Natural Estrous Cycle Research Articles

Integrated multiple transcriptomes in oviductal tissue across the porcine estrous cycle reveal functional roles in oocyte maturation and transport.

Understanding the changes in the swine female reproductive system is important for solving issues related to reproductive failure and litter size. Elucidating the regulatory mechanisms of the natural estrous cycle in the oviduct under non-fertilisation conditions can improve our understanding of its role in the reproductive system. Herein, whole transcriptome RNA sequencing of oviduct tissue samples was performed. The differentially expressed genes (DEGs) were identified for each time point relative to day 0 and classified into three clusters based on their expression patterns. Clusters 1 and 2 included genes involved in the physiological changes through the estrous cycle. Cluster 1 genes were mainly involved in PI3K-Akt signaling and steroid hormone biosynthesis pathways. Cluster 2 genes were involved in extracellular matrix-receptor interactions and protein digestion pathways. In Cluster 3, the DEGs were downregulated in the luteal phase; they were strongly associated with cell cycle, calcium signaling, and oocyte meiosis. The gene expression in the oviduct during the estrous cycle influenced oocyte transport and fertilization. Our findings provide a basis for successfully breeding pigs and elucidating the mechanisms underlying the changes in the pig oviduct during the estrous cycle.

Expression of SUMO associated proteins in the mouse endometrium is regulated by ovarian hormones throughout the estrous cycle.

The modification of proteins by small ubiquitin-like modifier (SUMO), known as SUMOylation, regulates biological function by changing protein transcription and translation. During the estrous cycle the endometrium undergoes continual change to processes including cell proliferation, secretion and exfoliation and these changes are regulated by the levels of ovarian hormones. Increasing the expression of SUMO family members has previously been shown to promote proliferation and invasion of endometrial cancer cells. However, limited research has been carried out into the expression and function of SUMO in the mammalian endometrium. In the present study, the level and localization of SUMO-associated proteins throughout the natural estrous cycle in the mouse uterus was determined using immunohistochemical staining and western blot analysis. The association between the spatiotemporal expression of these SUMO modified proteins and SENPs in endometrium and the concentration of ovarian hormones during estrous cycle was revealed. The present study clarified the role of SUMOylation in maintenance of normal estrous cycling and may have important significance in the study of hormone-dependent endometrial diseases.

COMPARATIVE STUDY OF FRUITFULNESS OF COW INSEMINATION OF A MILKING HERD AT VARIOUS LEVELS OF PRODUCTIVITY IN THE CONDITIONS OF BAYSERKE-AGRO LLP

A comparative analysis of the fruitfulness of cow artificial insemination of milking herd at variouslevels of productivity was carried out in the conditions of Bayserke-Agro LLP. A study of reproduction performanceof the milking herd was conducted based on the results of work performed from January 2018 to March 2019. Thecomparative data include cows artificially inseminated both according to the natural estrous cycle and according tothe hormonal stimulation scheme of the estrus according to the Ovsynch program. It was established that thevariability of the insemination index is directly dependent on the level of cow productivity, while the variability ofthis indicator in terms of lactation numbers has not been established. The service period and the insemination indexin high productive groups significantly exceed the optimal indicators, and in groups with milk yields of 6–9 thousandkg, relatively high reproductive qualities are observed, corresponding to zootechnic norms.

Dinámica folicular durante el ciclo estral natural en búfalas (Bubalus bubalis)

