Multihormonal regulation of progesterone synthesis in cultured human midluteal cells

The objectives of this investigation were to examine in vivo insulin like-growth factor-I (IGF-I) secretion by the human midcorpora lutea (mid-CL) and the effects of IGF-I, hCG, FSH, and human GH on progesterone (P) production by CL cells obtained from patients at laparotomy. We first examined whether the CL produces IGF-I by measuring IGF-I levels in the ovarian vein from the ovary bearing the CL. The IGF-I concentration in the ovarian vein bearing the CL (206 +/- 31 ng/mL) was significantly increased compared to the concentration in the contralateral ovarian vein (179.2 +/- 32 ng/mL; P < 0.05). Luteal cells isolated from mid-CL were cultured in serum-free medium 199 in the presence and absence of hCG, FSH, GH, and graded concentrations of IGF-I. At the end of the incubation period (24 h), P levels in the medium were measured by RIA. The treatment with IGF-I (0.1-10 ng/mL) showed a dose-dependent stimulatory action of IGF-I on P synthesis in the luteal cell system, being maximal between 5-10 ng/mL. The treatment with hCG (10 IU/mL), IGF-I (5 ng/mL), and GH (1000 ng/mL) increased basal P synthesis by 300%, 80%, and 30%, respectively (P < 0.001 and P < 0.05). FSH (100 ng/mL), either alone or in combination with IGF-I, failed to stimulate P synthesis. Treatment with IGF-I monoclonal antibody (1:5000) completely reduced P synthesis induced by 5 ng/mL IGF-I and slightly reduced basal P synthesis as well as GH-stimulated P synthesis by human midluteal cells. To further evaluate the specific role of IGF-I on luteal steroidogenesis, IGF-I receptor was identified by chemical cross-linking of [125I]IGF-I to mid-CL membranes. Experiments conducted in the absence and presence of unlabeled IGF-I (500 ng) revealed proteins with characteristics of the type I IGF receptor. These results are consistent with multihormonal regulation of P synthesis by the human mid-CL. hCG and IGF-I play a major role in the stimulation of P synthesis and, to a lesser extent, human GH. These in vivo and in vitro data suggest that the CL is a site of secretion, action, and reception of IGF-I during the midluteal phase.     

Follicle-stimulating hormone, human chorionic gonadotropin, and prolactin receptors in hamster corpora lutea or dispersed luteal cells during pregnancy

In vitro progesterone (P4) production by hamster luteal cells is stimulated throughout pregnancy by FSH and LH. Prolactin (PRL) by itself, however, increases P4 synthesis only on Day 12; on Day 4, FSH+LH+PRL induces optimal P4 secretion [Biol Reprod 1994; 51:43-49]. In light of these findings, in this study we investigated FSH, hCG, and PRL receptors in hamster CL or dispersed luteal cells on Days 4, 8, and 12 of pregnancy. Scatchard analysis of hamster CL on Days 4 and 8 showed considerably more unoccupied hCG receptors than FSH receptors: on Day 4, there was 9.5 fmol/mg protein for FSH binding sites vs. 1741 fmol/mg protein for hCG binding. Moreover, the binding affinity of hCG was greater than for FSH: the Day 4 Kd was 0.136 nM for hCG vs. 0.308 for FSH. Similar differences were observed on Day 8. Dispersed luteal cells (large+small cells) were incubated for 24 h with or without 10 ng of ovine FSH, LH, and PRL or human recombinant FSH (r-hFSH), alone or in different combinations. The cells were then washed and incubated for 4 h with iodinated hCG, FSH, or PRL with or without 100-fold excess of unlabeled hormones. The number of binding sites per 200,000 luteal cells did not change appreciably for FSH and hCG on Days 4 and 12 of pregnancy, whereas PRL binding sites significantly increased on Day 12.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of endothelin-1 on bovine luteal cell function: role in prostaglandin F2alpha-induced antisteroidogenic action

