Effects of echinomycin on endothelin-2 expression and ovulation in immature rats primed with gonadotropins

Echinomycin is a small-molecule inhibitor of hypoxia-inducible factor-1 DNA-binding activity, which plays a crucial role in ovarian ovulation in mammalians. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1alpha-mediated endothelin (ET)-2 expressions contributed to ovarian ovulation in response to human chorionic gonadotropin (hCG) during gonadotropin-induced superuvulation. By real-time RT-PCR analysis, ET-2 mRNA level was found to significantly decrease in the ovaries after echinomycin treatment, while HIF-1alpha mRNA and protein expression was not obviously changed. Further analysis also showed that these changes of ET-2 mRNA were consistent with HIF-1 activity in the ovaires, which is similar with HIF-1alpha and ET-2 expression in the granulosa cells with gonadotropin and echinomycin treatments. The results of HIF-1alpha and ET-2 expression in the granulosa cells transfected with cis-element oligodeoxynucleotide (dsODN) under gonadotropin treatment further indicated HIF-1alpha directly mediated the transcriptional activation of ET-2 during gonadotropin-induced superuvulation. Taken together, these results demonstrated that HIF-1alpha-mediated ET-2 transcriptional activation is one of the important mechanisms regulating gonadotropin-induced mammalian ovulatory precess in vivo.

[Expression of GSK-3 beta and beta-catenin proteins in the PMSG stimulated rat ovary]

The ovary is an example of a developing tissue in which developmental prosses occur throughout reproductive life. We investigate the expression of GSK-3 beta and beta-catenin-Wnt pathway molecules-in the rat ovary during follicular development. To induce follicular growth and development, 23 days old immature female rats were injected with 10 IU of PMSG. Forty and forty-eight hours after stimulation with PMSG, the sera was collected for hormone assay, and the ovary were dissected and prepared for immunohistochemistry[IHC[and western blot[WB]. Our IHC and WB analysis showed that the expression of pGSK-3 beta and active beta-catenin was increased in PMSG primed rats in compared to those of intact groups. However, the total GSK-3 beta and beta-catenin proteins remain unchanged. The results indicate this idea that gonadotropin [PMSG], stabilized beta-catenin in GSK-3 beta independent manner in the rat ovary during the follicular development

Effect of ovine follicular fluid peptide on ovarian responses and other organ weights in rats, Rattus norvegicus Berkenhout 1769.

The present study was aimed to study the effect of an ovine follicular fluid peptide on ovarian follicle and good oocyte numbers and weights of ovary, uterus, liver, pancreas and kidney in rats, R. norvegicus. A 30.1 kDa peptide was isolated from ovine follicular fluid by ammonium sulphate precipitation and then gel filtration. The peptide was tested at various levels in normal (22 and 36 day-old), superovulated (29 day-old) immature and 121-day old mature rats on the ovarian responses and other organ weights. The isolated peptide inhibited the growth of antral follicles in normal and superovulated rats. Ovarian, uterine weight and recovery of good oocytes were reduced when the peptide was administered at 100 microg dose. The peptide had no effect on kidney, liver, pancreas weight and recovery of preantral follicles.

Some analytical studies in relation to cyclicity of buffalo-Heifers

In this study, 40 non-cycling buffalo-heifers were used. The heifers were treated by exogenous sex steroids [Synchro-Mate-B] plus equine chorionic gonadotrophins [eCG] with or without carboxylic ionophore [Lasalocid] supplement for induction of estrus. Blood samples were collected from all heifers before treatment and from 10 positively responded heifers after treatment. Blood samples of 10 responded heifers [before and after treatment] in each group were subjected to study the effect of hormonal induction of cyclicity on metabolic profile testing. The results revealed that, the hormonal treatment without Lasalocid supplement did not alter Hb concentration, PCV%, ALT activity, total protein, albumin and urea nitrogen concentrations. While, the activities of plasma AST and ALP were significantly decreased and CPK activity, glucose and cholesterol concentrations were increased. Synchro-Mate-B implants plus eCG administration in Lasalocid supplemented cycling heifers did not lead to significant alterations in most of metabolic profile testing except PCV% and glucose concentration as compared to non-cycling buffalo-heifers supplemented with Lasalocid. Concentrations of plasma macro- and micro elements [Ca, Mg, Na, K and lithium] after induction of estrus by sex steroids plis eCG were not significantly differed in heifers either supplemented or not with Lasalocid. Thus, we can conclude that usage of Synchro-Mate-B implant plus eCG to induce estrus in prepubertal buffalo-heifers did not alter most of the metabolic profile parameters

Impact of PGF2 alpha administration on progesterone pattern during and after PMSG treatment in buffaloes

