Extension of corpus luteum lifespan and reduction of uterine secretion of prostaglandin F2 alpha of cows in response to recombinant interferon-tau

Two experiments tested the effect of recombinant ovine and bovine interferon-tau on corpus luteum lifespan, interestrous interval, and oxytocin-induced uterine secretion of prostaglandin F2 alpha. Cows received intrauterine injections of 100 micrograms of recombinant ovine interferon-tau plus 1.4 mg of BSA or of 1.5 mg of BSA alone in Experiment 1 and 200 micrograms of recombinant bovine interferon-tau plus 1.3 mg of BSA or 1.5 mg of BSA alone in Experiment 2. Twice daily injections (0700 and 1900 h) were split evenly between the uterine horns from d 14 to 24 of the experimental estrous cycle via an AI pipette in Experiment 1 and via intrauterine catheters in Experiment 2. On d 17, cows were injected with 100 IU of oxytocin, and plasma was collected for analysis of 13,14-dihydro-15-keto-prostaglandinF2 alpha. Recombinant ovine interferon-tau extended the lifespan of the corpus luteum (27.5 vs. 19.2 d) and interestrous interval (30.5 vs. 20.6 d) and abolished the oxytocin-induced increase in 13,14-dihydro-15-keto-prostaglandinF2 alpha, which peaked at 30 min for the BSA control group (210.8 pg/ml). Recombinant bovine interferon-tau also extended the lifespan of the corpus luteum (29.0 vs. 21.4 d) and interestrous interval (31.5 vs. 22.6 d) and abolished the oxytocin-induced increase in 13,14-dihydro-15-keto-prostaglandin F2 alpha, which peaked at 30 min for the BSA control group (205.6 pg/ml). In conclusion, recombinant ovine interferon-tau and recombinant bovine interferon-tau were effective antiluteolytic agents in cattle.     

Plasma progestins, estradiol, and luteinizing hormone following prostaglandin F2 alpha injection

Dairy animals, ranging from days 8 to 13 of the estrous cycle, were fitted with indwelling jugular catheters 1 day prior to either intramuscular injection of prostaglandin F2alpha free acid (30 mg, n=4) or intrauterine deposition of prostaglandin F2alpha free acid (10 mg, n = 3). Blood samples were collected at 6, 4, 2, and 0 h prior to administration of prostaglandin F2alpha and at 1, 3, and every 2 h thereafter until ovulation. Progestins, estradiol, and luteinizing hormone in plasma were measured by radioimmunoassay. Hormonal changes and interrelationships within animals were evaluated by least squares analyses. Decreases in progestins of plasma within 24 h indicated prostaglandin F2alpha induced luteolysis in six of the seven animals. Estradiol increased linearly from time of injection to 52 h postinjection. Intervals from administration of prostaglandin to onset of estrus, peak of luteinizing hormone, and ovulation were 74.9 +/- 21, 78.8 +/- 21, and 99.5 +/- 19 h.     

Effect of restraint stress on the preovulatory luteinizing hormone profile and ovulation in the rat

Plasma profiles of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured during restraint stress on the day of pro-oestrus; these profiles were considered in relation to ovulation rate on the next day. Rats bearing a permanent jugular vein cannula were subjected to restraint, which was started 0, 1 or 2 h before the presumed onset of the LH surge and ended just before the beginning of the dark period. Exposure to restraint resulted in a suppression of the secretion of both gonadotrophins on the day of pro-oestrus. Suppression of the LH surge was virtually complete (plasma LH < or = 0.2 ng/ml) in 15 out of 32 stressed rats, and the ovaries of these rats contained graafian follicles with oocytes in germinal vesicle stage. In these rats, the LH surge did not occur 24 h later. In the remaining 17 rats, restraint resulted in a considerable suppression of the LH surge. Of these rats, five had an ovulation rate of 100% and four ovulated partially. In unruptured follicles of the latter, the oocyte had not resumed meiosis and the follicle wall was not luteinized. In the remaining eight rats with a reduced LH surge, ovulations had not occurred and graafian follicles were unaffected. The results of this study indicate that during pro-oestrus restraint stress suppresses and does not delay the release of preovulatory gonadotrophins. Partial suppression of LH by restraint does not result in induction of meiotic resumption without subsequent ovulation or in luteinized unruptured follicles.     