Endothelin-1 (ET-1) a vasoactive peptide, is synthesized and secreted by endothelial cells. In the bovine corpus luteum (CL), endothelial cells constitute a major proportion (53.5%) of total CL cells. This study was designed to examine the effects of ET-1 on bovine luteal cell functions and its involvement in the action of PGF2alpha. To better define the cells implicated in this process, we used CL slices, whole CL-derived cells, and steroidogenic large (LLC) and small (SLC) luteal-like cells. High affinity binding sites for ET-1 (K(d), approximately 0.3 x 10(-9)) were present in both steroidogenic luteal cells. The binding affinity of ET-1 was 3 orders of magnitude higher than that of ET-3, and a selective ETA receptor antagonist (BQ123) competed similarly to ET-1, suggesting the presence of ETA receptors. The lack of effect of ET-3 on CL-derived cells further supported this conclusion. Both basal progesterone secretion and bovine LH (5 ng/ml)-stimulated progesterone secretion from CL-derived cells were significantly inhibited by ET-1 in a dose-dependent manner, whereas preincubation of these cells with ETA receptor antagonist prevented the inhibitory effect of added ET-1. Incubation of LLC with 10(-8) M ET-1 inhibited their progesterone secretion (114.8 vs. 176.7 ng/10(5) cells-20 h; P < 0.05). On the other hand, ET-1 did not affect progesterone production from SLC despite the presence of ET-binding sites. PGF2alpha only inhibited LH-stimulated progesterone secretion by luteal slices. This antisteroidogenic effect of PGF2alpha could be prevented by the addition of a selective ETA receptor antagonist. Luteal tissue and microvascular endothelial cells isolated from bovine CL produced ET-1; in contrast, the peptide was undetectable in the culture medium or in cell extracts of either LLC or SLC. These data support the concept that ET-1 may play a paracrine regulatory role in bovine luteal function and propose a novel role for this peptide in mediating PGF2alpha-induced luteal regression.     

Effect of endothelin-1 in man--impact on basal and stimulated concentrations of luteinizing hormone, follicle-stimulating hormone, thyrotropin, growth hormone, corticotropin, and prolactin

The effect of endothelin-1 on basal and stimulated serum (plasma) concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropin (TSH), prolactin (PRL), growth hormone (GH), and corticotropin was investigated in healthy male volunteers (n = 5). Intravenous (IV) administration of endothelin-1 (5 ng/kg/min for 15 minutes, followed by 2.5 ng/kg/min for 105 minutes) induced an increase in basal plasma concentrations of corticotropin. Serum concentrations of PRL, TSH, LH, FSH, and GH remained unchanged. The increase in serum concentrations of these pituitary hormones induced by IV administration of LH-releasing hormone ([LH-RH] 100 micrograms), thyrotropin RH ([TRH] 400 micrograms), GH-RH (100 micrograms), and corticotropin-releasing factor ([CRF] 100 micrograms) was suppressed in regard to PRL (P < .01) and GH (P < .01) and enhanced in regard to corticotropin (P < .01). Stimulated serum concentrations of LH and FSH also tended to be higher following administration of endothelin-1 (P < .05), whereas the increase in serum concentrations of TSH remained unchanged. Thus, when administered in pharmacological doses, endothelin-1 influences pituitary hormone secretion in man.     

Patterns of ovarian growth and development in cattle with a growth hormone receptor deficiency

Nutritionally induced changes in growth hormone (GH) and IGF-I are associated with decreased ovarian function and may partially explain infertility and anestrus in undernourished cattle. The reproductive importance of GH and IGF-I was tested in cattle with a GH receptor deficiency (GHRD) that have reduced blood IGF-I. Blood was collected daily for plasma, and ovaries were examined daily by ultrasonography for 3 wk during an estrous cycle (estrus = d 0) in GHRD (n = 8) and control (n = 8) cattle. On d 18, blood samples were collected every 10 min for 6 h to measure LH. The GHRD cattle had fewer small antral ovarian follicles (2 to 5 mm, P < .01). After estrous cycle d 5, the first-wave dominant follicle stopped growing in GHRD but continued growing in controls (P < .001). Size of the CL was equivalent for GHRD and controls until d 5, after which CL development slowed in GHRD (P < .01). Likewise, plasma progesterone concentrations were less in GHRD (P < .001). During the luteal phase, GHRD cattle failed to develop follicles greater than 10 mm in diameter (endocrine status x day, P < .05). Size and rate of growth of preovulatory follicles, plasma estradiol, plasma FSH, and plasma LH (d 18 bleed) were similar in GHRD and controls. In conclusion, an important role for GH, GH receptor, and IGF-I in ovarian function was supported because GHRD cattle had distinctly different patterns of ovarian development compared with control cattle.     

