Rabbit Ovary Research Articles

Studies of GnRH-A Active Immunization Effects on LH and FSH Secretion and Histostructure of the Ovary and Uterus in Rabbits

Abstract The objective of the study is to investigate the effects of active immunization against gonadotropin releasing hormone agonist (GnRH-A) on secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the pituitary, and to observe the histological structures and development about ovaries and uteri in female rabbits. 24 female rabbits (Oryctolagus cuniculus) were divided randomly into 4 groups (n=6), namely, experimental group I (EG-I), experimental II (EG-II), experimental III (EG-III), and control group (CG). Rabbits were subcutaneously injected with 1.0 mL GnRH-A (alarelin) antigen respectively at concentrations of 100, 100 and 50 ug mL” 1 respectively, in EG-I, EG-II and EG-III. Alarelin antigen was re-injected in EG-II and EG-III with the same dosage on 20 d. CG was a blank. The ovarian and uterine samples were collected aseptically at the end of the experiment of 70 d. The tissue slices were observed under light and electron microscopes. Serum concentrations of LH and FSH were measured with ELISA. The results showed that serum LH concentrations in EG-II and EG-III reached the peak levels on 50 and 40 d respectively, and LH level in EG-II exceeded other 3 groups on 50 d (i<>0.05). FSH level in EG-II was higher than those in EG-I, CG (PO.01) and EG-III (PO.05) on 40 d. GnRH-A could increase the number of primary follicles, enlarge the primary follicle vertical diameter (PFV) and primary follicle transverse diameter (PFT), and promote growth and maturation of follicles. The endometrial epithelium thickness (EET) and uterine wall thickness (UWT) in three EGs were less than that in CG (P<0.05). GnRH-A can increase the quantities of mitochondrial cristaes, cortex granules in cytoplasm, broaden and lengthen zona pellucidas and microvilli of oocytes. It also enlarged nuclei of ooxytes and mitochondria, thereby it promoted the development of oocytes. Re-injection of 100 ug alarelin antigen enhanced the secretion of LH and FSH. GnRH-A promoted the growth and maturation of ovaries and follicles, suppressed uterine development, and also influenced histostructure of ovaries and uteri in female rabbits.

Ovulating induction methods in rabbit does: The pituitary and ovarian responses

The aim of this study was to compare the pituitary and ovarian responses in rabbit does subjected to different methods of ovulation induction. Forty-eight receptive females were randomly distributed into six groups (N = 8) and were inseminated with standard glass catheters. Buserelin intramuscular (BM) does were inseminated using a pool of fresh heterospermic semen and an intramuscular injection of 1 μg of buserelin acetate to induce ovulation. Buserelin intravaginal (BV) does were inseminated in a similar way, but ovulation was induced with the GnRH analogue (10 μg of buserelin acetate) combined with 0.5 mL of semen extender. The raw semen (R) and saline groups (S) were inseminated with undiluted semen or saline, respectively, without any inducer of ovulation. Another group (A) received lumbar anaesthesia (1.5 mL of 2% lidocaine), and only the empty catheter was introduced into the vagina. The AR does were treated the same way as group A but were inseminated with raw semen instead of an empty catheter. Blood samples were collected to determine the LH concentrations before and after AI (30, 60, 90, and 120 minutes). Ovulation, pregnancy, and conception rates were determined after euthanasia on day 14 post AI. Ovulating does had higher mean LH concentrations than nonovulating does (197.9 vs. 45.9 ng/mL; P < 0.05). The ovulation rates of buserelin intramuscular and intravaginal does were 100%, and the pregnancy rates were 87.5% and 100%, respectively. Rabbit does in groups A and AR did not ovulate and had similar mean plasma LH concentrations after 60 minutes compared with the S group (49.4 and 49.2 ng/mL vs. 41.6 ng/mL, respectively), which reached ovulation and pregnancy rates of 37.5%. Does inseminated only with raw semen had an ovulation rate of 75% and a pregnancy rate of 62.5%; they also demonstrated higher plasma LH concentrations than does of the S, A, and AR groups. In conclusion, ovulation in rabbit does can be induced by exogenous GnRH administration (im and intravaginal). The high plasma LH concentration and ovulation rate in the R group with respect to the S and A groups could weakly indicate the presence of some molecules in the seminal plasma that could act on or be absorbed by vaginal mucosa. Sensory stimulation and “seminal factors” probably exert a synergy on the ovulation response as demonstrated by the comparison of LH release and the ovulation response in the R, S, RA, and A groups.

