Changes in ovarian follicles following acute infection with bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) has been associated with several reproductive problems in cattle, including poor fertility, early embryonic deaths, abortion and congenital anomalies. Little is known about the cause of poor fertility in cows acutely infected with BVDV. The purpose of this study was to identify changes in ovarian function following acute infection with noncytopathic BVDV. The ovaries of 5 BVDV sero-negative and virus-negative pubertal heifers were monitored daily for 4 consecutive estrous cycles. The position and diameter of all follicles (> 5 mm) and luteal structures were recorded. Daily plasma samples were collected to measure peripheral progesterone and estradiol levels. Each heifer was infected intranasally with noncytopathic BVDV following ovulation of the second estrous cycle. The maximum diameter and growth rate of dominant anovulatory and ovulatory follicles were significantly reduced following acute BVDV infection. Similarly, the number of subordinate follicles associated with both the anovulatory and ovulatory follicle was reduced following infection. There were no significant differences in other follicle or luteal dynamic parameters or in peripheral progesterone or estradiol levels. Ovarian follicular growth was different during the first 2 estrous cycles following acute infection with BVDV when compared with the 2 estrous cycles preceding infection. These differences may be important in explaining reduced fertility in herds with acute BVDV infection.     

Variability of ovarian structures and plasma progesterone profiles in dairy cows with ovarian cysts

Weekly reproductive health examinations were performed on 46 multiparous Holstein cows from 14 to 100 d post partum. Sixteen cows developed 19 nonsimultaneous ovarian cysts, with a mean day of first detection at 34.3 +/- 4.5 d post partum and a mean duration of 31.0 +/- 4.3 d after first detection. Coccygeal blood was collected three times weekly, and plasma progesterone concentrations were determined by radioimmunoassay. Cysts were diagnosed by palpation per rectum or by ultrasonography and classified as follicular or luteal cysts; the cows were not treated. Cows with a mean plasma progesterone concentration of < 1 ng/ml from the first day of detection (Day 1) of a cyst until Day 10 were classified as having a follicular cyst, and those with a mean plasma progesterone concentration of >/= 1 ng/ml from Day 1 to Day 10 were classified as having a luteal cyst. According to this classification, 58% of the cysts were follicular and 42% were luteal. There was an overall 47% agreement between classification by palpation and by ultrasonography on Day 1 with progesterone concentration during Days 1 to 10 after detection of the cyst. Detailed graphs of progesterone concentrations and area of largest follicles or cysts and corpora lutea demonstrate the variability of ovarian structures and progesterone profiles in cystic cows. Detection of a cyst at any one time accompanied by simultaneous measurement of progesterone can lead to different diagnoses of cyst type depending on the method of classification, the presence and age of luteinized tissue in the cyst and undetected corpora lutea.     

Effects of hyperadrenal states on luteinizing hormone in cattle

The effect of an induced hyperadrenal state on luteinizing hormone (LH) secretion and subsequent ovarian function was examined in both intact and adrenalectomized (ADRX) heifers. Treatments were begun on Day 2 or Day 16 of an estrous cycle in order to examine their effect on corpus luteum development or ovulation, respectively. In Experiment I, continuous intravenous infusion of ACTH (1.0 mg/24 h) to intact heifers decreased LH concentrations during the early phase of the cycle (Days 3-5). Treatment of ADRX heifers with hydrocortisone succinate (HS) (100 mg/24 h) did not appear to change mean LH concentrations, although da Rosa and Wagner (1981) have reported reduced plasma concentrations of progesterone at mid-cycle in these ACTH-treated intact heifers and HS-treated ADRX heifers. ACTH treatment of ADRX heifers had no effect on LH or progesterone. In the second study, there were similar frequencies of LH surges at the anticipated time of ovulation in all treatment groups. HS (100 mg/24 h) in ADRX heifers and ACTH (0.5 mg/24 h) in intact heifers was given continuously beginning on Day 16 of an estrous cycle. Although some animals in all groups exhibited LH surges, the ACTH-treated intact and HS-treated ADRX heifers failed to show a consistent subsequent increase in progesterone concentrations in plasma, suggesting a failure of luteal development. Although no difference was seen in baseline concentrations of LH, there was a greater difference between basal and overall mean LH concentrations in control groups than was observed in ACTH- or HS-treated animals. These induced hyperadrenal states resulted in depression of ovarian function as shown by decreased plasma progesterone during the luteal phase of the cycle. It is not known if other noncorticoid steroids from the adrenal cortex are necessary for a full expression of this effect.     