In vitro effects of CINC/gro, a member of the interleukin-8 family, on hormone secretion by rat anterior pituitary cells

We investigated the effects of CINC/gro on hormone secretion using normal rat anterior pituitary cells. In normal anterior pituitary cells, 10-100 ng/ml of CINC/gro significantly increased the secretion of PRL within 3 h of incubation, and two-fold enhancement of PRL secretion was induced by 100 ng/ml of CINC/gro within 24-h incubation, while the response of GH and ACTH secretions to CINC/gro was weak. On the other hand, CINC/gro suppressed basal LH and FSH secretions in a concentration-dependent manner. The percent inhibition of basal secretion by CINC/gro (50 ng/ml) within 24-h incubation was 70% for LH and 43% for FSH. Twenty-four-hour incubation with 100 ng/ml of IAP completely blocked the CINC/gro-stimulated PRL and GH secretions and CINC/gro's suppression of both basal LH and FSH secretions. These data demonstrate a new biological activity for CINC/gro and provide evidence for immune system regulation of anterior pituitary hormone secretion.     

Growth hormone bioactivity, insulin-like growth factors (IGFs), and IGF binding proteins in obese children

In obese children, both spontaneous and stimulated growth hormone (GH) secretion are impaired but a normal or increased height velocity is usually observed. This study was undertaken to explain the discrepancy between impaired GH secretion and normal height velocity. We evaluated the GH bioactivity (GH-BIO), GH serum level by immunofluorimetric assay (GH-IFMA), insulin-like growth factor-I (IGF-I), IGF-II, and IGF binding protein-1 (IGFBP-1), IGFBP-2, and IGFBP-3 in 21 prepubertal obese children (13 boys and eight girls) aged 5.7 to 9.4 years affected by simple obesity and in 32 (22 boys and 10 girls) age- and sex-matched normal-weight controls. The results were as follows (obese versus [v] controls): GH-IFMA, 4.84 +/- 3.54 v 23.7 +/- 2.04 microg/L (P < .001); GH-BIO, 0.60 +/- 0.45 v 1.84 +/- 0.15 U/mL (P < .001); IGF-I, 173.8 +/- 57.2 v 188.6 +/- 132.6 ng/mL (nonsignificant); IGF-II, 596.1 +/- 139.7 v 439.3 +/- 127.4 ng/mL (P < .001); IGFBP-1, 23.25 +/- 14.25 v 107 +/- 165.7 ng/mL (P < .05); IGFBP-2, 44.37 +/- 62.18 v 385.93 +/- 227.81 ng/mL (P < .001); IGFBP-3, 3.31 +/- 0.82 v 2.6 +/- 0.94 microg/mL (P < .05); and IGFs/IGFBPs, 1.32 +/- 0.32 v 1.07 +/- 0.34 (P < .05). In conclusion, in prepubertal obese children, not only immunoreactive but also bioactive GH concentrations were low. In these subjects, therefore, nutritional factors and insulin may contribute to sustain normal growth also by modulating several components of the IGF-IGFBP system.     

Plasma prolactin, growth hormone and progesterone concentrations in pseudopregnant, hysterectomized and pregnant goats

Jugular plasma prolactin (PRL), growth hormone (GH) and progesterone (P4) levels were estimated in goats under three different conditions with prolonged luteal function (P4 > or = 1 ng/ml): pseudopregnant animals (n = 4), goats hysterectomized during early pregnancy (n = 4) and does with normal pregnancy (n = 4). Mean duration (+/- S.E.M.) of luteal phases were 189 +/- 20, 171 +/- 10, and 147 +/- 2 days in the three groups, respectively. Until day 120, mean PRL levels were below 150 ng/ml in each group. After day 120 of the luteal phase, PRL concentrations were significantly higher than before, but continued to increase up to 800 ng/ml only in pregnant animals around parturition. Mean GH levels varied between 2 and 3 ng/ml in animals of each group during the luteal phase. Only after parturition, a significant elevation occurred. P4 levels in pseudopregnant animals were significantly lower than in the other two groups between days 10 and 55, and showed a gradual but continuous decline towards the end of the luteal phase. After hysterectomy of early pregnant animals, P4 concentrations decreased to levels measured in pseudopregnant animals but were significantly higher again as compared to pseudopregnant animals between days 121 and 150. It is concluded that a pseudopregnant condition, characterized by intrauterine fluid accumulation, is not related to increased plasma PRL and GH concentrations. The low and gradually decreasing plasma progesterone levels in the pseudopregnant animals probably reflect the absence of a luteotrophic stimulus by the conceptus. The progesterone profile in the animals that were hysterectomized during early pregnancy suggests that the corpora lutea of these does have been permanently changed by the presence of the conceptus during the first weeks of the luteal phase.     

