Studies on the relationship between paracoccidioidomycosis in ddY mice and their estrous cycle

The relationship between paracoccidioidomycosis in ddY mouse and its estrous cycle was studied. Adult ddY mice of both sexes were used as experimental animals. Estrous cycle of female mice was examined before inoculation of Paracoccidioides brasiliensis yeast cells and mice were divided into 5 groups such as proestrus, estrus, metestrus-I, metestrus-II and diestrus. Each mouse was inoculated intravenously with 10⁶ P. brasiliensis yeast cell units and sacrificed on day 28 after inoculation. Their internal organs were cultured, and in addition, their histopathologies were studied. As a result, there was no difference in the organ cultures among the male and the female mice of 5 groups. However, histopathologically, the female groups at estrus, metestrus-I and metestrus-II were affected more severely than the male group, and the susceptibility of the female mice to the fungus was closely related to their estrous cycles.Abbreviations BHI-D brain heart infusion agar supplemented with 1.0% of anhydrous dextrose - PAS periodic acid-Schiff techniques - PBS phosphate buffered saline solution - SD standard deviation     

Stage of the estrous cycle at the time of pregnant mare's serum gonadotropin injection affects pre-implantation embryo development in vitro in the mouse

The present study aims to analyze in the mouse the effect of the stage of the estrous cycle at the time of pregnant mare's serum gonadotropin (PMSG) injection on fertilization of ovulated cumulus-enclosed oocytes and later embryo development in vitro to the blastocyst stage. Quality of blastocysts was evaluated by staining and counting of total number of nuclei, mitotic index, percentage of apoptotic nuclei, and cell allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage. Superovulation of hybrid (C57Bl/6JIco female x CBA/JIco male) female mice of 4-6 weeks of age was induced by a priming injection of PMSG at different stages of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Our data indicate that injection of PMSG at the estrus phase gives the best outcome whereas injection of PMSG at the diestrus-1 or diestrus-2 phase provides the worst results. In fact, (1) total number of oocytes ovulated, number of ovulated oocytes enclosed by cumulus cells, and number of TE cells in day-5 blastocysts were significantly lower in diestrus-1 females than in estrus, diestrus-2 and proestrus mice; (2) percentage of day-5 blastocysts and total number of cells in day-5 blastocysts were lower in diestrus-1 and diestrus-2 females than in estrus and proestrus mice; and (3) percentage of apoptotic nuclei in day-5 blastocysts was lower in estrus mice than in diestrus-1, diestrus-2, or proestrus females. These data endorse previous studies suggesting that administration of gonadotropins in mice should be synchronized with the innate estrous cycle of females.     

The effect of estrogen on epithelial cell proliferation and differentiation in the crypts of the descending colon of the mouse: a radioautographic study

The regulatory role of estrogen on cell population kinetics in the descending colon was studied in intact female and ovariectomized mice. In the colonic crypts from intact mice, the crypt size (the number of epithelial cells per crypt column) and the proliferative activity of epithelial cells fluctuated slightly during the estrous cycle. Peak cellularity per crypt column was exhibted during estrus and early diestrus, whereas peaks in labeling index were seen during estrus and late metestrus. While the population size of mucous cells showed a minimal variation, the number of proliferative vacuolated cells per crypt column varied inversely with that of differentiated columnar cells during estrous cycle. The vacuolated cells were increased in number in the preovulatory phase and the columnar cells in the postovulatory phase. Three weeks after bilateral ovariectomy, the colonic crypt appeared to reach a new steady state, which was characterized by a small crypt size, a decrease in the number of differentiated cells, an increase in the relative number of proliferative cells and a relative increase in the proliferative activity of the crypt as compared to intact mice. When ovariectomized mice were treated with estrogen, the number of 3H-thymidine-labeled cells in the crypt was decreased as compared to untreated ovariectomized mice, the decrease being greater after a single injection than after multiple injections of estrogen, and the vacuolated-columnar cell line being affected more than mucous cell line. Meanwhile, the crypt size as well as the population size of differentiated cells in the crypt failed to return to normal after estrogen treatments. Thus, estrogen did not promote differentiation of epithelial cells in the crypt.     