Role of Angiotensin II in the Periovulatory Epidermal Growth Factor-Like Cascade in Bovine Granulosa Cells In Vitro1

Angiotensin II (AGT-2) induces follicular prostaglandin release in a number of species and ovulation in rabbits. Conversely, AGT-2 antagonists block ovulation in cattle. To determine the mechanism of action of AGT-2, we used a bovine granulosa cell model in which luteinizing hormone (LH) increased the expression of genes essential for ovulation in a time- and dose-dependent manner. The addition of AGT-2 to LH-stimulated cells significantly increased abundance of prostaglandin-endoperoxide synthase 2 (PTGS2) mRNA and protein, whereas AGT-2 alone had no effect. Upstream of PTGS2, AGT-2 increased abundance of mRNA encoding the epidermal growth factor-like ligands amphiregulin (AREG) and epiregulin (EREG) at 6 h posttreatment and abundance of a disintegrin and metalloprotease 17 (ADAM17), a sheddase, within 3 h of treatment. Inhibiting sheddase activity abolished the stimulatory effect of AGT-2 on AREG, EREG, and PTGS2 mRNA. The addition of selective AGT-2 antagonists to cells stimulated with LH plus AGT-2 demonstrated that AGT-2 did not act through the type 1 receptor and did not increase mitogen-activated protein kinase 3/1 phosphorylation. Combined with previous data from studies in vitro, we conclude that AGT-2 is an essential cofactor for LH in the early increase of ADAM expression/activity that induces the cascade of events leading to ovulation.

Angiotensin-(1-7) induces ovulation and steroidogenesis in perfused rabbit ovaries

A local renin-angiotensin system has been described in several organs, including the ovary; however, data indicating a role for angiotensin II in the induction of ovulation are controversial. We have previously shown the presence of a novel peptide, angiotensin-(1-7) [Ang-(1-7)], in the rat ovary and its effect on steroidogenesis. The objective of the present study was to determine whether Ang-(1-7) plays a role in ovulation. We first determined the presence and distribution of Ang-(1-7) and the receptor Mas in rabbit ovaries by immunohistochemistry. Angiotensin-(1-7) and Mas immunoreactivity were observed in interstitial cells and oocytes of immature ovaries. Immunoreactivity for Ang-(1-7) and Mas was also observed in theca and granulosa cells of preovulatory follicles in ovaries of gonadotrophin-stimulated rabbits. To verify the effect of Ang-(1-7) in ovulation and steroidogenesis, we used isolated ovaries from immature rabbits pretreated with equine chorionic gonadotrophin (50 i.u., 48 h before the experiment) and then perfused in vitro. The ovulatory efficiency was determined by the number of oocytes compared with the number of preovulatory follicles present in the ovary. Angiotensin-(1-7) stimulated oestradiol production and enhanced ovulatory efficiency, which was blocked by the specific Ang-(1-7) antagonist, A-779. Ovulation induced by human chorionic gonadotrophin was also antagonized by A-779. These results show, for the first time, the involvement of a novel regulatory peptide system, Ang-(1-7) and Mas, in the ovulatory process. More importantly, because A-779 antagonized hCG-induced ovulation, it may be inferred that Ang-(1-7) plays an important role in ovulation, possibly as a mediator of gonadotrophin action.

