Perturbation of estradiol-feedback control of luteinizing hormone secretion by immunoneutralization induces development of follicular cysts in cattle

Archetypal clustering reveals physiological mechanisms linking milk yield and fertility in dairy cattle

Fertility in dairy cattle has declined as an unintended consequence of single-trait selection for high milk yield. The unfavorable genetic correlation between milk yield and fertility is now well documented; however, the underlying physiological mechanisms are still uncertain. To understand the relationship between these traits, we developed a method that clusters variants with similar patterns of effects and, after the integration of gene expression data, identifies the genes through which they are likely to act. Biological processes that are enriched in the genes of each cluster were then identified. We identified several clusters with unique patterns of effects. One of the clusters included variants associated with increased milk yield and decreased fertility, where the "archetypal" variant (i.e., the one with the largest effect) was associated with the GC gene, whereas others were associated with TRIM32, LRRK2, and U6-associated snRNA. These genes have been linked to transcription and alternative splicing, suggesting that these processes are likely contributors to the unfavorable relationship between the 2 traits. Another cluster, with archetypal variant near DGAT1 and including variants associated with CDH2, BTRC, SFRP2, ZFHX3, and SLITRK5, appeared to affect milk yield but have little effect on fertility. These genes have been linked to insulin, adipose tissue, and energy metabolism. A third cluster with archetypal variant near ZNF613 and including variants associated with ROBO1, EFNA5, PALLD, GPC6, and PTPRT were associated with fertility but not milk yield. These genes have been linked to GnRH neuronal migration, embryonic development, or ovarian function. The use of archetypal clustering to group variants with similar patterns of effects may assist in identifying the biological processes underlying correlated traits. The method is hypothesis generating and requires experimental confirmation. However, we have uncovered several novel mechanisms potentially affecting milk production and fertility such as GnRH neuronal migration. We anticipate our method to be a starting point for experimental research into novel pathways, which have been previously unexplored within the context of dairy production.

Active immunization against GnRH as an alternative therapeutic approach for the management of Bos indicus oocyte donors diagnosed with chronic cystic ovarian disease

The aim of this study was to evaluate the effect of active immunization against GnRH in Nelore (Bos indicus) cows repeatedly used as oocyte donors that developed chronic cystic ovarian disease (COD). In the first experiment, ovarian and uterine features were first compared between COD cows (n = 15) and healthy cows (n = 22, cycling control group) from the same breed and herd. Cows with COD had a greater number of large (P < 0.0001) and medium follicles (P < 0.01) but lesser small follicles (P < 0.05) than cycling controls. Mucometra was diagnosed in 73.3% of COD cows, but in none of the controls. No difference in average thickness of the endometrium was detected between groups; however, endometrial thickness and mucometra score were negatively correlated (R = -0.73, P = 0.0029) in COD cows. In the second experiment, COD cows were randomly allocated into two experimental groups, which received two 1.0 mL SC injections of either an anti-GnRH vaccine (COD immunized group, n = 8) or saline (COD control group, n = 7), given 28 days apart. Cows were examined weekly by transrectal ultrasonography during nine consecutive weeks after the first injection to evaluate the number and distribution of follicles among size classes, endometrial thickness, and presence of clinical mucometra. Vaccination against GnRH resulted in a progressive suppression of follicle growth and a reduction in the average size of the largest follicle, as well as in the number of large follicles (P < 0.01) in COD immunized cows compared with COD controls from week 7 onwards. Conversely, the number of small follicles in the COD immunized group increased after week 5 and was greater (P = 0.0023) than controls on week 9. Endometrial thickness and mucometra score were not affected (P > 0.05) by immunization against GnRH. In the third experiment, the COD immunized cows with effective suppression of follicle growth four weeks after the 2nd injection (n = 6) were submitted to three consecutive ovum pick-up (OPU) sessions (weeks 10, 11, and 12) for in vitro embryo production (IVEP). Cumulus-oocyte complexes (COC) collected from slaughterhouse ovaries were used as controls for IVEP. COD cows with produced 25.0 ± 3.8 COC per OPU session with no apparent detrimental effect of anti-GnRH vaccine on oocyte developmental potential in vitro, i.e., we observed similar cleavage rate (P = 0.5914) and greater blastocyst rate (P = 0.0177) in immunized cows compared with COC from slaughterhouse controls. Finally, in the fourth experiment wave emergence and follicular dynamics after follicle ablation were compared between COD immunized cows with effective suppression of follicle growth and a subset (n = 6) of the cycling, control group. No follicles grew beyond 4 mm diameter after follicle ablation in the COD immunized group, whereas a normal follicular wave emergence occurred in cycling controls. Antral follicle count was similar between cycling controls and COD immunized groups at 24 h and 96 h post-follicle ablation (P > 0.05), but greater in cycling controls at 48 h and 72 h post-follicle ablation (P < 0.05). In summary, our results suggest that active immunization against GnRH is effective to induce the regression of follicular cysts as well as increase the number of small follicles growing on the ovaries, in oocyte donors diagnosed with chronic COD, with no apparent negative effect on oocyte developmental potential in vitro.

Direct evidence that KNDy neurons maintain gonadotropin pulses and folliculogenesis as the GnRH pulse generator

The gonadotropin-releasing hormone (GnRH) pulse is fundamental for mammalian reproduction: GnRH pulse regimens are needed as therapies for infertile women as continuous GnRH treatment paradoxically inhibits gonadotropin release. Circumstantial evidence suggests that the hypothalamic arcuate KNDy neurons expressing kisspeptin (encoded by Kiss1), neurokinin B (encoded by Tac3), and d ynorphin A serve as a GnRH pulse generator; however, no direct evidence is currently available. Here, we show that rescuing >20% KNDy neurons by transfecting Kiss1 inside arcuate Tac3 neurons, but not outside of these neurons, recovered folliculogenesis and luteinizing hormone (LH) pulses, an indicator of GnRH pulses, in female global Kiss1 knockout (KO) rats and that >90% conditional arcuate Kiss1 KO in newly generated Kiss1-floxed rats completely suppressed LH pulses. These results first provide direct evidence that KNDy neurons are the GnRH pulse generator, and at least 20% of KNDy neurons are sufficient to maintain folliculogenesis via generating GnRH/gonadotropin pulses.

Induction of cystic ovarian follicles (COFs) in cattle by using an intrafollicular injection of indomethacin

The aim of this study was to establish a model to induce cystic ovarian follicles (COFs) in cattle using the cyclooxygenase inhibitor, indomethacin. Eighteen Holstein-Frisian cattle were synchronized with prostaglandin F2alpha (PGF2α) and gonadotropin-releasing hormone (GnRH). Ultrasound-guided transvaginal intrafollicular injections were performed in 23 preovulatory follicles with different concentrations of indomethacin 16 h after GnRH administration. An injection of 0.2 ml 35 µM indomethacin solution (resulting in a final concentration of 8 µg/ml in the follicular fluid) was the minimal dosage leading to COF formation. The induced COFs reached a maximum mean diameter of 36.9 ± 4.5 mm eleven days after injection. The estrous cycle was extended to 25-39 days. Luteinization was first observed 4 days after injection, accompanied by a slight increase in plasma progesterone concentration. The bioactivity of indomethacin was demonstrated by the decrease of prostaglandin E2 in the follicular fluid of three animals. The method presented here is minimally invasive and allows for the generation of defined COFs for further investigations.