Thirteen buffalo-cows and 6 heifers were subjected for superovulatory treatment using 3000 iu PMSG [Gestyl], 25 mg PGF2-alpha [Lutalyse] were injected 48 hours after PMSG treatment and at day eight of the estrous cycle after superovulatory treatments. Ovarian and progesterone changes were studied in buffalo-cows and heifers during and after superovulatory treatments. 84.6% and 83.3% of buffalo-cows and heifers exhibited estrous within 2.46 +/- 0.78 and 2.4 +/- 1.14 days, respectively, following treatment with lutalyse. Whereas, the intervals averaged 3.27 +/- 1.05 and 3.4 +/- 1.14 days when treated at day 8 after superovulation in buffalo-cows and heifers, respectively. Plasma progesterone concentrations averaged 3.74 +/- 1.53 and 1.28 +/- 0.91 ng/ml before treatment with lutalyse in buffalo-cows and heifers, respectively, followed by significant decline 24 hours after treatment in both buffalo-cows and heifers [1.12 +/- 0.71 and 0.74 +/- 0.38 ng/ml, p <0.01] and reached the lowest concentration 72 hours after treatment [0.20 +/- 0.09 and 0.24 +/- 0.24 ng/ml, respectively]. A marked elevation in plasma progesterone concentration following superovulatory treatment in buffalo-cows [15.02 +/- 10.44 ng/ml] and heifers [17.87 +/- 10.72 ng/ml] was recorded

Induction of spermatogenesis by exogenous gonadotrophins during nonbreeding season in Calotes versicolor.

Treatment of exogenous gonadotrophins(PMSG, hCG and PMSG+hCG) to male C. versicolor during nonbreeding phase resulted in increased weight of testis and its diameter. The seminiferous tubular diameter was also increased and tubules were filled with spermatogenic elements like spermatogonia, primary and secondary spermatocytes and spermatids. The results suggest that mammalian nonpituitary gonadotrophins(PMSG and hCG) also posses the potency to stimulate spermatogenesis in reptilian testis. Lowered cholesterol levels of testis, increased weight and protein content of epididymis after gonadotrophins treatment indicate that the exogenous gonadotrophins could initiate the steroidogenesis in testis. Interstitial space was enlarged and filled with active Leydig cells. Spermatogenesis was not complete as no spermatozoa were observed in the lumen of seminiferous tubule. The factors essential for the completion of spermatogenesis are discussed.

Regulation of estrous cycle in hysterectomized albino rats by activation of follicular development.

Wistar strain albino rats were hysterectomized and the estrous cycle was compared with sham operated controls. Duration of estrous cycle in hysterectomized rats increased markedly with significant delay in the luteal phase and this was correlated to the inhibited follicular development of ovary. When these rats were treated with PGF2 alpha and PMSG and subjected to physical exercises, the estrous cycle was synchronised and the ovaries of such animals had active follicular development. Thus the deranged operation of sexual cycle in hysterectomized rats was regulated through physical exercises.

Effects of hCG and PMSG on responsiveness of ovary during period of delayed ovulation in an Indian vespertilionid bat, Scotophilus heathi.

Both hCG and PMSG treatments given either individually or sequentially between September and early February failed to induce ovulation in S. heathi, though they produced high degree of ovarian stimulation. The treatments induced ovarian enlargement, intense hyperaemia, marked changes in interstitial cells (ICs) and development of several antral follicles and varying degrees of abnormality in oocyte of most of the antral follicles. The percentage of abnormal oocytes in the ovary following hCG or PMSG treatment was dose-dependent.

Comparison of glucose-6-phosphate dehydrogenase activity in healthy and atretic follicles in rat ovary.

Changes in the glucose-6-phosphate dehydrogenase activity have been determined in relation to atresia of Graafian follicles in the rat ovary. Induction of atresia in follicles either due to absence of hCG in the hormonally stimulated immature ovaries or by repeated injections of pentobarbitone sodium to proestrous rats caused significant rise in the enzyme activity. Measurement of enzyme activity in isolated follicular compartments of healthy and atretic follicles revealed that it is significantly higher in the thecal tissue than the granulosa. Increase in enzyme activity in the atretic follicles than the healthy ones occurs due to its rise both in theca and granulosa cells. The significance of these changes in the enzyme activity in healthy and atretic follicles are discussed in relation to the precocious luteinization of cells in the follicular envelope with the onset of atresia.

Gonadotrophin-induced ovulation in melengestrol acetate treated female goat.

Adult, Black Bengal goats synchronized to oestrus with Melengestrol Acetate (MGA) could be subjected to superovulation with 1000 IU of the Pregnant Mare Serum Gonadotrophin (PMSG). However, with 500 IU of PMSG higher rate of ovulation observed only in goats above one year age was not significant. Results indicate that the successful superovulation in MGA synchronized goats depend both on the dosage of the PMSG, as well as upon the age of the treated animal.

Mode of action of centchroman at vaginal and ovarian level in immature rats.

Centchroman studied at various doses did not cause ovulation in immature rats as judged by morphological, histological and biochemical parameters whereas, 20 mg/kh dose caused early opening of vagina and cornification of the vaginal epithelial cells. However, no ovulation was detected by this regimen. No stimulatory effect was observed in the glycogen and cholesterol content in the ovaries of Centchroman treated rats. The effects on vagina persisted even in ovariectomised immature rats administered with Centchroman. The mode of various doses of Centchroman in immature rats as judged morphologically, histologically and biochemically has been discussed.