Slight influence of the estrous cycle stage on the mucosal and systemic specific antibody response induced after vaginal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis in mice

Since the immune response appears to be variable according to the hormonal stage of the mammalian female, the aim of this study was to determine whether estrous cycle stage modifies the mucosal and systemic immune responses induced by intraperitoneal and vaginal immunization of mice with protoxin Cry1Ac. We tested the influence of three immunizations on the specific antibody response elicited at estrus and diestrus, that were the same estrous cycle stages at which the antigen was applied. Both intraperitoneal and vaginal immunization of mice with Cry1Ac either at estrus or diestrus induces specific antibody responses at serum, vagina and large intestine. The stage of the estrous cycle have little or non influence in the magnitude of the response induced, since only at serum the IgM was slightly higher at estrus than at diestrus by both routes. At the large intestine only the IgA response elicited via the intraperitoneal route changed, being higher at diestrus, whereas at the vagina IgA response induced did not change significantly due to the cycle stage. Present results suggest that Cry1Ac may be used as an antigen carrier as it can elicit antibody responses at systemic level and at several mucosal sites including the vagina that are not modified significantly throughout the reproductive cycle.     

Immunocytochemical detection of estrogen and progesterone receptors in the rabbit submandibular gland.

Rabbit submandibular glands produce secretions involved in olfactory communication. The histology of these glands and their secretory activity are: sexually dimorphic; vary across the female reproductive cycle; and are modified by gonadectomy. This suggests that gonadal steroids regulate the structure and function of such glands. To further support this idea we assessed by immunocytochemistry the presence of estrogen and progesterone receptors in male and female rabbit submandibular glands. Immunoreactivity was detected only in the nucleus of acini cells. The number of estrogen receptor-immunoreactive cells/field varied among estrus (26 +/- 6; mean +/- S.E.), ovariectomized (19 +/- 2), and ovariectomized-estrogen-treated animals (13 +/- 3). Intact males showed a significantly smaller number of estrogen receptor-immunoreactive cells/field (12 +/- 1) than estrous females. Interestingly, progesterone receptor-immunoreactive cells were more abundant in estrous (32 +/- 7) than in ovariectomized animals (7 +/- 1). Estradiol benzoate (5 micrograms daily for 5 days) increased the number of progesterone receptor-immunoreactive cells/field in ovariectomized females (17 +/- 1). Intact males showed fewer progesterone receptor-immunoreactive cells/field (16 +/- 2) than estrous females. Results show that the rabbit submandibular gland is a target for estrogen and progesterone and support the idea that these hormones participate in regulating the physiology of this gland.     

Control of proceptive and receptive behavior by ovarian hormones in the Syrian hamster (Mesocricetus auratus)

Two studies examined the roles of estrogen with progesterone and of estrogen alone on the proceptive and receptive behavior of female hamsters. Proceptivity was measured in terms of proximity (approaching, leaving, and following by the female) and in time spent sniffing the male partner. During the 4-day natural estrous cycle, these measures change systematically although lordosis is seen only on Day 1 (estrus). With a constant dose of progesterone, both proceptive and receptive behavior were found to be estrogen dose dependent in ovariectomized females. At estrogen levels too low to induce lordosis, changes in proceptive behavior were seen; at the two highest levels of estrogen, lordosis was maximal but proceptive behavior continued to increase. With estrogen alone, levels of proceptive behavior were attained characteristic both of estrus and of the higher estrogen and progesterone dosage but were not accompanied by spontaneous lordosis. Factors indicating that proceptivity and receptivity may be under separate hormonal and neural control are discussed.     

