Gonadotropin-releasing Hormone Injection Research Articles

GnRH protective effects against long-term potentiation impairment induced by AANAT-siRNA

There is an interplay between the gonadotropin-releasing hormone (GnRH) and melatoninergic systems. The key enzyme of melatonin synthesis (arylalkylamine N-acetyltransferase, AANAT), and GnRH receptors are expressed in the hippocampus. While it has been shown that hippocampal AANAT enzyme activity is necessary for proper hippocampal cognitive function, their role in long-term potentiation (LTP) induction is not fully understood. In current study, the impact of GnRH on LTP induction was investigated, while hippocampal melatonin synthesis had been inhibited. The melatonin synthesis was inhibited by AANAT-siRNA administration, and LTP was induced using in vivo field potential electrophysiological recording.Animals were divided into 5 groups: Intact, vehicle, siRNA, GnRH and siRNA+GnRH. All animals, except intact group, experienced the stereotaxic surgery and intra-hippocampal cannulation to receive vehicle agent, AANAT siRNA (0.5 μg/hip), GnRH (1 ng/rat), and AANAT siRNA+GnRH. The recognition memory was assessed by Novel object recognition test. The field potential electrophysiology experiment was conducted by stimulating the Schaffer collateral pathway, and LTP induction was carried out through high-frequency stimulation (HFS). After recording, animals' brain was isolated and quickly frozen for further hippocampal melatonin levels measurement by LC-MS and AANAT mRNA levels by qRT-PCR.GnRH injection in the hippocampus increased local AANAT-mRNA expression and melatonin levels. GnRH-treated animals displayed higher LTP amplitude compared to intact, vehicle and siRNA groups. While the reduction in hippocampal melatonin levels by AANAT-siRNA inhibited LTP and impaired recognition memory, the GnRH prevented these adverse effects. The data suggests that GnRH have protective effects against AANAT-siRNA-induced LTP decline. The protective mechanism at least partially, may be related to the increased expression of local AANAT-mRNA.

100 Impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to embryo transfer

Abstract This study aimed to evaluate the impact of luteal blood perfusion and estrus expression on pregnancy rates of beef cows exposed to fixed-timed embryo transfer (FTET). Postpartum beef cows (n = 763) from 22 locations were exposed to a 7-d Select Synch + controlled internal drug releasing (CIDR) and breeding indicator patches were affixed upon CIDR removal. Estrus expression was assessed twice daily for 72 h and a 100-µg injection of gonadotropin-releasing hormone was administered to cows that failed to express estrus 72 h after CIDR removal. Brightness mode ultrasonography of the corpus luteum (CL) was conducted to select recipients for FTET 9 d after CIDR removal. Suitable recipients were assigned to receive a single fresh or frozen embryo derived from either in vitro (IVF) or in vivo (IVD) method. After embryo recipient selection, CL morphometries and blood perfusion (BP) were then assessed at the time of embryo transfer via transrectal ultrasonography. Embryo recipients were categorized according to CL area [small (< 3 cm²), medium (3 to 4 cm²), or large (> 4 cm²)] and based on the percentage of luteal area with blood perfusion signals [low (< 25%), medium (25 to 45%), or high (> 45%)]. Pregnancy diagnoses were performed between d 60 and 90 of gestation. Cows that failed to express estrus prior FTET had decreased (P ≤ 0.02) luteal area, luteal diameter, and pregnancy rates compared with cows that expressed estrus. Luteal area category had no effect (P = 0.61) on pregnancy rates. Embryo recipients that expressed estrus had similar (P = 0.12) luteal blood perfusion compared with recipients that failed to express estrus. Embryo recipients with high (P = 0.02) and medium (P = 0.05) BP had greater pregnancy rates compared with embryo recipients with low BP. There was no interaction between estrus expression and luteal BP (P = 0.84). In summary, estrus expression and luteal BP positively impacted pregnancy rates to embryo transfer and may be used to facilitate embryo recipient selection.

Effect of a Single Injection of GnRH Analog Alone and at the Time of AI on Reproductive Performance of Nili Ravi Buffaloes

Introduction: The gonadotropin-releasing hormone (GnRH) is a decapeptide hormone released from basal neurons of the hypothalamus. It stimulates the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary. The objective of the study was to evaluate the effect of a single injection of gonadotropin-releasing hormone (GnRH) analog at the time of artificial insemination (AI) on buffalo estrus, conception, pregnancy, and calving rate. Materials and methods: The anestrus nulliparous Nili Ravi buffalo heifers (n=80) were divided into 4 groups randomly. Group A (n=20) received only a single injection of GnRH analog at start of the experiment (Day 0), group B (n=20) received a single injection of GnRH analog at Day 0 and prostaglandine (PGF2α) at Day 7, group C (n=20) received progesterone sponge for 7 days, and group D (n=20) received progesterone sponge for 7 days and PGF2α at Day 9. In 2nd study, buffaloes (n=60) expressing first (n=20), second (n=20), and third (n=20) postpartum estrus were enrolled. Moreover, heifers (n=20), expressing estrus first time were also included. Animals (n=10) from each group, received a single injection of GnRH analog at the time of AI were named as treatment group and the control (n=10) did not receive any treatment. Pregnancy tests were performed with the help of ultrasound on days 35 and 65 post-AI. Results: The pregnancy and calving rates were lower in GnRH group compared to other treatments. Similarly, the administration of GnRH analog did not increase pregnancy rates in treatment groups. Conclusion: The single injection of GnRH analog alone at the time of AI did not improve the reproductive performance of buffaloes.

