Melatonin is a multifunctional molecule that mediates several circadian and seasonal reproductive processes. The exact role of melatonin in modulating reproduction, however, is not fully understood-especially its effects on the ovarian follicles and oocytes. This study was conducted to investigate the expressions of the ASMT and melatonin-receptor MTNR1A and MTNR1B genes in bovine oocytes and their cumulus cells, as well as the effects of melatonin on oocyte nuclear and cytoplasmic maturation in vitro. Cumulus-oocyte complexes (COCs) from abattoir ovaries were cultured in TCM-199 supplemented with melatonin at concentrations of 0, 10, 50, and 100 ng/ml. The expression of ASMT, MTNR1A, and MTNR1B genes was evaluated by RT-PCR. Moreover, the effects of melatonin on cumulus cell expansion, nuclear maturation, mitochondrial characteristics and COCs steroidogenesis were investigated. Furthermore, the level of reactive oxygen species (ROS) was evaluated in denuded oocytes. Our study revealed that ASMT and MTNR1A genes were expressed in COCs, while the MTNR1B gene was expressed only in oocytes. Additionally, melatonin supplementation at 10 and 50 ng/ml to in vitro maturation medium significantly enhanced oocyte nuclear maturation, cumulus cell expansion and altered the mitochondrial distribution patterns, but had no effects on oocyte mitochondrial activity and COCs steroidogenesis. Melatonin-treated oocytes had a significantly lower level of ROS than controls. The presence of melatonin receptors in COCs and its promoting effects on oocyte nuclear and cytoplasmic events, indicate the potentially important roles of this hormone in regulating bovine oocyte maturation. Moreover, the presence of ASMT transcript in COCs suggests the possible involvement of these cells in melatonin biosynthesis.

Abstract. The current study was performed to follow up the circulating hormonal changes and to correlate the findings with the physiological activity of the corpus luteum (CL) and placenta during pregnancy in goats. Blood samples were collected weekly from five goats during pregnancy for measuring steroid and protein hormones. A gradual increase was observed in immunoreactive (ir-) inhibin, with maximal levels at the 17th week. The plasma concentrations of estradiol and prolactin (PRL) showed nearly similar patterns during pregnancy, where they declined to basal levels during the first 4 weeks post-breeding and then increased significantly, with the maximal concentration during late pregnancy. The plasma FSH and LH concentrations were maintained at basal levels throughout the gestation period. The plasma progesterone concentration abruptly increased in the first week post-breeding and remained at high values throughout the pregnancy period. Immunohistochemical localization of inhibin alpha, betaA, betaB and steroidogenic enzymes cytochrome P450 aromatase, 3alpha-hydroxysteroid dehydrogenase (3betaHSD), cytochrome 17alpha-hydroxylase P450 and cholesterol side-chain cleavage cytochrome P450 in the cyclic and pregnant goat CL revealed positive immunoreactivity without affinity differences between the luteal and pregnancy stages. The placental syncytiotrophoblasts also showed positive staining, except for inhibin betaA and 3betaHSD. The giant binucleate cells of the placenta showed positive immunoreactions to PRL. These results suggest that the high concentrations of irinhibin, estradiol and PRL during late pregnancy are of placental origin and that the placenta may have a vital role in the maintenance of pregnancy, regulation of mammary growth and preparation for kidding and lactation in goats. Key words: Goat, Hormone, Inhibin, Placenta, Pregnancy (J. Reprod. Dev. 56: [243][244][245][246][247][248][249][250] 2010) tudying hormonal changes during the gestation period knocks down doors that block understanding of the regulatory mechanisms accompanying fetal development and maintenance of pregnancy; the most important stage of animal reproductive life. In goats, pregnancy is dependant on the corpus luteum (CL) with minimal contribution from placenta. However, day by day, scientists are working hard to discover the additional roles played by the placenta. The pattern of progesterone levels during pregnancy is changeable; it is low from mating until the 6th day [1], increases noticeably by the 3rd week and remains high until the 19th week [2][3][4][5][6][7]. Maintenance of progesterone secretion by the CL during pregnancy in the goat is luteinizing hormone (LH)-dependant; moreover, prolactin (PRL) is synergistic with LH in stimulating this function [8]. The highest concentration of estradiol in the blood is found 2 days before ovulation [1,9]; the concentration decreases during the first 30 days after mating and then increases again between weeks 7 and 11, with the maximal output near parturition [7,10].Up till now,...

