جستجوی مقالات مرتبط با کلیدواژه « Estrous cycle » در نشریات گروه « پزشکی »

Endometritis is a female reproductive disease characterized by the inflammation of the endometrial glandular and stromal tissues. It is usually occurred due to uterine contamination with infectious causes. Animal models of clinical endometritis are very important to prevent the incidence and treatment of endometritis. Vaginal cytology method is considered as a golden standard for determining the estrous cycle stage in female rats. The aim of this study was to induce endometritis in a rat model and determine the stages of the estrous cycle of this animal using vaginal cytology method in order to successfully induce this condition in this animal model.

Inflammation changes the production of endometrial cytokines, which may result in menstrual disorders and decreased endometrial reception by impaired endometrial tissue dysfunction. Increased expression of specific cytokines genes such as IL-6, IL-8 and TNF-α can be used to detect the severity and degree of endometritis. Uterine infections are known as a result of damage to the defense mechanisms of the uterine tissue, which are caused by physiological changes in the postpartum period. Another change that occurs in the postpartum period is the increase in the production of reactive oxygen species. The imbalance between the production of reactive oxygen species and its clearance leads to the creation of oxidative stress conditions. On the other hand, there is a significant relationship between inflammatory diseases such as endometritis and oxidative stress. On other hand, by accurately determining the estrous cycle of rats by using vaginal cytology, endometritis can be well induced in this species.

Neurogenesis is the process through which neurons are generated from neural stem cells. This process has been shown to occur in special zones of the adult brain including the subventricular zone (SVZ) of the lateral ventricles and the dentate gyrus of the hippocampus. Gonadal steroids affect different steps of neurogenesis, and cell proliferation seems to be increased by estrogens. This study aimed to investigate the neurogenic changes in the SVZ at different phases of the estrous cycle.

In this experimental study, 26 NMRI mice were used. The mice were identified by vaginal smear and then divided into 4 groups including proestrus (n=5), estrous (n=7), metestrus (n=7) and diestrous (n=7). Different stages of the estrous cycle were determined by staining vaginal smears. Also, the qualitative assessment of cell proliferation in the SVZ was performed by cresyl fast violet staining and glial fibrillary acidic protein (GFAP) immunohistochemistry at different stages of the estrous cycle.

In microscopic sections stained with cresyl violet, it was observed that cell density in the proestrus stage of the estrous cycle was greater than in any other stages of the estrous cycle. A comparison of sections stained with anti-GFAP showed that the density of astrocytes in proestrus was significantly higher than in other groups.

Proestrus stage of the estrous cycle is associated with increased cell proliferation and density of astrocytes in the SVZ of mice. Neurogenesis is correlated to changes in sex hormonal levels at different phases of the estrus cycle.

Background and Follicular atresia is a natural phenomenon throughout growth and development, but in excessive cases it causes disorders in the ovarian function which is the commonest cause of infertility. Outbreak of depression in women is twice as much as men. Electric-shock therapy could be used in the treatment of depression resistant to drugs. However, it has some side-effects. This research was conducted to study the effects of electric shock on ovarian follicular atresia. In this experimental study, 70 albino mice weighing 28±1.5g (9-12 weeks) with normal sex cycle were divided into 15 groups (n= 5 per group) after determining estrous cycle stages by vaginal smear. The mice were allocated into four control groups in four estrous cycle stages, four groups receiving one shock in every four stages, four groups receiving two- shocks (with interval of 4 hours) in each stage of sex cycle and two shock groups in all phases of the cycle with one and two shocks, respectively. The shock was given by a laboratory electric shock device and was tolerable for mice. The samples of ovarian tissues were stained with hematoxylin-eosin. The follicles were then examined and counted by scaled lens of a light microscope. In proestrus stage of sex cycle, a significant difference was seen between the one-shock group and other groups in mean rate of follicular atresia. This study indicated that receiving shock leads to an increase in the mean rate of atretic follicles and the most negative effect was observed in the one-shock group in proestrus phase.