Variation of food hoarding with the estrous cycle of Syrian golden hamsters (Mesocricetus auratus)

Food hoarding was assessed in 16 adult female Syrian golden hamsters (Mesocricetus auratus) across the stages of the estrous cycle. Results show that food hoarding is depressed on the day of behavioral estrus but does not vary among the other days of the cycle. Decreases in food hoarding appear to be correlated with high levels of estrogen and progesterone. The data are consistent with the hypothesis that food hoarding, food intake, and weight gain are controlled either by the same mechanism or by similar mechanisms in some female rodents.     

Uterine and ovarian blood flow during the estrous cycle in mares

Uterine and ovarian blood flow was investigated in four mares during two consecutive estrous cycles using transrectal color Doppler sonography. The uterine and ovarian arteries of both sides were scanned to obtain waves of blood flow velocity. The pulsatility index (PI) reflected blood flow. There were significant time trends in PI values of all uterine and ovarian blood vessels during the estrous cycle (P < 0.05). PI values did not differ between the uterine arteries ipsi- and contralateral to the corpus luteum or the ovulatory follicle. PI values of the uterine arteries showed a wave shaped profile throughout the estrous cycle. The highest PI values occurred on Days 0 and 1 (Day 0 = ovulation) and around Day 11, and the lowest PI values were measured around Days 5 and -2 of the estrous cycle. During diestrus (Days 0-15) PI values of the ovarian artery ipsilateral to the corpus luteum were significantly lower than PI values of the contralateral ovarian artery (P < 0.0001). No differences (P > 0.05) in resistance to ovarian blood flow occurred between sides during estrus (Days -6 to -1). In this cycle stage PI values decreased in both ovarian vessels (P < 0.05). During diestrus, high PI values of the ovarian artery ipsilateral to the corpus luteum were measured between Days 0 and 2, followed by a decline until Day 6 (P < 0.05). From this time on, the resistance to blood flow increased continuously until Day 15 (P < 0.05). The cyclic blood flow pattern in the contralateral ovarian artery was similar to that in the uterine arteries (r = 0.68; P < 0.0001). No correlations occurred between the diameter of the corpus luteum and the PI values of the ipsilateral ovarian artery (P > 0.05) during diestrus. During estrus, there was a negative relationship between growth of the diameter of the ovulatory follicle and changes in PI values of the dominant ovarian artery (r = -0.41; P < 0.05). PI values of the uterine arteries and of the ovarian artery ipsilateral to the ovulatory follicle were negatively related to estrogen (E) levels in plasma during estrus (uterine arteries: r = -0.21; P < 0.05; dominant ovarian artery: r = -0.35; P < 0.05). In diestrus, PI values of the dominant ovarian artery were negatively related to plasma progesterone levels (r = -0.38; P < 0.0001), but not the PI values of the uterine arteries (P > 0.05). The findings of this study show that there are characteristic changes in blood supply of the uterus and the ovaries throughout the equine estrous cycle. There are negative correlations between resistance to blood flow in the uterine and ovarian arteries and the plasma estrogen levels during estrus. In diestrus, there is a negative relationship between the resistance to ovarian blood flow and the progesterone levels.     