162 OVARIAN ULTRASOUND BIOMICROSCOPY IN RABBITS

Invasive methods (e.g. histology) limit serial assessment of ovarian structures in rabbits and impede progress in our understanding of factors responsible for inducing ovulation. Serial transrectal or transvaginal ultrasonography of ovarian structures has revolutionized our understanding of reproductive patterns in domestic animals, but the approach is limited in smaller species by the small physical size of the animal and the ovary. The advent of high-resolution ultrasound biomicroscopy (UBM), however, has permitted recent characterisation of ovarian dynamics in species as small as mice. As part of a larger study on factors influencing ovulation in rabbits, the objective of the present study was to validate UBM as a method of assessing ovarian structures in rabbits by comparing ultrasound image attributes with histological attributes. Female New Zealand White rabbits (n = 4; 5 to 5.5 months of age) were given ovulation-inducing treatments and examined daily by conventional transabdominal ultrasonography with a 12-MHz linear-array probe (MyLabTM5). Rabbits were killed with sodium pentobarbital 8 days after treatment. Ovarian UBM was performed ex situ in a water bath. A 25-MHz oscillating sector-array transducer (Visualsonics) was moved mechanically at a constant speed along the long axis of each ovary, and images were recorded (300 frames per 10-s cine-loop). After UBM, ovaries (n = 8) were fixed in 10% formaldehyde, embedded in paraffin, serial-sectioned at 10-μm thickness, and stained with Masson’s trichrome. Digital photomicrographs were taken of every third section of each ovary. For each ovary, follicles ≥0.6 mm and corpora lutea (CL) were counted and measured by scrolling through the UBM cine-loops and the serial micrographs. Ovarian follicles ≥1.5 mm were readily detected by conventional ultrasonography, and such follicles were present in the ovaries of all rabbits on the day of treatment, but CL structures were not clearly discernable during the 8 days after treatment. In vivo transabdominal UBM failed to yield satisfactory images of the ovaries probably because of high acoustic impedance of the body wall. The number (mean ± SEM) of CL detected by UBM ex situ in each pair of ovaries was highly correlated (r = 0.99; P &lt; 0.05) with the number detected by histology (8.5 ± 2.9 v. 8.8 ± 3.0). The diameter of CL was also highly correlated (2.1 ± 0.7 v. 1.8 ± 0.6 mm; r = 0.99; P &lt; 0.05). Similarly, a high correlation was detected between UBM and histology in the number of follicles ≥0.6 mm (17.3 ± 2.3 v. 19.0 ± 1.6; r = 0.96 P &lt; 0.05), and follicle diameter (1.1 ± 0.05 v. 1.1 ± 0.03 mm; r = 0.96; P &lt; 0.05). Interestingly, UBM of each ovary required on average 2 h compared with 30 h for histology. The results validate the accuracy of UBM for assessing rabbit ovaries ex situ, but identify limitations of present ultrasound approaches for examining rabbit ovaries in situ. Supported by the Natural Sciences and Engineering Research Council of Canada. The authors thank D. Nesbitt for assistance with histological procedures.

27 NEW FREEZING METHOD BY PULSED MAGNETIC FIELD EFFECTS; WHOLE OVARIES OF CYNOMOLGUS MONKEYS AND RABBITS

Introduction: There have been 12 birth reports following autotransplantation of frozen thawed ovaries so far. However, the function of frozen thawed ovaries does not last long due to follicle loss during the freezing-thawing and reimplantation process without anastomosis. Our objective was to establish a technique to cryopreserve the entire ovary, improve the recovery rate of ovarian cells, and maintain long-term ovarian function after transplantation. We report the successful transplantation of ovaries in cynomolgus monkeys and rabbits after cryopreservation by pulsed magnetic field effects.

Phosphodiesterase Inhibitor 3-Isobutyl-1-Methyl-Xanthine Affects Ovarian Morphology and Stimulates Reproduction in Rabbits

