH. The HGAIN heifers were younger (369 d; P < 0.001), were shorter at the hip (115 cm; P < 0.05) and had smaller pelvic area (140 cm²; P < 0.10), but body weight (321 kg) did not differ at puberty compared with LHGAIN heifers (460 d; 119 cm; 155 cm²; 347 kg, respectively). The HGAIN heifers had greater (P < 0.05) concentrations of LH, IGF-I, and insulin in serum and glucose in plasma during the first 84 d of treatment than LHGAIN heifers, whereas LHGAIN heifers had greater (P < 0.05) concentrations of GH in serum and NEFA in plasma than HGAIN heifers. On Day 68 of treatment, HGAIN heifers had less mean GH (P < 0.01) and greater (P < 0.05) LH pulse frequency than LHGAIN heifers, whereas LH pulse amplitude and mean LH did not differ (P > 0.10) between treatments. Treatment did not influence secretion of LH and GH at 1 and 3 wk before puberty. Mean GH concentrations in serum and GH pulse amplitude in all heifers were greater (P < 0.05) 2 to 9 d (12.9 and 40.7 ng/ml, respectively) than 16 to 23 d (10.4 and 20.0 ng/ml, respectively) before puberty. Nutrient restriction decreased LH pulse frequency and delayed puberty in beef heifers. Furthermore, dramatic changes in mean concentration and amplitude of GH pulses just before puberty in beef heifers may have a role in pubertal development.     

Acute effects of hypophysectomy and administration of pancreatic and thyroid hormones on circulating concentrations of somatomedin-C in young chickens: Relationship between growth hormone and somatomedin-C

The short-term control of plasma concentrations of somatomedin C (SmC) in young chicks was examined by either surgical removal of the pituitary gland or by the administration of hormones which affect plasma concentrations of growth hormone (GH). As expected, removal of the source of GH by hypophysectomy reduced plasma concentration of GH, these being suppressed by 95.7% within 1 hour. Hypophysectomy was rapidly followed by reductions in the plasma concentration of SmC. For instance, plasma concentrations of SmC were decreased to 53% of pretreatment one hour following hypophysectomy. This suggests both that SmC has a short half life and that the release of SmC into the circulation is tightly coupled to the presence of pituitary hormone(s), presumably including GH. Sham surgery also decreased plasma concentrations of GH but were without effect on plasma concentrations of SmC. The short term control of plasma concentrations of SmC was also examined by the acute administration of hormones, which affect GH secretion in vivo. Injections of thyroxine or triiodothyronine decreased the plasma concentration of GH but were without effect on the plasma concentration of SmC. On the other hand, the administration of either glucagon or insulin decreased the plasma concentration of both GH and SmC. The present data suggest that plasma concentrations of SmC do not simply reflect the GH status in young chickens.     

Studies on the functional relationship between thyroid, adrenal and gonadal hormones

In order to clarify the functional relationship between thyroid, adrenal and gonadal hormones, hypothyroidism was induced by administration of thiuoracil in adult male and female rats, and the effects of hypothyroidism on the adrenal and the gonadal axes were investigated in the present study. 1. The functional relationship between thyroid and adrenal hormones: Adrenal weights and corticosterone were lowered, whereas the secretion of ACTH, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) increased in hypothyroid rats compared to euthyroid rats. These results indicate that hypothyroidism causes adrenal dysfunction directly and results in hypersecretion of CRH and AVP from the hypothalamus. 2. The functional relationship between thyroid and gonadal hormones: The pituitary response to LHRH was lowered, whereas the testicular response to hCG was not changed in hypothyroid rats. Hypothyroidism suppressed copulatory behavior in male rats. These results suggest that hypothyroidism probably causes dysfunction in gonadal axis at the hypothalamic-pituitary level in male rats. In adult female rats, hypothyroidism inhibited the follicular development accompanied estradiol secretion, whereas plasma concentrations of progesterone and prolactin (PRL) increased in hypothyroid female rats. Hypothyroidism significantly increased the pituitary content of vasoactive intestinal peptide (VIP) though it did not affect dopamine synthesis. These results suggest that hypothyroidism increases pituitary content of VIP and this increased level of VIP likely affects PRL secretion in a paracrine or autocrine manner. In female rats, inhibition of gonadal function in hypothyroid rats mediated by hyperprolactinemia in addition to hypersecretion of endogenous CRH.     

Pulsatility of plasma growth hormone and hepatic growth hormone receptor characteristics of broiler chickens divergently selected for abdominal fat content

1. Plasma growth hormone (GH) pulsatility and hepatic GH receptor characteristics were compared in experimental lines of meat‐type chickens selected for high (HF) or low (LF) abdominal fat content.

2. Mean GH concentration, baseline and amplitude of pulses were slightly, but not significantly, greater in LF chickens. Length and frequency of pulses were similar.

3. LF chickens exhibited higher plasma triiodothyronine (T3) concentrations. This difference between genotypes disappeared when the diet was supplemented with 1 mg/kg T3.

4. Specific binding of GH to liver membranes was higher for the fat line but was depressed by T3 supplementation to the same level in both lines. No difference was observed between lines for affinity constants.

5. It is concluded that direct selection for leanness has a less pronounced, if any, effect on GH pulsatility as compared with selection for food conversion efficiency; therefore, different physiological mechanisms are triggered to achieve leanness.     

Plasma growth hormone, insulin, glucocorticoids and thyroid hormones in large, medium and small breeds of steers with and without an estradiol implant

Growth hormone secretory patterns and plasma concentrations of insulin, adrenal corticosteroids, thyroxine and triiodothyronine were measured in three types of steers with and without estradiol implants. The three types of cattle were large (Simmental), medium (Limousin) and small (Angus) frame size with medium, low and high propensity to deposit fat. Simmental steers had higher (P<.01) concentrations of growth hormone and lower (P<.01) concentrations of insulin as compared with Angus. Implanting the steers with estradiol increased (P<.01) growth hormone concentrations in all three groups, tended to decrease glucocorticoids and had no effect on insulin or thyroid hormone concentrations. There tended to be less frequent release of growth hormone, with secretory spikes of greater magnitude in the Simmental steers. The implants tended to increase the frequency of release of growth hormone in all three groups.