Suppression of luteal estradiol receptors and progesterone synthesis by a gonadotropin-releasing hormone agonist (WY-40972) during midgestation

Our recent studies demonstrated that the continuous administration of a gonadotropin-releasing hormone agonist (GnRH-Ag: WY-40972) in early pregnancy or midpregnancy induces abortion in rats by suppressing the plasma levels of progesterone (P) within 24 h. This fall in P levels is not accompanied by a fall in ovarian vein plasma testosterone (T) or estradiol (E). To determine whether the suppression of P by GnRH-Ag at midpregnancy is due to decreased E present in the corpora lutea (CL) and/or a decrease in luteal receptors of E, rats were treated continuously on Days 11-14 of pregnancy with 5 micrograms/day of GnRH-Ag delivered by an osmotic minipump. Ovarian blood samples were obtained on Day 12; at autopsy, CL were harvested and incubated with Medium 199 for 4 h at 37 degrees C under an atmosphere of 95% O2:5% CO2. Additional rats were killed on Day 12 or 14; CL were isolated from the ovary and pooled within the group for measurement of nuclear and cytosolic E receptors. While the net synthesis of P by CL in the GnRH-Ag-treated rats decreased to 40 +/- 14 from 138 +/- 54 ng/CL in controls, T and E levels were not different from their respective controls. Steroid levels in the ovarian vein plasma reflected a similar response. Nuclear E receptors levels were 211 and 198 in controls and 62 and 61 fmoles/mg DNA in the treated group on Days 12 and 14, respectively. These results suggest that GnRH-Ag has no effect on the ability of the luteal synthesis of T and E and that the anti-pregnancy effect of GnRH-Ag may be at the level of the CL due to the direct inhibitory effect of GnRH-Ag on the luteal synthesis of P which, in turn, results in a fall in E receptors in the CL. Alternatively, GnRH-Ag treatment could suppress luteal receptors for rat placental lactogen that, in turn, lower luteal E receptors, leading to a fall in luteal synthesis and release of P.     

Identification of neutralizing and nonneutralizing epitopes in the porcine reproductive and respiratory syndrome virus GP5 ectodomain

After infection of swine with porcine reproductive and respiratory syndrome virus (PRRSV), there is a rapid rise of PRRSV-specific nonneutralizing antibodies (NNA), while neutralizing antibodies (NA) are detectable not sooner than 3 weeks later. To characterize neutralizing epitopes, we selected phages from a 12-mer phage display library using anti-PRRSV neutralizing monoclonal antibody (MAb) ISU25-C1. In addition, phages carrying peptides recognized by swine antibodies with high seroneutralizing titer were isolated after subtracting from the library those clones binding to swine anti-PRRSV serum with no neutralizing activity. Two epitopes located in the ectodomain of PRRSV GP5 were identified. One of these epitopes, which we named epitope B, was recognized both by neutralizing MAb ISU25-C1 and swine neutralizing serum (NS) but not by swine nonneutralizing serum (NNS), indicating that it is a neutralizing epitope. Epitope B is sequential, conserved among isolates, and not immunodominant. Antibodies directed against it are detected in serum late after infection. In contrast, the other epitope, which we named epitope A, is hypervariable and immunodominant. Antibodies against it appear early after infection with PRRSV. This epitope is recognized by swine NNA but is not recognized by either neutralizing MAb ISU25-C1 or swine NA, indicating that it is not involved in PRRSV neutralization. During infection with PRRSV, epitope A may act as a decoy, eliciting most of the antibodies directed to GP5 and delaying the induction of NA against epitope B for at least 3 weeks. These results are relevant to the design of vaccines against PRRSV.     