El objetivo del estudio fue monitorear la dinámica folicular del ciclo estral natural de hembras bufalinas en Colombia. Se evaluaron los patrones de crecimiento y regresión de folículos ováricos de 11 búfalas durante dos ciclos estrales. Se realizaron exámenes ecográficos interdiarios de los ovarios para establecer patrones de ondas foliculares, número de ondas, día de emergencia, número de folículos reclutados, y características del folículo dominante (FD) y del cuerpo lúteo (CL). Las concentraciones de progesterona (P4) se determinaron por radioinmunoensayo. Se evaluaron 17 ciclos normales (2, 11 y 4 ciclos con una, dos y tres ondas foliculares, respectivamente). El intervalo inter-ovulatorio fue de 12.5 ± 2.7, 20.5 ± 1.2 y 28.8 ± 1.9 días para los ciclos con 1, 2 y 3 ondas foliculares, respectivamente. Las ondas foliculares emergieron los días 0 ± 2.3 en ciclos de una onda, los días 2.3 ± 1.0 y 10.5 ± 1.0 en ciclos de dos ondas y los días 1.25 ± 1.6, 8.0 ± 1.9 y 20.8 ± 1.6 (promedio ± e.e.) en ciclos de tres ondas. El diámetro máximo (cm) alcanzado por el FD fue de 1.2 ± 0.4 en ciclos de una onda, de 1.02 ± 0.2 y 1.3 ± 0.3 en ciclos de dos ondas, y de 1.2 ± 0.3, 1.3 ± 0.3 y 1.2 ± 0.3 en ciclos de tres ondas. La concentración de P4 en el día de máximo diámetro del CL en promedio fue de 7.2 ± 6.6 ng/ml. Se concluye que la dinámica folicular de la búfala colombiana se caracteriza por presentar patrones de una, dos y tres ondas foliculares, con predominio de ciclos de dos ondas.

Estrus Detection Through Vaginal pH in Saanen Etawah Crossbreed Goats.

In goats, weak estrus behavior is potentially caused by a decline in reproductive efficiency. In the present study, aim was to measure the vaginal pH to determine the accuracy of lust detection in Saanen Etawah crossbreed goats. Thirteen Saanen Etawah crossbred does (Capra hircus) with body condition score of 2-3 were used. The dose were fed concentrate, provided forage and water ad libitum. The experiment was conducted during the natural estrous cycle. Vaginal smears were collected from each dose every day over a 60 days period to determine the time of each phase of the estrous cycle. The vaginal pH was measured using pH indicator paper; simultaneously, the blood was sampled from the caudal vein into anticoagulant-coated tubes following estrous cycle, covering estrus (E/day-0), metestrus (M/day-3), diestrus (D/day-12) and proestrus (P/day-15). The concentration of plasma estrogen and cortisol was determined by solid phase competitive enzyme-linked immune sorbent assay and the correlation between vaginal pH with each phase of estrous cycle and estrogen level was found. The changes in vaginal pH were confirmed with estrogen and cortisol profile at each estrous phase. The highest vaginal pH and estrogen content were found during estrus, whereas, the lowest vaginal pH and estrogen content was found during diestrus. Furthermore, the cortisol level was significantly different in each phase of the estrous cycle; the highest level of cortisol was observed during proestrus. The correlation between vaginal pH and estrous phase indicates that the vaginal pH can be a useful parameter for estrus detection.

Estrogen and progesterone dependent expression of visfatin/NAMPT regulates proliferation and apoptosis in mice uterus during estrous cycle

Visfatin is an adipokine which has an endocrine effect on reproductive functions and regulates ovarian steroidogenesis. There is scant information about the expression, regulation, and functions of visfatin in the mammalian uterus. The present study examined expression and localization of visfatin in the mouse uterus at various stages of the natural estrous cycle, effects of estrogen and progesterone on localization and expression of visfatin in the ovariectomised mouse uterus and effect of visfatin inhibition by a specific inhibitor, FK866 on proliferation and apoptosis in the uterus. Western blot analysis of visfatin showed high expression in proestrus and metestrus while it declined in estrus and diestrus. Immulocalization study also showed strong immunostaining in the cells of endometrium, myometrium, luminal and glandular epithelium during proestrus and metestrus that estrus and diestrus. The uterine visfatin expression closely related to the increased estrogen levels in proestrus and suppressed when progesterone rose to a high level in diestrus. The treatment with estrogen to ovariectomised mice up-regulates visfatin, PCNA, and active caspase3 whereas progesterone up-regulates PCNA and down-regulates visfatin and active caspase3 expression in mouse uterus. The co-treatment with estrogen and progesterone up-regulates visfatin and down-regulates PCNA and active caspase3. In vitro study showed endogenous visfatin inhibition by FK866 increased expression of PCNA and BCL2 increased catalase activity while FK866 treatment decreased expression of active caspase3 and BAX with decreased SOD and GPx activity. BrdU labeling showed that inhibition of visfatin modulates the uterine proliferation. This study showed that expression of visfatin protein is steroid dependent in mouse uterus which is involved in the regulation of proliferation and apoptosis via modulating antioxidant system in the uterus of mice during the reproductive cycle.