Improving the efficiency of estrus synchronization in cows.

This study aimed to determine the effects of biologically active substances and electrical stimulation of the uterus in cows on the effectiveness of estrus synchronization. Ninety (n = 90) Kazakh white-headed cows were synchronized with two injections of gonadotropin-releasing hormone on days 0 and 9 and prostaglandin F2α on day 7. The cows were divided into six groups and, during the protocol, treated with biologically active substances (Tetramag, Selevetum, antiseptic-stimulator Dorogov 2 fraction, groups 2, 3, and 4). Cows in groups 5 and 6 were treated with the same substances but additionally had electrical stimulation of the uterus, while cows in group 1 were left untreated and served as a control. The results have shown that on Day 0, no differences were observed in E2 concentrations between the groups. However, on the 10th day, a significant disparity was noted in the E2 level among cows in group 6 compared to groups 2, 3, 4, and the control group. Conversely, no significant differences were observed between groups 5 and 6. Likewise, the fertility rate in cows from group 6 was significantly higher compared to groups 2, 3, 4, and the control group, with no significant differences between groups 5 and 6. It can be concluded that the utilization of electrical stimulation of the uterus and the inclusion of certain biological substances during the estrus synchronization protocol demonstrate a positive effect on the reproductive performance of beef cattle in Kazakhstan.

EFFECT OF GONADOTROPHIN RELEASING HORMONE ON FOLLICULAR DYNAMICS, LUTEINISING HORMONE, AND PROGESTERONE LEVELS IN BUNAJI COWS

This study evaluated the ovarian and hormonal responses of Bunaji cows to ovsynch protocol initiated at random oestrus cycle stages. Fifteen animals were arranged into three groups and treated as follows: control (n=5), 2mL normal saline; group A (n=5), 50mg Gonadotrophin releasing hormone (GnRH) on day 0 and day 9 followed by 500mg of Prostaglandin F2 alpha (PGF2a) on day 7; and group B (n=5) 100mg of GnRH on day 0 and day 9 followed by 500mg PGF2a on day 7. Ultrasound examination of the ovaries was carried out daily from d 1 to d 9 and, thereafter every 12h until ovulation was detected. Blood sampling was carried out at 30 min intervals for 6 h following the GnRH administration for determination of serum luteinizing hormone (LH) and once daily for 12 days after the injection of the first GnRH to determine plasma progesterone concentration. The ovarian response of the treated groups showed no significant difference between the two dosages of ovsynch protocol but differed significantly between the treated and the control groups. Peak values of serum LH obtained on day 0 and day 9 of GnRH administration differed significantly (P<0.05). Plasma progesterone increased among treated groups following injection of GnRH reaching a peak on day 7 compared to control, but did not differ among treated groups. In conclusion, GnRH at 50 mg and 100 mg was able to elicit adequate LH and progesterone responses that caused the disappearance of dominant follicles and, subsequent ovulation thereby increasing the reproductive efficiency of Bunaji cows.

PSII-12 Influence of Dietary Methionine and Guanidinoacetic Acid on Estrous Cycles and Early Pregnancy in Beef Heifers