Chamomile has several analgesic properties, while the mechanism of these effects in interaction with male sex hormones compared tofemales are not well known. This study aimedto evaluate the analgesic effects of hydro-alcoholic extract of chamomile in male mice, and two phases of femalesexual cycle (diestrus and proestrus) in the presence or absence of estrogen receptors. In this experimental study, adult mice of both genders(weight: 27±3 g) were divided into four groups of control, chamomile recipients (30 or 50 mg/kg), tamoxifen recipients (0.5 or 1 mg/kg), and recipients of combined tamoxifen (1 mg/kg) and chamomile (30 or 50 mg/kg). Drugs were administeredintraperitoneally in one milligram per a kilogram of the body weight, and formalin test was used to induce acute and chronic pain. In addition, cumulative length of foot licking was calculatedin seconds as theindicator of pain perception. In male mice,chamomile extract (30mg/kg) reduced acute pain (53±2, p<0.01)and chronic pain (71±2, p<0.001), and dosage of 50 mg/kgcould reduce acutepain (41±1, p<0.001) and chronic pain (73±2, p<0.001). In diestrus and proestrusfemales, chamomile extract could relieve acute pain at 50 mg/kg (42±2, p<0.05 and 39±1, p<0.05, respectively). As for the chronicphase of pain, chamomile extract (30 mg/kg) was effective in diestrus (72±1, p<0.01) and proestrus (80±2, p<0.001) female mice, whileit could reduce chronic pain at 50 mg/kgindiestrus (59±1, p<0.001) and proestrus (62±2, p<0.001) females. In male mice, the analgesic effects of the extract were more significant.In addition, tamoxifen (1mg/kg)reduced chronic pain in diestrus (81±3, p<0.05) and proestrus (92±2, p<0.05) female mice. In male mice,combination of chamomile (30 mg/kg) and tamoxifen (1mg/kg) decreased acutepain(43±3, p<0.05), andcombination of chamomile (50 mg/kg)and tamoxifen (1mg/kg) reduced acute pain (29±1, p<0.05) and chronic pain (41±2, p<0.01) in male mice. Moreover, the drug combination reduced acutepain (21±1, p<0.001) and chronic pain (44±3, p<0.01)in diestrus females, as well as proestrus ones(19±2, p<0.001) (43±3, p<0.001). According to the results of this study, analgesic effects of chamomile extract are gender-dependent,and these effects are more significant in male mice.Increased analgesic effectsof combinedchamomile and tamoxifen couldbe due to the interaction between estrogenreceptorsand analgesic agents of chamomil.

Usual fluctuations of sex hormones during the estrous cycle in female mice affect the hippocampal neurogenesis. The hippocampus also comprises many steroid receptors suggesting the modulatory effects of gonadal hormones on the hippocampal plasticity. Sex differences at the level of structure and function of the hippocampus are mostly due to the fluctuations of steroid hormones during the estrous cycle. The purpose of this study was to investigate the morphological changes in hippocampal astrocytes and also the expression of glial fibrillary acidic protein (GFAP) at different phases of the estrous cycle. In this study, different stages of the estrous cycle were determined in 6-8 week NMRI female mice by methylene blue-stained vaginal smears. The morphological changes of astrocytes in the hippocampus were investigated using GFAP immunohistochemistry. In addition to the morphological study, the expression of astrocytic marker was quantitatively evaluated. GFAP immunostaining showed the changes in the morphology of astrocytes and also in the serum level of estrogen during the estrous cycle. The highest concentrations of estrogen and GFAP reactivity were observed in the proestrus stage. Different stages of the estrous cycle in female mice were associated with morphological changes of hippocampal astrocytes and the alternation in the serum level of estrogen.

Sex differences in the morphology and function of the hippocampus have been reported in several species. Natural fluctuations of sex hormones during the estrous cycle affect the hippocampal neurogenesis of adult female. This study aimed to investigate the neurogenic changes in the hippocampus at different phases of estrous cycle. Different stages of the estrous cycle of the NMRI mice (6-8) mice were determined by staining of vaginal smears. Also, the qualitative assessment of cell proliferation in the dentate gyrus of hippocampus was performed by Nissl staining and Ki-67 immunostaining marker (Ki-67). The apoptosis was determined using the TUNEL assay. Diameter of the hippocampal vessels was measured at different stages of the estrous cycle. In microscopic sections stained with Cresyl Violet observed cell density in proestrous stage of estrous cycle was greater than any other stages of the estrous cycle. Comparison of sections stained with immunohistochemistry for Ki-67 staining showed that cell proliferation at proestrous are more than any other stages. The statistical analysis showed that vessel diameter was significantly greater at the proestrous stage than diestrous and metestrous. Also, TUNEL assay showed that cell death in the proestrous stage had the least reactivity. Proestrous stage of the estrous cycle was associated with increased cell proliferation and vessel diameter as well as reduced cell death in the dentate gyrus of the mice hippocampus.

Irregular sexual cycle due of improper hormone secretion is most common cause of infertility. Considering fact that women experience twice the rate of depression as men and electroconvulsive therapy (ECT) is one of used treatment methods, therefore this study was conducted to investigate the effect of electric shock on secretion of sex hormones.

In this experimental study 60 albino mice (weighting 28±1.5g and 9-12 weeks) with normal sex cycle were divided into 12 groups of 5 mice in each group after determining estrous cycle stages with vaginal smear: four control groups in our estrous cycle stages, four groups receiving one shock in each of four stages and four groups receiving two-shocks (with interval of 4 hours) in each stage of sex cycle. Shock operation was conducted with laboratory shock device and tolerable shock for mice. Blood samples were collected from mice in the same stage of receiving shock to measure sex hormones and assayed by ELISA method and compared.

Mean serum level of estrogen hormone showed significant difference only in the group receiving two shocks in metestrus stage)3.92±0.074(in comparison to control group of this stage)4.36±0.118) (p< 0.05). Only in diestrus stage, mean serum level of progesterone of one-shock group)5.264±0.243(and two shock group)5.24±0.029(showed no statistically significant difference in comparison to control group)5.466±0.102).