Developmental ability of oocytes retrieved from Meishan neonatal ovarian tissue grafted into nude mice

Ovarian xenografting makes it possible to obtain oocytes with fertilization ability from immature pigs of Western breeds. In this study, we applied these methods to the Meishan, an indigenous Chinese pig breed, and investigated the developmental competence of oocytes grown in their neonatal tissue after grafting into nude mice. First, mice harboring neonatal ovarian tissue were infused with follicle stimulating hormone (FSH) (62.5 U/ml) for 13 days starting at 10, 30, and 60 days after vaginal opening (D10‐, D30‐, and D60‐FSH groups, respectively). Development of antral follicles and their oocytes was most enhanced in the D60‐FSH group. For the next step, we examined the in vitro maturation ability of the oocytes recovered from host mice after infusion with FSH at a dose of 62.5 U/ml or 125 U/ml (FSH‐62.5 or ‐125 group) for 13 days starting at 60 days after vaginal opening. Many more oocytes with maturation ability were obtained from the FSH‐125 group. The FSH‐125 mature oocytes were fertilized in vitro, as shown by formation of male and female pronuclei, but did not reach the blastocyst stage. These results indicate that Meishan neonatal ovaries are able to produce oocytes with fertilization ability after being grafted into nude mice.

Establishment of a strain of haemophilia-A pigs by xenografting of foetal testicular tissue from neonatally moribund cloned pigs

Grafting of testicular tissue into immunodeficient mice makes it possible to obtain functional sperm from immature donor animals that cannot be used for reproduction. We have developed a porcine model of human haemophilia A (haemophilia-A pigs) by nuclear transfer cloning from foetal fibroblasts after disruption of the X-linked coagulation factor VIII (F8) gene. Despite having a recessive condition, female F8^+/- cloned pigs died of severe bleeding at an early age, as was the case for male F8^-/Y cloned pigs, thus making it impossible to obtain progeny. In this study, therefore, we produced sperm from F8^-/Y cloned pigs by grafting their foetal testicular tissue into nude mice. Two F8^+/- female pigs were generated from oocytes injected with xenogeneic sperm. Unlike the F8^+/- cloned pigs, they remained asymptomatic, and delivered five F8^-/Y and four F8^+/- pigs after being crossed with wild-type boars. The descendant F8^-/Y pigs conserved the haemophilia phenotype. Thus, the present F8^+/- pigs show resolution of the phenotypic abnormality, and will facilitate production of F8^-/Y pigs as founders of a strain of haemophilia-A pigs for the development of new therapeutics for haemophilia A. This strategy will be applicable to other genetically modified pigs.

Superovulatory response in Japanese Black cows receiving a single subcutaneous porcine follicle-stimulating hormone treatment or six intramuscular treatments over three days

To reduce labor for superovulation treatment by twice-daily intramuscular (im) administration of FSH for more than 3 to 4 days, we investigated the superovulatory responses of Japanese Black cows to porcine FSH (pFSH) used as a single subcutaneous (sc) administration at two different doses in two different volumes of saline. In experiment 1, 20 Armour units (AU) of pFSH dissolved in either 10 mL (treatment A; n = 14) or 50 mL (treatment B; n = 14) of saline was administered subcutaneously in the neck region. In experiment 2, 30 AU of pFSH dissolved in either 10 mL (treatment C; n = 15) or 50 mL (treatment D; n = 15) of saline was administered subcutaneously in the neck region. The control animals in experiment 1 (n = 14) and experiment 2 (n = 15) received 20 AU of pFSH administered intramuscularly twice daily in decreasing doses for more than 3 days. In experiment 1, mean (±SEM) numbers of CL (15.4 ± 2.5, 18.1 ± 3.4, and 17.2 ± 2.6), total number of ova and embryos (12.9 ± 1.4, 15.9 ± 3.5, and 16.2 ± 2.8), and transferable embryos (7.5 ± 2.0, 10.4 ± 2.8, and 8.0 ± 2.1) did not differ among treatments A, B, and control. In experiment 2, mean (±SEM) numbers of CL (20.5 ± 4.3, 20.4 ± 2.7, and 20.1 ± 3.4), total number of ova and embryos (21.7 ± 4.2, 17.3 ± 3.4, and 16.5 ± 3.2), and transferable embryos (8.1 ± 1.6, 9.3 ± 2.2, and 9.5 ± 1.9) did not differ among treatments C, D, and control. Although there were no differences in serum pFSH concentrations among the three treatments at each of the time points in experiment 1, in experiment 2, the serum pFSH concentration at 6 and 8 hours after pFSH administration in treatment C (3.1 ± 0.8, 2.7 ± 0.5 ng/mL, mean ± SEM) was significantly greater (P < 0.05) than in the control (0.7 ± 0.1, 1.1 ± 0.2 ng/mL). At 10 hours after administration, the pFSH concentration had decreased and there were no differences among the three treatments at subsequent time points. These results suggest that increasing the volume of saline or the dose of pFSH does not affect the absorption pattern of pFSH administered as a single sc administration. In conclusions, single sc administration of pFSH at a dose of 20 or 30 AU dissolved in 10 or 50 mL of saline is able to induce a superovulatory response comparable with that obtained by twice-daily im administration in Japanese Black cows.

Generation of live piglets for the first time using sperm retrieved from immature testicular tissue cryopreserved and grafted into nude mice

Cryopreservation of immature testicular tissues is essential for increasing the possibilities of offspring generation by testicular xenografting for agricultural or medical purposes. However, successful production of offspring from the sperm involved has never been reported previously. In the present study, therefore, using intracytoplasmic sperm injection (ICSI), we examined whether xenogeneic sperm obtained from immature pig testicular tissue after cryopreservation would have the capacity to produce live piglets. Testicular fragments from 9- to 11-day-old piglets were vitrified after 10- or 20-min immersion in vitrification solution containing ethylene glycol (EG), polyvinyl pyrrolidone (PVP) and trehalose as cryoprotectants, and then stored in liquid nitrogen for more than 140 days. Thirty nude mice were assigned to each immersion-time group. Testicular fragments were transplanted under the back skin of castrated mice immediately after warming and removal of the cryoprotectants. Blood and testicular grafts were then recovered from the recipient mice on days 60, 120, 180 and 230−350 (day 0 =  grafting). Histological assessment of the testicular grafts and analyses of inhibin and testosterone production revealed no significant differences between the two immersion-time groups, indicating equal growth activity of the cryopreserved tissues. A single sperm obtained from a mouse in each group on day 230−350 was injected into an in vitro-matured porcine oocyte, and then the ICSI oocytes were transferred to the oviducts of estrus-synchronized recipient gilts. One out of 4 gilts that had received oocytes fertilized using sperm from the 10-min immersion group delivered 2 live piglets, and one of another 4 gilts from the 20-min group delivered 4 live piglets. Thus, we have successfully generated porcine offspring utilizing sperm from immature testicular tissues after cryopreservation and transplantation into nude mice. The present model using pigs will be applicable to many large animals, since pigs are phylogenetically distant from the murine recipients.

Cystic ovaries in intermittently-suckled sows: follicle growth and endocrine profiles

This paper presents follicle development and hormone profiles for sows with normal ovulation or cystic follicles during an intermittent-suckling (IS) regime that started at Day 14 of lactation. Sows were subjected to separation from their piglets during blocks of 6h or 12h. In total, 8 out of 52 sows developed cystic follicles; either full cystic ovaries (n=6) or partial ovulation (n=2). Increase in follicle size of these sows was similar to that of normal ovulating sows until pre-ovulatory size at Day 5 after the start of separation, but from then on became larger (P<0.05). LH surge was smaller or absent in sows that developed (partially) cystic ovaries (0.4 ± 0.1 vs 3.6 ± 0.3 ngmL(-1); P<0.01). Peak levels of oestradiol (E2) were similar but high E2 levels persisted in sows that developed (partly) cystic ovaries and duration of oestrus tended to be longer. The risk of developing (partly) cystic ovaries was higher when IS occurred in blocks of 6h versus 12h (33 vs 10%). In conclusion, the appearance of cystic ovaries at approximately Day 20 of ongoing lactation was related to an insufficient LH surge, as is also the case in non-lactating sows.