The effect of N-acetylcysteine or bupropion on methamphetamine self-administration and methamphetamine–triggered reinstatement of female rats

N-acetylcysteine and bupropion are two promising candidate medications for treatment of substance use disorder. The effects of N-acetylcysteine or bupropion on methamphetamine self-administration of female rats are not well understood. To fill this gap, this study assessed the effects of N-acetylcysteine (0, 30, 60, or 120 mg/kg) and bupropion (0, 10, 30, and 60 mg/kg) on methamphetamine self-administration of female rats across the natural estrous cycle. Following a completed dose-response curve, responding for methamphetamine self-administration was extinguished and the effects of N-acetylcysteine or bupropion on methamphetamine-triggered reinstatement was evaluated in separate experiments. N-acetylcysteine did not decrease responding maintained by methamphetamine or methamphetamine-triggered reinstatement. Bupropion significantly decreased methamphetamine self-administration and methamphetamine-triggered reinstatement in female rats with highest dose (60 mg/kg) also significantly decreasing general chamber activity. In a companion experiment, testing the effect of bupropion on responding maintained by sucrose, we confirmed non-specificity of bupropion's effects as bupropion also decreased responding for sucrose. Considered together, our findings suggest that while N-acetylcysteine has considerable promise for treatment of cocaine dependence it may not generalize to other stimulants like methamphetamine. Furthermore, although bupropion has been shown to effectively decrease methamphetamine self-administration, and presently methamphetamine-triggered reinstatement, its locomotor and reward suppressing effects warrant further investigation including both sexes.

Lesion development is modulated by the natural estrous cycle and mouse strain in a minimally invasive model of endometriosis.

Many rodent models of endometriosis are invasive, involving surgery to implant donor endometrial tissue into recipient animals. Moreover, few studies have compared and contrasted lesions between rodent strains and estrous stages without exogenous hormone manipulation. This is despite extensive data demonstrating that genetic and hormonal factors can influence endometriosis progression. Here, we have refined a minimally invasive model of endometriosis using naturally cycling mice (donor and recipient matched for cycle phase) to investigate lesion development in two different strains (C57BL/6 and BALB/c), induced in estrous stages of high and low estrogen (proestrus or estrus, respectively), and with varying amounts of donor endometrial tissue (7.5-40 mg), injected intraperitoneally. The overall probability of developing endometriosis-like lesions was higher in proestrus than estrus, and increased with greater masses of donor tissue. Similarly, the total number of lesions (0-3) increased from 7.5 to 40 mg, and was significantly greater in proestrus C57BL/6 mice but not BALB/cs. The dominant lesion type also differed between mouse strains; C57BL/6 mice were more likely to develop dense-type lesions, whereas BALB/c mice developed a greater proportion of cystic type. These data further support a role for estrogen in the development of endometriosis, and that genetic variance can influence the degree and characteristics of lesions. Our minimally invasive model would be beneficial for studies with outcome measurements particularly sensitive to incisional injury, such as pain, or alterations to sex hormones, including fertility.

P-cresol and oleic acid as reliable biomarkers of estrus: evidence from synchronized Murrah buffaloes.

