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Abstract: The effects of a PRL-stimulating substance (sulpiride) on PRL and PGF2α secretion and on luteal and ovarian follicular dynamics were studied during the estrous cycle in mares. A control group (n = 9) and a sulpiride group (Sp; n = 10) were used. Sulpiride (25 mg) was given every 8 h from Day 13 postovulation to the next ovulation. Repeated sulpiride treatment did not appear to maintain PRL concentrations at 12-h intervals beyond Day 14. Therefore, the hypothesis that a long-term increase in PRL altered luteal and follicular end points was not testable. Hourly samples were collected from the hour of a treatment (Hour 0) to Hour 8 on Day 14. Concentrations of PRL increased to maximum at Hour 4 in the Sp group. The PRL pulses were more prominent (P < 0.008) in the sulpiride group (peak, 19.4 ± 1.9 ng/mL; mean ± SEM) than in the controls (11.5 ± 1.8 ng/mL). Concentrations of a metabolite of PGF2α (PGFM), number, and characteristics of PGFM pulses, and concentrations of progesterone during Hours 0 to 8 were not affected by the increased PRL. A novel observation was that the peak of a PRL pulse occurred at the same hour or 1 h later than the peak of a PGFM pulse in 8 of 8 PGFM pulses in the controls and in 6 of 10 pulses in the Sp group (P < 0.04), indicating that sulpiride interfered with the synchrony between PGFM and PRL pulses. The hypothesis that sulpiride treatment during the equine estrous cycle increases concentrations of PRL and the prominence of PRL pulses was supported. [Copyright &y& Elsevier]

Abstract: The beginning of postluteolysis (progesterone, <1 ng mL−1) in heifers was targeted by using 8 h after ultrasonic detection of a 25% decrease in CL area (cm2) and was designated Hour 0. Flunixin meglumine (FM; n = 10) to inhibit PGF2α secretion or vehicle (n = 9) were given intramuscularly at Hours 0, 4, 8, 16, 24, 32, and 40. The dose of FM was 2.5 mg/kg at each treatment. Blood sampling and measurement of the CL and dominant follicle were done every 8 h beginning 14 days postovulation in each group. Blood samples for detection of pulses of PRL and pulses of a metabolite of PGF2α (PGFM) were obtained every hour for 24 h beginning at Hour 0. Pulse concentrations of both PGFM and PRL were lower in the FM group than in the vehicle group. Concentration of PRL was greatest at the peak of a PGFM pulse. Neither CL area (cm2) nor progesterone concentration differed between groups during Hours 0 to 48 (postluteolysis). Ovulation occurred in nine of nine heifers in the vehicle group and in three of 10 heifers in the FM group. The anovulatory follicles in the FM group grew to 36.2 ± 2.9 mm, and the wall became thickened from apparent luteinization. The hypothesis that PGF2α was involved in the continued P4 decrease and structural CL regression during postluteolysis was not supported. However, the hypotheses that pulses of PGFM and PRL were temporally related and that systemic FM treatment induced an anovulatory follicle were supported. [Copyright &y& Elsevier]

Abstract: A pulse of a PGF2α metabolite (PGFM) was induced by treatment with 0.1mg of estradiol-17β on Day 15 (Day 0=ovulation; n =9 heifers). Blood samples were taken every 15min for 9h beginning at treatment (Hour 0). For PGFM and LH, an intraassay-CV method was used to detect fluctuations in the 15-min samples and pulses in the hourly samples. A mean of 6.9±0.4 PGFM fluctuations/9h were superimposed on the hourly PGFM concentrations, compared to 2.1±0.5 LH fluctuations/9h (P <0.02). An increase (P <0.02) in oxytocin began 15min before the beginning nadir of the PGFM pulse. A transient increase in progesterone did not occur at the beginning nadir of the PGFM pulse. Progesterone decreased (P <0.02) during the ascending portion and increased (P <0.03) as a rebound during the descending portion of the PGFM pulse. The peak of an LH pulse occurred 1.5±0.4h (range, 0.25–2.75h) after the peak of the PGFM pulse. The wide range in the interval from a PGFM peak to an LH peak obscured the contribution of increasing LH to the rebound. The results did not support the hypothesis that oxytocin and PGFM increase concurrently. Results supported the hypothesis that the immediate transient progesterone increase that has been demonstrated with exogenous PGF2α does not occur during the ascending portion of an endogenous PGFM pulse. The hypothesis that the progesterone rebound after the peak of a PGFM pulse is temporally related to an LH pulse was supported. [Copyright &y& Elsevier]

