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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
The OVX pig has been disappointing, showing only minor structural deterioration and bone loss.139-141 Its regular estrus cycle is shorter than in the human. Pigs, with Haversian remodeling, have been used to study skeletal effects of bisphosphonates, fluoride, and exercise.142-144 Peak bone mass occurs after age 3, confounding experimental efforts by introducing cost difficulties. More work is necessary for the pig to gain acceptance as a large animal model of estrogen depletion bone loss.
Unbiased research
Published in C. P. Khare, Evidence-based Ayurveda, 2019
To study the antiovulatory and abortifacient effects of ethanolic extract of Areca catechu in female rats, ethanolic extract of Areca catechu Linn. at 100 and 300 mg/kg doses were administered orally for 15 days. Vaginal smears were examined daily microscopically for estrus cycle. Rats were sacrificed on 16(th) day. Ovarian weight, cholesterol estimation, and histopathological studies were done. The abortifacient activity was studied in rats at 100 and 300 mg/kg doses administered orally from 6th to 15th day of pregnancy. Rats were laparotomised on the 19th day. The number of implantation sites and live fetuses were observed in both horns of the uterus.
Reproductive System and Mammary Gland
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Justin D. Vidal, Charles E. Wood, Karyn Colman, Katharine M. Whitney, Dianne M. Creasy
Heape (1900) referred to the dog as having 4 stages within the estrous cycle: proestrus, estrus, metestrus, and anestrus, and this terminology has been used and widely accepted over the years. The metestrus stage is, however, more accurately termed diestrus due to the active hormonal milieu at this time (Johnston et al. 2001) and is referred to as such in this chapter. The identification of the phases of the estrous cycle has traditionally been related to behavioral and/or clinical observations rather than hormonal or cytological characteristics and for the purposes of this chapter, the stages will be matched with endocrinologic and morphologic characteristics in line with the principal endpoints of toxicologic studies. The hormonal changes occurring through the estrous cycle from prepuberty or anestrus through proestrus, estrus and diestrus, have been reported for the dog in detail (Concannon et al. 1989; Concannon 2011; Gräf 1978; Johnston et al. 2001).
Chronic stress decreases fertility parameters in female rats
Published in Systems Biology in Reproductive Medicine, 2023
Fahiel Casillas, Alejandra Flores-González, Lizbeth Juárez-Rojas, Alma López, Miguel Betancourt, Eduardo Casas, Iván Bahena, Edmundo Bonilla, Socorro Retana-Márquez
In previously reported studies, our research group showed that in chronically stressed female rats, the stress produced alterations in the estrous cycle (prolonged proestrus and estrus; and absence of diestrus), decreased the number of pregnant females, as well as a decreased number of fetuses and increased fetal reabsorption (Retana-Márquez et al. 2020). These alterations were related to the effect that chronic stress has on negatively altering the hypothalamic-pituitary-ovary (HPO) axis. In this regard, it was reported that the levels of kisspeptin, GnRH, luteinizing hormone (LH), estradiol, and progesterone decrease mainly in the proestrus phase (Retana-Márquez et al. 2020), so this alteration of the HPO axis compromises the fertility of females. Subsequently, these results led us to evaluate the effect of chronic stress directly on the oocytes; it was found that their developmental potential is affected since there is a high percentage of dead and abnormal oocytes at all stages of the estrous cycle. It was also found that the number of in vivo mature oocytes significantly decreased in stressed females (Casillas et al. 2021) which would partially explain the affectation of female reproduction caused by stress. Therefore, in the present study, we aimed to evaluate the possible alterations by which the oocytes decrease their nuclear maturation. Several vital factors to achieve nuclear maturation were evaluated as well as other parameters in CCs.
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).
Immediate stress alters social and object interaction and recognition memory in nearly isogenic rat strains with differing stress reactivity
Published in Stress, 2021
Alice K. Schaack, Madaline Mocchi, Katherine J. Przybyl, Eva E. Redei
There were limitations in this study. Unexpectedly, some WMI males seriously wounded the juvenile during the SI sample trial and could not complete the test trial. The WMIs aggression therefore is likely underestimated. The WMI and WLI males had similar social recognition, but the removal of aggressive outliers may have concealed a difference in their social memories. Additionally, SI and NOR tests were performed in the rat’s home cage. The WMI and WLI strains are known to explore the open field, the typical setting for the NOR test, differently (Mehta et al., 2013; Will et al., 2003). Using the open field would have made it impossible to discern whether their behavior was truly different or if it reflected a difference in exploration style. The home cage setting eliminated this concern and reduced extraneous stress, but social behavior tests set in the home cage are often used to study aggression (Sandi & Haller, 2015). It is possible that the WMI males would not have exhibited the same aggression in a novel environment. Finally, estrus cycle was not tracked in females. Although previous studies have not found that estrus phase affected NOR performance (Sutcliffe et al., 2007), it is possible that estrus cycle data would have given more insight into the strain and sex differences described here.