Possible direct effect of gonadotropin releasing hormone on human endometrium and decidua

Decidualization of endometrial tissues, which is essential for implantation and the continuation of pregnancy, is induced by pituitary hormones that are regulated by gonadotropin releasing hormone (GnRH). Our objective was to determine the role of a direct action of GnRH on endometrial tissues by comparing the characteristics of receptors for GnRH in human endometrial and decidual tissues. Competitive binding studies were performed with the protease-resistant GnRH analogues, buserelin and [125I] buserelin. The effects of buserelin on phosphoinositol turnover were determined by the measurement of inositol 1,4,5-triphosphate(IP3). The values for the dissociation constant (Kd) and number of binding sites (Bmax) per unit protein versus buserelin for endometrial tissues did not differ from the values for decidual tissues. However, the Bmax per unit DNA was significantly higher in endometrial tissues. Also, buserelin induced a significant increase in IP3 in decidual tissue. These results indicate that GnRH may be a potential modulator of the function in human endometrium and decidua. The signal transduction mechanism for GnRH action appeared to involve the accelerated turnover of phosphoinositol.     

Hypothalamic areas involved in prostaglandin (PG)-induced gonadotropin release. I: effects of PGE2 and PGF2alpha implants on luteinizing hormone release

Ovariectomized rats had a cannula inserted unilaterally within various hypothalamic areas. Several days later they were primed with a sc dose of 10 microng of estradiol benzoate (Eb). Two days after priming they were etherized and an initial blood sample was drawn from the external jugular vein. An inner cannula containing PGE2 or PGF2alpha at its tip was inserted into the previously implanted outer cannula. Blood samples were drawn at 20, 40, 60, and 120 min following the implantation. PGE2 induced a 4-5-fold increase in plasma LH 40 to 60 min following its implantation in the arcuate nucleus-median eminence region (ARH-ME). Levels were already significantly elevated at 20 min. When PGE2 was placed slightly more dorsally, close to the ventromedial nucleus (VMH), LH titers rose to comparable levels but only after a delay of 120 min. PGE2 implanted in the caudal portion of the ARH-ME or dorsally in the VMH-dorsomedial nuclei, barely increased plasma LH, whereas its placement in the anterior portion of the ARH-ME clearly elevated LH titers. PGE2 implants located more than 1 mm lateral from the midline or outside the hypothalamus were ineffective. When PGE2 was placed in the preoptic area (POA) or anterior ventral portion of the anterior hypothalamic area (AHA), plasma LH levels rose strikingly, the first significant increase being observed at 20 min. PGE2 implants located in the vicinity of the paraventricular nucleus-dorsal portion of AHA were much less effective. PGF2alpha implanted in the ARH-ME or POA induced a small increase in plasma LH and the implantation of empty cannulae in the same areas was ineffective. Intrapituitary implants of PGE2 failed to alter plasma LH significantly. The results indicate that PGE2 acts at the ARH-ME region to induce LH release and that an even more effective site of action seems to be located in the POA-AHA. Since these are areas which contain LHRH, the results support the view that PGs can activated LHRH-secreting neurons in these regions.     

Effect of prostaglandin F2 alpha treatment before norgestomet and estradiol valerate treatment on regression, formation, and function of corpora lutea in beef heifers

Despite the presence of several human disease genes on chromosome 11q13, few of them have been molecularly cloned. Here, we report the construction of a contig map encompassing 11q13.1-q13.3 using bacteriophage P1 (P1), bacterial artificial chromosome (BAC), and P1-derived artificial chromosome (PAC). The contig map comprises 32 P1 clones, 27 BAC clones, 6 PAC clones, and 1 YAC clone and spans a 3-Mb region from D11S480 to D11S913. The map encompasses all the candidate loci of Bardet-Biedle syndrome type I (BBS1) and spinocerebellar ataxia type 5 (SCA5), one-third of the distal region for hereditary paraganglioma 2 (PGL2), and one-third of the central region for insulin-dependent diabetes mellitus 4 (IDDM4). In the process of map construction, 61 new sequence-tagged site (STS) markers were developed from the Not I linking clones and the termini of clone inserts. We have also mapped 30 ESTs on this map. This contig map will facilitate the isolation of polymorphic markers for a more refined analysis of the disease gene region and identification of candidate genes by direct cDNA selection, as well as prediction of gene function from sequence information of these bacterial clones.     