Increased resistance of splenectomized mice to Sporothrix schenckii infection

The susceptibility of splenectomized mice to Sporothrix schenckii was studied, and the role of the spleen in the host defense is discussed. S. schenckii Sp-1 and ddy male mice were used. The mice were divided into 3 groups consisting of splenectomized, sham-operated and intact mice. Each mouse was inoculated intravenously with 2×10⁶ yeast cells 7 days after operation and the mice were sacrified at adequate intervals for 30 days. Then histological sections stained with H&E or by PAS were prepared from various visceral organs. Using the liver sections the number of yeast cells in a 40 mm² was counted. Furthermore, the colony forming unit in 100 mg of the liver tissue was compared to each other.In the sham-operated and intact mice many purulent lesions appeared on the 5th day. On the 8th day mononuclear cells accumulated at the foci, and on the 10th day most of the foci became granulomatous. The number of yeast cells in granulomatous lesions reached a peak on the 10th day and thereafter decreased abruptly. On the other hand, in the splenectomized mice approximately half of foci became granulomatous on the 5th day, and the number of yeast cells in the foci began to decrease after the 5th day.There were definite differences in the colony forming unit between the splenectomized and sham-operated or intact mice sacrificed 9 days after inoculation. The colony forming unit of the former is 9.3×10⁵ on the average, while that of the latter two is 5.6×10⁶ and 5.1×10⁶ on the average, respectively.In conclusion the resistance of ddy mice to S. Schenckii infection is enhanced due to splenectomy.     

Sociosexual behavior and the ovulatory cycle of ponies (Equus caballus) observed in harem groups

Observations of sociosexual behavior of adult ponies, made on two harem groups (each comprised of one vasectomized male and three females), were correlated with follicular development and ovulation for a total of 15 cycles (minimum of 2 cycles per female). Mean cycle length (interovulatory interval) was found to be 19.7 days, with behavioral estrus lasting 7–8 days (5.5 days preovulatory; 2.3 days postovulatory). Estrous females typically showed increased frequencies of approaching and following the stallion, urinating, presenting, clitoral winking, and tail raising. Approaching and following the stallion appeared earlier and persisted longer than other estrous responses. Deviations from the modal estrous pattern included cycles with subestrus, continual estrus, behavioral estrus in the absence of ovulation, and displays of female mounting. Dominance tests revealed that a mare's status was unaffected by the phases of the estrous cycle. The presence of more than one estrous female affected the copulatory performance of both stallions, most notably in reduced latencies to first mount, intromission, and ejaculation, in spite of differences between the stallions in sexual vigor. Each stallion usually selected the dominant mare for copulation when there were multiple estrous females present, but mounts were not displayed exclusively to one female per test. The social testing situation made apparent the importance of use of space in sociosexual communication in this species, particularly in avoidance of the stallion by diestrous mares and standing alone or in proximity to him by estrous mares.     

Fluctuations of lactoferrin protein and messenger ribonucleic acid in the reproductive tract of the mouse during the estrous cycle.

The physiological role of lactoferrin (LF), the major estrogen-inducible protein in the murine uterus, is unclear; however, LF may be a useful marker for the study of estrogen action in the uterus. Thus, the expression of LF mRNA and the localization of the protein in genital tract tissues and secretions of female mice (6-8 wk old) at different stages of the estrous cycle were investigated. Uterine luminal fluid (ULF) was analyzed for LF by means of gel electrophoresis and Western blot techniques; LF mRNA and protein were identified in reproductive tract tissues through in situ hybridization and immunocytochemistry. At diestrus, the level of LF mRNA was low, and staining for the protein was very light in uterine epithelial cells; LF was undetectable in ULF. At proestrus, LF mRNA and protein increased in the uterine epithelium and LF was readily detectable in ULF. LF mRNA and protein reached the highest levels at estrus. At early metestrus as compared to estrus, LF mRNA and protein were detected in decreasing amounts in uterine epithelial cells; the protein was undetected in ULF. By late metestrus and diestrus, LF mRNA and protein returned to a low level, and the protein was undetectable in ULF. LF protein was also demonstrated by immunocytochemistry in the epithelium of the oviduct, cervix, and vagina. LF protein fluctuation similar to that observed in the uterus was seen in these tissues; however, the uterus demonstrated the most dramatic changes in the number of epithelial cells involved in LF production during the estrous cycle. In summary, LF mRNA and its expression in uterine epithelial cells of the mouse varied with the stage of the estrous cycle. These results, combined with previously reported findings that LF is a major constituent of mouse ULF under the influence of estrogen, suggest that LF may play an important role in normal reproductive processes.     

