Effects of kisspeptin-10 on progesterone secretion in cultured chicken ovarian granulosa cells from preovulatory (F1-F3) follicles

Enhancement of progesterone biosynthesis via kisspeptin stimulation: Upregulation of steroidogenic transcripts and phosphorylated extracellular signal-regulated kinase (p-ERK1/2) expression in the buffalo luteal cells

The presence of Kisspeptin (Kp) and its receptors in the corpus luteum (CL) of buffalo has recently been demonstrated. In this study, we investigated the role of Kp in the modulation of progesterone (P4) synthesis in vitro. The primary culture of bubaline luteal cells (LCs) was treated with 10, 50, and 100 nM of Kp and Kp antagonist (KpA) alongside a vehicle control. The combined effect of Kp and KpA was assessed at 100 nM concentration. Intracellular response to Kp treatment in the LCs was assessed by examining transcript profiles (LHR, STAR, CYP11A1, HSD3B1, and ERK1/2) using quantitative polymerase chain reaction (qPCR). In addition, the immunolocalization of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the LCs was studied using immunocytochemistry. Accumulation of P4 from the culture supernatant was determined using enzyme-linked immunosorbent assay (ELISA). The results indicated that LCs had a greater p-ERK1/2 expression in the Kp treatment groups. A significant increase in the P4 concentration was recorded at 50 nM and 100 nM Kp, while KpA did not affect the basal concentration of P4. However, the addition of KpA to the Kp-treated group at 100 nM concentration suppressed the Kp-induced P4 accumulation into a concentration similar to the control. There was significant upregulation of ERK1/2 and CYP11A1 expressions in the Kp-treated LCs at 100 nM (18.1 and 37fold, respectively, p < 0.01). However, the addition of KpA to Kp-treated LCs modulated ERK1/2, LHR, STAR, CYP11A1, and HSD3B1 at 100 nM concentration. It can be concluded that Kp at 100 nM stimulated P4 production, while the addition of KpA suppressed Kp-induced P4 production in the buffalo LCs culture. Furthermore, an increment in p-ERK1/2 expression in the LCs indicated activation of the Kp signaling pathway was associated with luteal steroidogenesis.

Kisspeptin stimulates sheep ovarian follicular development in vitro through homologous receptors

The present study was conducted to elucidate (1) the influence of kisspeptin (KP) on the in vitro development of preantral follicles (PFs) and (2) evolution of KP receptor gene (KISS1R) expression during ovarian follicular development in sheep. Kisspeptin was supplemented (0-100 µg/ml) in the culture medium of PFs for 6 days. The cumulus-oocyte complexes (COCs) from cultured PFs were subsequently matured to metaphase II (MII) for an additional 24 h. The proportions of PFs exhibiting growth, antrum formation, average increase in diameter, and maturation of oocytes to MII stage were the indicators of follicular development in vitro. The expression of the kisspeptin receptor gene at each development stages of in vivo developed (preantral, early antral, antral, large antral and COCs from Graafian follicles) and in vitro cultured PFs supplemented with KP was assessed using a real-time polymerase chain reaction. The best development in all the parameters under study was elicited with 10 µg/ml of KP. Supplementation of KP (10 µg/ml) in a medium containing other growth factors (insulin-like growth factor-I) and hormones (growth hormone, thyroxine, follicle-stimulating hormone) resulted in better PF development. The KISS1R gene was expressed in follicular cells and oocytes at all the development stages of both in vivo developed and in vitro cultured follicles. Higher KISS1R gene expression was supported by culture medium containing KP along with other hormones and growth factors. Accordingly, it is suggested that one of the mechanisms through which KP and other growth factors and hormones influence the ovarian follicular development in mammals is through the upregulation of expression of the KP receptor gene.

Kisspeptin stimulates oestradiol biosynthesis by upregulating steroidogenic transcripts and proliferation markers in the bubaline granulosa cells in vitro

Kisspeptin (Kp), an upstream regulator of GnRH release, is essential for the development and function of reproductive axis. Previously, we demonstrated the localization of Kp and its receptor (Kiss1r) in the active follicle in the bubaline ovary. Present study aimed to determine the effect of Kp on granulosa cell (GCs) functions, especially oestradiol (E2 ) and progesterone (P4 ) production, and differential expression of genes regulating the proliferation, apoptosis and steroidogenesis in the buffalo. The ovaries with 6-10 mm size follicles obtained from the cyclic buffaloes after slaughtering were used for isolation of GCs for in vitro study. The primary GCs culture was treated with Kp (0, 10, 50 and 100 nM) and incubated for 48 h. Production of E2 and P4 was estimated in the culture supernatant by ELISA. The expression of gonadotropin receptors (FSHR and LHR), steroidogenic genes (STAR, 3β-HSD, CYP19A1), proliferation marker (PCNA), apoptotic factors (CASP3 and BCL2) and Kp signalling molecule (extracellular signal-regulated kinase 1/2, ERK1/2 and p-ERK1/2) was studied in the GCs by qPCR. Significant E2 production was found in the Kp 50 and 100 nM groups (p < .05), whereas P4 production was reduced in Kp 100 nM group (p < .05). There was concomitant upregulation of FSHR, ERK1/2, STAR and CYP19A1 in the Kp 100 nM treated GCs. In addition, Kp at 100 nM stimulated the proliferation of GCs by upregulating the expression of BCL2 (5.0 fold) and PCNA (94.9 fold). Further, high immunoreactivity of p-ERK1/2 was observed in the Kp-treated GCs. It was concluded that Kp at 100 nM concentration stimulated E2 production by upregulating the steroidogenic pathway through ERK1/2, STAR and CYP19A1 and modulating PCNA and BCL2 expressions in the GCs. Further experiments are warranted using Kp antagonist in different combinations to establish the signalling pathway in Kp-mediated steroidogenesis in the GCs for developing strategies to control ovarian functions.

Kisspeptin promotes follicular development through its effects on modulation of P450 aromatase expression and steroidogenesis in sheep ovarian follicles

The present study was conducted to ascertain whether the role of kisspeptin in promoting in vitro development of preantral follicles was through the regulation of P450 aromatase gene expression and steroidogenesis in sheep. Accordingly, the cumulus cells and oocytes were collected from different development stages of preantral follicles grown in vivo and cultured in vitro in TCM199B (Group I), TCM199B + KP (10 μg/mL) (Group II) and Standard medium + KP (10 μg/mL). To measure the steroid (Estradiol-17β; E2 and Progesterone; P4 ) synthesis through ELISA, spent culture medium was collected separately from the same in vitro groups. E2 synthesis in the spent medium collected from all the three groups showed an increasing trend from PFs' exposed to respective culture media for 3 min to 2-day culture stage but decreased thereafter till 6-day culture stage. This is followed by a sharp increase in E2 concentration in the spent medium collected after in vitro maturation. However, P4 synthesis in group III followed increased pattern as the development progressed from PFs' exposed to culture medium for 3 min to in vitro maturation stage. The steroid production was observed at all stages of in vitro development in altered supplemented conditions. The steroid synthesis in the spent medium was highest in the 6 day cultured PFs' in Standard medium + KP matured in vitro for 24 h. Therefore, supplementation of kisspeptin along with other growth factors promoted steroid production in cultured preantral follicles far better than in other media.