The result of study indicated that electroshock operation had no effect on serum level of both hormones just in diestrus stage of estrous cycle.

Regarding the effects of dill extracts on the reproductive system of the female sex reported by many researches، in، the present study the effects of aqueous fraction of this extract were investigated. In this experimental study، 40 adult female rats were divided into 5 groups: control، low and high doses of aqueous fraction of extract (0. 5 and 5 g/kg، respectively) and low and high doses of ethanol and aqueous extract (0. 045 and 0. 45 g/kg، respectively) of dill seed. The animals were gavaged with 1 ml of the mentioned doses for 10 days. At the end of the experiment، blood samples were taken from their dorsal aorta to measure progesterone and estrogen concentration. The ovaries and uteri of the subjects were removed. Then histomorphometrical changes and intensity of reaction of glycoconjugates of ovary and uterus were measured using ConA، UEA، PNA، DBA، SBA lectins. The female rats were mated with male ones (4 in each group). Finally، the number of fetuses and their CRL and weight were measured. Duration of diestrus phase under high dose of aqueous extract increased 2 times compared to the control group. Uterus thickness، longitudinal and transverse diameters of ovaries، granulosa cells of corpus luteum diameters of the experimental groups decreased 1. 5 to 2 times compared to the control group''s. Female rats of the experimental groups did not get pregnant. Intensity of reactions of α-mannose، N-acetyl glucosamine، and N-acetyl galactoseamine of endometrium and ovarian cell surfaces changed after being stained by ConA، DBA and SBA. Oral administration of ethanol fraction and aqueous dill seeds extracts can induce infertility in female rats.

The active form of vitamin D3 (1, 25 (OH)2 vitamin D3) plays a critical role in the male or female reproductive organs. The activity of this hormone is mediated by an intranuclear receptor. The synthesis of this receptor is itself modulated by several hormones including estrogen. In this study, the expression of the nuclear receptor for 1, 25 (OH)2 D3 (Vitamin D receptor, VDR) in reproductive organs of cycling mice has been addressed. The estrous phases of Balb/c mice, including proestrus, metoestrus, estrus and diestrus were determined by cytomorphological study of vaginal smears. The mice were killed at each phase and endometrial samples were collected. Expression of VDR mRNA was assayed by semi-quantitative RT-PCR. Immunohistochemical analysis was used for the evaluation of VDR protein expression in uterus, ovary and fallopian tubes. VDR-specific transcripts were expressed in the endometrium of all stages of estrus cycle. The relative expression of VDR mRNA at estrus phase was more prominent compared to the other phases (p<0.001). Immunohistochemical analysis revealed that almost all endometrial cells, including stromal, luminal and glandular epithelial cells, Theca interna, Theca externa and Cumulus oophorus cells of ovary and fallopian epithelial cells highly express VDR. In rodents, mating occurs exclusively at estrus phase and having considered the potent immu-nosuppressive effects of 1, 25 (OH)2 D3, high expression of VDR at estrus phase might be a fundamental mechanism for the induction of active tolerance against paternal allogenic sperm antigens.

Estrogen and progesterone are supposed to modify pain sensitivity. However, the actual role of each of these steroid hormones in this respect is not well known. Plasma concentrations of these hormones show variation during estrous cycle. The role of alpha2 receptors in tonic pain has been pointed out. The aim of the present study was to investigate the agonist and antagonist effect of alpha2 adrenergic receptors on tonic pain sensitivity during all stages of estrous cycle in female rats.

Xylasine as alpha2 agonist and yohimbin as alpha2 antagonist were used via intraperitoneal route (IP). Adult rats weighing 180-200 grams were used. Animals were maintained on 12h reverse light/dark cycle for 7 days prior to the experiment. Water and food was available ad libitum. Formalin test was performed by subcutaneous injection of 50 l formalin (2.5%) solution into the hind paw. Formalin test was performed in all stages of estrous cycle for 60 minutes. Animals were divided into four groups 1- control group (intact animal), 2- Sham group (animals received 0.2 ml normal saline by IP route), 3- Agonist groups (animals received 0.2 ml xylasine 1, 3 mg/kg body weight by IP route) and 4- Antagonist group (animals received 0.2 ml yohimbine 1, 3 mg/kg body weight by IP route). Data were statistically analyzed using 2 way ANOVA test followed by Tukey's test as post-hoc test. P<0.05 was considered significant.

Results showed that xylasine significantly (p<0.05) decreases pain sensitivity in all stages of estrous cycle. Analgesic effect of xylasine was maximum in estrus stage of estrous cycle and minimum in metestrus stage of estrous cycle. Yohimbine significantly (p<0.05) increases pain sensitivity in all stages of estrous cycle. Hyperalgesic effect of yohimbine was maximum in metestrus stage of estrous cycle and minimum in estrus stage of estrous cycle.

These results indicate that alpha2 adrenergic system and endogenous steroids have an important role in pain sensitivity.