Relationships of serum insulin-like growth factor II concentrations to growth, compositional, and reproductive traits of swine

Insulin-like growth factors I and II (IGF-I and -II) are peptide hormones involved in metabolic regulation of growth. The objective of this study was to determine whether IGF-II concentration was predictive of growth, compositional, and reproductive traits of pigs. Forty male and sixty female pigs, divided equally between two locations, were weighed at 3-wk intervals from birth to 21 wk and bled at 9 and 21 wk of age. At each sampling, two blood samples were collected via jugular venipuncture at an interval of at least 1 h. Serum was separated and IGF-I, IGF-II, and growth hormone (GH) concentrations were determined via RIA. Traits measured included age at puberty and first parity litter size for gilts and backfat and longissimus muscle area. Blood was collected from a random sample of 52 progeny from 13 litters at 9 wk of age and serum was assayed for IGF-II concentrations. Effects of age, sex, location, and pig within sex x location on square-root transformed IGF-II concentrations were determined by analyzing data as a splitplot. Performance traits were fitted to a model including the effects of IGF-II concentration and combinations with IGF-I concentration, sex, location, and interactions. Concentrations of IGF-II were greater at 9 than at 21 wk of age (226.7 vs 159.3 ng/mL, respectively; P < .001) but did not differ between sexes. The correlation between serum IGF-II concentrations assayed from samples collected at 9 and 21 wk was .08. The partial correlations between IGF-I and IGF-II concentrations were .33 and .14 at 9 and 21 wk, respectively. The heritability of IGF-II concentration estimated from offspring-midparent regression was .08 +/- .20. Nine-week IGF-II concentration was positively associated with increased weight from weaning to 12 wk (P < .001). However, the sum of 9-wk IGF-I and IGF-II concentrations had a greater relationship to weight and gain in the growing phase than the concentration of either hormone alone. Concentration of IGF-II at 9 or 21 wk alone did not affect backfat thickness, longissimus muscle area, percentage lean, days to 100 kg, weight at 21 wk, age at puberty, or litter size. The sum of IGF-I and IGF-II concentrations was, however, associated with increased backfat and decreased days to 100 kg.     

Short stature associated with high circulating insulin-like growth factor (IGF)-binding protein-1 and low circulating IGF-II: effect of growth hormone therapy