Successful reproductive management in buffaloes depends on effective estrus detection. Urinary pheromones identified from natural estrous cycle have been reported to decipher estrus phase. However, its presence has not been analyzed in the urine after synchronization. Thus, our present investigation was to investigate the influence of synchronized estrus urine in bulls and to examine the presence of estrus-specific compounds ascertained in natural estrus in synchronized buffaloes. Mid-stream urine was collected from six synchronized buffaloes during various phases of estrous cycle and volatiles were examined using GC-MS. Sexual provocation in bulls was established by displaying persistent flehmen and frequent mounting towards estrus urine from synchronized animals. Totally forty-two volatile compounds were identified from three phases of estrous cycle, more specifically 4-methyl phenol (p-cresol) and 9-octadecenoic acid (oleic acid) in estrus urine of synchronized animal as similar to natural estrus. Hence, these chemical cues in buffalo urine might be employed as potential marker candidates for the development of an estrus detection aid.

The functional expression of transient receptor potential channels in the mouse endometrium.

Does mouse endometrial epithelial cells and stromal cells have a similar transient receptor potential (TRP)-channel expression profile and to that found in the human endometrium? Mouse endometrial epithelial and stromal cells have a distinct TRP channel expression profile analogous to what has been found in human endometrium, and hence suggests the mouse a good model to investigate the role of TRP channels in reproduction. An optimal intercellular communication between epithelial and stromal endometrial cells is crucial for successful reproduction. Members of the TRP family were recently described in the human endometrial stroma; however their functional expression in murine endometrium remains unspecified. Furthermore, epithelial and stromal cells have distinct functions in the reproductive process, implying the possibility for a different expression profile. However, knowledge about the functional expression pattern of TRP channels in either epithelial or stromal cells is not available. In this study, the expression pattern of TRP channels in the murine (C57BL/6 J strain) endometrium was investigated and compared to the human expression pattern. Therefore, expression was examined in uterine tissue isolated during the natural estrous cycle (n = 16) or during an induced menstrual cycle using the menstruating mouse model (n = 28). Next, the functional expression of TRP channels was assessed separately in endometrial epithelial and stromal cell populations. Quantitative RT-PCR was used to evaluate the relative mRNA expression of TRP channels in murine uterine tissue and cells. To further assess the functional expression in epithelial or stromal cells, primary endometrial cell cultures and Fura2-based calcium-microfluorimetry experiments were performed. The expression pattern of TRP channels during the natural estrous cycle or the induced menstrual cycle is analog to what has been shown in human samples. Furthermore, a very distinct expression pattern was observed in epithelial cells compared to stromal cells. Expression of TRPV4, TRPV6 and TRPM6 was significantly higher in epithelial cells whereas TRPV2, TRPC1/4 and TRPC6 were almost exclusively expressed in stromal cells. N/A. Although relevant mRNA levels are detected for TRPV6 and TRPM6, and TRPM4, lack of selective, available pharmacology restricted functional analysis of these ion channels. Successful reproduction, and more specifically embryo implantation, is a dynamic developmental process that integrates many signaling molecules into a precisely orchestrated program. Here, we describe the expression pattern of TRP channels in mouse endometrium that is similar to human tissue and their restricted functionality in either stromal cells or epithelial cells, suggesting a role in the epithelial-stromal crosstalk. These results will be very helpful to identify key players involved in the signaling cascades required for successful embryo implantation. In addition, these results illustrate that mouse endometrium is a valid representative for human endometrium to investigate TRP channels in the field of reproduction. The Research Foundation-Flanders (G.0856.13 N to J.V.); the Research Council of the Katholieke Universiteit Leuven (OT/13/113 to J.V. and PF-TRPLe to T.V.); the Planckaert-De Waele fund (to J.V.); Fonds Wetenschappelijk Onderzoek Belgium (to K.D.C. and A.H.). None of the authors have a conflict of interest.