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Abstract.To clarify the effect of lactation period on ovarian follicular activity and associated hormonal levels in goats, six goats were monitored daily by ultrasonographic examination with blood sampling during early (Days 5 to 25; Day 0 was the day of kidding) and late (Days 40 to 60) lactation. While the presence of a corpus luteum of pregnancy retarded follicular growth in the ipsilateral ovary until Days 11-13 postpartum, the total follicular number (TFN) and area (TFA) increased during late lactation due to the significant increase in the number of medium-and large-sized follicles and decrease in the number of small follicles. Four goats showed a similar pattern of follicular development during the period studied characterized by the emergence of five and six waves during the early and late lactation, respectively. The largest follicle diameter of the first three waves monitored during early lactation was significantly smaller as compared with the diameter of those existing during late lactation. TFN showed a positive correlation with FSH but showed a negative correlation with immunoreactive (ir-) inhibin and estradiol during the postpartum period. TFA was positively correlated with ir-inhibin, estradiol and PRL and negatively correlated with FSH during the monitored periods. The plasma levels of ir-inhibin and progesterone were significantly higher during late lactation compared with the levels recorded during early lactation. Ir-inhibin levels showed a significant positive correlation with LH and estradiol during early and late lactation but showed a negative correlation with FSH during the whole lactation period. LH was positively correlated with estradiol and PRL during early and late lactation, respectively. These results suggest that the lactation period has a detrimental effect on ovarian activity during the early postpartum period in goats. Key words: Goat, Gonadotropic hormones, Lactation, Ovary, Postpartum (J. Reprod. Dev. 58: 61-68 , 2012) T he understanding of ovarian follicular dynamics and its hormonal control in goats has increased in recent years due to the use of ultrasonography and provides information that is important for establishing improved methods to solve the problem of prolonged lactating anestrus in domestic animals [1]. Previous findings in other ruminants including the wave-like pattern of follicular growth, follicular dominance and the role of progesterone in follicular turnover, have been recently extended to the Caprine species [2]. Nevertheless, information regarding ovarian activity and the mechanisms regulating the postpartum anestrous period in goats is still scarce.Follicular activity resumed as early as Day 13 in the ovaries of postpartum goats, and medium-or large-sized follicles were present in the ovaries soon after [3]. Sosa [4] showed that the goat ovarian cyclicity resumed after complete uterine involution at the 5th week postpartum. In ewes, although follicles larger than 2 mm in diameter appeared as early as Day 5 postpartum [5], no follicles larger than 3 ...

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Abstract. The present study was conducted to characterize follicular development and its hormonal control during early pregnancy in goats. The ovaries of goats (n=8) were scanned daily for follicles (> or = 2 mm in diameter) and corpora lutea by transrectal ultrasound with blood sampling from the jugular vein for monitoring the hormonal changes during the first thirty-five days after mating. During early pregnancy, three (37.5%), four (50%) and one (12.5%) goat showed nine, eight and seven waves of follicular development, respectively. The corpora lutea were detected as early as Day 3.61 ± 0.45 (7.47 ± 0.43 mm) of pregnancy (Day 0=day of mating) and attained their maximal cross-sectional diameter (10.64 ± 0.37 mm) on Day 25.7 ± 0.8 of pregnancy, respectively. A transient rise in FSH levels was temporally associated with the day of follicular wave emergence (up to three days prior to wave emergence). The plasma LH and estradiol levels were negatively correlated with the progesterone concentration. The rise in plasma immunoreactive (ir) inhibin levels was negatively correlated with the FSH concentration and positively correlated with the number of large-sized follicles. Alternatively, the mean plasma ir-inhibin levels showed a noticeable decline with the progression of pregnancy. The present results demonstrated that follicular development during early pregnancy shows a wave-like pattern, with seven to nine waves developing until Day 35 after breeding, and that the number of follicular waves can be predicted by the number of FSH peaks. The current study also demonstrated that the role of inhibin as an FSH regulator is maintained throughout early pregnancy. Key words: Follicle development, Goat, Inhibin, Ovary, Pregnancy (J. Reprod. Dev. 56: [520][521][522][523][524][525][526] 2010) ollicular development during the estrous cycle in goats is characterized by wave-like patterns [1,2]. Each wave of follicular growth consists of a cohort of small follicles that continue to grow into one or more large preovulatory follicles through three main events, recruitment, selection and dominance, while the others undergo atresia [3]. The number of follicular waves per cycle varies from two to five, with a four-wave pattern being the most predominant [1,2]. Follicular growth throughout pregnancy has been described in ruminants [4,5], with less attention being given to goats [6].Repeated ultrasound scanning of pregnant cow (monotocous species) and ewe (polytocous species) ovaries revealed that the regularity of the emergence of follicular waves did not change during early pregnancy [4,5,7,8] and that waves of follicular growth continued regularly under conditions of basal LH and FSH [8], but decreased progressively as pregnancy progressed [9,10]. It was noticeable that the location and diameter of the largest follicles and the total number of follicles were drastically affected with the presence of the corpus luteum (CL) of pregnancy and the conceptus [5,7,8].In goats, limited studies have been conducted to characterize follicu...