Normal reproductive development of offspring derived by intracytoplasmic injection of porcine sperm grown in host mice

For establishment of gonadal xenografting, it is essential to clarify whether offspring derived from gametes grown in host mice harboring xenografts have normal reproductive development. This study examined the secretory profiles of gonadal hormones in relation to sexual maturation or ovarian cyclicity in pigs generated by intracytoplasmic sperm injection using xenogeneic sperm (Xeno-ICSI pigs, four males and one female). We also assessed the developmental activity of gametes obtained from these pigs using in vitro culture systems, or by mating with conventionally produced (conventional) pigs. During the growth of male Xeno-ICSI pigs, serum inhibin and testosterone concentrations were generally within ranges for those hormones in conventional pigs. Histologically, there were no differences in the growth and differentiation of seminiferous tubules between Xeno-ICSI and conventional pigs. Parameters of semen quality, including volume, pH, sperm concentration, and the percentage of motile sperm were not different from those in conventional pigs. Among the Xeno-ICSI pigs, individual differences were noted in the ability of sperm to penetrate oocytes and to produce blastocysts. However, oocytes after in vitro fertilization using these sperm developed into blastocysts containing more than 31 cells. One conventional sow delivered 12 piglets after being mated with a male Xeno-ICSI pig. During growth of the female Xeno-ICSI pig, serum progesterone concentrations had a sudden increase at 41 wk of age, suggesting CL formation. After puberty, this animal showed cyclic changes in the serum concentrations of progesterone and inhibin, and delivered 10 piglets after AI using fresh sperm obtained from a conventional boar. In conclusion, these findings demonstrated that both male and female Xeno-ICSI pigs had normal reproductive abilities.

Follicular persistence induced by adrenocorticotropic hormone administration in goats

The objective of the present study was to examine the effect of adrenocorticotropic hormone (ACTH) administration on the induction of persistent cystic follicle in the goat in order to establish a method to experimentally induce cystic follicle. Four cross-bred goats were intramuscularly administered ACTH at 0.78 and 6.25 µg/10 kg twice a day from Days 15 to 21 (Day 0 was defined as the day of last estrus). Follicular status in the ovary was monitored by ultrasound examination. The plasma concentrations of estradiol, progesterone and cortisol were measured. Treatment with ACTH at the 0.78 and 6.25 µg/10 kg levels caused persistent follicles (> 10 days delay from the expected ovulation date) in 50% of the goats in both treatment groups. In those animals, ovulation occurred 17 and 27 days and 11 and 12 days after the expected days in the 0.78 and 6.25 µg/10 kg groups, respectively. The maximum follicle diameters were 10 and 9 mm in the 0.78 and 6.25 µg/10 kg ACTH groups, respectively. In the control group, the estradiol concentration increased on Day 18 and remained at a high level for a few days. However, such an increase was not seen in both ACTH groups. The estradiol concentration increased gradually from Days 21 to 27 in the 6.25 µg/10 kg ACTH group. These results suggest the possibility that ACTH induces persistent follicles in goats, which may be related to the delay of the onset of estradiol secretion followed by its maintenance at a high concentration.

Effect of exogenous circulating anti-bPL antibodies on bovine placental lactogen measurements in foetal samples

Background

The involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating antibodies are present together with the hormone, the procedure for hormonal measurement becomes considerably complex. The aim of this study was the immunoneutralization of bovine placental lactogen (bPL) concentrations in bovine foetal circulation by direct infusion of rabbit anti-bPL purified immunoglobulins (IgG) via a foetal catheter (in vivo study). The ability of a RIA based on guinea pig anti-bPL antiserum, for the measurement of bPL concentrations in samples containing exogenous rabbit anti-bPL immunoglobulins, was also analyzed in in vitro and in vivo conditions.

Methods

Six bovine foetuses were chronic cannulated on the aorta via the medial tarsal artery. Infusion of rabbit anti-bPL IgG was performed during late gestation. Pooled rabbit anti-bPL antisera had a maximal neutralization capacity of 25 μg bPL/mL of immunoglobulin. Interference of rabbit anti-bPL immunoglobulin with radioimmunoassay measurement using guinea pig anti-bPL as primary antibody was first evaluated in vitro. Polyclonal anti-bPL antibodies raised in rabbit were added in foetal sera to produce 100 samples with known antibodies titers (dilutions ranging from 1:2,500 till 1:1,280,000).

Result(s)

Assessment of the interference of rabbit anti-bPL antibody showed that bPL concentrations were significantly lower (P < 0.05) in samples added with dilutions of rabbit antiserum lower than 1:80,000 (one foetus) or 1:10,000 (four foetuses). It was also shown that the recovery of added bPL (12 ng/mL) was markedly reduced in those samples in which exogenous rabbit anti-bPL were added at dilutions lower than 1:20,000. Concentrations of foetal bPL were determined in samples from cannulated foetuses. In foetuses 1 and 6, bPL concentrations remained almost unchanged (<5 ng/mL) during the whole experimental period. In Foetus 3, bPL concentrations decreased immediately after IgG infusion and thereafter, they increased until parturition.

Conclusion(s)

The use of a bPL RIA using a guinea pig anti-bPL as primary antiserum allowed for the measurement of bPL concentrations in foetal plasma in presence of rabbit anti-bPL IgG into the foetal circulation. Long-term foetal catheterization allowed for the study of the influence of direct infusion of anti-bPL IgG on peripheral bPL concentrations in bovine foetuses.

Peripheral concentrations of inhibin A, ovarian steroids, and gonadotropins associated with follicular development throughout the estrous cycle of the sow

We investigated changes in peripheral concentrations of inhibin A, total inhibin, steroids, and gonadotropins throughout the intact estrous cycle of the sow in relation to ovarian changes determined by daily transrectal ultrasonography. All visible follicles of 3 mm or more in diameter were classified as small (≥3 and <6 mm) or large (≥6 mm). Follicular recruitment was identified in two periods of the cycle: one from the late luteal to the follicular phase, characterized by an increase in the number of small follicles followed by the appearance of large follicles; and another during the early luteal phase, consisting only of increased numbers of small follicles. Plasma concentrations of inhibin A increased (P<0.05), coinciding with the two periods of follicle emergence. Estradiol (E2) levels increased (P<0.05) during the follicular phase, but not during the early luteal phase. An inverse relationship (P<0.01) between the patterns of inhibin and FSH concentrations was noted around the two periods of follicle emergence, but there was no relationship (P≥0.1) between the patterns of plasma E2and FSH during the early luteal phase. In conclusion, measurement of plasma inhibin A levels combined with ultrasonographic examination of the ovaries revealed two periods of synchronous follicular growth during the sow's estrous cycle. The results strongly suggest that inhibin A functions as a negative feedback regulator of FSH secretion throughout the estrous cycle, whereas E2appears to influence FSH secretion only during the follicular phase.