Hormonal oscillations during the estrous cycle influence the morphophysiology of the gerbil (Meriones unguiculatus) female prostate (skene paraurethral glands)

The hormonal oscillations that occur during the female reproductive cycle influence the morphophysiology of several organs of the reproductive system. The female prostate is a functional organ sensitive to the action of steroidal hormones, but it is not known whether the hormonal oscillations that occur during the reproductive cycle can alter the biology of this gland. Thus, the present work aims to evaluate the morphofunctional aspects of the female prostate during the gerbil estrous cycle. For this purpose, morphological, morphometric-stereological, serological, and immunocytochemical analyses were carried out. The results of the present study show that the hormonal oscillations that occurred during the estrous cycle altered both the structure and functionality of the gerbil female prostate. These alterations include increased prostatic growth and augmented secretory activity during the proestrus and estrus phases and a gradual decrease of the secretory activity and glandular development in the diestrus I and II phases. These cyclical oscillations appear to be determined by the hormonal peaks of estrogen in diestrus II and by the high levels of progesterone during estrus, since the androgen levels remained constant throughout the estrous cycle.     

Stage of the estrous cycle at the time of pregnant mare's serum gonadotropin injection affects the quality of ovulated oocytes in the mouse

The present study aims to analyze the effect of the stage of the estrous cycle at the time of pregnant mare's serum gonadotropin (PMSG) injection on number and quality of mouse oocytes retrieved from oviducts after exogenous ovarian stimulation. Cellular and morphological traits of ovulated oocytes from hybrid (C57Bl/6JIco female X CBA/JIco male) female mice of 12, 40-42, 50-52 or 57-62 weeks of age were analyzed. Superovulation was induced by a priming injection of PMSG at different stages of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Injection of PMSG at diestrus-1 was associated with: (1) increased percentage of cumulus-free oocytes; (2) raised total percentage of oocytes without polar body; (3) increased total percentage of oocytes with intracytoplasmic mitochondrial aggregates; (4) decreased percentage of oocytes with a normal distribution of chromosomes in the metaphase II plate; and (5) raised percentage of oocytes with chromosome scattering when compared to injection at estrus, diestrus-2, and proestrus stage. On the contrary, estrus females displayed the highest percentage of oocytes with a normal distribution of chromosomes in the metaphase II plate and the lowest percentage of oocytes denuded of cumulus cells, without polar body, with intracytoplasmic mitochondrial aggregates and/or with chromosome scattering. These data suggest that administration of gonadotropins in mice should be synchronized with the innate estrous cycle of females to optimize the quality of oocytes collected from oviducts.     

A morphological study of uterine alterations in mice due to exposure to cadmium

We investigated the morphologic and molecular effects of exposure to cadmium (Cd) for 30 and 60 days on the uteri of mice. We assessed uterine morphometric measurements, eosinophilia, mast cell numbers, endometrial apoptosis, proliferation and estrogen receptor alpha (ERα) immunoreactivity. We examined vaginal smears that reflected the hormonal alterations in the female reproductive tract. Because the female reproductive tract exhibits different morphology at each stage of the estrous cycle, we sacrificed all animals at estrus to make appropriate comparisons. Female BALB/c mice were exposed to 200 ppm Cd in their drinking water for either 30 or 60 days. Cd exposure caused significant decreases in endometrial thickness and number of glands in estrus phase uteri. The endometrial eosinophilia in the groups exposed to Cd also decreased compared to controls. Cd exposure increased the number of mast cells. Luminal and glandular epithelia were examined using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and by immunostaining proliferating cell nuclear antigen (PCNA) and estrogen receptor α (ERα). Compared to controls, the apoptotic index increased with time in both Cd exposed groups, while the proliferation index decreased. ERα immunoreactivity was decreased in both Cd exposed groups compared to controls; the decrease was most apparent in the 30 day Cd group. We found that 60 day Cd exposure increased apoptosis in the endometrium, which may affect the receptivity of the uterus for implantation.     