Influence of human chorionic gonadotropin on pregnancy rates in lactating dairy and beef cows

Single subcutaneous injection of 1500 IU human chorionic gonadotropin or placebo injections were given at the time of insemination in lactating dairy and beef cows to determine their effects on rates of pregnancy. Pregnancy rates at first service in 161 control and 145 treated dairy cows were 52.8% and 44.8%, respectively. Similar rates for 136 control and 145 treated beef cows were 54.4% and 54.5%. Injections of human chorionic gonadotropin were not effective in stimulating conception rates in lactating dairy or beer cows under field conditions.     

Effect of summer heat stress on serum luteinizing hormone and progresterone values in Holstein-Friesian cows in Arizona

Serum-luteinizing hormone and progesterone values were measured in lactating and nonlactating Holstein-Friesian cows to evaluate their relationship with reduced fertility observed during hot summer months in Arizona. The stress of hot weather had no effect on frequency of preovulatory increase of luteinizing hormone nor on the interval between the preovulatory increase and ovulation in either lactating or nonlactating cows. Progesterone values were significantly (P less than 0.05) increased in lactating cows which became hyperthermic during hot weather, yet progesterone values did not change in nonlactating cows which had remained homeothermic. A similar relationship was observed between fertility and serum progesterone values, and between fertility and degree of thermal stress caused by hot weather. Decreased fertility and increased serum progesterone values were associated with increased environmental temperature and hyperthermia.     

Resumption of follicular waves in beef cows is not associated with periparturient changes in follicle-stimulating hormone heterogeneity despite major changes in steroid and luteinizing hormone concentrations

To test the hypothesis that emergence of follicle waves postpartum is associated with a change in circulating FSH isoform distribution, 10 Limousin-cross suckler cows were blood sampled daily from 5 wk prepartum until first ovulation postpartum for FSH, LH, estradiol (E2), and progesterone assay. Follicular growth was monitored daily by ultrasonography from Days 5 to 10 postpartum until first ovulation. Distributions of circulating FSH isoforms were characterized (n = 4 per group) by chromatofocusing at 1) 18-33 days prepartum, 2) 3-5 days prepartum, 3) the first postpartum FSH rise responsible for emergence of the first follicle wave, and 4) the FSH rise that stimulated the ovulatory follicle wave. The interval to detection of the first postpartum dominant follicle (DF) was 9.6 +/- 0.58 days. The number of DF before first ovulation was 2.1 +/- 0.18, and first ovulation occurred at 28.6 +/- 1.54 days postpartum. Serum E2 concentrations were higher (p = 0.0001) in cows during the 5-wk period prepartum (53.8 +/- 6.29 pg/ml) than in the postpartum period up to first ovulation (1.5 +/- 0.15 pg/ml). In late pregnancy, there was an absence of recurrent FSH rises and LH concentrations were decreased (p < 0.0001) compared with those in the postpartum period. The emergence of each follicle wave postpartum was preceded by a 2- to 4-day rise in FSH concentrations. The pattern of FSH isoform distribution did not differ (p > or = 0.75) between the pre- and postpartum periods.     

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.     

Negative influence of O-linked oligosaccharides of high molecular weight equine chorionic gonadotropin on its luteinizing hormone and follicle-stimulating hormone receptor-binding activities