Abstract: The role of LH in luteolysis and development of the ovulatory follicle and the involvement of GnRH receptors in estradiol (E2) stimulation of LH secretion were studied in heifers. A pulse of PGF2α, as indicated by a metabolite, was induced by E2 treatment on Day 15 (Day 0 = ovulation) and LH concentration was reduced with a GnRH-receptor antagonist (acyline) on Days 15, 16, and 17. Blood samples were collected every 6 h on Days 14–17 and hourly for 10 h beginning at the Day-15 treatments. Four groups were used (n = 6): control, acyline, E2, and E2/acyline. The number of LH pulses/heifer during the 10 h posttreatment was greater (P < 0.0002) in the E2 group (2.3 ± 0.4, mean ± SEM) than in the acyline group (0.2 ± 0.2) and was intermediate in the E2/acyline group (1.4 ± 0.2). Concentrations of progesterone in samples collected every 6 h on Day 15 showed a group-by-hour interaction (P < 0.02); concentrations decreased in the acyline group but not in the control group. The 12 heifers in the combined acyline and E2/acyline groups had three follicular waves compared to two waves in 10 of 12 heifers in the combined control and E2 groups. Results (1) supported the hypothesis that LH delays the progesterone decrease associated with luteolysis, (2) supported the hypothesis that LH has a positive effect on the continued development and growth of the selected ovulatory follicle, and (3) indicated that E2 stimulates LH production through an intracellular pathway that involves GnRH receptors on the gonadotropes and a pathway that does not involve the receptors. [Copyright &y& Elsevier]

Abstract: Ovarian acyclicity is one of the most important causes of infertility in water buffalo. Recent studies have indicated alterations in the composition of follicular fluid during the condition. The aim of this study was to determine the changes in follicular fluid concentrations of estradiol, progesterone and insulin during ovarian acyclicity in water buffalo. Ovaries were collected from 50 acyclic and 95 cyclic (control) buffaloes and follicular fluid was aspirated from small (5.0–6.9mm), medium (7.0–9.9mm) and large (≥10.0mm) sized follicles. Estradiol concentration was lower (P <0.0001) in acyclic (1.4±0.09ng/ml) than in cyclic (3.3±0.18ng/ml) buffaloes. Regardless of the ovarian cyclic status, there was an increase (P <0.01) in estradiol concentration with the increase in follicle size; the mean concentrations were 2.4±0.16ng/ml, 2.8±0.29ng/ml and 3.5±0.41ng/ml in small, medium and large follicles, respectively. A higher (P <0.001) progesterone concentration was recorded in acyclic (24.3±2.61ng/ml) compared to the cyclic (7.6±0.79ng/ml) group. Furthermore, acyclic buffaloes had a lower (P <0.05) concentration of insulin in the follicular fluid than that of cyclic buffaloes (15.2±1.55μIU/ml versus 25.9±2.78μIU/ml, respectively). In conclusion, acyclic buffaloes have lower concentrations of estradiol and insulin concurrent with higher concentrations of progesterone in the follicular fluid. These hormonal changes in the follicular microenvironment are possibly a manifestation of the disturbances in the normal follicular development leading to anovulation and anestrus in acyclic buffaloes. [Copyright &y& Elsevier]

Abstract: The objective of this study was to examine the follicular fluid biochemical and hormonal changes associated with ovarian follicular cysts in buffalo. Follicular fluid was aspirated from eight cysts and eight preovulatory follicles, and subjected to biochemical and hormonal analyses. Cysts were characterized by a greater (P <0.01) concentration of nitric oxide and lesser concentrations of ascorbic acid and glucose than that of preovulatory follicles (P <0.01 and P <0.05, respectively). Furthermore, follicular cysts had greater concentrations of progesterone (P <0.001), triiodothyronine (T3) and cortisol (P <0.05) and lesser concentrations of insulin (P <0.001) than preovulatory follicles. The results indicate follicular cysts in buffalo have an altered biochemical and hormonal composition. The alterations include increases in nitric oxide, progesterone, cortisol and T3 concentrations with a concurrent reduction in ascorbic acid, insulin and glucose concentrations. The study suggests that greater progesterone concentrations possibly inhibit the onset of LH surge resulting in formation of follicular cysts in buffalo. In addition, it implies the plausible role of intra-ovarian regulators such as nitric oxide, ascorbic acid and insulin in development of the condition. [Copyright &y& Elsevier]

Abstract: Circulating concentrations of hormones were determined each hour in 13 heifers from the end of the luteolytic period to ovulation (follicular phase, 3.5 days). Diameter of the preovulatory follicle was determined every 8 hours, and the time of ovulation was determined hourly. The diameter of the preovulatory follicle decreased 0.8 ± 0.1 mm/h in heifers when there was 1 to 3 hours between the last two diameter measurements before ovulation. The concentration of progesterone (P4) after the end of the luteolytic period (P4 < 1 ng/mL) changed (P < 0.0001), as shown by a continued decrease until Hour −57 (Hour 0 = ovulation), then was maintained at approximately 0.2 ng/mL until 2 hours before the peak of the LH surge at Hour −26, and then a decrease to 0.1 ng/mL along with a decrease in estradiol-17β. Concentrations of LH gradually increased (P < 0.007) and concentrations of FSH gradually decreased (P < 0.0001) after the end of luteolysis until the beginning nadirs of the respective preovulatory surges. A cluster of prolactin (PRL) pulses occurred (P < 0.0001) each day with approximately 24 hours between the maximum value of successive clusters. Hourly concentrations of a PGF2α metabolite decreased (P < 0.007) until Hour −40, but did not differ among hours thereafter. Novel observations included the gradual increase in LH and decrease in FSH until the beginning of the preovulatory surges and follicle diameter decrease a few hours before ovulation. Results supported the following hypotheses: (1) change in the low circulating P4 concentrations during the follicular phase are temporally associated with change in LH concentrations; and (2) PRL pulses occur in a cluster each day during the follicular phase of the estrous cycle. [Copyright &y& Elsevier]