Abstract Interest is growing in methods to apply precision nutritional supplements strategically during the peri-conceptual period to enhance progeny performance of beef females. Studies where supplemental methionine (MET) was provided to bovine females in the peri-conceptual period demonstrated epigenetic modifications in muscle of the progeny. Guanidinoacetic acid (GAA) has been fed directly to livestock to increase creatine synthesis, but has not been evaluated for use in fetal programming. We fed MET and GAA to cross-bred heifers during the peri-conceptual period as a 2 x 2 factorial design to influence carcass characteristics of their steer calves. It was, therefore, important to determine if the interactions of dietary MET and GAA in the peri-conceptual period would alter reproductive efficiency. The null hypothesis was that these supplements would not alter reproductive efficiency of beef heifers when fed in the peri-conceptual period. Heifers were divided into four breeding groups for management purposes. On day -63, heifers (n = 20/diet, age = 384.1 ± 1.1 d) were assigned HeatTime collars and individually fed MET (10 g/d), GAA (40 g/d), the combination (MET + GAA), or ground corn carrier (CON) for 126 days. On day -9, heifers received 100 mg of gonadotropin releasing hormone and a CIDR. On day -2, the CIDR was removed and luteolysis was initiated with 25 mg of prostaglandin F2a. All heifers were inseminated with male sexed semen from a single sire and administered a second 100 mg injection of gonadotropin releasing hormone on day 0. On day 63, a blood sample was collected from all pregnant heifers (CON n = 10; MET n = 8; GAA n = 7; MET + GAA n =10) to evaluate circulating progesterone concentrations. Reproductive tracts were collected to determine CL weight, gravid uterine weight, and placentome number. Data were analyzed using the MIXED procedure of SAS with group, MET, GAA, and the interaction of MET and GAA as fixed effects. Days to first estrus were greater and number of estrus events prior to synchronization were fewer in CON heifers compared with supplemented heifers (P < 0.05). Luteal weight tended to be greater in heifers supplemented with MET compared with CON and GAA heifers (P = 0.09), but peak intensity of estrus, concentration of progesterone at day 63 of pregnancy, gravid uterine weight, and placentome number did not differ due to diet (P > 0.10). Supplementation with MET or GAA may improve onset of puberty but does not negatively alter reproductive performance in cross-bred beef heifers. These supplements can be used for fetal programming of muscle development in steer progeny without negatively impacting reproductive performance in the breeding herd. USDA is an equal opportunity provider and employer. Funded in part by USDA-NIFA-AFRI # 2022-67015-36196.

PSIV-17 Postnatal Obesity Amplifies Gnrh-Induced Lh Release in Prenatal Testosterone-Treated Female Sheep

Abstract Polycystic ovary syndrome (PCOS) is the most common hormonal disorder in females of reproductive age. Hypersecretion of luteinizing hormone (LH), partly due to increased pituitary sensitivity to gonadotrophin-releasing hormone (GnRH), is a significant cause of infertility in women with PCOS. Moreover, obesity amplifies the severity of reproductive dysfunction in PCOS. In sheep, testosterone (T) excess during gestational days (GD) 30 to 90 results in GnRH-mediated LH hypersecretion and recapitulates the PCOS phenotype. This study investigated 1) if mid-gestation (GD 60 to 90) is the susceptibility window for programming pituitary hypersensitivity to GnRH, and 2) the contribution of postnatal obesity in modulating LH responsiveness to GnRH. Suffolk ewes received T propionate (T; 100 mg i.m.) or corn oil (C; vehicle) twice weekly from GD 60 to 90 (term = 147 d). At 5 mo of age, T lambs were assigned randomly to either a maintenance (100% of NRC requirements) or overfed diet (130% of NRC requirements), and Control lambs were fed the maintenance diet. During the anestrous period (late summer), ewes (n = 8/group; ~17 mo of age) received a GnRH bolus injection (2 ng/kg) intravenously every 1.5 h and blood samples were collected at 15-min intervals for a 6-h period. Despite animals being in seasonal anestrous, few endogenous LH pulses were evident during the 6 h-sampling period. To avoid confounding, only clear responses to GnRH challenge that occurred within 15 to 45 min after each GnRH injection were considered for further analyses. Mean number of exogenous GnRH-induced LH responses that met these criteria did not differ between groups and averaged 1.81 ± 0.27 pulses/animal. The parameters of these GnRH-induced responses were analyzed as one-way ANOVA with Tukey’s HSD post-hoc analysis. Mean LH pulse peak was greater (P < 0.05) in T overfed ewes (4.59 ± 0.49 ng/mL) compared with T maintenance (2.19 ± 0.61 ng/mL) and Control ewes (2.58 ± 0.53 ng/mL). Additionally, amplitude of LH pulses was greater (P < 0.05) in T overfed ewes (2.66 ± 0.39 ng/mL) compared with T maintenance (1.03 ± 0.48 ng/mL) and tended (P = 0.089) to be greater in T overfed compared with Control ewes (1.41 ± 0.42 ng/mL). LH pulse peak and amplitude in T maintenance did not differ from Control ewes. In conclusion, failure of GD 60 to 90 T treatment to increase GnRH responsiveness as opposed to our earlier finding of increased responsiveness in GD 30 to 90 T-treaded sheep indicates that the susceptibility window for programming pituitary hypersensitivity to GnRH lies between GD 30 to 60. Postnatal obesity may act as an independent activational signal in amplifying the pituitary sensitivity to GnRH in female sheep. This premise is supported by observations that obesity exacerbates pituitary-mediated LH hypersecretion in women with PCOS. Research support: NIH-NICHD (R01HD099096).