Three equine CG (eCG) forms with identical amino acid sequences but different mol wt and monosaccharide compositions were isolated from a crude eCG preparation and designated eCG-L (low mol wt), eCG-M (medium mol wt), and eCG-H (high mol wt). No differences in primary structure between each form and the known sequence of eCG were observed. SDS-PAGE of these preparations under reducing conditions revealed that the mol wt differences between them were due only to the different sizes of their beta-subunits. Carbohydrate compositions suggested an increase in O-glycosylation in the higher mol wt forms. N-Linked glycopeptide fragments obtained from eCG beta-subunits by endoproteinase Lys-C digestion had identical electrophoretic mobilities. Thus, the different molecular sizes of the beta-subunits were associated only with disparities in O-glycosylation of their C-terminal extension. When tested in a LH and several FSH radioligand assay systems, eCG-H proved to have significantly lower receptor-binding activities than eCG-L and eCG-M. Endo-beta-galactosidase digestion increased the FSH receptor-binding activity of all eCG forms; however, partially deglycosylated eCG-H remained the least active form. Thus, the O-linked oligosaccharides of eCG-H exert a negative influence on its receptor-binding activity.     

Effect of prostaglandin F2alpha on the lysosomal membranes of eye tissues

It was demonstrated that both in vitro and in intravenous injection of prostaglandin F2alpha there occurred labilization of the membranes of sclera and ciliary body lysosomes, in difference from the cornea in rabbits. Glycosidase activity appeared in the vitreous body under the effect of prostaglandin, which was absent under normal conditions.     

Effect of gonadotrophin on cell and matrix retention and expression of metalloproteinases and their inhibitor in cultured human granulosa cells modelling corpus luteum function

A retrospective cohort study in 1794 male ceramic workers in the Netherlands was carried out to analyze the lung cancer risk in relation to crystalline silica exposure and silicosis. They had all been employed for two years or longer in ceramic industries between 1972 and 1982. During a health survey, 124 cases of simple pneumoconiosis were diagnosed; after 14 years of follow-up, 161 deaths had occurred. No increased overall and cause-specific mortality was found in the total group of ceramic workers, and a statistically significant cumulative dose-response relation for silica exposure and lung cancer did not emerge. An excess lung cancer mortality appeared among workers with simple pneumoconiosis. The authors conclude that the disease process resulting in silicosis in the ceramic industry carries an increased risk of lung cancer, which is supportive of a nongenotoxic pathway.     

Fate of the dominant follicle, embryonal survival, and pregnancy rates in dairy cattle treated with prostaglandin F2 alpha and progestins in the absence or presence of a functional corpus luteum

Our objective was to examine the role of progestin type on serum concentrations of progesterone (p4) and estradiol-17 beta (E2), ovarian follicular dynamics, and fertility in cattle in the presence or absence of a corpus luteum (CL) in an estrus synchronization scheme using progestin and PGF2 alpha. In Exp. 1, 325 cows and heifers were given one injection of PGF2 alpha (d 0) and then assigned randomly within parity to five treatments: to receive a second PGF2 alpha injection 14 d later (control); to receive norgestomet (NORG) for 7 d beginning on d 8, with a second PGF2 alpha injection given either 1 d (NORG + no CL) or 6 d (NORG + CL) after insertion; or to receive a P4-releasing intravaginal device (PRID) in lieu of norgestomet at comparable times. Presence or absence of a CL was based on concentrations of serum P4 on d 14. Pregnancy rates after insemination were greater (P < .01) with luteal treatments than with nonluteal treatments. Embryonal survival between two stages of pregnancy was 87.6%. In Exp. 2, ovarian structures in 50 cows were examined daily using ultrasonography and the same five treatments. Diameter of the ovulatory follicle was greater (P < .05) with the nonluteal treatments (NORG and PRID + no CL) than with the control and luteal treatments (PRID and NORG + CL). Replacement of the dominant follicle during progestin treatment was altered by treatment (luteal status) and stage of the estrous cycle. Fertility was not enhanced by exogenous progestins when a CL was present. In the absence of a CL, progestin (P4 less than NORG at the doses used) reduced fertility by increasing E2 and the diameter of the ovulatory follicle and decreasing turnover of dominant follicles.     