We evaluated the temporal (24, 48 and 72 hours) and dose-dependent (5, 10, and 100 ng/mL of LH, IGF-1, and EGF, respectively) production and secretion of progesterone (P4) in cultured luteal cells from different stages of estrous cycle as well as the expression of steroidogenic acute regulatory protein (STARD1), cytochrome P450 cholesterol side-chain cleavage (CYP11A1), and 3β-hydroxysteroid dehydrogenase (HSD3B), anti-apoptotic gene PCNA, and pro-apoptotic gene BAX in luteal cells of mid-luteal phase in buffalo. Samples from early luteal phase (ELP; Day 1 to 4; n = 4), mid-luteal phase (MLP; Day 5 to 10; n = 4), and late luteal phase (LLP; Day 11 to 16; n = 4) of estrous cycle were collected. Progesterone was assayed by RIA, whereas mRNA expression was determined by quantitative real-time polymerase chain reaction. Results depicted that highest dose (100 ng/mL) of LH, IGF-1, and EGF and longer duration of time brought about a (P < 0.05) rise in P4 level and expression of steroidogenic enzymes and PCNA compared with the lower level(s) and control while, all treatments (P < 0.05) inhibited BAX expression in a time dependent-manner. Analysis of interaction between stage and treatments revealed that LH treatment (P < 0.05) increased P4 production compared with IGF-1 and EGF in ELP and MLP. However in LLP, treatment with IGF-1 and EGF significantly (P < 0.05) increased P4 production compared with LH treatment. Summarizing, our study explores the steroidogenic potential of LH and growth factors across different luteal stages in buffalo, which on promoting steroidogenic enzyme expression and cell viability culminated in enhanced P4 production in luteal cells. [ABSTRACT FROM AUTHOR]

Abstract: Evidence obtained during recent years provided has insight into the regulation of corpus luteum (CL) development, function, and regression by locally produced ghrelin. The present study was carried out to evaluate the expression and localization of ghrelin and its receptor (GHS-R1a) in bubaline CL during different stages of the estrous cycle and investigate the role of ghrelin on progesterone (P4) production along with messenger RNA (mRNA) expression of P4 synthesis intermediates. The mRNA and protein expression of ghrelin and GHS-R1a was significantly greater in mid- and late luteal phases. Both factors were localized in luteal cells, exclusively in the cytoplasm. Immunoreactivity of ghrelin and GHS-R1a was greater during mid- and late luteal phases. Luteal cells were cultured in vitro and treated with ghrelin each at 1, 10, and 100 ng/mL concentrations for 48 h after obtaining 75% to 80% confluence. At a dose of 1 ng/mL, there was no significant difference in P4 secretion between control and treatment group. At 10 and 100 ng/mL, there was a decrease (P < 0.05) in P4 concentration, cytochrome P45011A1 (CYP11A1), and 3-beta-hydroxysteroid dehydrogenase mRNA expression and localization. There was no difference in mRNA expression of steroidogenic acute regulatory protein between control and treatment group. In summary, the present study provided evidence that ghrelin and its receptor are expressed in bubaline CL and are localized exclusively in the cell cytoplasm and ghrelin has an inhibitory effect on P4 production in buffalo. [Copyright &y& Elsevier]

Abstract: The objective of this study was to characterize the temporal profile of pregnancy-associated glycoproteins (PAGs; isoforms 1–11) across different stages of gestation in the Barbari goat. Placentae were collected from local abattoir, classified according to crown rump length of the corresponding foetus into five groups (0–30, 31–60, 61–90, 91–120, and 121–150 days of gestation), and used for relative quantification of mRNA expression by Pfaffl method. In addition, adult female goats (pregnant, n =7; non-pregnant, n =5) were used to estimate weekly plasma PAG and progesterone (P4) concentrations. The relative mRNA expression of PAGs was greater (p <0.05) during 31–60 days of gestation, which correlated well with the temporal changes in plasma PAG concentrations. Relative expression of PAGs decreased steadily as gestation advanced with minimum expression observed just before parturition, except for PAG-4 and PAG-8 that showed constantly higher expression throughout pregnancy. Plasma PAG and P4 concentrations showed a distinct temporal pattern with a significant increase beginning at 2 weeks and return to basal levels by 20 weeks of gestation. However, PAG concentrations reached a peak earlier in gestation (8 weeks) than P4 (10–14 weeks). Correlation analysis indicated a strong positive association (r =0.748, p <0.01) between plasma PAG and P4 concentrations. In conclusion, results of this study indicate a distinct temporal pattern of PAG expression and secretion during gestation in the Barbari goat. The temporal changes in PAGs and the positive association with P4 are suggestive of their role in maintenance of pregnancy and progressive foetal development. [Copyright &y& Elsevier]