Role of kisspeptin-10 and betacellulin in control of feline ovarian cell functions

The action of betacellulin (BTC) on basic ovarian cell functions and interrelationships with kisspeptin (KISS) was investigated. For this purpose, we examined (1) the effect of the addition of BTC (0, 1, 10, and 100 ng/ml) given alone or in combination with KISS (10 ng/ml) on cultured feline ovarian fragments or granulosa cells. Viability, proliferation (accumulation of cyclin B1) and apoptosis (accumulation of bax), and the release of steroid hormones (progesterone, testosterone, and estradiol) were analyzed by using the Trypan blue exclusion test, quantitative immunocytochemistry, and ELISA. The addition of KISS alone increased proliferation, apoptosis, progesterone, estradiol release, and decreased testosterone but did not affect viability. The addition of BTC alone decreased cell proliferation, apoptosis, progesterone, testosterone, and estradiol release but did not influence viability. Furthermore, BTC mainly inhibited the stimulatory action of KISS on feline ovarian functions. The findings of our study suggest the effects of KISS on basic ovarian functions. We also observed the influence of BTC on these functions and its ability to modify the effects of KISS on these processes.

The role of Kisspeptin signaling in Oocyte maturation

Kisspeptins (KPs) secreted from the hypothalamic KP neurons act on KP receptors (KPRs) in gonadotropin (GPN) releasing hormone (GnRH) neurons to produce GnRH. GnRH acts on pituitary gonadotrophs to induce secretion of GPNs, namely follicle stimulating hormone (FSH) and luteinizing hormone (LH), which are essential for ovarian follicle development, oocyte maturation and ovulation. Thus, hypothalamic KPs regulate oocyte maturation indirectly through GPNs. KPs and KPRs are also expressed in the ovarian follicles across species. Recent studies demonstrated that intraovarian KPs also act directly on the KPRs expressed in oocytes to promote oocyte maturation and ovulation. In this review article, we have summarized published reports on the role of hypothalamic and ovarian KP-signaling in oocyte maturation. Gonadal steroid hormones regulate KP secretion from hypothalamic KP neurons, which in turn induces GPN secretion from the hypothalamic-pituitary (HP) axis. On the other hand, GPNs secreted from the HP axis act on the granulosa cells (GCs) and upregulate the expression of ovarian KPs. While KPs are expressed predominantly in the GCs, the KPRs are in the oocytes. Expression of KPs in the ovaries increases with the progression of the estrous cycle and peaks during the preovulatory GPN surge. Intrafollicular KP levels in the ovaries rise with the advancement of developmental stages. Moreover, loss of KPRs in oocytes in mice leads to failure of oocyte maturation and ovulation similar to that of premature ovarian insufficiency (POI). These findings suggest that GC-derived KPs may act on the KPRs in oocytes during their preovulatory maturation. In addition to the intraovarian role of KP-signaling in oocyte maturation, in vivo, a direct role of KP has been identified during in vitro maturation of sheep, porcine, and rat oocytes. KP-stimulation of rat oocytes, in vitro, resulted in Ca2+ release and activation of the mitogen-activated protein kinase, extracellular signal-regulated kinase 1 and 2. In vitro treatment of rat or porcine oocytes with KPs upregulated messenger RNA levels of the factors that favor oocyte maturation. In clinical trials, human KP-54 has also been administered successfully to patients undergoing assisted reproductive technologies (ARTs) for increasing oocyte maturation. Exogenous KPs can induce GPN secretion from hypothalamus; however, the possibility of direct KP action on the oocytes cannot be excluded. Understanding the direct in vivo and in vitro roles of KP-signaling in oocyte maturation will help in developing novel KP-based ARTs.

Kisspeptin-10 Promotes Progesterone Synthesis in Bovine Ovarian Granulosa Cells via Downregulation of microRNA-1246

The objective of this study was to clarify the effect of kisspeptin-10 (kp-10) on the synthesis of progesterone (P4) in bovine granulosa cells (BGCs) and its mechanisms via microRNA 1246 (miR-1246). According to the results, we found that treating with kp-10 for 24 h could increase P4 level, the mRNA expression of the steroidogenesis-related gene steroidogenic acute regulatory protein (StAR), free cholesterol content, and decrease miR-1246 expression in BGCs. Overexpression of miR-1246 significantly inhibited P4 synthesis, StAR mRNA expression, and free cholesterol content in BGCs, whereas underexpression of miR-1246 significantly reversed this effect in BGCs. Additionally, overexpression of miR-1246 counteracted the accelerative effect of kp-10 on P4 synthesis, StAR mRNA expression, and free cholesterol content in BGCs. Conversely, underexpression of miR-1246 enhanced the accelerative effect of kp-10 on P4 synthesis, StAR mRNA expression, and free cholesterol content in BGCs. Meanwhile, results of dual-luciferase reporter assays indicated that miR-1246 targeted the 3′UTR of StAR in BGCs. These results demonstrated that kp-10 induced P4 synthesis in BGCs by promoting free cholesterol transport via regulating expression of miR-1246/StAR.

Expression profile of the Kisspeptin/Kiss1r system and angiogenic and immunological mediators in the ovary of cyclic and pregnant cats

The Kisspeptin/Kiss1r system has been studied in mammalian ovaries. However, there are still no studies on the modulation of this system and its relationship with angiogenic and immunological mediators in the ovary of domestic cats, especially during pregnancy. We evaluated the expression of Kisspeptin/Kiss1r and angiogenic and immunological mediators during folliculogenesis, luteogenesis and luteal regression of cyclic and pregnant cats. The ovary exhibited moderate to intense expression for Kiss1, VEGF, Flk-1, INFγ and MIF in oocytes and the follicular wall, while Kiss1r expression was low in granulosa cells. In these cells, there was also a greater expression of Kiss1, INFγ and MIF, mainly in secondary follicles, while tertiary and preovulatory follicles exhibited greater expression of VEGF and Flk-1 in this layer. In luteogenesis, Kiss1 immunostaining was higher in mature corpora lutea (MCL) of pregnant cats compared to vacuolated CL (VCL) and corpus albicans (CA). Pregnancy also increased the luteal gene expression of Kiss1 as well as Kiss1, Kiss1r, Flk-1, and MIF immunostaining in MCL, while reduced the area of VEGF expression in VCL and luteal mRNA expression of Mif when compared to non-pregnant animals. In addition, positive gene correlation between Kiss1r and Mif was observed in the CL. Kiss1, Kiss1r, Vegf and Mif expression were lower in the CA of cats in anestrus. These findings reveal that the expression of Kisspeptin/Kiss1r and angiogenic and immunological mediators, in the ovary of domestic cats, depend on the follicular and luteal stage, and the luteal expression of these mediators is influenced by pregnancy.