The intermittent suckling regimen in pigs: consequences for reproductive performance of sows

Intermittent suckling (IS), a system in which the sow and the piglets are separated for a number of hours per day during lactation, is put forward as a system that can increase piglet welfare around weaning and also induce lactational oestrus. To be of practical use, IS regimes need to result in a predictable oestrus and good reproductive performance. This review describes the effects of IS on sow reproductive performance. During IS, the LH pulsatility pattern switches to a high frequency, low amplitude release during separation, as is normally observed at weaning. In sows that ovulate during IS, LH pulsatility remains higher than in anovulatory sows. Around 90% of the IS sows show follicle growth up to pre-ovulatory size in a similar time period as sows post-weaning. Depending on the stage of lactation that IS commenced, 13% (day 21) to 21% (day 14) of the sows with pre-ovulatory follicles did not ovulate, but follicles either regressed or developed into cystic follicles. In the ovulatory IS sows oestradiol production is comparable but the LH surge is lower with an early start of IS (day 14) when compared with the weaned sows. Continuation of IS post-ovulation has negative effects on pregnancy rate, embryo development and progesterone levels. Factors related to lactation (e.g. a high metabolic clearance rate), may play a role in this. In conclusion, IS can result in a fertile oestrus when the timing of start of IS and duration of IS are taken into account, but for practical use IS regimes result in a too variable reproductive performance.

Endocrine status and development of porcine testicular tissues in host mice

Clarification of the endocrine status of host mice provides us with basic knowledge with which we can manipulate the growth and function of xenografted testicular tissues. We investigated the hormonal profiles of castrated mice grafted with porcine immature testicular tissues from 30 to 210 or more days after grafting (day 0=castration and grafting). The serum follicle stimulating hormone (FSH) concentrations of the host mice declined (P<0.05) from day 60 compared with those of the castrated, ungrafted mice. The serum inhibin and testosterone levels were higher (P<0.05) than those in the castrated, ungrafted mice from days 30 and 90 days, respectively. The inhibin levels further increased (P<0.05) from day 90, during which time the levels were higher (P<0.05) than those in the intact male mice. In the grafts, formation of lumens occurred in the seminiferous cords on day 90 and spermatozoa appeared in the lumens from day 120. However, spermatogenesis in the grafts did not reach the qualitatively normal levels observed in adult boars. The intensity of the immune reaction to inhibin alpha subunits in the Sertoli cells of the grafts decreased with differentiation of the seminiferous tubules. The present findings indicate that a feedback loop was established between the mouse hypothalamo-pituitary axis and the grafted porcine tissues from 60 days post-grafting. The results also indicate that the serum inhibin levels in the host mice remained high even after the appearance of lumens in the seminiferous tubules of the grafted tissues; this is strikingly different to the situation in normal male animals, in which the serum inhibin levels decline at around the time of tubular differentiation. The lack of efferent ducts in the tubules of the grafted tissues probably caused the accumulation of inhibin to be released into the lumens, resulting in high concentrations of circulating inhibin. These high levels of inhibin may directly affect spermatogenic activity and suppress FSH secretion.

Production of inhibin A and inhibin B in boars: changes in testicular and circulating levels of dimeric inhibins and characterization of inhibin forms during testis growth

We investigated the production of inhibin in boars from the infantile to pubertal periods by: (1) measurement of testicular and circulating levels of inhibin, (2) characterization of inhibin forms and (3) localization of inhibin alpha subunits in the testis. Total inhibin levels in the testis increased until 8 weeks of age but then declined to much lower values at 15 weeks. Testicular inhibin A and inhibin B were high until 8 weeks. Circulating levels of total inhibin and inhibin A were also high until 8 weeks, then declined from 10 weeks; inhibin B was not detected, because of low sensitivity of the inhibin B assay. Analyses of inhibin A and inhibin B levels in the eluted fractions obtained from testes after immunoaffinity chromatography and SDS-PAGE showed the presence of a peak of approximately 45 kDa until 10 weeks of age. As the boars aged, the levels of inhibin A and inhibin B increased in the molecular weight region of 29-31 kDa. The fractions corresponding to 29 and 30 kDa suppressed FSH release from rat pituitary cells, but the 45 kDa fraction had no FSH-suppressing activity. Total amounts of inhibin A isolated from the SDS gels were similar to those of inhibin B until 10 weeks of age, but were three times higher than those of inhibin B between 15 and 25 weeks. Further fractionation by reverse phase high-performance liquid chromatography revealed that the 29-31 kDa immunoreactive material was composed of mature forms of inhibin A and inhibin B, in addition to a 26 kDa alpha monomer. Immunohistochemistry indicated that positive immunostaining for the alpha subunits was observed in Sertoli cells from the infantile to pubertal periods. Elongated spermatids also showed positive signals at age 25 weeks. These results clearly indicated that: (1) the boar testis has the ability to produce inhibin A and inhibin B during the infantile period but inhibin A is the predominant form towards puberty and (2) the molecular weight forms of inhibin and the sites of production of inhibin change with testicular development.

Negative Effect of Estradiol on Luteinizing Hormone Throughout the Ovulatory Luteinizing Hormone Surge in Mares1

The negative effect of estradiol-17beta (E2) on LH, based on exogenous E2 treatments, and the reciprocal effect of LH on endogenous E2, based on hCG treatments, were studied throughout the ovulatory follicular wave during a total of 103 equine estrous cycles in seven experiments. An initial study developed E2 treatment protocols that approximated physiologic E2 concentrations during the estrous cycle. On Day 13 (ovulation = Day 0), when basal concentrations of E2 and LH precede the ovulatory surges, exogenous E2 significantly depressed LH concentrations to below basal levels. Ablation of all follicles > or = 10 mm when the largest was > or =20 mm resulted in an increase in percentage change in LH concentration within 8 h that was greater (P < 0.03) than for controls or E2-treated/follicle-ablated mares. Significant decreases in LH occurred when E2 was given when the largest follicle was either > or =25 mm, > or =28 mm, > or =35 mm, or near ovulation. Treatment with 200 or 2000 IU of hCG did not affect E2 concentrations during the initial portion of the LH surge (largest follicle, > or =25 mm), but 2000 IU significantly depressed E2 concentrations before ovulation (largest follicle, > or =35 mm). Results indicated a continuous negative effect of E2 on LH throughout the ovulatory follicular wave and may be related to the long LH surge and the long follicular phase in mares. Results also indicated that a reciprocal negative effect of LH on E2 does not develop until the E2 surge reaches a peak.

Possible role of 5'AMP-activated protein kinase in the metformin-mediated arrest of bovine oocytes at the germinal vesicle stage during in vitro maturation

The 5'AMP-activated protein kinase (AMPK) activation is involved in the meiotic maturation of oocytes in the ovaries of mice and pigs. However, its effects on the oocyte appear to be species-specific. We investigated the patterns of AMPK and mitogen-activated protein kinases (MAPK3/1) phosphorylation during bovine in vitro maturation (IVM) and the effects of metformin, an AMPK activator, on oocyte maturation in cumulus-oocyte complexes (COCs) and denuded bovine oocytes (DOs). In bovine COCs, PRKAA Thr172 phosphorylation decreased, whereas MAPK3/1 phosphorylation increased in both oocytes and cumulus cells during IVM. Metformin (5 and 10 mM) arrested oocytes at the GV stage in COCs but not in DOs. In COCs, this arrest was associated with the inhibition of cumulus cell expansion, an increase in PRKAA Thr172 phosphorylation, and a decrease in MAPK3/1 phosphorylation in both oocytes and cumulus cells. However, the addition of compound C (10 muM), an inhibitor of AMPK, accelerated the initiation of the GV breakdown (GVBD) process without any alteration of MAPK3/1 phosphorylation in oocytes from bovine COCs. Metformin decreased AURKA and CCNB1 protein levels in oocytes. Moreover, after 1 h of IVM, metformin decreased RPS6 phosphorylation and increased EEF2 phosphorylation, suggesting that protein synthesis rates were lower in oocytes from metformin-treated COCs. Most oocytes were arrested after the GVBD stage following the treatment of COCs with the MEK inhibitor, U0126 (100 micromoles). Thus, in bovine COCs, metformin blocks meiotic progression at the GV stage, activates PRKAA, and inhibits MAPK3/1 phosphorylation in both the oocytes and cumulus cells during IVM. Moreover, cumulus cells were essential for the effects of metformin on bovine oocyte maturation, whereas MAPK3/1 phosphorylation was not.