Mechanisms and predictors of menses resumption once normal weight is reached in anorexia nervosa

BackgroundIn cases of Anorexia Nervosa (AN), achieving weight gain recovery beyond the lower limits set by the World Health Organization and normalizing classical nutritional markers appears to be essential for most patients. However, this is not always adequate to restore menstrual cycles. This discrepancy can cause concern for both patients and healthcare providers, and can impact the medical management of these individuals. Thus, the purpose of this study was to assess the ability of anthropometric and hormonal factors to predict the resumption of menstrual cycles in individuals with anorexia nervosa upon reaching a normal body weight.MethodPatients with AN who had achieved a normal Body Mass Index but had not yet resumed their menstrual cycles (referred to as ANRec) were evaluated on two occasions: first at visit 1 and then again 6 months later, provided their body weight remained stable over this period (visit 2). Among the 46 ANRec patients who reached visit 2, they were categorized into two groups: 20 with persistent amenorrhea (PA-ANRec) and 26 who had regained their menstrual cycles (RM-ANRec). Anthropometric measurements, several hormone levels, Luteinizing Hormone (LH) pulsatility over a 4-h period, and LH response to gonadotropin-releasing hormone injection (LH/GnRH) were then compared between the two groups at visit 1.ResultsPatients in the RM-ANRec group exhibited higher levels of follicular stimulating hormone, estradiol, inhibin B, LH/GnRH, and lower levels of ghrelin compared to those in the PA-ANRec group. Analysis of Receiver Operating Characteristic curves indicated that having ≥ 2 LH pulses over a 4-h period, LH/GnRH levels ≥ 33 IU/l, and inhibin B levels > 63 pg/ml predicted the resumption of menstrual cycles with a high degree of specificity (87%, 100%, and 100%, respectively) and sensitivity (82%, 80%, and 79%, respectively).ConclusionsThese three hormonal tests, of which two are straightforward to perform, demonstrated a high predictive accuracy for the resumption of menstrual cycles. They could offer valuable support for the management of individuals with AN upon achieving normalized weight. Negative results from these tests could assist clinicians and patients in maintaining their efforts to attain individualized metabolic targets.Trial registrationIORG0004981.

Effect of the GnRH stimulation test on Canine Prostatic-Specific Esterase (CPSE).

The gonadotropin-releasing hormone (GnRH) stimulation test is used to investigate testicular production of testosterone (T) when performing a breeding soundness examination. In male dogs with fertility problems, the prostate should also be investigated as prostatic conditions may frequently lower semen quality. Serum concentrations of canine prostatic-specific esterase (CPSE) increase in dogs with benign prostatic hyperplasia (BPH). When performing a breeding soundness examination in a male dog, GnRH administration is frequently done at the beginning of the process and then both T and CPSE are assayed on the same serum sample collected 1 h following the GnRH injection. The aim of this study was to assess whether or not the administration of GnRH may alter CPSE concentrations in dogs with a healthy prostate. Twenty-eight client-owned intact adult male dogs were included in the study. Following a 7-day sexual rest all male dogs underwent a clinical examination and an ultrasonographic examination of the prostatic gland. Prostatic size and parenchyma of every tested dog were evaluated by ultrasonography to assess prostatic conditions. Two different GnRH stimulation protocols were used, A = gonadorelin 50μg/dog SC (n = 15) and B = buserelin 0.12 μg/kg IV (n = 13). T and CPSE concentrations were measured before and 1 h after GnRH administration by a laser-induced fluorescence analysis. Buserelin and gonadorelin were equally effective in causing a significant increase in serum T concentrations in the post GnRH sample. When considering the 28 dogs together, CPSE concentrations did not change following the stimulation test with either GnRH compound; however, in 4/28 cases, the post GnRH value was markedly increased to values compatible with a diagnosis of BPH. There was no difference in the action of buserelin or gonadorelin in causing an increase in serum T concentrations. CPSE secretion was increased in approximately 15% of dogs treated with either buserelin or gonadorelin. Therefore, whenever performing diagnostic testing in intact male dogs, CPSE should not be assayed on a post-GnRH serum sample.

Effect of oestrus synchronisation through ovulation delay by vaccination against foot-and-mouth disease in Hanwoo (Bos taurus coreanae) cows.

In Korean cattle, after foot-and-mouth disease (FMD) vaccination, anovulation increases, acute immune response is stimulated. Here, we aimed to improve the fertility rate by ovulation delay caused by the foot-and-mouth disease vaccine. 160 cows (control, FMD, FMD+Gn250 and FMD+Gn500 groups, with 40 cows each) were used. We analysed the ovulation delay, ovulation rate, conception rate and acute-phase immune responses. In the group vaccinated only with FMD, the average follicle size was maintained at 12mm and ovulation was delayed. The ovulation rate of the FMD+Gn500 group (500μg gonadotropin-releasing hormone (GnRH) injections 3 days after the FMD vaccination) was the highest at 81.8%. The ovulation rate of the FMD+Gn250 group (250μg GnRH injections 3 days after FMD vaccination) was 54.5%, and that of the control group (not FMD vaccinated) was 53.3%. The conception rate was 52.5% (19/40) in the control group, 37.5% (15/40) in the FMD+Gn250 group, and 67.5% (27/40) in the FMD+Gn500 group. Analysis of acute-phase immune response revealed that the plasma contents of haptoglobin and serum amyloid A increased up to 7 days after vaccination against FMD in all the experimental groups, except the control group. We concluded that ovulation delay can be employed to improve conception rate after FMD vaccination through a modified ovulation synchronisation method with GnRH.