Expression of kisspeptin and its receptor in different functional classes of ovarian follicle in the buffalo (Bubalus bubalis)

Recently, we reported the differential expression of kisspeptinergic system in the bubaline hypothalamus and corpus luteum. Here, we document the expression of kisspeptin (Kp) and its receptor (Kiss1r) in the ovarian follicles of the buffalo with respect to the functional status. Follicles of ≥10 to ≤13 mm diameter (n = 45) were retrospectively categorized into active (n = 18), intermediate (n = 16) and atretic (n = 11) follicles based on the concentrations of intrafollicular progesterone (P₄) and estradiol (E₂). The P₄:E₂ ratio was significantly lower in the active follicle (0.43 ± 0.08) than that of the intermediate (3.46 ± 0.53) and atretic (28.4 ± 10.6) follicles (P < 0.05). Relative fold change in the transcripts of kisspeptin (Kiss1), Kiss1r, gonadotrophin receptors, steroid acute regulatory protein (StAR), cytochrome P450 family 11 subfamily A member 1 (CYP11A1), cytochrome P450 Family 19 subfamily A member 1 (CYP19A1), insulin like growth factor -1 (IGF-1), apoptotic factors (caspase 3 and B-cell lymphoma 2, BCL2) was calculated using qPCR in the follicular wall of the three categories of follicle (n = 8/group). In another experiment, histological sections of the ovary (n = 41) were used to group the follicles as described above and immunostaining of Kp, Kiss1r and aromatase was done. A significant upregulation of StAR, CYP11A1 and CYP19A1 in the active follicles supported the endocrine basis of follicular classification. The transcripts of Kiss1 and Kiss1r were upregulated by 19.45 fold and 4.25 fold, respectively in the active follicle as compared to other groups. Immunolocalization studies revealed that Kp and Kiss1r were localized to the basal and antral granulosa cells (GC) of the active and intermediate follicles; however, the staining intensity was stronger in the former group. Strong expression of CYP19A1 in the GC layer of active follicle supported the histological basis of defining the functional status of the follicle. It is concluded that the follicular compartment of the bubaline ovary expressed the constituents of kisspeptinergic system. The expression of Kp and Kiss1r was influenced by the functional status of the follicle with intense localization in the GC layer of the active follicles.

Kisspeptin as autocrine/paracrine regulator of human ovarian cell functions: Possible interrelationships with FSH and its receptor

The present study aims to examine the role of kisspeptin (KP), FSH, and its receptor (FSHR), and their interrelationships in the control of basic human ovarian granulosa cells functions. We investigated: (1) the ability of granulosa cells to produce KP and FSHR, (2) the role of KP in the control of ovarian functions, and (3) the ability of KP to affect FSHR and to modify the FSH action on ovarian functions. The effects of KP alone (0, 10 and 100 ng/mL); or of KP (10 and 100 ng/mL) in combination with FSH (10 ng/mL) on cultured human granulosa cells were assessed. Viability, markers of proliferation (PCNA and cyclin B1) and apoptosis (bax and caspase 3), as well as accumulation of KP, FSHR, and steroid hormones, IGF-I, oxytocin (OT), and prostaglandin E2 (PGE2) release were analyzed by the Trypan blue exclusion test, quantitative immunocytochemistry, and ELISA. KP given at a low dose (10 ng/mL) stimulated viability, proliferation, inhibited apoptosis, promoted the release of progesterone (P4), estradiol (E2), IGF-I, OT, and PGE2, the accumulation of FSHR, but not testosterone (T) release. KP given at a high dose (100 ng/mL) had the opposite, inhibitory effect. FSH stimulated cell viability, proliferation and inhibited apoptosis, promoted P4, T, E2, IGF-I, and OT, but not PGE2 release. Furthermore, KP at a low dose promoted the stimulatory effect of FSH on viability, proliferation, P4, E2, and OT release, promoted its inhibitory action on apoptosis, but did not modify its action on T, IGF-I, and PGE2 output. KP at a high dose prevented and inverted FSH action. These results suggest an intra-ovarian production and a functional interrelationship between KP and FSH/FSHR in direct regulation of basic ovarian cell functions (viability, proliferation, apoptosis, and hormones release). The capability of KP to stimulate FSHR, the ability of FSH to promote ovarian functions, as well as the similarity of KP (10 ng/mL) and FSH action on granulosa cells' viability, proliferation, apoptosis, steroid hormones, IGF-I, OT, and PGE2 release, suggest that FSH influence these cells could be mediated by KP. Moreover, the capability of KP (100 ng/mL) to decrease FSHR accumulation, basal and FSH-induced ovarian parameters, suggest that KP can suppress some ovarian granulosa cell functions via down-regulation of FSHR. These observations propose the existence of the FSH-KP axis up-regulating human ovarian cell functions.

Gametogenic and steroidogenic action of kisspeptin-10 in the Asian catfish, Clarias batrachus: Putative underlying mechanistic cascade

Unlike mammals, two kisspeptins genes encoding, kiss1 and kiss2 are detected in fishes with highly varied and contradictory difference in their reproductive activities. The present study was undertaken to examine the direct action of kisspeptin-10 and its role in gonadal activities in the gonadally quiescent Asian catfish using native mammalian kisspeptin decapeptide (KP-10) involving in vivo and in vitro approaches. The in vivo KP-10 treatment caused precocious onset of gametogenesis and its rapid progression, as was evident from the appearance of advanced stages of ovarian follicles in ovary, and advanced germ cells (spermatocytes/ spermatids) in the testis of the treated Clarias batrachus in comparison to the control gonads. It also elevated the steroid levels in gonads of the catfish in vivo and in vitro conditions. Simultaneously, it increased the expressions of key steroidogenic enzymes like 3β-HSD, 17β-HSD, and StAR protein, responsible for transfer of cholesterol from outer to inner membrane of the mitochondria of steroidogenic cells. Concurrently, it augmented the activities of 3β-HSD and 17β-HSD in the ovarian explants. The expressions of MAPK component (pERK1/2 and ERK1/2) were also up-regulated by KP-10 in gonadal explants. Thus, the data suggest that kisspeptin-10 stimulates gametogenesis by enhancing gonadal steroid production. The study also describes the putative mechanistic cascade of steroidogenic actions of kisspeptin-10 in the catfish so much so in teleost fish. The study also suggests that, kisspeptin may act locally to regulate gonadal activities in an autocrine/paracine manner, independent of known extra-gonadal factors in the catfish.