Obligatory roles for follicle-stimulating hormone (FSH), estradiol and androgens in the induction of small polyfollicular ovarian cysts in hypophysectomized immature rats

Immature hypophysectomized (HYPOXD) rats develop large, polyfollicular ovarian cysts in response to unabated, combined stimulation by subovulatory doses of human chorionic gonadotropin (hCG) and highly purified ovine follicle-stimulating hormone (FSH). Further, circulating amounts of androstenedione (A4) and estradiol (E2), but not testosterone or dihydrotestosterone (DHT), change in parallel with the development of these cysts. To determine the potential roles of either A4 or E2 at the level of the ovary in the induction of ovarian cysts, pellets containing either (1) cholesterol (placebo; controls); (2) A4; or (3) E2 were administered subcutaneously (sc) to immature HYPOXD rats. Some of these animals also received either twice-daily sc injections of 1 IU hCG, or daily s.c. injections of 2 microg FSH, for 13 days. Ovaries and sera were harvested from all treatment groups on the morning of day 14 of the combined-hormone treatment schedule. As expected, ovaries from HYPOXD rats treated with placebo, A4, or E2 pellets (with or without hCG) failed to display antral follicles. Ovaries from HYPOXD rats treated with FSH and a placebo pellet displayed polyfollicular, atretic, small antral follicles with unstimulated thecal shells. In addition, the ovarian stromal-interstitial tissue had an unstimulated appearance. In contrast, ovaries from HYPOXD rats treated with FSH plus either A4 or E2 implants displayed stimulated stromal-interstitial tissue as well as small follicular cysts and precysts with stimulated thecal shells. The number of cysts and precysts observed in the largest ovarian cross-sections for animals treated with FSH + A4 (17.0 +/- 3.0) was less than that observed in the largest ovarian cross-sections for HYPOXD rats treated with FSH + E2 (40.2 +/- 10.1; p < 0.05). To determine if the development of ovarian cysts in response to FSH + A4 was due, at least in part, to the metabolism of A4 to E2, HYPOXD rats were treated with either (1) placebo pellets; (2) pellets containing dihydrotestosterone (DHT) which cannot be metabolized to estrogen; (3) E2 pellets plus DHT pellets (E2 + DHT); (4) FSH + DHT; or (5) FSH + E2 + DHT. The largest ovarian cross-sections from FSH + DHT-treated HYPOXD rats displayed 18.3 +/- 4.1 small follicles with a mean diameter of approximately 0.437 mm which possessed few granulosa cells. The thecal and stromal-interstitial tissues in these ovaries were unstimulated, which indicates that these small degenerating follicles were atretic rather than cystic. In contrast, the largest ovarian cross-sections from FSH + E2 + DHT-treated HYPOXD rats displayed 51.6 +/- 2.4 cysts with stimulated thecal shells and a mean diameter of approximately 0.634 mm. Further, these cysts were arranged in a "string of pearls" pattern and the ovarian stromal-interstitial tissue possessed a stimulated appearance. These data demonstrate a direct, unambiguous role at the level of the ovary for unabated tonic stimulation by FSH plus estrogen in the development of small polyfollicular cysts in HYPOXD rats. Further, the data also indicate that, at least in HYPOXD rats, combined, tonic stimulation by FSH plus estrogen and androgen is sufficient for the development of small, polyfollicular ovarian cysts in a "string of pearls" pattern. These observations are in distinct contrast to our previous observations that tonic stimulation by FSH + hCG results in the induction of large ovarian cysts in HYPOXD rats and provide tantalizing new insights regarding the potential importance of specific hormones at the level of the ovary in the induction of specific types of cystic follicles.

Changes in the Peripheral Concentrations of Inhibin, Follicle-Stimulating Hormone, Luteinizing Hormone, Progesterone and Estradiol-17.BETA. During Turnover of Cystic Follicles in Dairy Cows with Spontaneous Follicular Cysts

Several studies have clarified that the follicular cysts degenerate and are replaced by newly growing follicles that develop into new follicular cysts without ovulation, i.e., turnover of ovarian follicular cysts in cows. However, the relativity of endocrinological changes, including the inhibin profile during turnover of spontaneous follicular cysts in dairy cows, is still unclear. In the present study, the relationship between turnover of follicular cysts and changes in the peripheral blood concentrations of progesterone (P), estradiol-17beta (E(2)), luteinizing hormone (LH), follicle stimulating hormone (FSH) and inhibin were examined in lactating dairy cows. Five cows diagnosed with follicular cysts (follicles of more than 25 mm in diameter in the absence of a corpus luteum) were investigated. Their ovarian dynamics were monitored using ultrasonography, and blood samples were collected at 2- or 3- day intervals throughout the experiment. The day when a follicle fated to become a follicular cyst reached more than 8 mm in diameter was defined as the start of a cystic follicular wave. Four of the 5 cows exhibited a similar patterns of cystic follicular changes and hormone profiles. The data from the 4 cows was used for analysis of the relationships between turnover of cystic follicles and the hormone profiles. Two or three new cystic follicular waves occurred in each cow during the experimental period. The mean diameter of the cystic follicles was more than 25 mm 13 to 15 days after the start of the cystic follicular wave, and it began to decrease 1 to 6 days before the start of the subsequent cystic follicular wave. The levels of E(2) and inhibin tended to decrease for 7 to 9 days before the start of a new cystic follicular wave and to increase concomitantly with new follicular cyst growth. The levels of FSH rose for 1 to 3 days before the start of a new cystic follicular wave. The present study clarified the relationship between FSH and inhibin during turnover of spontaneous follicular cysts in dairy cows and found that it was very similar to previous results for cows. The present results suggest that an increase in FSH secretion following a reduction in inhibin secretion triggers turnover of cystic follicles in cows with spontaneous follicular cysts.

Effects of gonadotrophin treatments on meiotic and developmental competence of oocytes in porcine primordial follicles following xenografting to nude mice

Our objective was to improve the developmental ability of oocytes in porcine primordial follicles xenografted to nude mice, by treating the host mice with gonadotrophins to accelerate follicular growth. Ovarian tissues from 20-day-old piglets, in which most of the follicles were primordial, were transplanted under the kidney capsules of ovariectomized nude mice. Gonadotrophin treatments were commenced around 60 days after vaginal cornification in the mice. Ovarian grafts were obtained 2 or 3 days after treatment with equine chorionic gonadotrophin (eCG-2 and eCG-3 groups), after porcine FSH infusion for 7 or 14 days, or after infusion of porcine FSH for 14 days with a single injection of estradiol antiserum (FSH-7, FSH-14 and FSH-14EA groups, respectively). Gonadotrophin treatments accelerated follicular growth within the xenografts compared with that in control mice given no gonadotrophins, consistent with higher (P < 0.05) circulating inhibin levels in the gonadotrophin-treated mice. In contrast, circulating mouse FSH levels were significantly (P < 0.05) depressed. We recovered large numbers of full-sized oocytes with meiotic competence to the mature stage from the eCG-3, FSH-7, and FSH-14EA, unlike in the control group. Moreover, 56% of matured oocytes with the first polar body (n = 39) were fertilized in vitro in the FSH-14EA group. After in vitro fertilization and subsequent culture for 7 days, one blastocyst was obtained from each of the eCG-3, FSH-7 and, FSH-14EA groups, whereas no blastocysts appeared in the other groups. Exogenous gonadotrophins--not mouse FSH--stimulated the growing follicles that had developed from the primordial follicles in the xenografts: the effects were incomplete but improved to some extent the meiotic and developmental abilities of the oocytes.