The aim of our study is to examine the influence of administration of 3-isobutyl-l-methyl-xanthine (IBMX), inhibitor of cAMP and cGMP phosphodiesterases on ovarian functions (folliculogenesis, atresia and luteogenesis), as well as on some reproductive parameters in rabbits whose ovarian cycle and ovulation was induced by gonadotropins. Ovarian cycle and ovulation of control rabbits were induced by PMSG followed by hCG administration. Experimental animals received 20IU/kg PMSG and 35IU/kg hCG together with IBMX (at 5, 25 or 50 μg/animal). After ovulation and mating, the animals were sacrificed. Histological slides of ovaries were prepared, and the presence of follicles and different stages of luteinisation and atresia were evaluated by light microscopy. The pronuclear stage eggs were flushed out from the oviducts and cultured up to blastocyst cell stage. Numbers of ovarian Corpora lutea, ovulated oocytes and oocyte-derived embryos reaching blastocyst stage were determined. Administration of IBMX was able to increase the proportion of luteinised follicles. Furthermore, IBMX treatment promoted occurrence of atresia in the remaining follicles after the gonadotropin treatment. Finally, IBMX increased the number of Corpora lutea, number of harvested zygotes and embryos at blastocyst stage derived from these zygotes after culture. These data demonstrate that IBMX can enhance the stimulatory effect of gonadotropins on the rabbit ovarian follicle luteinisation, atresia, ovulation, zygote and embryo yield and development. Furthermore, they confirm the involvement of cyclic nucleotide-dependent intracellular mechanisms in the control of rabbit reproductive functions and potential practical usefulness of IBMX in improvement of farm animal reproduction and fertility.

Phosphodiesterase inhibitor 3-isobutyl-methyl-xanthine affects rabbit ovaries and oviduct

The aim of our study was to examine the influence of 3-isobutyl-1-methyl-xanthine (IBMX), an inhibitor of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) phosphodiesterases on rabbit reproductive system. The ovarian cycle and ovulation of control rabbits were induced by gonadotropin releasing hormone (GnRH) or equine chorionic gonadotropin (eCG) followed by the human chorionic gonadotropin (hCG) administration. Experimental animals received GnRH together with IBMX (at 50 or 500 μg/animal) or eCG and hCG together with IBMX (at 5 or 257 μg/animal). After mating and insemination, blood samples were collected and analyzed for concentrations of progesterone and estradiol by RIA; some animals from the control and IBMX-treated groups were killed. The presence of follicles at different stages of development was evaluated by a light microscopy. Isolated ovarian fragments were cultured for 2 days. The secretion of progesterone and estradiol was assessed by RIA. The expression of markers of proliferation (PCNA and cyclin B1) and apoptosis (bax) in ovarian fragments was evaluated by Western-blotting. Epithelial cells were isolated from oviducts and cultured for 2 days. The expression of markers of proliferation (PCNA, ERK1,2-related MAP kinase) and apoptosis (bax, bcl-2) in the oviductal cells was evaluated by immunocytochemistry. It was observed, that the ovaries of rabbits treated with IBMX contained more secondary follicles, than control rabbits. Administration of IBMX reduced blood level of progesterone, but did not affect blood estradiol. Fragments of ovaries isolated from rabbits treated with IBMX released more estradiol, but not progesterone, than ovarian cells isolated from the control animals. IBMX injections substantially decreased the expression of the upper (23 kD), but not the bottom (24 kD) fraction of bax. IBMX administration did not affect PCNA, but it caused a decrease in the upper fraction (54 kD) and an increase in the bottom fraction (55 kD) of cyclin B1. Oviductal cells isolated from the IBMX-treated animals, contained less marker of apoptosis – bax (but not bcl-2) and proliferation – ERK1,2-related MAP kinase (but not PCNA) than control animals. These observations demonstrate the involvement of cyclic nucleotide-dependent intracellular mechanisms in control of rabbit reproductive functions: ovarian folliculogenesis, apoptosis, proliferation and steroid hormone release, as well as proliferation and apoptosis of the oviductal cells.

Gonadotropin-regulated expressions of lanosterol 14α-demethylase, sterol Δ14-reductase and C-4 sterol methyl oxidase contribute to the accumulation of meiosis-activating sterol in rabbit gonads