Interrelationships between kisspeptin and FSH in control of porcine ovarian cell functions

The existing knowledge of the direct action of kisspeptin on the ovary needs to be expanded. In our study, the direct effects of kisspeptin on basic ovarian cell functions and their response to FSH were examined. We studied the effect of kisspeptin alone (0, 1, 10, and 100 ng/mL) and of kisspeptin (1, 10, and 100 ng/mL) in combination with FSH (10 ng/mL) on cultured porcine granulosa cells. Markers of viability, proliferation (accumulation of proliferating cell nuclear antigen [PCNA] and cyclin B1), and apoptosis (accumulation of bax and caspase 3), as well as the release of steroid hormones and IGF-I were analyzed using the trypan blue exclusion test, quantitative immunocytochemistry, and ELISA. Addition of kisspeptin at lower doses (1 and 10 ng/mL) increased cell viability, the accumulation of PCNA and cyclin B1, decreased the accumulation of bax and caspase 3, and promoted release of progesterone, estradiol, and IGF-I, but not testosterone. A high dose (100 ng/mL) of kisspeptin had the opposite, inhibitory effect. The addition of FSH increased cell viability, proliferation, decreased apoptosis, and promoted progesterone, testosterone, estradiol, and IGF-I release. Kisspeptin at lower doses supported the stimulatory action of FSH on viability, PCNA and cyclin B1 accumulation, and release of progesterone and estradiol, promoted its inhibitory action on bax and caspase 3 accumulation, but did not modify its action on testosterone and IGF-I release. On the contrary, kisspeptin at a high dose inhibited and even reversed the FSH effect. FSH mimicked and promoted both the stimulatory and inhibitory action of kisspeptin on all examined ovarian functions besides IGF-I release. These observations show that kisspeptin can directly regulate basal ovarian cell functions. Furthermore, they demonstrate the functional interrelationships between kisspeptin and FSH in direct regulation of ovarian functions.

Roles of kisspeptin in IVF/ICSI-treated infertile women and in human granulosa cells

Kisspeptin, a crucial central regulator of reproduction, has been used as a trigger in in vitro fertilization (IVF) treatment. This study aimed to investigate the roles of kisspeptin in IVF treatment in infertile females (n = 30); and in steroidogenesis in human granulosa-like tumor cell line (KGN). In the human study, blood was collected at three time points including (1) the beginning of gonadotropin stimulation (Phase I), (2) around eight days after gonadotropin stimulation (Phase II), and (3) on the day of ovum pick-up (Phase III). Follicular fluid (FF) was collected at Phase III. Serum human chorionic gonadotropin (hCG) was measured 15 days after embryo transfer and fetal heart beats were determined around 42 days of menstrual cycle to classify the subjects into successful and unsuccessful groups. FF kisspeptin levels were higher in successful compared with unsuccessful subjects (P < 0.01). Kisspeptin levels were significantly higher in FF than in serum in successful subjects (P < 0.05) but were comparable in unsuccessful subjects. Serum kisspeptin was comparable among three phases in the successful group but its levels in Phase III were significantly lower compared with Phase I in the unsuccessful group (P < 0.01). Serum kisspeptin in Phase II/III had positive correlations with serum E2 in Phases II and III and the outcomes of IVF/intracytoplasmic sperm injection (ICSI) treatment including serum hCG levels. For the cell experiment (n = 3), kisspeptin treatment in the presence of FSH together with IGF-1 enhanced CYP19A1 (aromatase) mRNA expression compared with control. FSH alone increased aromatase concentrations in the supernatant compared with control and kisspeptin at the dose of 10^-2 mmol/L with FSH enhanced aromatase concentrations in the supernatant compared with FSH alone (P < 0.001 all). In conclusion, kisspeptin enhanced aromatase expression and secretion and was associated with positive outcomes of IVF/ICSI treatment. Further studies regarding supplementation of kisspeptin could reveal its beneficial effects on IVF/ICSI treatment.

Effects of Osthole on Progesterone Secretion in Chicken Preovulatory Follicles Granulosa Cells

Simple Summary

Progesterone produced by granulosa cells regulates the diverse reproductive events in poultry. Osthole is a natural compound extracted from Cnidium. In this study, we confirmed Osthole up-regulated the progesterone secretion though elevating the expression of key proteins in the process of progesterone synthesis. These results indicate Osthole could be used in the pre-peak phase and (or) the peak phase to maximize the output of egg production in laying hens. Moreover, it provided a new idea that natural compounds may be the target library to screen the potential drugs used in poultry to increase the egg quality and yield.

Abstract

Osthole (Ost) is an active constituent of Cnidium monnieri (L.) Cusson which possesses anti-inflammatory and anti-oxidative properties. It also has estrogen-like activity and can stimulate corticosterone secretion. The present study was aimed to check the role of Ost on progesterone (P4) secretion in cultured granulosa cells obtained from hen preovulatory follicles. Different concentrations (5, 2.5, and 1.25 µg/mL) of Ost was added to granulosa cells for 6, 12, 18, and 24 h to investigate the level of progesterone secretions using enzyme linked immunosorbent assay (ELISA). The results showed that progesterone secretion was significantly increased in cells treated with Ost at 2.5 μg/mL. Also, qRT-PCR showed that mRNA expression of steroidogenic acute regulatory protein (StAR) was significantly up-regulated by Ost at 2.5 μg/mL concentration. Cytochrome P450 side-chain cleavage (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) was significantly up-regulated by Ost. However, no significant differences were observed for the expression of proliferating cell nuclear antigen (PCNA). The protein expression of StAR, P450scc and 3β-HSD were significantly up-regulated by Ost treatment. The concentration of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in cell lysates showed no change with Ost treatment at 2.5 μg/mL by ELISA. An ROS kit showed non-significant difference in the level of reactive oxygen species (ROS). In conclusion, Ost treatment at a concentration of 2.5 μg/mL for 24 h had significantly up-regulated P4 secretion by elevating P450scc, 3β-HSD and StAR at both gene and protein level in granulosa cells obtained from hen preovulatory follicles.