Efficacy of a modified Double-Ovsynch protocol for the enhancement of reproductive performance in Hanwoo cattle.

We aimed to evaluate the efficacy of a modified Double-Ovsynch protocol vs artificial insemination following estrus detection (AIED) for the enhancement of reproductive performance in Hanwoo cattle. Four hundred twelve Hanwoo cows were allocated to two treatment groups. The first group of cows were administered gonadotropin releasing hormone (GnRH) on Day 36 (±0.6), prostaglandin F2α (PGF2α) on Day 46 (8 to 12 days later), and GnRH on Day 49, which was followed by Ovsynch, consisting of an injection of GnRH on Day 56, PGF2α on Day 63, and GnRH 56 h and timed AI (TAI) 16 h later (modified Double-Ovsynch group, n = 203). The second group of cows underwent AIED (AIED group, n = 209) and were designated as controls. The pregnancy per AI 60 days after the first AI was higher in the modified Double- Ovsynch (68.5%) than in the AIED (56.5%) group, resulting in a higher probability of pregnancy per AI (odds ratio: 1.68, p<0.05). Moreover, cows in the modified Double- Ovsynch group were more likely (hazard ratio: 1.28, p<0.05) to be pregnant by 150 days after calving than cows in the AIED group, and this difference was associated with a lower mean number of AIs per conception (1.27 vs 1.39, p<0.05) and a shorter median interval between calving and pregnancy (72 vs 78 days, p<0.1). The modified Double-Ovsynch protocol, adjusted according to the herd visit schedule, can be readily used to increase the pregnancy per AI following the first AI and to shorten the interval between calving and pregnancy in beef herds.

Exogenous gonadotropin releasing hormone (GnRH) modulates scrotal and testicular biometrics, libido, endocrinological and heamatological profiles in Ganjam goat under humid tropical coastal ecosystem of Odisha

Objective: To assess the effect of exogenous gonadotropin releasing hormone (GnRH) in libido, scrotal and testicular biometrics, endocrinological and heamatological profiles of Ganjam goat buck during winter and pre-monsoon seasons. Methods: Forty eight healty Ganjam goat bucks of 3-4 years old were equally divided into the control and treatment groups. The control group received distilled water as placebo, while the treatment group received GnRH injection (4 μg Buserelin acetate/mL) once a week for four months. Body weight, scrotal circumference and testicular parameters (testicular volume, testicular weight and testis index), endocrinological profiles [follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone], sex behavioural profiles (libido score, mating ability score, and sex behavioural score) and heamatological profiles (red blood cells, white blood cells, haemoglobin, and packed cell volume) were estimated. Results: The libido, scrotal and testicular biometrics, and endocrinological profiles significantly differed between the control and GnRH-treated bucks within and between the seasons within the two groups (P&lt;0.05). Body weight, scrotal circumference, testicular volume, testicular weight, testis index, FSH, LH, testosterone, libido score, mating ability score, sex behavioural score, red blood cells, haemoglobin and packed cell volume were significantly higher in the GnRH-treated bucks compared to the control bucks in pre-monsoon and winter seasons (P&lt;0.05). Body weight, scrotal circumference, testicular volume, testicular weight, testis index, FSH, LH, testosterone, libido score, mating ability score, sex behavioural score, red blood cell counts (in treatment), and haemoglobin were significantly higher in pre-monsoon compared to winter season in the experimental groups (P&lt;0.05). The white blood cell counts neither differed between seasons nor between the two groups. Conclusions: Exogenous GnRH supplementation and pre-monsoon season have higher beneficial effects in improvement of endocrinological profiles with cascading beneficial effects on scrotal circumference, testicular volume, testicular weight, and sex behavioural profiles, which in turn will improve the sperm production and its cryo-survivability and fertility rate in Ganjam goat.