The effects of paradoxical sleep deprivation on estrous cycles of the female rats

The present purpose was to examine how sleep deprivation affects the estrous cycle of the female rat. Paradoxical sleep-deprived (PSD) adult female Wistar rats were compared to home-cage control (CTRL) on their estrous cyclicity. Forty-four PSD and forty-four CTRL female rats were distributed into 4 subgroups of 11 animals each according to the phase of estrous cycle and were subjected to sleep deprivation for 96 h by the multiple platform technique. After PSD period, vaginal estrous cycles were taken for an additional 9 days. Animals that were submitted to PSD in diestrus phase (PSD-diestrus) had their estrous cycles disrupted during the recovery period by showing a constant diestrus during the first week. As for hormone alterations, progesterone concentrations were statistically higher in PSD-diestrus compared to respective phase control and to PSD-proestrus and PSD-estrus rats while CTRL-metestrus had higher levels than CTRL-proestrus and estrus groups. Testosterone was significantly decreased in PSD-estrus in relation to PSD-proestrus and PSD-diestrus groups and was lower in CTRL-diestrus rats than in home-cage rats in proestrus. In addition, PSD-diestrus phase exhibited higher concentrations of corticosterone and lower estrogen than the respective control rats. These data indicate that PSD may modulate the ovarian hormone release through alterations in hormonal-neurochemical mechanisms.     

Estrogen and progesterone concentrations in bovine milk during the estrous cycle

Estrogen and progesterone concentrations in milk during the estrous cycle were estimated in 18 normally cycling Holstein dairy cows. The estrogen and progesterone concentrations in milk during the estrous cycle followed the pattern described for them in blood in the corresponding period. During most of the estrous cycle, estrogen concentration remained at approximately 200 pg/ml and reached a proestrous peak of 360 +/- 127 pg/ml on day 19. The progesterone concentration in milk during the estrous cycle increased to a peak on day 13 (45.5 +/- 6.6 ng/ml) and thereafter declined towards estrus. Estrus detection/prediction based on milk progesterone concentrations appears feasible in view of the significant differences in milk progesterone concentrations between the early luteal (post-ovulatory), luteal and rapid follicular growth periods of the estrous cycle.     

Influence of the estrous cycle and prostaglandins on utero-ovarian vein blood flow in the rat

The blood flow rate in the utero-ovarian vein (UOV) has been measured in adult female rats during the different phases of the estrous cycle. It was observed that the blood flow rate in the UOV is high at proestrus and at estrus and low during diestrus days 1 and 2. The intravenous injection of 10 μg PGF_2α or PGE₂ diminishes the blood flow rate in the UOV. The efficacy of the two PGs in reducing blood flow is different in the various phases of the estrous cycle, being maximal during the day of estrus.     

Influence of the estrous cycle and prostaglandins on utero-ovarian vein blood flow in the rat

The blood flow rate in the utero-ovarian vein (UOV) has been measured in adult female rats during the different phases of the estrous cycle. It was observed that the blood flow rate in the UOV is high at proestrus and at estrus and low during diestrus days 1 and 2. The intravenous injection of 10 μg PGF_2α or PGE₂ diminishes the blood flow rate in the UOV. The efficacy of the two PGs in reducing blood flow is different in the various phases of the estrous cycle, being maximal during the day of estrus.     

Influence of the estrous cycle and prostaglandins on utero-ovarian vein blood flow in the rat.

The blood flow rate in the utero-ovarian vein (UOV) has been measured in adult female rats during the different phases of the estrous cycle. It was observed that the blood flow rate in the UOV is high at proestrus and at estrus and low during diestrus days 1 and 2. The intravenous injection of 10 mug PGF2alpha or PGE2 diminishes the blood flow rate in the UOV. The efficacy of the two PGs in reducing blood flow is different in the various phases of the estrous cycle, being maximal during the day of estrus.