Nitrophenols are negative modulators of steroidogenesis in preovulatory follicles of the hen (Gallus domesticus) ovary: An in vitro and in vivo study

This study assessed the effects of 4-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) on steroidogenesis in the granulosa layers (GLs) and theca layers (TLs) of chicken preovulatory follicles in vitro and in vivo. In the in vitro experiment, three of the largest yellow preovulatory follicles (F3 < F2 < F1) were exposed to PNP or PNMC (10^-8-10^-4 M), ovine luteinising hormone (oLH; 10 ng/mL), and combinations of oLH and PNP or PNMC (10^-6 M). In the in vivo experiment, laying hens were treated for 6 days with PNP or PNMC (10 mg/kg). In vitro experiments revealed that PNP and PNMC decreased basal and oLH-stimulated P4 secretion from the GL as well as T and E2 secretion from the TLs of F3-F1 follicles. Treatment of laying hens with nitrophenols lowered plasma concentrations of luteinising hormone and all three steroids. The reduction of steroid secretion was associated with decrease in LHR, HSD3B1 and CYP19A1 mRNA expression in the GL and/or TLs of the preovulatory follicles, both in vitro and in vivo. Moreover, PNP decreased HSD3B protein expression in the GL of F2 follicles in vitro and in vivo, while PNMC diminished its expression in the GL of F1 follicles in vivo. In vitro, nitrophenols did not affect CYP19A1 protein expression; however, nitrophenols inhibited its expression in the TLs of F3 and F2 follicles in vivo. The results obtained clearly demonstrate that nitrophenols are negative modulators of steroidogenesis in chicken preovulatory follicles and, in consequence, may not only impair ovulation process, but also affect function of the hypothalamic-pituitary-ovarian axis.

Origin and Evolution of the Neuroendocrine Control of Reproduction in Vertebrates, With Special Focus on Genome and Gene Duplications

In humans, as in the other mammals, the neuroendocrine control of reproduction is ensured by the brain-pituitary gonadotropic axis. Multiple internal and environmental cues are integrated via brain neuronal networks, ultimately leading to the modulation of the activity of gonadotropin-releasing hormone (GnRH) neurons. The decapeptide GnRH is released into the hypothalamic-hypophysial portal blood system and stimulates the production of pituitary glycoprotein hormones, the two gonadotropins luteinizing hormone and follicle-stimulating hormone. A novel actor, the neuropeptide kisspeptin, acting upstream of GnRH, has attracted increasing attention in recent years. Other neuropeptides, such as gonadotropin-inhibiting hormone/RF-amide related peptide, and other members of the RF-amide peptide superfamily, as well as various nonpeptidic neuromediators such as dopamine and serotonin also provide a large panel of stimulatory or inhibitory regulators. This paper addresses the origin and evolution of the vertebrate gonadotropic axis. Brain-pituitary neuroendocrine axes are typical of vertebrates, the pituitary gland, mediator and amplifier of brain control on peripheral organs, being a vertebrate innovation. The paper reviews, from molecular and functional perspectives, the evolution across vertebrate radiation of some key actors of the vertebrate neuroendocrine control of reproduction and traces back their origin along the vertebrate lineage and in other metazoa before the emergence of vertebrates. A focus is given on how gene duplications, resulting from either local events or from whole genome duplication events, and followed by paralogous gene loss or conservation, might have shaped the evolutionary scenarios of current families of key actors of the gonadotropic axis.

Reproductive functions of Kisspeptin/KISS1R Systems in the Periphery

Kisspeptin and its G protein-coupled receptor KISS1R play key roles in mammalian reproduction due to their involvement in the onset of puberty and control of the hypothalamic-pituitary-gonadal axis. However, recent studies have indicated a potential role of extra-hypothalamic kisspeptin in reproductive function. Here, we summarize recent advances in our understanding of the physiological significance of kisspeptin/KISS1R in the peripheral reproductive system (including the ovary, testis, uterus, and placenta) and the potential role of kisspeptin/KISS1R in reproductive diseases. A comprehensive understanding of the expression, function, and potential molecular mechanisms of kisspeptin/KISS1R in the peripheral reproductive system will contribute to the diagnosis, treatment and prevention of reproductive diseases.

Genistein increases progesterone secretion by elevating related enzymes in chicken granulosa cells

Genistein, a biologically active isoflavone, exists in many soy products. It is well known that genistein binds to both oestrogen receptor alpha (ERα) and oestrogen receptor beta (ERβ), but it has a higher affinity to ERβ. Genistein can also bind to the G protein-coupled receptor 30 (GPR30, also known as G protein-coupled oestrogen receptor 1 or GPER). Furthermore, weak oestrogenic activity has been found in genistein, but the mechanism of action remains unknown. The aim of this study was to investigate the in vitro effects of genistein on the secretion of progesterone (P4) and oestradiol (E2) in chicken granulosa cells harvested from follicles, as well as the mRNA expression of ERs in these cells. In addition, we examined the expression of key enzymes including steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in the process of P4 synthesis. The results showed that genistein did not affect the viability of granulosa cells, nor was the proliferating cell nuclear antigen (PCNA) protein changed. Among the 1-, 10-, 100-, and 1,000-nM concentrations tested, treatment with 1 nM genistein for 48 h significantly increased P4 but did not affect E2 secretion. Real-time PCR results showed that the ERβ gene expression in granulosa cells was markedly upregulated by 1 nM genistein treatment for 48 h, but there was no significant difference in ERα and GPR30 expression. Genistein also increased the gene expression of StAR, P450scc and 3β-HSD in the cultured granulosa cells. These results indicate that genistein acts directly on chicken granulosa cells to increase P4 production by upregulating the gene expression of key enzymes through binding in ERβ. It may exert positive effects on the reproduction of late-laying hens and act as an effective and safe feed additive for animals.

Kisspeptin/kisspeptin receptor system in pseudopregnant rabbit corpora lutea: presence and function

Kisspeptin (KiSS) and its related receptors (KiSS1R) have a critical role in the reproduction of mammals. The KiSS/KiSS1R system is expressed in numerous reproductive organs including the ovary. Here, we studied the expression of the KiSS/KiSS1R system and its functional role in rabbit corpora lutea (CL) at days 4 (early-), 9 (mid-), and 13 (late-stage) of pseudopregnancy. In vitro progesterone, prostaglandin (PG) F2α (PGF2α) and E2 (PGE2) productions and prostaglandin-endoperoxide synthase 1 (PTGS1) and 2 (PTGS2) activities were evaluated. Immune reactivity (IR) for KiSS and KiSS1R were detected in luteal cells at nuclear and cytoplasmic level at all luteal stage for KiSS and only at early- and mid-stage for KiSS1R; IR decreased from early- to later stages of pseudopregnancy. The KiSS-10 augmented progesterone and PGE2 and diminished PGF2α secretions by early- and mid-CL; KiSS-10 reduced PTGS2 activity at early- and mid-stages, but did not affect PTGS1 at any luteal stages. The antagonist KiSS-234 counteracted all KiSS-10 effects. This study shows that the KiSS/KiSS1R system is expressed in CL of pseudopregnant rabbits and exerts a luteotropic action by down-regulating PTGS2, which decreases PGF2α and increases PGE2 and progesterone.