Successful long term culture of immature porcine sertoli cells in the reconstructed testicular cell cord

The ultimate goal of this study was to establish an in vitro system to produce sperms. To pursue this goal, immature porcine testicular cells were cultured in stereostructural form and cultured testicular cord was investigated morphologically. At 4 weeks of age, the seminiferous tubules of the porcine testes consisted of undifferentiated germ cells (gonocytes and undifferentiated spermatogonia) and immature Sertoli cells. The interstitial tissue was largely occupied by Leydig cells. The testes were enzymatically digested, and the dispersed cells were encapsulated with alginate either immediately or after freeze-thawing. The resulting testicular cell cords were cultured for up to 10 weeks. After 2 weeks of culture, Sertoli cells, which were identified by their inhibin-positive reaction in immunohistochemistry, and Leydig cells, which were identified by their morphological characteristics, were observed in the cords. Neither undifferentiated nor differentiated types of germ cells were detected. The number of cells in the cords progressively decreased during the culture period. In order to discover the fate of the Sertoli cells, the level of inhibin in the spent media was determined. Inhibin in the media was at a detectable level after 2 days of culture. The levels increased and peaked at 2 weeks. When frozen-thawed testicular cells were applied to the culture, the peak level was maintained for over 8 weeks, in contrast to the gradual decrease of inhibin level when fresh cells were cultured. These results indicate that the culture conditions can sustain the survival of Sertoli cells. Further improvement is required for proliferation and differentiation of germ cells.

Formation of Follicular Cysts in Cattle and Therapeutic Effects of Controlled Internal Drug Release

Follicular cysts in cattle result from excessive growth of the dominant follicle without ovulation and still constitute a major reproductive disorder in this species. One key hormonal characteristic of cows with follicular cysts is the lack of an LH surge, although they have increased plasma estradiol concentrations. Another is a relatively high level of pulsatile secretion of LH that promotes continued growth of the dominant follicle. These LH characteristics seem to result from a functional abnormality in the feedback regulation of LH secretion by estradiol. Treatment with controlled internal drug release devices that increase circulating progesterone levels is effective in resolving follicular cystic conditions by 1) lowering pulsatile LH secretion and 2) restoring the ability of the hypothalamo-pituitary axis to generate an LH surge in response to an increase in circulating estradiol.

Changes in Circulating and Testicular Levels of Inhibin A and B During Postnatal Development in Bulls

We investigated testicular and circulating levels of dimeric inhibins in Holstein bulls from the infantile to postpubertal periods (5 to 50 weeks of age) and examined the relationship between the profiles of circulating dimeric inhibins and FSH. Concentrations of total inhibin and inhibin B in the testis were highest at 4 to 5 weeks of age but decreased gradually as the bulls aged. Testicular inhibin A levels showed a gradual decline to a nadir at 15 to 26 weeks of age, but by 39 weeks, they were high again. The contents of total inhibin, inhibin A, and inhibin B per testis generally increased with age. Fractionation of testicular homogenates obtained from 15-week-old bulls by a combination of immunoaffinity chromatography and SDS-PAGE confirmed the presence of two major molecular weight forms (32 and 45 kDa) of dimeric inhibins in the testes. Circulating levels of total inhibin and inhibin A showed a significant increase in bulls at around 10 to 14 weeks of age compared to the levels between 5 and 7 weeks of age but decreased thereafter. However, immunoreactivity for inhibin B was not detected in the peripheral circulation, probably because of low sensitivity of the inhibin B assays. The concentrations of plasma FSH were high at 5 weeks of age but declined to lower levels between 11 and 40 weeks, and then increased from 41 weeks onward. There was no significant correlation between the plasma levels of FSH and inhibin A or total inhibin. The results clearly indicate that the bull testis produces inhibin A and B and secretes at least inhibin A into the circulation during postnatal development. However, the profile of circulating FSH in bulls shows no reciprocal relationship with the inhibin A or total inhibin profile during the postnatal period.

Hormonal and Metabolic Profiles of High-yielding Dairy Cows Prior to Ovarian Cyst formation or First Ovulation Post Partum

The present study aimed to investigate the pathogenesis of cystic ovarian disease (COD) in high-yielding dairy cows postpartum (pp). Hormonal and metabolic profiles during the first 3 weeks pp as well as during the final week prior to ovulation/cyst formation, were compared between dairy cows that developed either an ovulatory follicle (OV) or a cyst (CYST) < day 60 pp. Thirty-four lactations of 28 high-yielding (9500 kg/305 days) Holstein-Friesian dairy cows were studied. Ovaries of cows were scanned twice a week from day 10 pp on, until ovulation/cyst formation. Milk yield data, body condition scores and blood samples, for determination of oestradiol-17beta, insulin, beta-OH-butyrate and non-esterified fatty acids, were collected simultaneously. Milk samples for progesterone analysis were collected daily. Four lactations were excluded from further analysis because of irregular pp ovarian cyclicity, excluding COD. Eight lactations (26.7%) developed a cyst, while 22 lactations ovulated < days 60 pp. Ovulation and cyst formation occurred at similar times pp. Metabolic and hormonal profiles did not differ between CYST and OV lactations during the first 3 weeks pp. In the final week prior to cyst formation/ovulation, insulin concentrations were lower in CYST than in OV lactations while no differences were observed for any of the other parameters tested. In two lactations, cyst formation was preceded by suprabasal progesterone and increased oestradiol-17beta concentrations. These results suggest that cyst formation in high-yielding dairy cows pp is associated with lower insulin levels but not with other distinct hormonal and metabolic alterations. However from this study, we cannot exclude the involvement of subtle hormonal and metabolic changes in the pathogenesis of ovarian cysts. Suprabasal progesterone, and altered oestradiol-17beta concentrations, seem to play a minor role in cyst formation.

Decreased gonadotropin-releasing hormone neuronal activity is associated with decreased fertility and dysregulation of food intake in the female GPR-4 transgenic rat

Expression of a cAMP-specific phosphodiesterase in GnRH neurons in the GPR-4 transgenic rat resulted in decreased LH levels and pulse frequency and diminished fertility. We have characterized changes in fertility, adiposity, and reproductive and metabolic hormones with age. Although LH levels were decreased in 3-, 6-, and 9-month-old GPR-4 females relative to wild-type (WT) controls, GPR-4 females did not become anovulatory until 6 months of age. No differences were observed in FSH, estradiol, or androstenedione levels in 3-, 6-, or 9-month-old GPR-4 and WT females. At 9 months of age, GPR-4 females had significantly increased abdominal and sc fat depot weights that were associated with increased leptin and insulin levels not observed in WT females. We tested the hypothesis that metabolic changes observed at 9 months of age were the result of dysregulation of the mechanisms controlling energy balance. Two-month-old female GPR-4 rats placed on a high-energy diet gained weight at a rate significantly greater than WT females and, after 24 d, developed the same metabolic phenotype observed in 9-month-old GRP-4 females (increased abdominal and sc fat associated with elevated leptin and insulin concentrations). Overeating did not correlate with changes in estradiol or androstenedione levels. We conclude that decreased GnRH neuronal activity is closely associated with decreased reproductive function and dysregulation of food intake.