Effects of arterial infusions of adrenalin and acetylcholine on luteal secretion of progesterone and oxytocin in goats

The effects of close intra-arterial infusion of acetylcholine and adrenalin on ovarian secretion of progesterone and oxytocin were examined on Day 10 of the estrous cycle in goats (estrus = Day 0). Acetylcholine (15 micrograms/min) was without effect, but adrenalin (10 micrograms/min) significantly (P < 0.001) raised both progesterone and oxytocin concentrations in ovarian vein plasma. These results show that luteal hormone secretion is enhanced in the goat by beta-adrenergic stimulation and suggest that, as in the sheep and cow, there may be neuroendocrine involvement in the regulation of caprine luteal function.     

Direct effect of prolactin, induced by TRH injection, on ovarian oestradiol secretion in the ewe

The effect of sustained high plasma levels of prolactin, induced by repeated 2-h i.v. injections of thyrotrophin-releasing hormone (TRH; 20 micrograms), on ovarian oestradiol secretion and plasma levels of LH and FSH was investigated during the preovulatory period in the ewe. Plasma levels of progesterone declined at the same rate after prostaglandin-induced luteal regression in control and TRH-treated ewes. However, TRH treatment resulted in a significant increase in plasma levels of LH and FSH compared to controls from 12 h after luteal regression until 5 to 6 h before the start of the preovulatory surge of LH. In spite of this, and a similar increase in pulse frequency of LH in control and TRH-treated ewes, ovarian oestradiol secretion was significantly suppressed in TRH-treated ewes compared to that in control ewes. The preovulatory surge of LH and FSH, the second FSH peak and subsequent luteal function in terms of plasma levels of progesterone were not significantly different between control and TRH-treated ewes. These results show that TRH treatment, presumably by maintaining elevated plasma levels of prolactin, results in suppression of oestradiol secretion by a direct effect on the ovary in the ewe.     

猪繁殖与呼吸综合征病毒分子生物学研究进展

猪繁殖与呼吸综合征病毒(PRRSV)是严重危害养猪业的病原,对PRRSV的分子生物学研究进展进行了综述,主要包括PRRSV的基因组结构、病毒的非结构蛋白和结构蛋白及其功能、致病机理及复制与转录等.     

Investigation of wild boar (Sus scrofa) for porcine reproductive and respiratory syndrome in some territories of Russia

Samples of blood sera and internal organs were collected from 90 shot wild boars (Sus scrofa) in five regions of Russian Federation. Blood sera were tested for antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) using enzyme-linked immunosorbent assay (ELISA). In addition, samples of internal organs (lungs, lymph nodes, spleen) were tested by polymerase chain reaction (nested PCR) for PRRSV antigen. The result of our investigation showed that all samples were negative. However, PRRSV is widespread in domestic swine throughout Russia including the examined regions. Since the results show the absence of PRRSV infection in wild boars in the five examined regions of Russia, wild boars seem not to play any role in the epidemiology of PRRSV in Russia.     

Reproductive seasonality in female Iberian red deer (Cervus elaphus hispanicus)

This study characterized the seasonal pattern of luteal cyclicity in Iberian red deer (n=16), by measuring plasma progesterone concentrations in hinds (female red deer) twice per week from calving (May and June) 1996 until May 1997. In eight of these hinds we also examined plasma prolactin profiles to assess seasonal responses to photoperiod. Plasma progesterone concentration in the 16 hinds studied indicated that the reproductive pattern is seasonal, and lasts for 5.73 +/- 0.27 months. After calving, progesterone levels remained basal (no luteal activity) for several months, except in a hind that lost her calf just after calving, and thus did not have to suckle it. This hind showed two consecutive estrus cycles in the month following calving, which suggests that suckling has an inhibiting effect on the resumption of ovarian activity. These results also showed that as long as the hinds do not become pregnant, they show between 5 and 10 estrus cycles per reproductive season (8.06 +/- 0.35), ranging between 105 and 249 days from onset of the first cycle to end of the last one. Uninterrupted cycling lasted for 3.5-6.4 months (mean, 4.6 +/- 0.24). Cyclic luteal activity was found from October to February in all hinds, with a smaller, but notable proportion in September (56.25%) and March (68.8%), whereas it was negligible in the remaining period. Our results show a reproductive season similar to or longer than that recorded by other authors. Prolactin plasma concentrations showed a yearly trend following that of photoperiod, with peak concentrations from April to July, a decrease in August, minimal concentrations from September to February and a sharp increase in March.     