The direct and indirect effects of kisspeptin-54 on granulosa lutein cell function

STUDY QUESTION

What are the in vivo and in vitro actions of kisspeptin-54 on the expression of genes involved in ovarian reproductive function, steroidogenesis and ovarian hyperstimulation syndrome (OHSS) in granulosa lutein (GL) cells when compared with traditional triggers of oocyte maturation?

SUMMARY ANSWER

The use of kisspeptin-54 as an oocyte maturation trigger augmented expression of genes involved in ovarian steroidogenesis in human GL cells including, FSH receptor (FSHR), LH/hCG receptor (LHCGR), steroid acute regulatory protein (STAR), aromatase, estrogen receptors alpha and beta (ESR1, ESR2), 3-beta-hydroxysteroid dehydrogenase type 2 (3BHSD2) and inhibin A (INHBA), when compared to traditional maturation triggers, but did not alter markers of OHSS.

WHAT IS KNOWN ALREADY

hCG is the most widely used trigger of oocyte maturation, but is associated with an increased risk of OHSS. The use of GnRH agonists to trigger oocyte maturation is a safer alternative to hCG. More recently, kisspeptin-54 has emerged as a novel therapeutic option that safely triggers oocyte maturation even in women at high risk of OHSS. Kisspeptin indirectly stimulates gonadotropin secretion by acting on hypothalamic GnRH neurons. Kisspeptin and its receptor are also expressed in the human ovary, but there is limited data on the direct action of kisspeptin on the ovary.

STUDY DESIGN SIZE, DURATION

Forty-eight women undergoing IVF treatment for infertility consented to kisspeptin-54 triggering and/or granulosa cell collection and were included in the study. Twelve women received hCG, 12 received GnRH agonist and 24 received kisspeptin-54 to trigger oocyte maturation. In the kisspeptin-54 group, 12 received one injection of kisseptin-54 (9.6 nmol/kg) and 12 received two injections of kisspeptin-54 at a 10 h interval (9.6 nmol/kg × 2).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Follicular fluid was aspirated and pooled from follicles during the retrieval of oocytes for IVF/ICSI. GL cells were isolated and either RNA extracted immediately or cultured in vitro ± kisspeptin or hCG.

MAIN RESULTS AND THE ROLE OF CHANCE

GL cells from women who had received kisspeptin-54 had a 14-fold and 8-fold higher gene expression of FSHR and a 2-fold (ns) and 2.5-fold (P < 0.05) higher expression of LHCGR than GL cells from women who had received hCG or GnRH agonist, respectively. CYP19A1 expression was 3.6-fold (P < 0.05) and 4.5-fold (P < 0.05) higher, STAR expression was 3.4-fold (P < 0.01) and 1.8-fold (P < 0.05) higher, HSD3B2 expression was 7.5- (P < 0.01) and 2.5-fold higher (P < 0.05), INHBA was 2.5-fold (P < 0.01) and 2.5-fold (P < 0.01) higher in GL cells from women who had received kisspeptin-54 than hCG or GnRHa, respectively. ESR1 (P < 0.05) and ESR2 (P < 0.05) both showed 3-fold higher expression in cells from kisspeptin treated than GnRHa treated women. Markers of vascular permeability and oocyte growth factors were unchanged (VEGFA, SERPINF1, CDH5, amphiregulin, epiregulin). Gene expression of kisspeptin receptor was unchanged. Whereas treating GL cells in vitro with hCG induced steroidogenic gene expression, kisspeptin-54 had no significant direct effects on either OHSS genes or steroidogenic genes.

LIMITATIONS REASONS FOR CAUTION

Most women in the study had PCOS, which may limit applicability to other patient groups. For the analysis of the in vitro effects of kisspeptin-54, it is important to note that GL cells had already been exposed in vivo to an alternate maturation trigger.

WIDER IMPLICATIONS OF THE FINDINGS

The profile of serum gonadotropins seen with kisspeptin administration compared to other triggers more closely resemble that of the natural cycle as compared with hCG. Thus, kisspeptin could potentially permit an ovarian environment augmented for steroidogenesis, in particular progesterone synthesis, which is required for embryo implantation.

STUDY FUNDING/COMPETING INTEREST(S)

Dr Owens is supported by an Imperial College London PhD Scholarship. Dr Abbara is supported by an National Institute of Health Research Academic Clinical Lectureship. The authors do not have any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01667406.

Altered expression of the kisspeptin/KISS1R and neurokinin B/NK3R systems in mural granulosa and cumulus cells of patients with polycystic ovarian syndrome

PURPOSE

The neurokinin B (NKB)/NK₃ receptor (NK3R) and kisspeptin (KISS1)/kisspeptin receptor (KISS1R), two systems essential for reproduction, are present in human granulosa cells (GCs) of healthy women and contribute to the control of fertility, at least partially, by acting on the gonads. However, little is known about the expression of these systems in GCs of women with polycystic ovarian syndrome (PCOS). The aim of this study was to analyze the expression of NKB/NK3R and KISS1/KISS1R in mural granulosa (MGCs) and cumulus cells (CCs) of PCOS women.

METHODS

A cross-sectional study was performed in 46 healthy women and 43 PCOS women undergoing controlled ovarian stimulation. MGCs and CCs were collected from pre-ovulatory follicles after transvaginal ultrasound-guided oocyte retrieval and the expression of the genes encoding NKB (TAC3), NK3R (TACR3), KISS1, and its receptor (KISS1R) was analyzed using real-time quantitative RT-PCR.

RESULTS

TAC3, TACR3, and KISS1 mRNA levels were decreased in MGCs and CCs of PCOS women. TAC3 positively correlated with KISS1 in MGCs of healthy women and TACR3 was positively associated with KISS1R in CCs from healthy women. These associations were not observed in PCOS women.

CONCLUSION

The NKB/NK3R and KISS1/KISS1R systems are dysregulated in MGCs and CCs of PCOS women. The lower expression of these systems in GCs could contribute to the abnormal follicle development and defective ovulation that characterize the pathogenesis of PCOS.

Molecular mechanism of mercuric chloride inhibiting progesterone secretion in ovarian granulosa cells of laying hens

This study investigated the effect of mercury (Hg) on progesterone secretion in ovarian granulosa cells of laying hens. The gene expressions of steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD), cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway and intracellular calcium ion (Ca²⁺ ) were further investigated to uncover the molecular mechanism. Results revealed that the cell viability was gradually decreased after Hg exposure from 0 to 24 hr. Besides, progesterone secretion was significantly decreased (p < 0.05) as the concentration of Hg increased from 0 to 4 μM followed by a plateau in 6 μM Hg group at 12-hr time point. Compared with 0 μM Hg group, 4 and 6 μM Hg for 48 hr had significantly decreased progesterone secretion (p < 0.05), while Hg exposure for 6 and 24 hr had no apparent effect on progesterone secretion. In addition, positive correlations occurred among intracellular progesterone, cAMP, PKA, mRNA expressions of StAR, P450scc and 3β-HSD at 12-h and 24-h time points. On the contrary, intracellular Ca²⁺ level was negatively related to cAMP level at 6 time point and was negatively correlated with progesterone and PKA level at 48 time point. It could be concluded that Hg dose- and time-dependently inhibited progesterone secretion by means of attenuating cAMP-PKA signal pathway, gene expressions of StAR, P450scc and 3β-HSD and enhancing intracellular Ca²⁺ in ovarian granulosa cells of laying hens.