Evaluation of hormonal protocols for induction of synchronized estrus on reproductive indices in Kangal-Akkaraman ewes during the outbreeding season

The objective of this study was to assess the effect of human chorionic gonadotropin (hCG) and gonadotropin-releasing hormone (GnRH) treatment before sponge insertion and anti-Müllerian hormone (AMH) concentration in ewes which were either pregnant or non-pregnant during the previous breeding season. In the study, 375 (3–6-year-old) Kangal-Akkaraman ewes that conceived or did not conceive in the preceding breeding season, and 36 rams (3–6-year-old) were used. The sheep were randomly divided into 5 equal groups. Blood samples were taken before stimulation (day −4), the day stimulation was initiated (day 0), after stimulation (day 9), on the mating day (days 11–12). AMH concentrations were measured in the samples taken on − 4th day. As a conventional method, a sponge containing 20 mg of flugeston acetate (Chronogest® CR, MSD, Turkey) was placed intravaginally (day 0) into to study ewes. The ewes were intramuscularly administered 131.5 µg prostaglandin F2α (Estrumate, MSD, Turkey) and 600 IU equine chorionic gonadotropin (Chronogest® PMSG 6000, MSD, Turkey) simultaneously with sponge removal 9 days after insertion. No other treatment was applied to group 5 which served as control. Ewes in groups 1, 2, and 3 received an intramuscular injection of GnRH (4.2 µg of Buserelin acetate, Receptal, MSD, Turkey) at the time of insertion of progesterone sponge. GnRH or 600 IU hCG (Chorulon®, MSD, UK) was administered 4 days prior to sponge insertion for the ewes in the groups 2, and 3, respectively. As for the group 5 group, hCG (instead of GnRH) was administered to the ewes at the beginning of the progesterone treatment. Ewes in estrus were detected with a teaser ram and taken into a different pen with rams. Transrectal ultrasonography (Mindray DP50/Vet/US, rectal probe) was achieved during days the 30–35 following mating. Transabdominal ultrasonography was achieved during days 60–65 to detect late embryonic and early fetal death. The estrus rate was 71.19 % out of breeding season for all ewes. The pregnancy rate on day 30 post-mating was 32 % in the control group and was 31.00 %. No significant differences were observed between groups for pregnancy rates on day 30. The mean pregnancy rate in sheep that conceived and did not conceived in the preceding breeding season of the study was 32.03 % and 32.06 % respectively (P > 0.05). After treatments, AMH concentrations in non-pregnant were significantly higher than pregnant ewes (P < 0.005). In conclusion, although the AMH concentration is significantly higher in non-pregnant ewes, the AMH concentration may not be a suitable biomarker to predict induction success outside breeding season. Progesterone-based protocols may achieve an acceptable reproductive outcome in lactating ewes and the ones which experienced infertility.

The Steroid Hormone Profile in Etawah Crossbreed Goat While Ovulation Induced using The Selectsynch Method

This study aimed to provide alternative information and solutions in an effort to increase reproductive productivity in etawah crossbreed goats (PE). The sample used in this study was 10 female PE with an average age of 2.5 - 3 years and primiparous at least . Ovulation induction was performed using 0.1 mg intra-muscular Gonadotropin-Releasing Hormone (GnRH), after seven days injection of Prostaglandin F2α (PGF2α) was given as much as 2.5 mg submucosa of the vulva, followed by a second injection of GnRH as much as 0,2 mg intramuscular in samples that have really experienced heat and selected selectively according to the signs of natural heat shown by the sample and followed by insemination as much as 2 doses or 0.50 ml of frozen semen. Blood sampling was performed at H0, H7th, H14th and H21th after insemination. All blood samples were collected and progesterone and estrogen hormone profiles were examined using the ELISA method. From the results of the ELISA test, the mean progesterone hormone profile H0 = 4.798 ng / ml, H7th = 4.887 ng / ml, H14th = 4.824 ng / ml, H21th = 5.148 ng / ml. The profile of the hormone estrogen at H0 = 19,461 pg / ml, H7th = 17,457 pg / ml, H14th = 18,248 pg / ml, H21th = 17,515 pg / ml. This study showed an increase in the levels of the progesterone hormone at H0 to H7th, then slightly decreased in H14th and a significant increase in H21th. For the estrogen hormone, there is a decrease from H0 to H7th then there is a slight increase in H14th and decreases again in H21th.

Relationship between reproductive hormones and migration distance in a polygynous songbird, the Red-winged Blackbird (Agelaius phoeniceus)

Many bird species migrate to southern overwintering locations to avoid harsh conditions at their breeding grounds, but at the cost of an energetically demanding migration that may delay their spring reproductive development. Previous work on the relationship between migration distance and reproductive readiness has primarily focused on early season baseline testosterone in both males and females. However, for females, testosterone alone may not be the appropriate measurement of reproductive development. Estradiol, a metabolite of testosterone that is essential for breeding behaviors and reproduction, should also be measured. Furthermore, baseline testosterone varies throughout the day and may change due to social interactions that occurred prior to sampling. Injection of gonadotropin-releasing hormone (GnRH) elicits an individual’s maximum potential testosterone production, minimizing daily and social variation. We explored relationships between migration distance and reproductive status after arrival to the breeding ground in Red-winged Blackbirds (Agelaius phoeniceus). We predicted that individuals that travel a shorter distance will have higher levels of reproductive hormones upon arrival given they are able to invest less in migration and more in reproduction. This is important because individuals that breed earlier often have higher reproductive success. In females, we measured baseline estradiol and testosterone. In males, we assessed baseline and GnRH-induced testosterone. Hormone values were related to migration distance, estimated by stable isotope analysis of claw samples collected before breeding began in eastern North Dakota. We found that males with shorter inferred migration distances have higher baseline testosterone upon arrival. However, inferred migration distance was not correlated with GnRH-induced testosterone. Female inferred migration distance was not correlated with baseline testosterone, but it was correlated with baseline estradiol. Females with higher testosterone had lower estradiol, suggesting that testosterone in females is not a reliable indicator of estradiol levels, thus readiness to breed. Our observations suggest that baseline hormone levels were related to migration distance, but baseline testosterone alone may not provide a complete assessment of a male or female’s preparedness to breed following spring migration.