We report a case of short stature associated with high circulating levels of insulin-like growth factor (IGF)-binding protein-1 (IGFBP-10 and low levels of IGF-II responsive to pharmacological treatment with GH. Our patient suffered severe growth failure from birth (2.06 SD below the mean for normal full-term boys, and 5.2 and 7.3 SD below the mean at 5 and 10 months). Studies carried out before referral to our pediatric unit included normal 46,XY karyotype and normal encephalic imaging. Other endocrine and metabolic alterations and other systemic diseases were excluded. At 1.7 yr of age (length, 6.1 SD; weight, 4.6 SD; head circumference, 1.4 SD below the mean, respectively) the patient was referred to our pediatric unit. The baseline GH concentration was 31 microg/L, and the peak after an arginine load was 59.6 microg/L. In the same samples GH bioactivity was nearly superimposable (RIA/Nb2 bioactivity ratio = 0.9). Fasting insulin and glucose concentrations were 7.4 microU/mL and 65 mg/dL, respectively, both normally responsive to an oral glucose load. GH insensitivity was excluded by a basal IGF-I concentration (64 ng/mL) in the normal range for 0- to 5-yr-old boys and its increase after 2 IU/day hGH administration for 4 days. IGFBP-3 (0.5 microg/mL) was slightly reduced, whereas IGFBP-1 (2218 and 1515 ng/mL in two different basal samples) was well above the normal values for age and was suppressible by GH (maximum suppression, -77% at 84 h) and glucose load (maximum suppression, -46% at 150 min). The basal IGF-II concentration was below the normal range (86 ng/mL), whereas IGFBP-2 was normal (258 ng/mL). Analysis of the promoter region of IGFBP-1 and IGF-II failed to find major alterations. Neutral gel filtration of serum showed that almost all IGF-I activity was in the 35- to 45-kDa complex, coincident with IGFBP-1 peak, while the 150-kDa complex was absent, although the acid-labile subunit was normally represented. At 2.86 yr (height, 65.8 cm; height SD score, -7.3; height velocity SD score, -5) the patient underwent treatment with 7 IU/week human GH; after 4 months, the patient's height was 68.5 cm (height SD score, -6.9) corresponding to a growth velocity of 8.3 cm/yr (0.3 height velocity SD score). IGFBP-1 was reduced (216 ng/mL), although still in the high range, whereas IGF-I (71 ng/mL), IGFBP-3 (0.62 microg/mL), and IGF-II (111 ng/mL) were only slightly increased. The IGF-I profile showed activity in the 150-kDa region. In conclusion, we speculate that the increased IGFBP-1 values found in this patient produce 1) inhibition of IGF-I biological activity and, therefore, a resistance to IGF-I not due to a receptor defect for this hormone; 2) inhibition of formation of the circulating 150-kDa ternary complex and, therefore, an accelerated clearance rate of IGF peptides; 3) inhibition of the feedback action on GH, leading to increased GH levels, which could suggest the diagnosis of GH insensitivity syndrome; and 4) inhibition of body growth.     

Differential responses of granulosa cells from small and large follicles to follicle stimulating hormone (FSH) during the menstrual cycle and acyclicity: effects of tumour necrosis factor-alpha

This study determined effects of follicle stimulating hormone (FSH) alone and in combination with tumour necrosis factor (TNF), on granulosa cells from small (5-10 mm diameter) and large (>10-25 mm) follicles during follicular and luteal phases of the cycle and during periods of acyclicity. Granulosa cells were collected from ovaries of premenopausal women undergoing oophorectomy. The cells were cultured with human FSH (2 ng/ml) and testosterone (1 microM) in the presence or absence of human TNF-alpha (20 ng/ml). Media were removed at 48 and 96 h after culture and progesterone, oestradiol and cAMP in media were measured by radioimmunoassays. FSH stimulated the accumulation of oestradiol from granulosa cells of small follicles during the follicular and luteal phases but not during acyclicity; and TNF reduced oestradiol accumulation in the presence of FSH. Interestingly, in granulosa cells from small follicles, progesterone and cAMP secretion increased in response to FSH and neither was affected by TNF. Thus, TNF specifically inhibited the conversion of testosterone to oestradiol in granulosa cells from small follicles. FSH stimulated oestradiol production by granulosa cells of large follicles obtained only during the follicular phase of the cycle and TNF inhibited the FSH-induced oestradiol secretion. Granulosa cells obtained from large follicles during the luteal phase and during acyclicity did not accumulate oestradiol in response to FSH. However, FSH increased progesterone and cAMP secretion by granulosa cells obtained from large follicles during the follicular and luteal phases. During the luteal phase alone, TNF in combination with FSH increased progesterone accumulation above that of FSH alone. FSH did not increase progesterone, oestradiol or cAMP secretion by granulosa cells obtained from large follicles during acyclicity. Thus, FSH increases progesterone, oestradiol and cAMP secretion by granulosa cells of small follicles during the follicular and luteal phases and TNF appears to inhibit FSH-induced oestradiol secretion specifically in those cells. In large follicles, FSH-stimulated granulosa cell secretion of oestradiol is limited to the follicular phase and this effect can be inhibited by TNF. In addition, when granulosa cells of large follicles do not increase oestradiol secretion in response to FSH, TNF stimulates progesterone secretion.     