Mesenchymal Stem Cells in Restoration of Fertility at Experimental Pelvic Inflammatory Disease.

Inflammatory disorders account for a significant percentage of gynecologic diseases, particularly in women of reproductive age. It is known that stem cells have anti-inflammatory and regenerative properties. Based on this, we investigated the effect of intravenous administration of cryopreserved mesenchymal stem cells (cMSCs) of bone marrow on experimental chronic inflammation of the ovaries. The paper shows that on the 21st day after cMSC therapy, leukocyte infiltration of ovaries was slightly relative to the control group without treatment, and the ratio of developing and atretic follicles in the animals with cMSC injection dramatically increased, while in the control, it still remained on the side of atretic forms. The number of apoptotic oocytes after stimulation of superovulation in the control group was significantly higher (85.3 ± 5.2%) than that in the animals with therapy (5.7 ± 0.8%). Relative number of fertilized eggs in the group with cMSC therapy was higher by 40% compare to that in the control. Pregnancy rate in natural estrous cycle after cell administration increased by 20%, and average number of litters in this group was two times significantly higher than that in the control. So the intravenous injection of cMSCs has the restorative effect on the fertility at experimental pelvic inflammatory disease.

Alterations in the threshold of the potassium concentration to evoke cortical spreading depression during the natural estrous cycle in mice

Cortical spreading depression (CSD) has been implicated in a variety of neurological disorders. However, the relationship between serum sex hormones and susceptibility to the development of CSD in naturally estrous cycling female animals is largely unknown. The natural estrous cycle of mice consists of four stages, namely, proestrus, estrus, metestrus and diestrus. We measured the serum concentration of estradiol and progesterone in estrus and diestrus and compared the minimum potassium concentrations necessary to evoke CSD in each stage and in males. In diestrus, the minimum potassium concentration required to evoke CSD was significantly lower compared to the other three phases and male animals. The serum level of estradiol is significantly higher and serum level of progesterone is significantly lower in diestrus compared to estrus. Furthermore, when we administered an estrogen receptor antagonist, the susceptibility to the development of CSD was decreased. Conversely, the administration of a progesterone receptor antagonist increased the susceptibility to CSD. Our results demonstrated that neuronal excitability related to CSD induction differs among the natural estrous phases in mice.

Кріоконсервовані мультипотентні мезенхімальні стромальні клітини у відновленні фертильності тварин із хронічним запаленням яєчників

The paper describes the influence of multipotent cryopreserved mesenchymal stromal bone marrow cells under conditions of intravenous administration alone and in combination with ‘Thymalinum’ (immune regulatory peptide complex from cattle thymus) on the fertility of mice with chronic inflammation of ovaries. The animals injected with a physiological saline were assumed as the control. To the day 21 following intravenous injection of cryopreserved multipotent mesenchymal stromal cells alone and in combination with ‘Thymalinum’ to the mice with chronic inflammation of ovaries an increase in a relative number of fertilized ova during superovulation (38 and 33%, respectively) was found, as well as in a pregnancy rate in natural estrous cycle (20 and 23% respectively) and the average litter number (98 and 83%, respectively) compared to the control animals. ‘Thymalinum’ application per se did not affect significantly the studied indices. The difference in body weight between the mice of experimental and control groups was observed only at early terms of observation, and to the day 15 it disappeared. Probl Cryobiol Cryomed 2016; 26(1):84-92.

Effects of summer heat stress on physiological variables, ovulation and progesterone secretion in Pelibuey ewes under natural outdoor conditions in an arid region.

Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects of summer thermal stress on physiologic variables, estrous behavior, ovulation and corpus luteum functionality under natural conditions of an arid region. In summer and autumn, daily estrous detection with a ram fitted with an apron and blood sample collections were performed during two natural estrous cycles. An environment of heat stress was detected in summer and thermoneutral in autumn. Rectal temperature and respiratory frequency were greater (P < 0.01) in summer than in autumn during the morning and afternoon. Season did not affect (P > 0.05) live weight, body condition, length of estrous cycle or percentage of ewes in estrous and ovulating. Compared with autumn, serum progesterone concentrations in summer decreased (P < 0.05) between days 8 and 14 of the estrous cycle. It is concluded that under outdoor conditions of arid regions, while estrous and ovulatory activities of Pelibuey ewes were not affected by summer thermal stress, the corpus luteum functionality was decreased.

Felis catus ovary as a model to study follicle biology in vitro.

The current study was designed to evaluate the response of individual intact antral follicles from adult female domestic cats to a luteinizing hormone (LH) stimulus in vitro by assessing cumulus-oocyte expansion (C-OE) and steroid production. C-OE and steroid levels (estradiol [E2] and progesterone [P4]) obtained from individual antral feline follicles (n = 366 follicles; n = 56 cats) were analyzed after 12 or 24 h of culture in the presence or absence of LH (low [3.4 ng/ml] or high [100 ng/ml]). At the end of the culture, the highest percentage of expanded cumulus-oocyte complexes (COCs) was observed in the LH groups at 12 or 24 h in comparison to their controls (p < 0.001). There was a significant increase in expanded COCs when comparing LH concentrations (high vs. low) at 12 or 24 h. Higher levels of both E2 and P4 were observed in the media from antral follicles after 12 and 24 h of culture in the presence of LH (both concentration, p < 0.05). There was no association between hormone levels and follicle diameter; high variability was observed in the steroid levels produced by antral follicles within all treatment groups. These data indicate, for the first time, that feline antral follicles (0.5-2 mm) from different stages of the natural estrous cycle can be cultured and will respond to an LH stimulus, based on an increase in steroid levels as well as C-OE after 12 or 24 h in culture.

Follicular dynamics, corpus luteum growth and regression in multiparous buffalo cows and buffalo heifers

ABSTRACTObjective. Characterize the follicular dynamics and luteal growth and regression pattern of multiparous (MB) and heifer (BH) Murrah buffaloes in Colombian tropical conditions. Material and methods. Ten MB and ten BH were synchronized with a progesterone-releasing intravaginal device. No artificial insemination was performed during the estrous and daily ultrasound examinations were performed 15 days later to determine the number and diameter of the structures present in both ovaries in the subsequent natural estrous cycle. The Student’s T test was used to evaluate differences between MB and BH. All data are presented as mean ± standard deviation. Results. The length of the estrous cycle was 22.00±4.50 days for MB and 22.00±2.70 days for BH. Follicular growth occurs in one (n=1; 5.89%), two (n=14; 82.35%) or three waves (n=2; 11.76%). The first wave initiated the day after ovulation with the recruitment of 8.33±2.06 and 10.00±2.72 follicles in MB and BH, while the second wave started on day 11.00±2.00 and 10.50±2.82, presenting 8.37±2.26 and 8.00±1.51 follicles. The third wave began on day 16.21±3.10 showing 6.50±1.70 follicles, only BM had three waves. The maximum luteal diameter was 19.58±4.16 mm and 17.74±3.32 mm respectively. There were no significant differences between the groups for these variables. Conclusions. These results show that the follicular development in buffaloes occurs in waves, where two waves is the most common pattern, as previously reported by other authors.