Meiosis-activating sterol (MAS), the intermediate of cholesterol biosynthesis, is an important lipophilic molecule mediating gonadotropins’ action in inducing oocyte meiotic resumptions in various mammalian species. With respect to MAS's physiological relevance during oocyte maturation in the rabbit, early study has demonstrated that luteinizing hormone (LH), but not follicle stimulating hormone (FSH) can induce FF-MAS accumulation facilitating oocyte maturation in rabbits. However, the potential underlying mechanism for the MAS accumulation in the rabbit gonad remained unclear. We hypothesized that differential expression of MAS synthetic and metabolic enzymes would contribute to the timely MAS accumulation in the rabbit gonad. To address this issue, in the present investigation, we first cloned the cDNAs encoding there pre- and post-MAS enzymes, lanosterol 14α-demethylase (CYP51), sterol Δ14-reductase (14-SR) and C-4 sterol methyl oxidase (C4MO), respectively, using rapid amplification of cDNA ends (RACE) cloning, and then performed northern hybridization experiments to explore their expression profiles in the rabbit ovary, testis, and various other tissues. We observed that CYP51 expression was significantly upregulated only by LH/hCG in the antral follicle exhibiting its peak levels in preovulatory follicles; whereas both FSH and LH significantly downregulated 14-SR expression with the progression of antral follicular development. These findings provided here novel evidence that an inverse upregulation of CYP51 and downregulation of 14-SR expression under FSH/LH stimulation functions as the machinery for FF-MAS accumulation in preovulatory follicles prior to ovulation in the rabbit.

Cloning of Rabbit Bone Morphogenetic Protein 15 and Its Expression During &lt;I&gt;in vitro&lt;/I&gt; Maturation of Rabbit Oocytes

Partial cDNA sequence of rabbit BMP15 was cloned by RT-PCR from rabbit ovaries, showing a similarity of 83%−90% with the BMP15 nucleotide sequences in humans, mice, ovine, sheep, cows and pigs. The expression of BMP15 in rabbit cumulus-oocyte complexs during oocytes in vitro maturation (IVM) was measured by fluorescent quantitative RT-PCR method. BMP15 was expressed at low levels in immature oocytes and increased to the highest level at 16 h of IVM, which coincides with the time of cumulus cell expansion, then declined slowly under IVM cultivation. The expression pattern of BMP15 suggested that it might be important in cumulus expansion in rabbits.

Phosphodiesterase inhibitor 3-isobutyl-methyl-xanthine stimulates reproduction in rabbit females

The aim of our study was to examine the influence of 3-isobutyl-1-methyl-xanthine (IBMX), an inhibitor of cyclic adenosine monophosphate and cyclic guanosine monophosphate phosphodiesterases, on the reproductive efficiency of gonadotropin-stimulated rabbits ( Oryctolagus cuniculus, Leporidae, Lagomorpha ). The ovarian cycle and ovulation of control rabbits was induced by pregnant mare serum gonadotropin (PMSG) followed by administration of human chorionic gonadotropin (hCG; first series of experiments) or gonadotropin-releasing hormone (GnRH; second series of experiments). Experimental animals received PMSG and hCG together with IBMX (at 5 or 25 μg/animal) or GnRH together with IBMX (at 50 or 500 μg/animal). After ovulation and mating, in the first series of experiments, animals were killed; the pronuclear-stage eggs were flushed from the oviducts and cultured up to blastocyst cell stage. Numbers of ovarian corpora lutea, ovulated oocytes, and oocyte-derived embryos reaching blastocyst stage were determined. In the second series of experiments, all the animals were kept until parturition, when the pregnancy and birth rate, litter size, and number, viability, and body weight of pups were recorded. IBMX injections at doses of 5 or 25 μg/animal significantly increased the number of ovulations/corpora lutea, harvested zygotes, and embryos derived from these zygotes. Administration of IBMX at doses of 500 μg/animal or 50 μg/animal to nulliparous young animals (4.5 mo of age) significantly increased their pregnancy rate and birth rate, litter size, and litter weight. In multiparous old animals (2 yr of age), IBMX at a dose of 50 μg/animal, but not 500 μg/animal, significantly increased their pregnancy rate and litter size, but not the birth rate, number of pups per female, or litter weight. These data demonstrate that (1) IBMX can enhance the stimulatory effect of GnRH/gonadotropins on rabbit ovulation, oocyte maturation, embryo yield and development, pregnancy and birth rate, and number, viability, and body weight of pups; (2) nulliparous young females (4.5 mo of age) are more sensitive to IBMX treatments than the multiparous old animals (2 yr of age); and (3) cyclic nucleotides–dependent intracellular mechanisms are involved in control of rabbit reproductive functions and IBMX, an activator of these mechanisms, can be a stimulator of reproduction and fertility.