Free and total insulin-like growth factors and insulin-like growth factor binding proteins during 14 days of growth hormone administration in healthy adults

The objective was to investigate the effect of growth hormone (GH) administration on circulating levels of free insulin-like growth factors (IGFs) in healthy adults. Eight healthy male subjects were given placebo and two doses of GH (3 and 6 IU/m2 per day) for 14 days in a double-blind crossover study. Fasting blood samples were obtained every second day. Free IGF-I and IGF-II were determined by ultrafiltration of serum. Total IGF-I and IGF-II were measured after acid-ethanol extraction. In addition, GH, insulin, IGF binding protein 1 (IGFBP-1) and IGFBP-3 were measured. Serum-free and total IGF-I increased in a dose-dependent manner during the 14 days of GH administration. After 14 days, serum-free IGF-I values were 610 +/- 100 ng/l (mean +/- SEM) (placebo), 2760 +/- 190 ng/l (3 IU/ m2) and 3720 +/- 240 ng/l (6 IU/m2) (p = 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.004 for 3 IU/m2 vs 6 IU/m2). Total IGF-I values were 190 +/- 10 micrograms/l (placebo), 525 +/- 10 (3 IU/m2), and 655 +/- 40 micrograms/l (6 IU/m2) (p < 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.04 for 3 IU/m2). There were no differences in the levels of free or total IGF-II during the three study periods. Insulin-like growth factor binding protein 1 was decreased during GH administration (p = 0.04 for placebo vs 3 IU/m2; p = 0.006 for placebo vs 6 IU/m2). In conclusion, fasting serum free IGF-I increased dose dependently during GH administration and free IGF-I increased relatively more than total IGF-I. This may partly be due to the decrease in IGFBP-1.     

Recombinant human inhibin-A administered early in the menstrual cycle alters concurrent pituitary and follicular, plus subsequent luteal, function in rhesus monkeys

Inhibin, a suppressor of pituitary FSH secretion in nonprimate species, may also act in the ovary to regulate follicular development. To examine whether inhibin has similar actions in primates, female rhesus monkeys (n = 3/treatment), exhibiting regular menstrual cycles, received sc injections of either vehicle or 60 micrograms/kg recombinant human inhibin-A at 0800 and 1600 h for 5 days beginning at menses. The vehicle-treated monkeys displayed menstrual cycles of normal length, with the follicular (11.3 +/- 2.5 days, mean +/- SE) and luteal (16.3 +/- 2.5 days) phases demarcated by midcycle peaks in serum estradiol (E) and bioactive LH. After the first inhibin injection, levels of immunoreactive inhibin A peaked at 10 ng/mL within 1 h and returned to baseline (< 0.1 ng/mL) before the second injection 8 h later. Although serum E and LH did not change, bioactive FSH decreased (to 66% of pretreatment levels, P < 0.05) within 8 h. Within 1 day, circulating bioactive FSH was less (P < 0.05) in inhibin-treated monkeys, compared with controls. By 2-3 days, serum E levels were also markedly (P < 0.05) reduced in inhibin-treated animals, whereas bioactive LH rose 3-fold (P < 0.05). After inhibin treatment, the midcycle rises in serum E and LH were delayed; hence, the follicular phase was prolonged (15.0 +/- 2.6 days, P < 0.05), compared with controls. Although the patterns and levels of serum LH circulating during the subsequent luteal phase seemed comparable in both groups, mean progesterone levels were suppressed to 2-3 ng/mL (P < 0.05) during the midluteal phase in inhibin-treated monkeys. However, the length of the luteal phase in inhibin-treated cycles (13.0 +/- 2.6 days) was not significantly altered. We conclude that exogenous inhibin rapidly diminishes pituitary FSH secretion in female monkeys during the early follicular phase of the menstrual cycle. This action, and/or other actions directly on the ovary, leads to subsequent effects on follicular steroidogenesis and pituitary LH secretion that culminate in an aberrant ovarian cycle characterized by an insufficient luteal phase. The study identifies, for the first time, possible activities and roles of inhibin during the ovarian cycle in primates.     