Endocrine monitoring of the ovarian cycle and pregnancy in the saddle-back tamarin (Saguinus fuscicollis) by measurement of steroid conjugates in urine

Direct measurements of urinary immunoreactive estrone conjugates (E1C) and pregnanediol glucuronide (PdG), were applied to monitoring the ovarian cycle (n = 9) and pregnancy (3 full term pregnancies, 2 mid-term abortions) in Saguinus fuscicollis. During the ovarian cycle, urinary E1C concentrations revealed a high degree of day-to-day variability and appeared to be uninformative in reflecting cyclic ovarian function. In contrast, PdG was a reliable indicator of ovarian cyclicity with excretion patterns corresponding well with plasma progesterone profiles. Luteal phase PdG concentrations were on average 4–7–fold higher than corresponding follicular phase values. On the basis of changes in circulating progesterone, a mean cycle length of 25.7 ±1.0 days with an average follicular phase of 7.1 ± 0.6 days and a mean luteal phase of 18.6 ± 0.7 days, was found (n = 14 cycles). Following conception, both urinary steroid conjugate concentrations increased and elevated levels were maintained beyond the normal luteal phase length, allowing pregnancy to be determined at around day 25–30. During mid- to late pregnancy, PdG levels declined while E1C concentrations continued to be elevated until approximately 6 weeks before parturition when a decrease occurred. Both hormones showed a clear and rapid fall to follicular phase values following termination of pregnancy at either parturition or mid-term abortion. Post partum ovulations (n = 5) occurred on average 17–18 days following birth with four ovulations leading to conceptions. The results demonstrate the potential of urinary steroid conjugate analysis as a practical and reliable method for non-invasive monitoring of reproductive status in the female saddle-back tamarin. © 1995 Wiley-Liss, Inc.     

Assessment of possible luteolytic effect on intra-ovarian injection of prostaglandin F-2ALPHA in the human.

A group of five patients awaiting laparoscopic tubal diathermy were followed by daily assay of luteinising hormone (LH) and progesterone. Between five and eight days after the LH peak, prostaglandin F-2ALPHA (PGF-2ALPHA) was injected into either the corpus luteum or the ovarian stroma. Doses of 100 mu-g into the corpus tuteum, 1000 mu-g into the adjacent stroma and 500 mu-g into an indeterminate ovarian structure had no effect on peripheral plasma progesterone levels or uterine bleeding. An injection of 500 mu-g or 1000 mu-g given unequivocally into the corpus luteum produced a rapid and profound fall in plasma progesterone levels, the nadir coinciding with the onset of uterine bleeding which commenced 24 hours after the injection and persisted for more than seven days. Injection of 100 mu-g in the same volume of saline had no such effect. Despite continued bleeding plasma progesterone levels returned to normal luteal levels for three days and then fell again.     