Characterizing seasonal transitions: Breeding-like morphology and behavior during the late non-breeding season in green anole lizards

Seasonally breeding animals, such as green anole lizards (Anolis carolinensis), allow for the examination of the control of reproduction during different reproductive states. During the breeding season, the gonads are large and reproductively active. Following the breeding season, gonads regress and become less active, and the lizards enter a refractory period where breeding is inhibited. After this stage, a post-refractory period occurs during which the lizards are still in a non-breeding state, but environmental changes can trigger the onset of breeding. However, it is unclear what causes these changes in reproductive state and we hypothesized that this may be due to alterations in gonadotropin-releasing hormone (GnRH) signaling. The present study aimed to identify morphological and behavioral differences in GnRH- and saline-injected refractory and post-refractory male anoles when housed under the same non-breeding environmental conditions. We found that post-refractory anoles had increased testicular weight, recrudescence, sperm presence, and reproductive behavior, with no impact of GnRH injection. Renal sex segment size and steroidogenic acute regulatory protein (StAR) mRNA levels did not differ among groups, indicating that testosterone levels likely had not increased in post-refractory lizards. Post-refractory anoles in this study were beginning to transition towards a breeding state without exposure to changing environmental conditions, and GnRH was not necessary for these changes. These data reveal a complex interaction between the activation of breeding, changing environmental conditions, and the underlying physiology regulating reproduction in seasonally breeding lizards. Future studies are needed to further elucidate the mechanisms that regulate this relationship.

Characteristics of Libido and Testosterone Concentration of Polled and Horned Bali Bulls after GnRH Injection

Bali cattle are one of the original Indonesian germplasm, which in its development were found to be hornless or polled. Polled are Balinese cattle whose horns do not grow naturally, but have the same characteristics as those with horns. However, there are indications that polled have a lower libido. The purpose of this study was to determine the characteristics of libido and testosterone concentration after gonadotrophin releasing hormone (GnRH) injection. In this study each of 7 male polled and horned Bali cattle aged 3.5-6 years were used. Libido characteristics were observed by recording the first time the male fondled the teaser until ejaculation, while the testosterone concentration was measured using blood plasma taken on day 0 or before injection, day 7&lt;sup&gt;th&lt;/sup&gt;, and day 14&lt;sup&gt;th&lt;/sup&gt; after GnRH injection. Testosterone analysis used enzyme linked immunosorbent assay (ELISA) method. The results showed that the libido of polled was not different (P&amp;gt;0.05) compared to that of the horned on the 0, 7&lt;sup&gt;th&lt;/sup&gt; and 14&lt;sup&gt;th&lt;/sup&gt; days after GnRH injection. However, in polled on the 7&lt;sup&gt;th&lt;/sup&gt; day after GnRH injection, it was significantly lower than on day 0 and 14, but on day 0 it was not different with day 14. Testosterone concentration on day 7 after injection of GnRH was not different (P&amp;gt;0.05) compared to day 0 both in polled and horned bulls, but on day 14 after injection was significantly higher (P&amp;lt;0.05) in horned than polled. In conclusion, polled and horned Bali bulls had high libido with a score of +1, but on the 7&lt;sup&gt;th&lt;/sup&gt; day after GnRH injection, polled had lower libido than horns. The testosterone concentrations of polled and horned on day 7 after GnRH injection were not different compared to day 0, while the 14&lt;sup&gt;th&lt;/sup&gt; day was higher in horned bull.