LEVEL OF ESTRADIOL 17-β SERUM AND OVARIAN FOLLICULARE DYNAMICS IN SHORT ESTROUS CYCLE OF BALI CATTLE

The aims of the research were to confirm the short estrous cycles and determine the blood level ofestradiol 17-β and ovarian follicukar dynamics in these cases. The research was conducted using sevenBali cattle, approximately 2 years of age, kept in healthy condition with normal estrous cycles.Observation of estrus symptoms was performed daily. Ovarian follicles was examined and measuredusing ultrasonography started at the estrus day. Blood samples were collected from jugular vein, bloodsample collection and ultrasonographical examination of the ovaries were performed daily in the sametime. Serum level of estradiol 17-β was performed using EIA. The short cycle estrus were observed in 4Bali cattle (n=7) among natural estrous cycle. They have only one wave ovarian follicular developmentwhereas the maximal size of ovarian follicles ovulation likes the normal cycle The duration of shortestrous cycle was 7-10 days with normal usual estrus behavior. The peak of blood serum level was107.77 ± 55.94 pg/ml when the diameter dominant follicle of short estrous cycle was reached 10.5 ±0.38 mm. It can be concluded that the short estrous cycles may occur in Bali cattle after puberty amongnormal cycles.

バークシャー種における自然発情下での経腟採卵条件の検討

バークシャー種における自然発情下での経腟採卵条件の検討

Determination of anti-Müllerian hormone at estrus during a synchronized and a natural bovine estrous cycle

Anti-Müllerian hormone (AMH) has been correlated with phenotypic indicators of fertility. However, the effects of exogenous hormones used during estrus synchronization on AMH have not been evaluated. Therefore, the objective of this experiment was to determine whether concentrations of AMH at estrus are similar between a synchronized compared with a natural estrous cycle. Nulliparous dairy and beef heifers (n = 68) were synchronized with the Select Synch + controlled internal drug release (CIDR) protocol (GnRH + CIDR-7 d-CIDR removal + PG). Heifers were observed for expression of estrus every 6 h until 84 h after the injection of PG. Visual detection of the subsequent estrus, considered natural estrus, occurred every 6 h from day 16 to 24 after synchronized estrus. At the time of standing estrus, ovarian structures in heifers were evaluated by transrectal ultrasonography. Blood samples were collected at estrus for analysis of concentrations of AMH during the synchronized and natural estrous cycles. The GLM and CORR procedures of SAS were used to analyze data. Concentrations of AMH between natural and synchronized estrus were positively correlated (r = 0.67; P < 0.001). Mean concentration of AMH did not differ (P > 0.05) between the natural (0.0543 ± 0.0076 ng/mL) or synchronized (0.0428 ± 0.0076 ng/mL) estrous cycles. In conclusion, concentrations of AMH were similar between natural and synchronized estrous cycles. Concentrations of AMH in natural and synchronized estrous cycles were highly correlated within individual heifers and varied among heifers with beef heifers having increased (P < 0.05) concentrations of AMH compared with dairy heifers (0.0638 ± 0.01 and 0.0402 ± 0.01 ng/mL, respectively).

Impaired Fertility and FSH Synthesis in Gonadotrope-Specific Foxl2 Knockout Mice

Impairments in pituitary FSH synthesis or action cause infertility. However, causes of FSH dysregulation are poorly described, in part because of our incomplete understanding of mechanisms controlling FSH synthesis. Previously, we discovered a critical role for forkhead protein L2 (FOXL2) in activin-stimulated FSH β-subunit (Fshb) transcription in immortalized cells in vitro. Here, we tested the hypothesis that FOXL2 is required for FSH synthesis in vivo. Using a Cre/lox approach, we selectively ablated Foxl2 in murine anterior pituitary gonadotrope cells. Conditional knockout (cKO) mice developed overtly normally but were subfertile in adulthood. Testis size and spermatogenesis were significantly impaired in cKO males. cKO females exhibited reduced ovarian weight and ovulated fewer oocytes in natural estrous cycles compared with controls. In contrast, ovaries of juvenile cKO females showed normal responses to exogenous gonadotropin stimulation. Both male and female cKO mice were FSH deficient, secondary to diminished pituitary Fshb mRNA production. Basal and activin-stimulated Fshb expression was similarly impaired in Foxl2 depleted primary pituitary cultures. Collectively, these data definitively establish FOXL2 as the first identified gonadotrope-restricted transcription factor required for selective FSH synthesis in vivo.