Angiotensin-(1-7) in the Rabbit Ovary: A Novel Local Regulator of Ovulation.

Several studies have shown the presence of the Renin-Angiotensin System (RAS) components in mammalian ovaries and their involvement in events such as follicular development, steroidogenesis, follicular atresia and ovulation. Recently, we have shown in the rat ovary the presence of a novel peptide of this system, the Angiotensin-(1-7). We have also shown the stimulatory effect of Ang-(1-7) on estradiol and progesterone production in ovaries of eCG pre-treated immature rats perfused in vitro. In the present study we determined the presence of Ang-(1-7) as well as of the MAS-receptor in the rabbit ovaries by immunohistochemistry (IHC). Furthermore, we evaluated the effect of Ang-(1-7) in the steroidogenesis and ovulation in rabbit ovary. IHC was carried out using Avidin-Biotin Peroxidase method, in slices of ovaries prefixed with Bouin. Ang-(1-7) and MAS immunoreactivity were observed in interstitial cells and oocytes. Immunoreactivity for Ang-(1-7) and MAS were observed also in theca and granulosa cells of preovulatory follicles in ovaries of eCG pretreated rabbits and in corpora lutea of mated rabbits. In order to verify the effect of Ang-(1-7) in the steroidogenesis and ovulation, immature female rabbits received eCG s.c. injection (50UI) 48h before the experiment. The ovaries of rabbits, anesthetized with Ketamina/Xilazina, were isolated and perfused during 10h in a closed circuit system with medium 199 containing BSA, heparin 0.2UI/ml, insulin 0.02UI/mL. Temperature (37°C), pH (7.4) and pressure are maintained constant. After a 1-hour stabilization period, the first sample of 1.8 mL was withdrawn and Ang-(1-7), A-779, hCG or combinations of them were added to the medium. The concentration of estradiol and progesterone were measured by radioimmunoassay. The oocytes present in the medium were counted using a reverse phase microscope. The ovulatory efficiency was determined by number of oocytes compared to the number of preovulatory follicles present in the ovary. Ang-(1-7) stimulated the estradiol and progesterone production and the effect was blocked by A-779, the specific Ang-(1-7) antagonist. Ang-(1-7) enhanced the ovulatory efficiency and the effect was antagonized by A-779. The ovulation induced by hCG was reduced by A-779, which seems to indicate the participation of endogenous Ang-(1-7) as a mediator of gonadotropins in the ovulatory process. Taken together these results show the involvement of a novel regulatory peptide in the ovulation. Financial Support: CAPES, CNPq, FAPEMIG. (poster)

Male and female equality: still far from goal

Male and female equality: still far from goal

EFFECT OF DIETARY PROTIEN LEVEL ON REPRODUCTIVE PERFORMANCE AND SOME PHYSIOLOGICAL PARAMETERS OF NEW-ZEALAND WHITE RABBIT DOES EXPOSED TO SHORT FEED RESTRICTION PERIOD

This shady aimed to investigate the effect of three levels of dietary protein on reproductive performance of rabbit does exposed to short feed restriction period before the first insemination. Thirty NZW rabbit does, average live body weight of 23479 and about 17 weeks of age, were used. All does were fed restrictively 75% of ad‌IrbiWm for 15 days from 17 to 19 weeks of age. The rabbit does were fed a basal diet containing 16.4% crude protein (0') and 2510 DE Kcal./Kg diet. Three diets were formulated to provide 16.4, 17.6 or 18.9% CP, respectively. At the beginning of 20 weeks of age rabbit does (10 does per level) were randomly assigned to one of the three experimental diets (low, medium or high 0%). At mid pregnancy, three does from each CP level were slaughtered to evaluate genital weight and histcpattiolegical studies. Besides, blood samples were also collected to determine some hematological and hormonal parameters. Results showed that conception rate and the number of services per conception were improved in the medium CP level group compared with the other levels. The values of fitter are and weight at tell were the highest In the high CP level. The RBCs counts were increased by feeding low CP level. The LH and FSH concentrations increased, whi'e 1-3 decreased in medium ce level. The histopathologIcal observations indicated that there were more primary and growing follicles near the outer surface in Urea alboginea in ovaries of rabbit does fed medium CP level. Also, the uterine well of this group had gravid endarnetrium with rich blood vascular supply in serosal layer. It Is concluded that before mating, rabbit does fed diet with 17.6% CP flushing post short feed restriction improved sexual maturity, ovarian activity and decreased fetal mortality.

