Reproductive parameters of dairy goats submitted to estrus synchronization with prostaglandin F2a associated or not to hCG at estrous onset

Coodernação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES)

Assessment of micronucleus frequency in the peripheral blood of female rats in persistent estrus treated with selective estrogen receptor modulators

The aim of this study was to evaluate micronucleus (MN) frequency in polychromatic erythrocytes (PCE) of female rats in persistent estrus (a model developed to mimic polycystic ovary syndrome) treated with selective estrogen receptor modulators (SERMs, tamoxifen, and raloxifene). Forty female Wistar-Hannover rats were divided into four groups of 10 animals each: Group I (normally cycling rats) and Group II (persistent estrus) both received only vehicle, while Group III (persistent estrus) was treated with tamoxifen (250 mu g/animal/day) and Group IV (persistent estrus) was treated with raloxifene (750 mu g/animal/day). Tamoxifen and raloxifene were given by oral gavage beginning on postnatal day 90 and continuing for 30 consecutive days. Peripheral blood samples were collected from tails 1 day following the last exposure. Blood smears were made on glass slides and stained with 10% Giemsa solution. ANOVA and a Tukey post-hoc test were used for data analysis. Mean percentages of MN were 1.82 +/- 0.13, 5.20 +/- 0.24, 3.32 +/- 0.13, and 3.04 +/- 0.12 in Groups I, II, III, and IV, respectively. The results indicate that tamoxifen and raloxifene similarly reduced the formation of MNPCE of female rats in persistent estrus (P < 0.0001 for Groups III and IV vs. Group II), using the dosages and time periods applied in the present study. The data suggest possibly antimutagenic effects of SERMs under high levels of estrogens. The findings also suggest that this is an interesting animal model for studying the genotoxicity of estrogens. Environ. Mol. Mutagen. 2012. (C) 2011 Wiley Periodicals, Inc.

An in vitro study on spontaneous myometrial contractility in the mare during estrus and diestrus

Uterine smooth muscle specimens were collected from euthanatized mares in estrus and diestrus. Longitudinal and circular specimens were mounted in organ baths and the signals transcribed to a Grass polygraph. After equilibration time and 2 g preload, their physiologic isometric contractility was recorded for a continuous 2.0 h. Area under the curve, frequency and time occupied by contractions were studied. Differences between cycle phases, between muscle layers, and over the recorded time periods were statistically evaluated using linear mixed-effect models. In the mare, physiologic contractility of the uterus decreased significantly over time for all variables evaluated (time as covariate on a continuous scale). For area under the curve, there was a significant effect of muscle layer (longitudinal > circular). For frequency, higher values were recorded in estrus for circular smooth muscle layer, whereas higher values were seen in longitudinal smooth muscle layers during diestrus. In longitudinal layer and in diestrus, more time was occupied by contractions than in circular layer, and in estrus. This study is describing physiologic myometrial motility in the organ bath depending on cycle phase.

Strategies for Artificial Insemination of Cattle at Synchronized Ovulation or Synchronized Estrus

Two synchronization protocols in lactating dairy and beef cows and in dairy heifers were tested for efficacy of breeding by artificial insemination (AI) with or without estrus detection. Controls received three prostaglandin F2a (PGF2a) injections 14 days apart before AI at observed estrus. Pregnancy rates were compared with animals on the Ovsynch protocol that combined gonadotropin releasing hormone (GnRH) and PGF2a treatments with a timed AI 16 to 20 hours after the second GnRH injection. The pregnancy rates were similar at synchronized ovulation to fixed-time AI in lactating cows, but not effective in heifers because of the lack of synchronization.

Comparison of Various Methods of Estrus Detection in Synchronized Virgin Beef Heifers