Cellular localization of ovarian proopiomelanocortin messenger RNA during follicular and luteal development in the rat

Opioid peptides are expressed in the reproductive system and have been reported to regulate reproductive function. The present study used in situ hybridization to selectively localize ovarian cells containing high levels of proopiomelanocortin (POMC) mRNA, an opioid precursor, during different stages of ovarian development. Prepubertal rats were primed with PMSG to stimulate follicular development, followed by hCG to induce ovulation. Treatment groups consisted of control (no treatment), PMSG (2 days post-PMSG), 1 day corpus luteum (CL; 1 day post-hCG), and 8 day CL (8 days post-hCG). POMC mRNA-containing cells were present in antral follicles, CL, and the interstitial compartment. With gonadotropin treatment, the percentage of follicles containing heavily labeled cells increased in the PMSG and 1 day CL groups. The number of POMC mRNA-containing cells per follicle also increased in the 1 day CL group. In the CL, no difference was observed in the percentage of CL exhibiting labeled cells between the 1 day CL and 8 day CL groups; however, more labeled luteal cells per CL were present in the 1 day CL group. A marked increase in POMC mRNA-containing cells was observed in the interstitial compartment of the 1 day CL group. These results indicate that the number of POMC mRNA-containing cells increases with follicular development and CL formation; however, the ovarian distribution suggests that the labeled cells could be nonendocrine cells, possibly white blood cells. The in situ hybridization findings are indicative of low total concentrations of ovarian POMC mRNA, suggesting mainly an autocrine or paracrine role for POMC or POMC-derived peptides.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum LH,progesterone and estradiol-17β levels throughout the ovarian cycle,during the early stage of pregnancy and after the parturition and the abortion in the common marmoset,Callithrix jacchus

In the ovarian cycle of common marmosets, serum progesterone began to increase at two to three days after estradiol-17β or LH surge, attained a peak of 25–70 ng/ml and then declined to a level of under 2 ng/ml before the ensuing rise in estradiol-17β and LH. Serum estradiol-17β increased to 700–5,500 pg/ml during the luteal phase, synchronizing with progesterone. It is suggested that the corpus luteum secreted estradiol-17β as well as progesterone. The cycle length as determined from the interval between successive LH surges was approximately 28 days. During the luteal phase, the levels of progesterone and estradiol-17β were higher than in Old World monkeys and women, but marmosets were not accompanied by any clinical symptoms due to excessive progesterone and estradiol-17β. This suggests that such unresponsiveness to progesterone and estradiol-17β in marmosets reflects the small amount of estradiol-17β receptor and presumably also the lower function of the post receptor system. Recovery of the post-partum ovarian cycle in two marmosets differed from that observed in Old World monkeys and women. The first LH surge was found on the ninth and tenth day after parturition and the first ovulation led to the next pregnancy. This suggests that the suckling stimulus of newborns in the common marmoset does not cause any delay in recovery of the ovarian cycle. In three cases of abortion, the recovery of the ovarian cycle was almost the same as that in the case of normal parturition: the first LH surge appeared on the 10th, 14th, and 34th day after abortion.     

Leptin in the bovine corpus luteum: receptor expression and effects on progesterone production

In cattle, leptin has been implicated in the control of ovarian function and has been shown to modulate steroid production by theca and granulosa cells in a number of species. However, a direct effect of leptin on bovine luteal function has not been demonstrated. This study was conducted to determine if the leptin receptor (OB-R) is expressed in the bovine corpus luteum (CL), and to examine the effects of leptin on progesterone production by dispersed luteal cells in vitro. RT-PCR was used to detect the presence of OB-R and, more specifically, the long, biologically active isoform (OB-Rb), in CL, collected on days 2-18 of the oestrous cycle (n=18). The effects of leptin on progesterone production were investigated in dispersed luteal cells prepared from CL collected on days 5 and 8 (n=14) of the cycle. The dispersed luteal cells were cultured for 24 hr with recombinant human leptin and/or LR3-IGF-1 and/or LH. OB-Rs, in particular, OB-Rb, were expressed in the CL at all stages of development. Progesterone production by luteal cells was increased (P<0.001) by treatment with LH (10 ng/ml) but treatment with leptin alone had no effect. However, in the presence of IGF-1 (100 ng/ml), leptin (10 ng/ml) caused a significant (P<0.005) increase in progesterone production. In conclusion, we have shown that the leptin receptor is expressed in the bovine CL and have demonstrated a modulatory effect of leptin on luteal progesterone production in vitro.     

Ovarian and adrenal function during the estrous cycle of the sow.