Progesterone and Preterm Labor—Still No Definite Answers

In 1930, Willard Allen and George Corner named the steroid hormone that they had extracted from rabbit ovaries “progestin” because they believed, rightly, that it helped maintain pregnancy.1 Removal of progesterone, or blockage of its receptors, reliably ends pregnancy at all gestational ages, and in many nonhuman species, falling levels precipitate natural labor.2 Progestins thus have been an obvious candidate treatment for the major health problem of preterm labor. Therapeutic studies in pregnancy have been limited because natural progesterone given orally is rapidly metabolized in the liver, and synthetic progestins that are not rapidly metabolized have androgenic effects, giving rise . . .

Ischemia-reperfusion injury of rabbit ovary and protective effect of trapidil: an experimental study

We aimed to detect the protective effect of trapidil in ischemia-reperfusion (IR) injury due to ovarian torsion and detorsion. Thirty-two pubertal New Zealand albino rabbits were used. Adnexal torsion was created by rotating the left adnexa including the tubal and ovarian vessels in a 360 degrees clockwise direction. Adnexal detorsion was done by untwisting the adnexa. In the IR group, left oopherectomy was performed after 3 h of adnexal torsion and 3 h of adnexal detorsion. In the study group, a 3-h adnexal torsion was performed and trapidil was administered intraperitoneally as a single dose of 40 mg/kg, 1 h before detorsion. The left oopherectomy was performed after a 3-h adnexal detorsion. In the sham group, sham operation was performed followed by left oopherectomy. In the control group, normal ovarian tissue was evaluated. Catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels of ovarian tissue were determined for each group. The values of SOD and GSH-Px activities in the IR group were significantly decreased (P < 0.05). In addition, the MDA level was significantly higher in the IR group (P < 0.01). The trapidil-administered group showed significant increase in the levels of GSH-Px (P < 0.05), catalase (P < 0.05), SOD (P < 0.05), and decreased MDA levels (P < 0.05) compared to those in the IR group. The study has shown that trapidil treatment prevents ischemia induced oxidative damage in the ovarian tissues of rabbits.

Ovulation induced by mucosa vaginal absorption of buserelin and triptorelin in rabbit

The aim of this study was to evaluate the supplementation of semen extender with two synthetic GnRH analogues (buserelin and triptorelin) to induce ovulation in rabbit does submitted to artificial insemination. In a first experiment, 255 receptive multiparous does were inseminated with 0.5 mL of Tris–citrate–glucose extender supplemented or not with two GnRH synthetic analogues. Experimental groups were: NC (not supplemented extender), PC (not supplemented extender and does treated with 1 μg of buserelin i.m.), B2 (2 μg per female buserelin supplemented extender), B5 (5 μg per female buserelin supplemented extender), T2 (2 μg per female triptorelin supplemented extender) and T5 (5 μg per female triptorelin supplemented extender). Thirteen does of NC females ovulated, reaching an ovulation rate similar to the other groups. Ovulation rate was similar in all groups (11.4–12.5). The efficiency of ovulation induction was very low (32.5%) in NC group and showed the higher results in PC females (97.8%). Only B5 females reached similar ovulation induction response than PC group. In a second experiment, 702 receptive does were inseminated to compare fertility and prolificacy parameters from the conventional insemination technique (control group, females treated with 1 μg per female of buserelin intramuscularly) versus a supplementation with buserelin or triptorelin (5 μg per female) in semen extender (B5 and T5 groups, respectively). Fertility and prolificacy parameters were similar among the groups (77.8% fertility rate, 73.9% kindling rate, 9.4 live born and 9.9 total born). This study demonstrate the possibility of ovulation induction in rabbits by adding two GnRH synthetic analogues in the seminal doses and open up new prospects for changing rabbit insemination procedures.