Methods of heat detection were compared in the Mid- Crest Area Cattle Evaluation Program (MACEP) heifer development program in the 1998-breeding season. A total of 189 heifers from thirteen consignors entered the program on November 10, 1997. These heifers were condition scored, hip height measured, weighed, disposition scored, booster vaccinated, and treated for parasites at the time of arrival. Determination of the heifer’s mature weight was made and a target of 65% of their mature weight at breeding was established. The ration was designed to meet this goal. The heifers were kept in a dry lot until all heifers were AI bred once. The heifers were periodically weighed and condition scored to monitor their gains and the ration was adjusted as needed. The estrus synchronization program consisted of an oral progesterone analog for 14 days; 17 days after completion of the progesterone analog treatment a single injection of prostaglandin was given and the heifers were then estrus detected. Two concurrent methods of estrus detection were utilized: 1) Ovatec â electronic breeding probe (probe), 2) HeatWatchâ estrus detection system (HW), and 3) a combination of probe and HW. Probe readings were obtained each 12 hours and the heifers were continuously monitored for estrus activity using the HW system. The probe was used as the primary estrus detection method and the HW system was used as a back-up system. Those heifers that did not demonstrate any estrus signs prior to 96 hours post prostaglandin treatment were mass inseminated at 96 hours. Post AI breeding, 151 of the heifers were placed on pasture and ran with clean-up bulls for 60 days. The remaining heifers left the program after the AI breeding was completed. Pregnancy to the AI breeding was determined by ultrasound on June 29, 1998. Results from using both probe and HW were 60% pregnant by AI, probe alone was 32% pregnant by AI, and HW alone was 27% pregnant by AI. The result of mass insemination was 20% pregnant by AI.

Cyclical DNA Methyltransferase 3a Expression Is a Seasonal and Estrus Timer in Reproductive Tissues

Acknowledgments This work was funded by the University of Aberdeen CLSM grant to TJS. EWJL was funded by a Society for Reproduction and Fertility undergraduate scholarship. TJS conceived the project, designed experiments, analyzed data and wrote the manuscript. EWJL conducted experiments and analyzed the data. CC conducted the immunocytochemistry. ML conducted HEK293 cell culture assays. EMC and ASB provided technical assistance. The authors thank Gerald Lincoln for critical feedback on a previous version of this manuscript.

Recovery of reproductive activity and fertility of Saanen goats affected by hydrometra after cloprostenol treatment and estrus induction during the non-breeding season (preliminary data).

2016

Route of Oxytocin administration and nonsurgical embryo recovery in Santa Inês ewes after induction synchronous estrus.

Oxytocin has been used to promote cervical dilation with the objective to access uterus both in artificial insemination and transcervical embryo recovery in sheep and goats. The objective of this study was to test the effect of two routes of oxytocin administration on nonsurgical embryo recovery efficiency in Santa Inês ewes after induction of synchronous estrus. Results of this study showed that nonsurgical transcervical embryo recovery can be efficiently done in some ewes; a higher number of individuals is needed to conclude that transcervical embryo recovery can be efficiently done in ewes and surgery embryo collections can be avoided in near to 60% of pluriparous Santa Inês ewes; and that the route of oxytocin administration did not affect the parameters evaluated.

Morphological features and vascularization study of caprine cyclic corpus luteum

Corpus luteum is a temporary endocrine gland that regulates either the estrous cycle and pregnancy. It presents extreme dependency on the adequate blood supply. This work aims to evaluate goat corpus luteum (CL) vascular density (VD) over the estrous cycle. For that purpose, 20 females were submitted to estrus synchronization/ovulation treatment using a medroxyprogesterone intra-vaginal sponge as well as intramuscular (IM) application of cloprostenol and equine chorionic gonadotrophine (eCG). After sponge removal, estrus was identified at about 72hs. Once treatment was over, female goats were then subdivided into 4 groups (n=5 each) and slaughtered on days 2, 12, 16 and 22 after ovulation (p.o). Ovaries were collected, withdrawn and weighted. CL and ovaries had size and area recorded. Blood samples were collected and the plasma progesterone (P4) was measured through RIA commercial kits. The VD was 24.42±6.66, 36.26±5.61, 8.59±2.2 and 3.97±1.12 vessels/mm² for days 2, 12, 16 and 22 p.o, respectively. Progesterone plasma concentrations were 0.49±0.08, 2.63±0.66, 0.61±0.14 and 0.22±0.04ng/ml for days 2, 12, 16 e 22 p.o, respectively. Studied parameters were affected by the estrous cycle phase. Values greater than 12 p.o were observed. In the present work we observed that ovulation occurred predominantly in the right ovary (70% of the animals), which in turn presented bigger measures than the contra lateral one. There is a meaningful relationship between the weight and size of the ovary and these of CL (r=0.87, r=0.70, respectively, p<0.05). It is possible to conclude that morphology of goat's ovaries and plasma progesterone concentration changed according to estrous cycle stages. We propose these parameters can be used as indicators of CL functional activity.