Comparison of growth characteristics of in vitro cultured granulosa cells from geese follicles at different developmental stages

Granulosa cells (GCs) are essential components of follicles and are involved in regulating the process of follicles development. However, comparative studies on GCs isolated from different staged follicles have not been conducted in goose. The aim of the present study was to identify the growth characteristics of goose GCs from pre-hierarchical (6–10 mm) and hierarchical (F4–F2, F1) follicles. Our results showed that the three cohorts of cells had different tolerance to collagenase and had noticeable morphological differences. The F1 granulosa layers were fully digested by 0.1% collagenase, while higher concentration (0.3%) was used for both F4–F2 and pre-hierarchical granulosa layers. In the state of suspension, the diameter of F1 individual cell was larger than the other two cohorts. However, after adhering to the culture plate, cells of F1 just had changes in the diameter accompanied by small bright spots, while both pre-hierarchical and F4–F2 GCs proliferated rapidly with spreading and irregularly shaped voids. Furthermore, all attached cells could be stained by the follicle-stimulating hormone receptor antibody. Analyses of both growth curve and the mRNA expression profiles of genes related to cellular proliferation, apoptosis, and steroidogenesis suggested that three cohorts of in vitro cultured GCs had different physiological viability and functions. Taken together, the present study not only revealed differences of the growth characteristics among three cohorts of goose GCs from pre-hierarchical, F4–F2 and F1 follicles, but also optimized the in vitro culture system of geese different staged GCs.

Kisspeptin-10 inhibits OHSS by suppressing VEGF secretion

The aim of the present study was to elucidate the effects of kisspeptin-10 (Kp-10) on ovarian hyperstimulation syndrome (OHSS) and its related mechanism in OHSS rat models, human umbilical vein endothelial cells (HUVECs) and human luteinized granulosa cells. OHSS is a systemic disorder with high vascular permeability (VP) and ovarian enlargement. KISS1R (KISS1 receptor) is the specific receptor of kisspeptin. The kisspeptin/KISS1R system inhibits the expression of vascular endothelial growth factor (VEGF), which is the main regulator of VP. In our study, decreased expression of Kiss1r was observed in both ovaries and lung tissue of OHSS rats. Injection of exogenous Kp-10 inhibited the increase of VP and VEGF while promoting the expression of Kiss1r in both the ovarian and lung tissue of OHSS rats. Using HUVECs, we revealed that a high level of 17-β estradiol (E2), a feature of OHSS, suppressed the expression of KISS1R and increased VEGF and nitric oxide (NO) through estrogen receptors (ESR2). Furthermore, KISS1R mRNA also decreased in the luteinized human granulosa cells of high-risk OHSS patients, and was consistent with the results in rat models and HUVECs. In conclusion, Kp-10 prevents the increased VP of OHSS by the activation of KISS1R and the inhibition of VEGF.

Effect of kisspeptin on the proliferation and apoptosis of bovine granulosa cells

Previous studies have shown that kisspeptin (Kp-10) is expressed in mammalian ovaries; however, the expression and role of Kp-10 in bovine ovarian granulosa cells are still unclear. In this study, we assessed the expression of Kp-10 and its effects on the proliferation and apoptosis of bovine granulosa cells. Immunohistochemical analysis showed that Kp-10 was expressed in the cytoplasm of bovine ovarian granulosa cells. Moreover, MTT assays showed that 100nM Kp-10 significantly inhibited the viability of granulosa cells (P<0.05). Flow cytometry analysis showed that Kp-10 could significantly increase accumulation of cells in the G₁ phase, decrease accumulation of cells in the S phase, and promote apoptosis in bovine granulosa cells (P<0.05). Additionally, Kp-10 decreased the mRNA levels of Bcl-2, an anti-apoptotic gene; increased the mRNA levels of caspase-3, a pro-apoptotic gene; and increased the mRNA levels of Fas and Fasl (P< 0.05). Thus, our findings demonstrated for the first time that Kp-10 inhibited proliferation and promoted apoptosis in bovine ovarian granulosa cells. These findings provide insights into our understanding of the role of Kp-10 in mediating the proliferation of bovine granulosa cells.

Kisspeptin/Kisspeptin Receptor System in the Ovary

Kisspeptins are a family of neuropeptides that are critical for initiating puberty and regulating ovulation in sexually mature females via the central control of the hypothalamic-pituitary-gonadal axis. Recent studies have shown that kisspeptin and its receptor kisspeptin receptor (KISS1R) are expressed in the mammalian ovary. Convincing evidence indicates that kisspeptins can activate a wide variety of signals via its binding to KISS1R. Experimental data gathered recently suggest a putative role of kisspeptin signaling in the direct control of ovarian function, including follicular development, oocyte maturation, steroidogenesis, and ovulation. Dysregulation or naturally occurring mutations of the kisspeptin/KISS1R system may negatively affect the ovarian function, leading to reproductive pathology or female infertility. A comprehensive understanding of the expression, actions, and underlying molecular mechanisms of this system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in reproductive diseases and infertility.

Peripheral and Central Mechanisms Involved in the Hormonal Control of Male and Female Reproduction

Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the luteinising hormone (LH) surge, which is mediated by oestradiol (E2 ) and neuroprogesterone interacting to stimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recent evidence indicates the involvement of both classical and membrane E2 and progesterone signalling in this pathway. A metabolite of gonadotrophin-releasing hormone (GnRH), GnRH-(1-5), has been shown to stimulate GnRH expression and secretion, and has a role in the regulation of lordosis. Additionally, gonadotrophin release-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurones in birds. Stress-induced changes in GnIH have been shown to alter breeding behaviour in birds, demonstrating another mechanism for the molecular control of reproduction. Peripherally, paracrine and autocrine actions within the gonad have been suggested as therapeutic targets for infertility in both males and females. Dysfunction of testicular prostaglandin synthesis is a possible cause of idiopathic male infertility. Indeed, local production of melatonin and corticotrophin-releasing hormone could influence spermatogenesis via immune pathways in the gonad. In females, vascular endothelial growth factor A has been implicated in an angiogenic process that mediates development of the corpus luteum and thus fertility via the Notch signalling pathway. Age-induced decreases in fertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally, morphological changes in the arcuate nucleus of the hypothalamus influence female sexual receptivity in rats. The processes mediating these morphological changes have been shown to involve the rapid effects of E2 controlling synaptogenesis in this hypothalamic nucleus. In summary, this review highlights new research in these areas, focusing on recent findings concerning the molecular mechanisms involved in the central and peripheral hormonal control of reproduction.