Resynchronization of ovulation and timed insemination in lactating dairy cows

The objective was to compare pregnancy rates to resynchronization and timed AI (TAI) protocols in lactating dairy cows that received GnRH at 23 d and were diagnosed not pregnant at 30 d after the pre-enrollment AI. Nonpregnant cows (624) at ultrasonography on day 30 (study day 0) were classified as diestrus (74.8%), metestrus (5.6%) and without a CL (19.5%). Cows in diestrus were assigned either to the GnRH group (PGF2alpha on day 0, GnRH on day 2 and TAI 16 h later, n = 238) or the estradiol cypionate (ECP) group (PGF2alpha on day 0, ECP on day 1, and TAI 36 h later, n = 229). Cows in metestrus were assigned to the Modified Heatsynch Group (GnRH on day 0, PGF(2alpha) on day 7, ECP on day 8 and TAI on day 9, n = 35). Cows without a CL (n = 122) were classified either as proestrus (10.6%), ovarian cysts (7.5%) or anestrus (1.4%), and assigned to factorial treatments (i.e., use of GnRH versus CIDR) to either the GnRH group (GnRH on day 0, PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 28), the CIDR group (CIDR insert from days 0 to 7, PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 34), the GnRH + CIDR group (GnRH on day 0, CIDR insert from days 0 to 7, PGF2alpha on day 7, GnRH on day 9 and TAI 16h later, n = 32), and the control group (PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 28). For cows without a CL, plasma P4 concentrations were determined on days 0, 7, 10 and 17 and ovarian structures determined on days 0, 7 and 17. Pregnancy rates were evaluated at 30, 55 and 90 d after the resynchronized AI. For cows in diestrus, there were no differences in pregnancy rates on days 30, 55 and 90 for cows in the GnRH (27.5, 26.5 and 24.2%) or ECP (29.1, 25.5 and 24.1%) groups. In addition, there were no differences in pregnancy losses between days 30 and 55 and 55 and 90 between the GnRH (7.0 and 8.6%) and ECP (9.8 and 5.4%) groups. For cows without a CL, GnRH on day 0 increased the proportion of cows with a CL on days 7 and 17 and plasma P4 concentration on day 17 in cows with ovarian cysts but not for cows in proestrus. The CIDR insert increased pregnancy rate in cows with ovarian cysts but reduced pregnancy rate for cows in proestrus.

Resynchronization of ovulation and timed insemination in lactating dairy cows

The objective was to compare pregnancy rates and pregnancy losses in lactating dairy cows that were diagnosed not pregnant and re-inseminated following either the Ovsynch or Heatsynch protocols. Also evaluated were the effects of stages of the estrous cycle, ovarian cysts and anestrus on pregnancy rates for both treatments. Non-pregnant cows (n = 332) as determined by ultrasonography on day 27 post-AI (study day 0) were divided into two groups. Cows in the Ovsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, GnRH on day 9, and timed AI (TAI) 16 h later (day 10). Cows in the Heatsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, estradiol cypionate (ECP) on day 8, and TAI 48 h later (day 10). Cows detected in estrus on days 8 and 9 were inseminated and included in the study. On day 0, cows were classified according to different stages of the estrous cycle, or presence of ovarian cysts or anestrus. Pregnancy rates were evaluated 27, 45 and 90 days after resynchronized AI. Overall, there was no difference in pregnancy rates on days 27, 45 and 90 between cows in the Ovsynch (25.2, 17.5, and 13.9%) and Heatsynch (25.8, 19.9, and 16.1%) groups. There was no difference in pregnancy losses from days 27 to 45 and days 45 to 90 for cows in the Ovsynch (25.0 and 17.9%) and Heatsynch (14.7 and 10.3%) groups. However, pregnancy rates were increased when cows in metestrus were subjected to the Heatsynch protocol and cows with ovarian cysts were subjected to the Ovsynch protocol.

A preclinical pharmacokinetic/pharmacodynamic approach to determine a dose of GnRH, for treatment of ovarian follicular cyst in cattle

The objective of this study was to explore the value of a preclinical PK/PD approach to determine a gonadotropin-releasing hormone (GnRH) dose in cows using the pituitary LH response as a surrogate endpoint. Using an indirect effect model with stimulation of the LH entry rate, the in vivo basic pharmacodynamic parameters of GnRH were determined. The EC(50) of GnRH was 51 +/- 16 pg/mL, the EC(50) being the GnRH plasma concentration able to produce 50% of the maximum possible stimulation (S(max)) of the hypophysis (S(max) = 48 +/- 13). From individual PK/PD parameters, the ED(50) of GnRH, i.e. the estimated dose of GnRH required to determine half the maximum possible stimulating effect on LH release, was calculated to 62 microg/h per cow. Using the PK/PD model, the GnRH dose required to achieve a selected breakpoint value of 5 ng/mL for maximum LH concentration (surrogate value for LH concentration predicting clinical efficacy for cystic conditions), was 52 +/- 18 microg and for a standard GnRH dose of 100 microg, the mean maximum plasma LH concentration predicted by the model was 7.22 +/- 0.98 ng/mL.

Plasma concentrations of inhibin A in cattle with follicular cysts: relationships with turnover of follicular waves and plasma levels of gonadotropins and steroid hormones

We investigated the profiles of circulating levels of inhibin A and total inhibin in beef cows with follicular cysts in relation to the patterns of follicular development and circulating gonadotropins and steroid hormones. Turnover of follicular waves was monitored in five cows every 2 days for 70 days from 10 days after detection of estrus without ovulation. The mean interwave intervals were 19.6 +/- 1.0 days (n = 18 waves with cysts from the five cows). Circulating levels of inhibin A were approximately 170 pg/ml before emergence of follicular waves with cysts and increased (P < 0.05) concomitantly with follicle emergence. High concentrations of inhibin A (greater than 300 pg/ml) were noted for 7 days during the growth phase of cystic follicles, but inhibin A levels decreased gradually when development of the cysts reached a plateau. This profile of inhibin A was similar to those of total inhibin and estradiol, but was inversely related to the changes in plasma FSH concentrations. LH pulse frequency and mean concentrations of LH in cows with cysts were higher than those observed in the luteal phase of normal cyclic cows. These results indicate that the capacity to secrete inhibin, as well as estradiol, is maintained in cystic follicles, the growth of which is extended by LH secretion at levels greater than those seen in the normal luteal phase. Inhibin A plays an important role in the extension of interwave intervals by suppressing recruitment of a new cohort of follicles.

The postpartum uterus

The cow is notable among the domestic species for the almost ubiquitous bacterial contamination of the uterine lumen after parturition and the high incidence of clinical uterine disease. Such uterine disease not only disrupts uterine tissues, but also ovarian follicle growth and function by perturbation of the hypothalamus, pituitary, and ovary. Other events such as the postpartum negative energy balance also have similar multilevel effects on postpartum endocrinology. Return of ovarian cyclical activity is dependent on the innate immune system resolving uterine bacterial contamination,prompt uterine involution, and a short interval to the negative energy balance nadir. Although the risk factors for uterine disease have been described, preventive strategies are not widely adopted. Thus, veterinarians must identify and treat uterine disease efficiently to limit their negative effect on fertility.