Associação da medroxiprogesterona ao protocolo Ovsynch para inseminação artificial em tempo fixo de búfalas cíclicas (Bubalus bubalis) criadas na Amazônia Oriental

O presente estudo visou avaliar os efeitos da associação da medroxiprogesterona (análogo sintético da progesterona) ao protocolo Ovsynch sobre o crescimento folicular, a ovulação e a taxa de concepção de búfalas criadas na Amazônia Oriental (Tracuateua-PA). Vinte e sete fêmeas adultas (G1 n=14 e G2 n=13), cíclicas, sem bezerro ao pé e com ECC 3,5 foram submetidas a Ovsynch. Os animais do G2 receberam 60 mg de medroxiprogesterona entre D0 e D7 (D0=início do tratamento). A ultra-sonografia ovariana foi realizada nos D 0, 7, 9 e 10. O contingente de folículos pequenos diferiu no D7 (G1: 4,57±0,60 versus G2: 6,54±0,67; P=0,05). Tempo e tratamento influenciaram o diâmetro folicular no D7. O crescimento do folículo dominante entre D7 e D9 foi maior nos animais tratados (G1: 2,05±0,49 mm/dia versus 3,48±0,41 mm/dia; P<0,05). Mais animais do G1 ovularam precocemente (35,71% versus 30,77%), porém isso não afetou as taxas de concepção (G1: 50,00% e G2: 30,77%; P>0,05). Os achados sugerem que a medroxiprogesterona (1) aumenta recrutamento folicular e retarda o crescimento dos folículos com diâmetro maior que 5,0 mm entre D0 e D7; (2) sua retirada incrementa em 1,7 vezes o crescimento folicular do D7 ao D9; (3) pode contribuir para a ovulação de folículos maiores e, em tese, para maior formação de tecido luteínico; (4) não promove ovulação precoce após o Ovsynch; (5) não eleva as taxas de concepção após sincronização de fêmeas cíclicas e com bom escore corporal, devendo ser avaliada para uso em fêmeas acíclicas ou com ECC mais baixo.

Melatonin reduces LH, 17 beta-estradiol and induces differential regulation of sex steroid receptors in reproductive tissues during rat ovulation

Background: Melatonin is associated with direct or indirect actions upon female reproductive function. However, its effects on sex hormones and steroid receptors during ovulation are not clearly defined. This study aimed to verify whether exposure to long-term melatonin is able to cause reproductive hormonal disturbances as well as their role on sex steroid receptors in the rat ovary, oviduct and uterus during ovulation. Methods: Twenty-four adult Wistar rats, 60 days old (+/-250 g) were randomly divided into two groups. Control group (Co): received 0.9% NaCl 0.3 mL + 95% ethanol 0.04 mL as vehicle; Melatonin-treated group (MEL): received vehicle + melatonin [ 100 mu g/100 g BW/day] both intraperitoneally during 60 days. All animals were euthanized by decapitation during the morning estrus at 4 a. m. Results: Melatonin significantly reduced the plasma levels of LH and 17 beta-estradiol, while urinary 6-sulfatoximelatonin (STM) was increased at the morning estrus. In addition, melatonin promoted differential regulation of the estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR) and melatonin receptor (MTR) along the reproductive tissues. In ovary, melatonin induced a down-regulation of ER-alpha and PRB levels. Conversely, it was observed that PRA and MT1R were up-regulated. In oviduct, AR and ER-alpha levels were down-regulated, in contrast to high expression of both PRA and PRB. Finally, the ER-beta and PRB levels were down-regulated in uterus tissue and only MT1R was up-regulated. Conclusions: We suggest that melatonin partially suppress the hypothalamus-pituitary-ovarian axis, in addition, it induces differential regulation of sex steroid receptors in the ovary, oviduct and uterus during ovulation.

Hormone-regulated expression and distribution of versican in mouse uterine tissues

Background: Remodeling of the extracellular matrix is one of the most striking features observed in the uterus during the estrous cycle and after hormone replacement. Versican (VER) is a hyaluronan-binding proteoglycan that undergoes RNA alternative splicing, generating four distinct isoforms. This study analyzed the synthesis and distribution of VER in mouse uterine tissues during the estrous cycle, in ovariectomized (OVX) animals and after 17beta-estradiol (E2) and medroxyprogesterone (MPA) treatments, either alone or in combination. Methods: Uteri from mice in all phases of the estrous cycle, and animals subjected to ovariectomy and hormone replacement were collected for immunoperoxidase staining for versican, as well as PCR and quantitative Real Time PCR. Results: In diestrus and proestrus, VER was exclusively expressed in the endometrial stroma. In estrus and metaestrus, VER was present in both endometrial stroma and myometrium. In OVX mice, VER immunoreaction was abolished in all uterine tissues. VER expression was restored by E2, MPA and E2+MPA treatments. Real Time PCR analysis showed that VER expression increases considerably in the MPA-treated group. Analysis of mRNA identified isoforms V0, V1 and V3 in the mouse uterus. Conclusion: These results show that the expression of versican in uterine tissues is modulated by ovarian steroid hormones, in a tissue-specific manner. VER is induced in the myometrium exclusively by E2, whereas MPA induces VER deposition only in the endometrial stroma.