Localization of angiotensin-(1–7) and its receptor mas in the human ovary

Angiotensin (Ang)-(1–7) is a biologically active member of the renin-angiotensin system, which can be generated by processing of Ang I by endopeptidases or of Ang II by the newly characterized Angiotensin Converting Enzyme type 2 (ACE-2), in addition to less specific peptidases. Ang-(1–7) acts through the receptor Mas, a specific G protein-coupled seven transmembrane domain protein receptor encoded by the protooncogene mas. Ang-(1–7) has been identified in rat and rabbit ovaries, where it plays a role in ovulation and ovarian steroidogenesis.

Progesterone and Preterm Labor — Still No Definite Answers

In 1930, Willard Allen and George Corner named the steroid hormone that they had extracted from rabbit ovaries “progestin” because they believed, rightly, that it helped maintain pregnancy.1 Removal of progesterone, or blockage of its receptors, reliably ends pregnancy at all gestational ages, and in many nonhuman species, falling levels precipitate natural labor.2 Progestins thus have been an obvious candidate treatment for the major health problem of preterm labor. Therapeutic studies in pregnancy have been limited because natural progesterone given orally is rapidly metabolized in the liver, and synthetic progestins that are not rapidly metabolized have androgenic effects, giving rise . . .

351 EFFECTS OF FETAL CALF SERUM, GROWTH FACTOR, AND HORMONE SUPPLEMENTATION DURING IN VITRO MATURATION ON PARTHENOGENETIC ACTIVATION AND EMBRYO DEVELOPMENT OF FOLLICULAR RABBIT OOCYTES

Improvement of the in vitro maturation (IVM) system for rabbit oocytes could play a role in rabbit biotechnology. Our goal was to improve IVM to have an efficient source of rabbit oocytes for further studies on nuclear transfer. The effects of FCS, growth factors, and hormone supplementation on oocyte maturation, activation, and embryo development rates were evaluated. Rabbit ovaries were transferred from the slaughterhouse to the laboratory in PBS. Oocytes were collected by aspiration and subjected to IVM in 3 types of media based on TCM-199. In one group, growth factors (50 ng mL−1 of insulin-like growth factor-I and 10 ng mL−1 of epidermal growth factor) and hormones (5 IU mL−1 of hCG and 5 IU mL−1 of pregnant mare serum gonadotropin) and BSA were added to the IVM medium (IVM+); in the other groups, IVM medium was supplemented with either 10% (IVM + 10% FCS) or 20% FCS (IVM + 20% FCS). Maturation was assessed by the presence of a polar body after 16 h. Matured oocytes were activated twice by electric stimuli (3 DC pulses, 1.6 kV cm−1, 60 µs) and twice by chemical activation (incubation with 2.5 mM 6-DMAP for 30 min, second time for 2 h) and cultured in vitro in Earle's balanced salt solution complete medium at 38.5°C under 5% CO2 in air. Cleavage rates were recorded 16 h after activation and the blastocyst rates were recorded at Day 5 of in vitro culture. Data were analyzed by ANOVA. Maturation rates did not differ between the treatment groups (Table 1). There was no significant difference in cleavage rates between the IVM+ and the IVM + 10% FCS groups; however, the cleavage rate of the IVM + 20% FCS group was significantly lower compared with the others (Table 1; P &amp;lt; 0.05). Development to the blastocyst did not differ significantly between the treatment groups (Table 1; P &amp;lt; 0.05). The results showed that high (20%) FCS supplementation during IVM had a detrimental effect on oocyte cleavage. Hormonal and growth factor supplementation had no beneficial effects on maturation, activation rates, or blastocyst formation, and in fact were not essential for in vitro embryo production in the rabbit. Table 1.Effect of hormonal and growth factor supplementation on embryo development in rabbit oocytes The project was supported by RABIOTECH OMFB-00330/2004, EU FP6 (MEXT-CT-2003-509582, and 518240), Wellcome Trust (Grant No. 070246), and TET CH-28/04.