The concentrations of plasma estrogens, progesterone, and corticosteroids and of urinary pregnanediol, pregnanetriol, ketogenic steroids, and corticosteroids were determined as indicators of ovarian and adrenal function throughout a normal sow's estrous cycle. Two broad peaks of plasma estrogen, one lasting 11–12 days during estrus and another 6-day peak period during the early part of the luteal phase were detected. Plasma progesterone was elevated during the late follicular and luteal phase. Two broad peaks of plasma corticoids appeared, one following the decrease of plasma progesterone and the second 7–14 days later. Those elevations in plasma corticoids occurred when estrogen titres were elevated. Urinary determinations generally reflected plasma findings. Estrogen levels began to rise during the follicular phase while a reasonably high progesterone level was evident. Estrogen titres never decreased to non-detectable levels. An interrelationship between adrenal function and ovarian estrogen production is suggested.     

Complete Genome Sequence of Two Variant Porcine Reproductive and Respiratory Syndrome Viruses Isolated from Vaccinated Piglets

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to affect the Chinese swine industry. Since 2006, variant PRRSV strains sharing two unique discontinuous deletions of 30 amino acids in the nonstructural protein Nsp2 have become dominant in Chinese swine herds and have caused huge economic losses to the swine industry in China. Here we report the complete genome sequence of two novel PRRSV variants isolated from vaccinated piglets with additional amino acid deletions in Nsp2.     

Ovarian function in Nelore (Bos taurus indicus) cows after post-ovulation hormonal treatments

Maternal recognition of pregnancy in the cow requires successful signaling by the conceptus to block luteolysis. Conceptus growth and function depend on an optimal uterine environment, regulated by luteal progesterone. The objective of this study was to test strategies to optimize luteal function, as well as prevent a dominant follicle from initiating luteolysis. Nelore (Bos taurus indicus) beef cows (n=40) were submitted to a GnRH/PGF(2alpha)/GnRH protocol. Cows that ovulated from a dominant ovarian follicle (ovulation=Day 0) were allocated to receive: no additional treatment (G(C); n=7); 3000IU of hCG on Day 5 (G(hCG); n=5); 5mg of estradiol-17beta on Day 12 (G(E2); n=6); or 3000IU of hCG on Day 5 and 5mg of estradiol-17beta on Day 12 (G(hCG/E2); n=5). Ultrasonographic imaging of the ovaries, assessment of plasma progesterone concentration, and detection of estrus were done daily from Day 5 to the day of subsequent ovulation. Treatment with hCG induced an accessory CL, increased CL volume, and plasma progesterone concentration throughout the luteal phase (P<0.01). Estradiol-17beta induced atresia and recruitment of a new wave of follicular growth; it eliminated a potentially estrogen-active, growing ovarian follicle within the critical period for maternal recognition of pregnancy, but it also hastened luteolysis (Days 16 or 17 vs. Days 18 or 19 in non-treated cows). In conclusion, the approaches tested enhanced luteal function (hCG) and altered ovarian follicular dynamics (estradiol-17beta), but were unable to extend the life-span of the CL in Nelore cows.     

Progesterone-binding protein in the corpus luteum, blood and lymph of sheep

A protein which binds progesterone but not cortisol was found in luteal cytosol, utero-ovarian venous plasma, ovarian lymph and jugular venous plasma of sheep. The protein was isolated from other steroid-binding activities present in luteal cytosol and plasma by de-adsorption from hydroxyapatite with 40 mM phosphate. In all cases, it bound progesterone at 4 degrees C with an equilibrium affinity constant of the order of 10(6) l/mol, but did not bind cortisol. After chromatography on hydroxyapatite and Sephadex G-200, the protein obtained from utero-ovarian venous plasma had lost much of its steroid-binding activity, but migrated as a monomer of molecular weight 64 000 in polyacrylamide gel. Bovine luteal cytosol is reported to contain two proteins which bind progesterone similarly. In ruminants, these proteins may participate in the biosynthesis and secretion of progesterone from luteal cells and its transport in blood.