Estrus characteristics, ovarian response to synchronization hormones, and fertility of crossbred dairy heifers managed under a semi-intensive system

This study aimed to characterize estrus sign/s which best predict the time of ovulation and determine ovarian responses to different synchronization protocols and conception rates to fixed-time artificial insemination in Boran*Holstein crossbred heifers. In the first part of the study, twenty-seven heifers were observed for estrus signs (from induced and natural) and the relationship of various estrus signs with ovulation time was evaluated by using ultrasonography. In the second part, 91 Boran*Holstein crossbred heifers were randomly grouped into three groups. Group one heifers (n=28) received 100μg gonadotropin-releasing hormone (GnRH) on day zero (D0), 500μg prostaglandin F2α (PGF2α) on day 7 and 100μg of GnRH on day 9. Group 2 heifers (n=32) were treated as group one but additionally received progesterone as controlled internal drug release (CIDR). Group three heifers (n=31) were treated as those in group 2 but without injection with GnRH on day 0. In all the 3 groups’ insemination was made at 19h of the second GnRH. The results showed that irrespective of estrus source type (induced or natural), score for standing to be mounted, mounting other heifers, and non-receptive mount by other heifers showed a strong positive correlation with ovulation time (r=0.67, P&lt;0.05). Standing estrus duration, and time elapsed from standing estrus to ovulation were shorter (P&lt;0.05) in induced estrus. The conception rate was 39.3% in synchronized ovulation in the absence of CIDR. The conception rate in timed insemination was 56.3% when ovulation was synchronized by combining CIDR, PGF2α, and GnRH. In conclusion injection of GnRH on day zero together with treatment with CIDR improved ovulation rate, the number of new corpus luteum, and conception rate. Heifers that ovulated within the first 24h after timed insemination had a higher (P&lt;0.05) conception rate than heifers ovulated after 24h of timed insemination. Cycling heifers at day zero had a greater (P&lt;0.05) conception rate than non-cycling.

Possible roles of gonadotropin-releasing hormone (GnRH) and melatonin in the control of gonadal development of clam Ruditapes philippinarum

Gonadotropin-releasing Hormone (GnRH) is a key reproductive endocrine regulator, and melatonin is considered as a potent candidate in the regulation of photoperiod-related reproductive endocrinology. Nevertheless, their function during gonadal development of molluscs has not been uncovered yet. In the present study, RNAi of GnRH and melatonin injection were conducted on marine bivalve manila clam Ruditapes philippinarum. Tissue section showed that gonadal development was significantly inhibited in male clams injected with GnRH dsRNA for 21 days. For GnRH RNAi treatment group, the expression levels of steroid synthetic enzyme genes 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), cytochrome P450 (CYP3A) and melatonin receptor homolog (MTNR) gene were significantly down-regulated in female clams while significantly up-regulated in male clams. In melatonin injection group, the expression of GnRH was significantly inhibited and the expression of 3β-HSD, 17β-HSD, CYP3A and MTNR genes also increased which was in line with the GnRH dsRNA injection group in male clams. These results suggest that melatonin may affect GnRH expression and both have effects on gonadal development of bivalves. This study provides evidence for understanding the effects of melatonin and GnRH on reproductive endocrinology and gonadal development in bivalve molluscs.

Induction of ovulation after artificial insemination in rabbits: Intramuscular injection of gonadotropin-releasing hormone (GnRH) agonist vs. intravenous administration of mated doe serum

BACKGROUND: Rabbits are reflex ovulators with the ovulatory process triggered by neuro-hormonal impulses generated during natural mating. When applying artificial insemination (AI), an array of biostimulation techniques and/or exogenous hormones (e.g., gonadotropin-releasing hormone (GnRH) or its analogues) must be used to induce ovulations in female rabbits. However, the effectiveness of various biostimulation techniques and exogenous hormones is not always satisfactory and the use of GnRH analogues is additionally associated with high production costs. Therefore, developing an alternative inexpensive, efficient and safe treatment for the induction of ovulation in artificially inseminated does is urgently needed. OBJECTIVES: In the present study, we examined and compared the effects of mated doe serum (MDS) and GnRH analogue (Gonadorelin) administered immediately after artificial insemination on circulating concentrations of luteinizing hormone (LH) and fertility in New Zealand does. METHODS: Forty artificially inseminated does were allocated to four equinumerous groups that received: 0.2 ml of saline i.m. (Control G), 0.8 µg of Gonadorelin dissolved in 0.2 ml of saline i.m. (Treatment G), 2.5 ml of mixed sex normal rabbit serum i.v. (Control M) or 2.5 ml of mated doe serum (MDS)/doe i.v. (Treatment M). RESULTS: A peak in systemic LH concentrations occurred earlier in Treatment M compared with Treatment G does (71 vs. 107 min post-AI, respectively; P≤ 0.05); mean LH concentrations did not vary (P≤ 0.05) from the pre-AI values in both control groups. Serum LH concentrations remained higher (P≤ 0.05) in Treatment M compared with Treatment G does from 30 to 90 min post-AI but they were greater (P≤ 0.05) in Treatment G than in Treatment M group at 120 and 160 min after AI. Gonadorelin and MDS injections both resulted in the same kindling rate (80%) at each of the four consecutive AI’s (initiated 30 days post-partum) and they were significantly greater than those recorded in control animals (20%). CONCLUSION: It can be concluded that MDS administration is an effective treatment to induce ovulations in rabbits, with the repeatability like that achieved with a GnRH analogue.