Ovarian function in cows submitted to acute stress during proestrus

Studies in which ACTH was administrated in heifers after the occurrence of luteolysis showed a delay in the onset of estrus and the estrus duration was shortened. This study evaluated the effect of acute stress by road transportation on estrous behavior and ovulation, monitored by serum progesterone and cortisol concentrations in cows at the periovulatory period, using a crossover design. Eleven crossbred cows, divided into Control and Transport groups had their estrus cycle synchronized with GnRH, an intravaginal progesterone device, and cloprostenol. Thirty hours after withdrawal of the device, the animals of the Transport group were transported for 60 min by truck and those from the Control group remained at pasture. Ovarian ultrasound examination was performed every 12 h from device withdrawal until ovulation in every cow. From the day after removal of the device until ovulation estrous behavior was monitored 24 h a day. Blood samples for serum cortisol and progesterone concentrations were taken at -90, -60, 0, 30, 60 and 180 min in relation to the end of transportation. Transportation during the estrous period induced stress in cows as reflected by changes in serum concentrations of progesterone and cortisol. However, we did not detect impairment in estrus expression, estrus duration or ovulation (P>0.05). (C) 2010 Elsevier B.V. All rights reserved.

Reproductive cycles in Bos indicus cattle

Several studies using transrectal ovarian ultrasonic scanning in Bos taurus (B. taurus) cattle and more recently in Bos indicus (B. Indicus) females evaluated the reproductive cycles of heifers and cows under different conditions. In general, B. indicus cattle have more follicles and more follicular waves during the estrous cycle and ovulate from smaller follicles than B. taurus. Consequently B. indicus females have smaller corpora lutea and it is assumed circulating concentrations of estradiol and progesterone are also less. However, these findings may vary depending on the nutritional status and regimen in which the animals are managed. Moreover, there are significant differences between B. taurus and B. indicus regarding follicle size at the time of deviation of the dominant follicle. These differences in ovarian function between B. indicus and B. taurus, e.g. greater antral follicle population are, probably, the main reasons for the great success of in vitro embryo production programs in Zebu cattle, especially in Brazil. (C) 2011 Elsevier B.V. All rights reserved.

Ultrastructural evaluation of gingival glycosaminoglycans in ovariectomized rats: Effects of steroid hormone therapy

Background/Aims: To evaluate the behavior of glycosaminoglycans (GAGs) in rat gingiva and the effects of lack of sexual steroids and the hormonal therapy with estrogen and dexamethasone (DEX). Methods: 40 female rats were divided into four groups: GI: animals in permanent estrus; GII: ovariectomized (OVX) animals + vehicle; GIII: OVX animals treated with 17 beta-estradiol benzoate (10 mu g/kg), and GIV: OVX animals treated with 17 beta-estradiol benzoate (10 mu g/kg) + DEX (3 mg/kg). After treatment, the gingiva was removed and its GAGs content was evaluated by electronic microscopy after stained by cuprolinic blue technique. Results: The electron-microscopic data showed that low values of chondroitin sulfate were found in castrated animals (35.05 +/- 3.58%) compared to other groups (GI: 41.17 +/- 1.13; GIII: 48.04 +/- 2.60; GIV: 49.09 +/- 2.68%). In contrast, the amount of dermatan sulfate in GII (57.70 +/- 2.50%) was higher than in the other groups (GI: 46.12 +/- 1.30; GIII: 42.65 +/- 2.98; GIV: 42.68 +/- 5.43%). Conclusions: GAGs may be influenced by estradiol, and DEX did not seem to antagonize the role of estradiol in the GAGs of gingiva. The histotypical structure of gingiva is related to the amount of chondroitin sulfate. Consequently, the estrogen therapy may be important for gingival health. Copyright (C) 2007 S. Karger AG, Basel.