Acute effects of prostaglandin F2 alpha, luteinizing hormone, and estradiol on second messenger systems and on the secretion of oxytocin and progesterone from granulosa and early luteal cells of the ewe

Previous reports have suggested that gonadotropins, estradiol, and prostaglandin F2 alpha (PGF2 alpha) have varying effects on progesterone and oxytocin synthesis or secretion in cultured granulosa and luteal cells collected at different stages of the estrous cycle. The experiments reported here were designed to investigate whether effects of these agonists on secretion of hormones and their coupling to second messenger systems changed around the time of ovulation. Granulosa cells and Day 2 luteal cells of the ewe were cultured for three days and then treated for 30 min with varying doses of PGF2 alpha, LH, or estradiol. LH increased intracellular cAMP at both stages, but granulosa cells were more responsive in terms of both minimum effective dose (10 compared with 100 ng/ml) and degree of stimulation. LH caused no change in intracellular inositol phosphate levels. Both granulosa and early luteal cells responded to LH treatment by an increase in progesterone output in a dose-responsive fashion. PGF2 alpha increased inositol phosphate accumulation in cells collected at both stages of the cycle. All doses tested (10(-6)-10(-8) M) stimulated the release of oxytocin into the culture medium from both granulosa and luteal cells. Progesterone secretion was also increased, but only at the highest dose (10(-6) M). Estradiol treatment (10(-6) M) did not affect either the inositol phosphate or cAMP second messenger systems, but it did inhibit the secretion of oxytocin from granulosa cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of acute pharmacological reduction of plasma free fatty acids on growth hormone (GH) releasing hormone-induced GH secretion in obese adults with and without hypopituitarism

In obesity, there is a markedly decreased GH secretion. The diagnosis of GH deficiency (GHD) in adults is based on peak GH responses to stimulation tests. In the severely obese, peak GH levels after pharmacological stimulation are often in the range that is observed in hypopituitary patients. To distinguish obese subjects from GHD patients, it will be necessary to demonstrate that reduced GH responsiveness to a given test is reversible in the former, but not in the latter, group. Recent studies have shown that reduction of plasma free fatty acids (FFA) with acipimox in obese patients restores their somatotrope responsiveness. There are no data evaluating GH responsiveness to acipimox plus GHRH in obese adults with hypopituitarism. The aim of the present study was to evaluate the effect of acute pharmacological reduction of plasma FFA on GHRH-mediated GH secretion in obese normal subjects and obese adults with hypopituitarism. Eight obese patients with a body mass index of 34.2+/-1.2; eight obese adults with hypopituitarism, with a body mass index of 35.5+/-1.9; and six control subjects were studied. All the patients showed an impaired response to an insulin-tolerance test (0.15 U/kg, i.v.), with a peak GH secretion of less than 3 microg/L. Two tests were carried out. On one day, they were given GHRH (100 microg, i.v., 0 min), preceded by placebo; and blood samples were taken every 15 min for 60 min. On the second day, they were given GHRH (100 microg, i.v., 0 min), preceded by acipimox (250 mg, orally, at -270 min and -60 min); and blood samples were taken every 15 min for 60 min. The administration of acipimox induced a FFA reduction during the entire test. Normal control subjects had a mean peak (microg/L) of 23.8+/-4.8 after GHRH-induced GH secretion; previous acipimox administration increased GHRH-induced GH secretion, with a mean peak of 54.7+/-14.5. In obese patients, GHRH-induced GH secretion was markedly reduced, with a mean peak (microg/L) of 3.9+/-1; previous administration of acipimox markedly increased GHRH-mediated GH secretion, with a mean peak of 16.0+/-3.2 (P < 0.05). In obese adults with hypopituitarism, GHRH-induced GH secretion was markedly reduced, with a mean peak (microg/L) of 2+/-0.7; previous acipimox administration did not significantly modify GHRH-mediated GH secretion, with a mean peak of 3.3+/-1.1 (P < 0.05). The GH response of obese patients and obese adults with hypopituitarism was similar after GHRH alone. In contrast, the GH response after GHRH plus acipimox, was markedly decreased in obese adults with hypopituitarism (mean peak, 3.3+/-1.1), compared with obese patients (mean peak, 16.0+/-3.2) (P < 0.05) and control subjects (mean peak, 54.7+/-14.5) (P < 0.01). In conclusion, GH secretion, after GHRH-plus-acipimox administration, is reduced in obese adults with hypopituitarism patients, when compared with obese normal patients. Testing with GHRH plus acipimox is safe and is free from side effects and could be used for the diagnosis of GHD in adults.