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Reproductive Efficiency in Dairy Cows: Change in Trends!
Published in Juan Carlos Gardón, Katy Satué, Biotechnologies Applied to Animal Reproduction, 2020
Ana Heras-Molina, José Luis Pesantez Pacheco, Susana Astiz
Cows express a number of behavioral changes during estrus, like an increase in chin resting, anogenital licking and sniffing, aggressive interaction, mounting other cows and modifications in feed intake, and rumination time (Helmer and Britt, 1985; Kerbrat and Disenhaus, 2004; Stevenson and Britt, 2017). Other changes during estrus have been studied, such as vaginal cytology and pH, electrical resistance of vaginal mucus and genital tissues, body temperature, pulse and heart rates, blood flow, pheromones, blood metabolites and hormones, and milk yield (Stevenson and Britt, 2017).
Animal Models of Osteopenia or Osteoporosis
Published in Yuehuei H. An, Richard J. Friedman, Animal Models in Orthopaedic Research, 2020
Donald B. Kimmel, Erica L. Moran, Earl R. Bogoch
Ewes have a regular estrus cycle during fall and winter, but show anestrus during longer days.145 Post-OVX skeletal behavior is less consistent than in post-menopausal women, rats, or monkeys.146 Bone biomarkers indicate accelerated remodeling by three months post-OVX;147 marginal relative osteopenia occurs at a few bone sites by 6-12 months post-OVX.148 Fluoride and glucocorticoid effects in ewes parallel findings in other animals and humans.122,129,149-151 Aged sheep pose little problem for handling. Existing data thus reveal inconsistent OVX-related bone loss as in pigs. New data that assess the age of peak bone mass and more data on post-OVX bone loss are needed to validate the adult ewe as a model of osteoporosis.
Long-Term Effects of Perinatal Exposure to Hormones and Related Substances on Normal and Neoplastic Growth of Murine Mammary Glands
Published in Takao Mori, Hiroshi Nagasawa, Toxicity of Hormones in Perinatal Life, 2020
The amount of hormone acting on the target cells is one of the essential factors for cell growth. Accumulated data strongly suggest considerable alteration in hormone secretion of anterior pituitary and ovaries by perinatal hormone treatments.6 Kalland et al.26 reported that in female NMRI mice 5 μg DES treatment for the first 5 days of postnatal life enhanced pituitary response to estrogen for prolactin secretion in later life. In estrogenized and androgenized rats, Vaticôn et al.27 found the difference between estrogen and androgen to be the ability to alter the prolactin control system and higher sensitivity in females than males in the hypothalamic response to the treatments. Loss of cyclicity of hormone secretion was also induced by neonatal hormone treatments. Plasma prolactin level was higher in neonatally estrogenized or prolactinized mice than in the control at metaestrus/diestrus; however, no difference was observed in the level at proestrus/estrus.28 Continued estrus is usually seen in neonatally hormone-treated animals. The increased prolactin secretion in these animals is dependent upon ovaries,29 implying a critical role for sustained secretion of estrogen in this process.
Bone morphogenetic protein-9 maybe an important factor which improves insulin resistance in PCOS
Published in Gynecological Endocrinology, 2022
Xiaoying Yuan, Qi Huang, Jing Li, Qu Yao, Han Zhang, Qian Wang, Lin Zhang, Ying Zhang, Gangyi Yang, Ling Li, Xin Liao
The rats’ estrus cycle was evaluated under a microscopic by analysis of the predominant cell type in vaginal smears obtained every morning. Vaginal smears were taken on the 10th day after the start of the cycle. at 08:00, 15:00, and 22:00 every day, One estrus cycle lasts 5 days, and 2 consecutive cycles were observed. The smears were taken stained with Wright-Giemsa stains. The ratio of superficial cells to parabasal cells was observed to determine the estrous stage. The typical rat estrous cycle is divided into four phases: the pro-estrous period (7-21 h; many nuclear epithelial cells and a few keratinized epithelial cells), estrus period (9-15 h; numerous cornified keratinocytes and a few nucleated epithelial cells), postoestrus period (10-14 h; cornified epithelial cells and white blood cells), and anestrus period (60-70 h; numerous white blood cells and abundant mucus).
The pheromone affects reproductive physiology and behavior by regulating hormone in juvenile mice
Published in Growth Factors, 2022
Bing Hu, Zhongxiang Mo, Jianlin Jiang, Jinning Liang, Minlin Wei, Xiujuan Zhu, Yuan Liang, Yunhao Liu, Qiaojuan Huang, Yiqiang Ouyang, Junming Sun
The mechanism of precocious puberty has remained a mystery (Michielsen, Roza, and van Marle 2020). It is imperative to elucidate the mechanism of sexual maturity by studying precocious puberty. In females, the first estrus is activated through the action of HPG axis, which directs the hormonal level in body and drives the female for first estrus and afterwards the ovulation process (Latronico, Brito, and Carel 2016; Bradley et al. 2020; Sharafuddin et al. 1994). However, the mechanism of hypothalamus stimulation has yet been unclear. We hypothesized that the first estrus in females may be due to the constant stimulation of multiparous female pheromones in the brain from the fetal stage to sexual maturity. The pheromone in urine of a multiparous female may be an exogenous, persistent neural signal that reaches up to a certain threshold and stimulate the hypothalamus to secrete gonadotropin-releasing hormone, which induces precocious puberty. However, more research is necessary to elucidate the underlying mechanism of the stimulating threshold.
The effectiveness of resveratrol in treatment of PCOS on the basis of experimental model in rats
Published in Gynecological Endocrinology, 2021
Maria Yarmolinskaya, Olga Bulgakova, Elena Abashova, Valentina Borodina, Tatyana Tral
Laboratory animals were included in the study in the estrus phase. Prior to the experiment, all of them underwent blood sampling from peripheral part of tail to determine the level of sRAGE by enzyme immunoassay method using the RayBio Rat RAGE ELISA Kit test system, USA. Then, for a period of 2 months, the rats received solution of letrozole orally. After 60 days, the rats again underwent blood sampling to determine the level of sRAGE. Further, after appropriate preoperative preparation, the rats underwent left-side ovariectomy for histological confirmation of the effectiveness of letrozole in formation of PCOS model. Surgeries were performed under general anesthesia using zolazepam hydrochloride 100 at a dosage of 30 mg/kg intramuscularly. Surgical access site was freed from the wool cover by chemical depilation cream, containing potassium thioglycolate, after which laparotomy was performed followed by left-side ovariectomy. During the first 4 days after surgery, antibacterial drug ceftriaxone 100 mg/kg and non-steroidal anti-inflammatory drug ketoprofen 40 mg/kg were administered intramuscularly once and twice a day respectively in order to prevent postoperative complications.