Immune responses to intestinal parasites: protection, pathology and prophylaxis

It has been suggested that adjunctive growth hormone (GH) therapy improves ovarian response and in vitro fertilization (IVF) outcome in specific groups of patients. The correlation between insulin-like growth factor (IGF) and GH is well established. The aim of this study was to determine whether changes in plasma GH correlate with IGF blood levels in patients during IVF treatment. Thirty-six women undergoing IVF and embryo transfer (ET) were examined. Ovarian stimulation was carried out by gonadotropin-releasing hormone agonists (GnRHa) and gonadotropins. Blood was drawn at the early and late follicular phase, on the day of human chorionic gonadotropin (hCG) injection and at the mid- and the late luteal phases. The samples were assayed for IGF-I, IGF-II, IGF-binding protein-3 (IGF BP-3), GH and estradiol. According to the IGF-I and GH plasma levels, patients were divided into three major groups: Group I consisted of patients in whom peak levels of GH reached more than 4 ng/ml and IGF-I decreased significantly. In this group, estradiol levels were 1863 +/- 149 pg/ml. Group II consisted of patients in whom peak blood GH levels did not exceed 2.5 ng/ml and the IGF-I level remained unchanged. In this group estradiol levels were 630 +/- 57 pg/ml. Group III consisted of patients in whom blood GH levels were low and remained unchanged while estradiol levels were 1600 +/- 420 pg/ml. In this group no significant increase in IGF-levels were observed. There was no significant change in the levels of either IGF-II or IGF BP-3 in any of the groups. We can conclude that (1) there is a negative correlation between GH and IGF-I plasma levels in patients undergoing controlled ovarian hyperstimulation (COH)-IVF, when levels of estradiol and GH are elevated; (2) plasma levels of IGF-I under ovarian hyperstimulation are probably regulated by a multifactorial system; and (3) no correlation was found between the plasma levels of IGF-I and those of IGF-II and IGF BP-3 in all patient groups.     

Effects of prenatal androgenization and postnatal steroid treatment on growth hormone, insulin-like growth factor I and II, insulin, thyroxine, and triidothyronine concentrations in beef heifers

A 2 x 3 factorial arrangement of treatments was used to elucidate the mechanism(s) by which prenatal androgenization improves postnatal rate and efficiency of growth and composition of gain in beef heifers. Fifteen control (C) and 15 prenatally androgenized (PA) Angus x Simmental heifers (prenatal treatment, Pretrt) received no (N), estrogen (E), or estrogen and testosterone (ET) implants postnatally (postnatal treatment, Posttrt) to evaluate whether the postpubertal growth response after prenatal androgenization could be induced in prepubertal heifers. Blood was collected from the heifers at 6 +/- 1, 9 +/- 1, and 12 +/- 1 mo of age and analyzed from serum concentrations of growth hormone (GH), IGF-I, IGF-II, insulin, thyroxine (T4), and triiodothyronine (T3). Season of the year had a greater effect on hormone concentrations than either Pretrt or Posttrt, and there were no Pretrt x Posttrt interactions. Prenatal treatment, PA, had no effect on GH; however, Posttrt E and ET increased (P < .001) GH concentrations. Prenatal treatment, PA, increased (P < .05) IGF-I concentrations, and there was a nonsignificant increase (P = .11) in IGF-I concentrations with Posttrt E and ET. Concentrations of IGF-II were unaffected by Pretrt PA; however, they were lower (P < .01) in the Posttrt E and ET groups. Insulin, T4, T3, BW, and ADG were not affected by Pretrt and Posttrt. Concentrations of GH and IGF-I were increased in heifers that received Pretrt PA and(or) Posttrt E and ET in a manner to support improved growth performance; however, BW and ADG were similar. In prepubertal beef heifers, factors in addition to increased GH and IGF-I seem to be necessary for improved growth performance.     

Serum concentrations of luteinizing hormone, growth hormone, and cortisol in gilts treated with N-methyl-D,L-aspartate during the estrous cycle or after ovariectomy