This study aimed to determine the most reliable method to evaluate capacitation of buffalo frozen/thawed sperm. Frozen/thawed sperm cells were incubated in Tyrode albumin lactate pyruvate medium (TALP) in absence of capacitating agents (control) and in presence of 10 g/ml heparin for 2 and 4 h. Capacitation was assessed by Trypan blue/Giemsa after lysophosphatidylcholine (LPC) exposure, chlortetracycline (CTC) fluorescence assay and immunelocalization of tyrosine phosphorylated protein. Furthermore, we evaluated the effect of heparin on penetration, cleavage rates and kinetics of embryo development after heterologous IVF. The percentage of LPC-induced acrosome reacted (AR)-sperm increased (P<0.05) with heparin compared to the control after 2 h (28.2 vs 24.4%, respectively) and 4 h (35.1 vs 32.0 %, respectively). No differences in CTC pattern B (capacitated sperm) were found between groups and incubation times (on average 63%). On the contrary, heparin decreased (P<0.01) the percentage of tyrosine phosphorylation pattern A after 2 and 4 h (34.3 and 35.3%, respectively) compared to the control (54.5 and 51.8%, respectively) and increased (P<0.01) that of pattern EA after 2 and 4 h (59.2 and 54.2 %, respectively) compared to the control group (44.7 and 45.2 %, respectively). Both cleavage and penetration rates, as well as the percentage of fast developing embryos, were higher (P<0.01) in the heparin-treated group (77.2, 80.4 and 74.0 %, respectively) compared to the control (56.6, 58.0 and 55.2 %, respectively). In conclusion, Trypan blue/Giemsa staining to evaluate LPC-induced AR and tyrosine protein phosphorylation assay can be successfully used to evaluate capacitation of buffalo frozen/thawed semen.

The aim of this work was to evaluate the effect of relaxin, known to improve fertility parameters of frozen-thawed sperm in other species (Miah et al. 2006 J. Reprod. Dev. 52, 773–779; Miah et al. 2007 Anim. Sci. J. 78, 495–502), on buffalo sperm motility, capacitation, and fertilizing capability. Frozen-thawed sperm from 2 bulls (4 replicates each) were separated by Percoll, diluted to a 20 × 106 mL–1 concentration and incubated in TALP medium in the absence of capacitating agents (negative control), in the presence of 10 μg mL–1 of heparin (positive control) and 100 ng mL–1 of relaxin for 2 h. Following incubation, sperm were exposed for 15 min to 60 mg mL–1 of lysophosphatidylcholine, a fusogenic agent known to induce the acrosome reaction only on capacitated sperm. To evaluate acrosome-reacted (AR) live sperm, cells were fixed and stained with Trypan blue-Giemsa (Kovacs and Foote 1992 Biotech. Histochem. 67, 119–124) and evaluated (800 sperm counted/group). Sperm motility was examined by a phase contrast microscope, whereas the fertilizing capability was evaluated by heterologous IVF. Abattoir-derived bovine oocytes (n = 258, 86 per group) were in vitro matured and fertilized according to standard procedures (Rubessa et al. 2011 Theriogenology 76, 1347–1355) with buffalo sperm in the absence of capacitating agents and in the presence of 10 μg mL–1 of heparin and 100 ng mL–1 of relaxin. Twenty hours after IVF, presumptive zygotes were denuded and cultured in SOF for 24 h, when cleavage rate was evaluated and confirmed by fixation with absolute ethanol overnight and staining with 2.5 μg mL–1 of Hoechst 33342 after zona removal by pronase (2 mg mL–1) digestion. The differences in the percentages of AR sperm and cleavage among groups were analysed by a chi square test and those in sperm motility by Student's t-test. Acrosomal loss was observed in 10.8% of the sperm after thawing, which may indicate freezing-induced capacitation, and, hence, this value was detracted from the percentages of AR recorded following incubation. After 2 h of incubation, 100 ng mL–1 of relaxin significantly (P < 0.05) increased the percentages of live AR sperm (P < 0.05) compared with the negative control (31.3 ± 2.2 and 25.8 ± 2.8, respectively), with intermediate results in the positive control (27.0 ± 2.2). Motility was significantly improved (P < 0.05) when sperm were exposed to 100 ng mL–1 of relaxin compared with both the negative and positive control (73.7 ± 2.4, 60.0 ± 4.1, and 60.0 ± 7.1, respectively). A significant (P < 0.05) improvement of cleavage rate was recorded both in the positive control (71.5 ± 4.8) and in the group treated with 100 ng mL–1 of relaxin (70.7 ± 0.5) compared with negative control (52.1 ± 1.5). In conclusion, these preliminary results indicate that relaxin at the concentration of 100 ng mL–1 improves sperm motility, capacitation, and the IVF capability of buffalo sperm.