Transrectal ultrasonic diagnosis of ovarian follicular cysts in goats and treatment with GnRH

Cystic ovarian disease is an important cause of reproductive failure. The objective of this study was to evaluate transrectal ultrasonography as a diagnostic tool and gonadotropin-releasing hormone (GnRH) as a therapeutic approach for ovarian follicular cysts in goats. Goats were considered to have a follicular cyst(s) if a non-echoic structure >10 mm in diameter was detected in the absence of corpora lutea (CL) in three ultrasonic examinations performed at 5-day intervals. After diagnosis (Day 0), goats with ovarian follicular cysts (n = 5) were treated with a single bolus injection of 10.5 microg synthetic GnRH followed by administration of 125 microg prostaglandin F2alpha (PGF2alpha) 10 days later. Five blood samples were collected at 5-day intervals for determination of progesterone and estradiol-17beta. For detection of LH surge, blood samples were collected every 2 h. Ovulation rate was determined and pregnancy was confirmed by transrectal ultrasonography. The results showed that transrectal ultrasonography is reliable for diagnosis of ovarian follicular cysts and the mean diameter of the follicular cysts was 12.6 +/- 0.4 mm. Plasma concentrations of progesterone and estradiol-17beta at the time of diagnosis of follicular cysts (Day 0) were 0.7 +/- 0.2 ng/ml and 12.7 +/- 0.9 pg/ml, respectively. The concentration of progesterone increased to 4.0 +/- 0.5 ng/ml 10 days after administration of GnRH indicating luteinization of the ovarian follicular cysts concomitant with a decrease in the concentration of estradiol-17beta (3.5 +/- 0.4 pg/ml). Administration of GnRH to cystic goats resulted in a surge of LH within 2 h of treatment. The interval from PGF2alpha injection to the preovulatory LH surge was 62.8 +/- 1.4 h. All goats exhibited estrus 55.2 +/- 2.3 h after PGF2alpha injection and four goats out of the five ovulated. The ovulation rate was 1.5 +/- 0.3. In conclusion, results of this study suggest that transrectal ultrasonography is a reliable tool for diagnosis of ovarian follicular cysts. In addition, GnRH can be used to effectively treat ovarian follicular cysts in goats with 80% success rate.

Retrospective Analysis of the Efficacy of Controlled Internal Drug Release in Follicular Cysts in an Embryo Donor Beef Herd

We investigated the efficacy of a controlled internal drug release (CIDR) device in the reproductive management of an embryo donor beef herd. Superovulation of embryo donors was routinely induced by a combination of FSH and prostaglandin F(2)alpha analogue (PGF(2)alpha) at intervals of a few months, and after embryo recovery estrus of the donors was synchronized with PGF2(2)alpha. Between 1996 and 1998, approximately 20% of donors were diagnosed as having follicular cysts every year. Twenty-eight cases of follicular cysts recorded between 1997 and 1998 were treated with a CIDR device for 14 days to evaluate the efficacy of CIDR in resolving follicular cysts in donor herds. Initial recovery was defined as the occurrence of ovulation with estrous behavior and subsequent formation of a corpus luteum after removal of the CIDR. Initial recovery was recognized in all cases (n=28). Follicular cysts did not recur after repeated embryo recovery in 64% of the initially recovered donors, but in 36% of affected donors cysts recurred after the next embryo recovery. Subsequently, with a CIDR device instead of PGF(2)alpha, we synchronized estrus after embryo recovery in the same herd from 1999 to 2000, to investigate the ability of CIDR to prevent the initiation of follicular cysts. Of the donors used between 1999 and 2000, approximately 30% had a history of follicular cysts. Use of CIDR for estrous synchronization after embryo recovery lowered the incidence of follicular cysts to 3% in 1999 and 0% in 2000. Treatment with CIDR proved effective at resolving follicular cysts in the embryo donor beef herd and enabled re-use of donors affected with follicular cysts. CIDR is also likely to be efficacious in lowering the occurrence of follicular cysts in donor herds when it is used for estrous synchronization after embryo recovery.

Maturation and fertilization of porcine oocytes from primordial follicles by a combination of xenografting and in vitro culture

Our objective was to develop a method of endowing oocytes from porcine primordial follicles with full maturation and fertilizing ability as a model for ovarian xenografting of large mammals. Ovarian tissues from 20-day-old piglets, in which most of the follicles were primordial, were transplanted under the capsules of both kidneys of ovariectomized athymic mice. The host mice were treated with 5 IU of equine chorionic gonadotropin (eCG) for 10 days (eCG-10), 30 days (eCG-30), or 60 days (eCG-60) after detection of cornified epithelial cells in their vaginal smears. Cumulus-oocyte complexes, ovarian grafts, and blood samples were obtained 48 h after eCG treatment. Forty-five to 70 days after grafting, the host mice in all groups for the first time showed vaginal cornification, accompanied by the formation of a small number of antral follicles in the grafts. However, we recovered large numbers of full-sized oocytes only from mice in the eCG-60 group; the numbers of full-sized oocytes in the other groups were low. Peripheral levels of total inhibin were highest in the eCG-60 group; this supports our finding that the most enhanced growth of antral follicles occurred in this eCG-60 group. Of 573 oocytes obtained from the eCG-60 group, 98 (17%) were at the metaphase II stage after in vitro culture for maturation. Moreover, 55% of matured oocytes with the first polar body (n = 20) were fertilized in vitro. These results clearly demonstrate that fertilization of oocytes from porcine primordial follicles is achievable by a combination of xenografting and in vitro culture.

Molecular weight forms of inhibin a and inhibin B in the bovine testis change with age

To investigate alterations in the molecular weight forms of inhibin in bull testis from the infantile (4-5 wk of age) to postpubertal (49-56 wk of age) periods, testicular homogenates were obtained from animals of various ages and fractionated by a combination of immunoaffinity chromatography and SDS-PAGE. Subsequently, the fractions eluted from the SDS gels were assayed for total inhibin, inhibin A, and inhibin B by fluoroimmunoassay or immunofluorometric assays (IFMAs) and for inhibin bioactivity by an in vitro bioassay. The molecular mass patterns of inhibin A and inhibin B in the testis, as determined by the dimer-specific IFMAs, showed the presence of a peak of approximate 47 kDa until 21-26 wk of age. However, the peak disappeared after 31-32 wk of age. As bulls aged, especially after 31-32 wk of age, inhibin A and inhibin B levels increased in the molecular mass region of 27-34 kDa. Total inhibin showed two peaks, of between 20 and 26 kDa and at approximately 47 kDa, until 21-26 wk of age and a single peak between 20 and 30 kDa after 31-32 wk of age. The eluted fractions corresponding to 29, 31, or 47 kDa gave a dose-response curve that was parallel to the curve generated with 32-kDa inhibin A or 29-kDa inhibin B standard in the IFMA for inhibin A or inhibin B. The fractions corresponding to 29 and 31 kDa suppressed basal release of FSH from rat pituitary cells, but the 47-kDa fraction had a lower FSH-suppressing activity. In the testes of older bulls, immunoblot analysis revealed the presence of a 29-kDa band cross-reacting with inhibin alpha and inhibin betaB antibodies and of a 31-kDa band cross-reacting with inhibin alpha and inhibin betaA antibodies. The 47-kDa band was recognized by the alpha, betaA, and betaB antibodies. Immunohistochemisty of the testis at each age showed that inhibin alpha subunits were found exclusively in Sertoli cells, but the intensity of immunostaining diminished in older bulls, in parallel with the decrease in the testicular concentrations of total inhibin. We conclude that 1) bovine Sertoli cells produce both inhibin A and inhibin B, 2) inhibin production in Sertoli cells during the prepubertal period is characterized by the 47 kDa inhibin-related material that contains precursor forms of inhibin A and inhibin B, and 3) the proportion of the mature forms of inhibin A and inhibin B increases as bulls age, although total inhibin production in Setroli cells decreases.