The objective of this experiment was to determine the effects of n-methyl-d,l-aspartate (NMA), an agonist of the neurotransmitter glutamate, on circulating concentrations of LH, GH, and cortisol in gilts treated during the luteal (n = 4) or follicular (n = 4) phase of the estrous cycle, or after ovariectomy (n = 4). Blood was sampled every 15 min for 10 h on each of two consecutive days. On the 1st d, two gilts from each group received i.v. injections of NMA (10 mg/kg BW) at h 4 and 6, and the remaining gilts received .9% saline (vehicle). The following day, gilts that had received NMA on the 1st d received vehicle, and gilts that had received vehicle on d 1 received NMA. All gilts received an i.v. challenge of GnRH (.1 microg/kg BW) at h 8 on each day. The NMA treatment increased (P < .01) LH pulse frequency in luteal-phase gilts by 125%. In contrast, NMA decreased (P < .05) mean concentrations of LH by 48% and suppressed (P < .01) LH pulse frequency by 33% in ovariectomized gilts. No characteristics of LH secretion were affected (P > .05) by NMA in follicular phase gilts. Serum LH concentrations for the 2-h period following GnRH were lower (P < .05) in follicular-phase gilts than in ovariectomized gilts and were 1.15 +/- .09 (mean +/- SE), .81 +/- .05, and .51 +/- .17 ng/mL for ovariectomized, luteal-phase, and follicular-phase gilts, respectively. Treatment with NMA increased circulating concentrations of GH by 334% (P < .01) and cortisol by 77% (P < .03) in all gilts. We suggest that the effects of NMA on LH release in gilts depend on the circulating steroidal milieu. In contrast, NMA evokes secretion of GH and cortisol irrespective of the reproductive status of treated gilts.     

Role of growth hormone and insulin-like growth factor-I in mammary development

Mammary glands from 3- to 4-week-old mice were incubated in whole organ culture to determine the effects of GH, PRL, and insulin-like growth factor-I (IGF-I) on lobulo-alveolar development and milk protein expression. Virgin mice were implanted with pellets of estrogen and progesterone (1:1000). After 9 days, abdominal no. 4 glands were removed and place on siliconized lens paper in Waymouths' medium supplemented with insulin (Ins), aldosterone, hydrocortisone, and epidermal growth factor. Concentrations of bovine GH, ovine GH, rat GH, or ovine PRL added to the medium varied from 0-1 micrograms/ml. IGF-I was added to replace either Ins or PRL up to 1 microgram/ml. When glands were incubated with Ins, aldosterone, hydrocortisone, and 250 ng/ml PRL, they exhibited lobulo-alveolar development and expressed the milk protein beta-casein. When GH was substituted for PRL, little lobulo-alveolar development occurred, although beta-casein mRNA was expressed at low levels. Either PRL or GH at 1 microgram/ml induced lobulo-alveolar development and beta-casein mRNA. Addition of epidermal growth factor to whole organ culture with GH or PRL (1 microgram/ml) was equally effective in stimulating lobulo-alveolar development. IGF-I did not substitute for PRL, GH, or insulin in tissue maintenance. It is clear that GH at high concentrations can act directly on mouse mammary tissue to induce both lobulo-alveolar development and casein expression.     

Effects of different test conditions on MICs of food animal growth-promoting antibacterial agents for enterococci

To examine whether luteal phase defect is, in part, causally related to insufficient gonadotrophin stimulation, we compared the relation of the increment of serum progesterone concentrations in response to human chorionic gonadotrophin (HCG) with its basal level at mid-luteal phase. Thirty-eight naturally cycling infertile women aged between 27-41 years old were evaluated for hormonal responses to HCG injection at the mid-luteal phase. We measured luteinizing hormone (LH), follicle stimulating hormone (FSH), oestradiol and progesterone concentrations, before and 1, 2 and 3 h after the administration of HCG (5000 IU, i.m.) 7 days after ovulation verified by ultrasonography. Eleven out of 38 women exhibited progesterone concentrations below 10 ng/ml (low progesterone group), and those remaining showed progesterone concentrations of > or = 10 ng/ml (normal progesterone group). The basal LH, FSH and oestradiol concentrations were essentially the same in both groups. Progesterone concentrations rose significantly 1 h after the injection and levelled off thereafter. The increment of progesterone concentrations at 1 h in the normal progesterone group was 5.7 ng/ml on the average, whereas that in low progesterone group was 1.1 ng/ml. Furthermore, the percentage increase in progesterone concentrations at 1 h in the normal progesterone group was significantly greater than that in the low progesterone group. Both groups equally exhibited significant but marginal increases in oestradiol concentrations 1 h after the injection. LH and FSH concentrations at 3 h decreased significantly in both groups. In summary, HCG readily stimulates progesterone production in normally functioning corpus luteum whereas its stimulatory effect is minimal on malfunctioning corpus luteum. This suggests that luteal phase defect is not caused by inadequate gonadotrophin stimulation and, therefore, does not benefit from HCG administration.