Kisspeptin is involved in ovarian follicular development during aging in rats

We have previously reported that kisspeptin (KP) may be under the control of the sympathetic innervation of the ovary. Considering that the sympathetic activity of the ovary increases with aging, it is possible that ovarian KP also increases during this period and participates in follicular development. To evaluate this possibility, we determined ovarian KP expression and its action on follicular development during reproductive aging in rats. We measured ovarian KP mRNA and protein levels in 6-, 8-, 10- and 12-month-old rats. To evaluate follicular developmental changes, intraovarian administration of KP or its antagonist, peptide 234 (P234), was performed using a mini-osmotic pump, and to evaluate FSH receptor (FSHR) changes in the senescent ovary, we stimulated cultured ovaries with KP, P234 and isoproterenol (ISO). Our results shows that KP expression in the ovary was increased in 10- and 12-month-old rats compared with 6-month-old rats, and this increase in KP was strongly correlated with the increase in ovarian norepinephrine observed with aging. The administration of KP produced an increase in corpora lutea and type III follicles in 6- and 10-month-old rats, which was reversed by P234 administration at 10 months. In addition, KP decreased the number and size of antral follicles in 6- and 10-month-old rats, while P234 administration produced an increase in these structures at the same ages. In ovarian cultures KP prevented the induction of FSHR by ISO. These results suggest that intraovarian KP negatively participates in the acquisition of FSHR, indicating a local role in the regulation of follicular development and ovulation during reproductive aging.

Molecular cloning and expression patterns of the cholesterol side chain cleavage enzyme (CYP11A1) gene during the reproductive cycle in goose (Anas cygnoides)

Background

CYP11A1, a gene belonging to the family 11 of cytochrome P450, encodes a crucial steroidogenic enzyme that catalyzes the initial step in the production of all classes of steroids. Many studies show that CYP11A1 plays a role in ovary function. However, the role of CYP11A1 in goose reproductive cycle remains largely unknown.

Results

In this study, full-length CYP11A1 cDNA of Zhedong goose was obtained using reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The cDNA consisted of a 96-base pair (bp) 5′untranslated region (UTR), a 179-bp 3′UTR and a 1509-bp open reading frame. The open reading frame encodes a putative 503 amino acid protein that shares high homology with CYP11A1 of other birds. The amino acid sequence possesses conserved domains of the P450 superfamily, which include the steroid-binding domain and the heme-binding region. Real-time quantitative polymerase chain reaction (qPCR) analysis revealed CYP11A1 mRNA was expressed ubiquitously in every Zhedong goose tissue analyzed, including the heart, liver, glandular stomach, lung, spleen, kidney, intestinum tenue, intestinum crassum, cerebrum, cerebellum, muscle, oviduct, pituitary, hypothalamus and ovary.. The relatively low levels of CYP11A1 mRNA were detected in pituitary, ovary and oviduct tissues at ovulation when compared with levels at oviposition. Interestingly, higher expression was observed in ovary and oviduct tissues during brooding. Lastly, higher mRNA expression of Yangzhou geese was detected during the ovulation period than that of Zhedong geese.

Conclusions

Our findings reveal the sequence characterization and expression patterns of the CYP11A1 gene during the goose reproductive cycle, which may provides correlative evidence that CYP11A1 expression is important in reproduction activity.

Transcriptome profiling identifies differentially expressed genes in Huoyan goose ovaries between the laying period and ceased period

The Huoyan goose is famous for its high egg-laying performance and is listed as a nationally protected domestic animal by the Chinese government. To elucidate the key regulatory genes involved in Huoyan goose egg laying, RNA from ovarian tissue during the ceased and laying periods was sequenced using the Illumina HiSeq 2000 sequencing platform. More than 12 million reads were produced in ceased and laying libraries that included 11,896,423 and 12,534,799 clean reads, respectively. More than 20% of the reads were matched to the reference genome, and 23% of the reads were matched to reference genes. Genes with a false discovery rate (FDR) ≤0.001 and log₂ratio ≧1 or ≤−1 were characterized as differentially expressed, and 344 up-regulated and 344 down-regulated genes were classified into functional categories. Twelve genes that are mainly involved in pathways for reproduction regulation, such as steroid hormone biosynthesis, GnRH signaling pathways, oocyte meiosis, progesterone-mediated oocyte maturation, steroid biosynthesis, calcium signaling pathways, and G-protein coupled receptor signaling pathway were selected for validation by a quantitative real-time polymerase chain reaction (qRT-PCR) analysis, the qRT-PCR results are consistent with the general expression patterns of those genes from the Illumina sequencing. These data provide comprehensive gene expression information at the transcriptional level that might increase our understanding of the Huoyan goose's reproductive biology.

Kisspeptin-10 enhanced egg production in quails associated with the increase of triglyceride synthesis in liver

Our previous results showed that kisspeptin-10 (Kp-10) injections via intraperitoneal (i.p.) once daily for three weeks notably promoted the egg laying rate in quails. In order to investigate the mechanism behind the effects of Kp-10 on enhancing the egg laying rate in birds, this study focused on the alternations of lipids synthesis in liver after Kp-10 injections. 75 female quails (22 d of age) were allocated to three groups randomly, and subjected to 0 (control, Con), 10 nmol (low dosage, L) and 100 nmol (high dosage, H) Kp-10 injections via i.p. once daily for three weeks, respectively. At d 52, quails were sacrificed and sampled for further analyses. Serum E2 concentration was increased by Kp-10 injections, and reached statistical significance in H group. Serum triglyceride (TG) concentrations were increased by 46.7% in L group and 36.8% in H group, respectively, but did not reach statistical significance, and TG contents in liver were significantly elevated by Kp-10 injections in a dose-dependent manner. Serum total cholesterol (Tch) concentrations significantly decreased in H group, while in H group the hepatic Tch content was markedly increased. The level of non-esterified fatty acid (NEFA), apolipoprotein A1 and B (apoA1 and apoB) were not altered by Kp-10 injections. The genes expression of sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthetase (FAS), apolipoprotein VLDL-II (apoVLDL-II), cholesterol 7α-hydroxylase (CYP7A1) and vitellogenin II (VTG-II) were significantly up-regulated by high but not low dosage of Kp-10 injection compared to the control group. However, the expression of SREBP-2, acetyl-CoA carboxylase (ACCα), malic enzyme (ME), stearoyl-CoA (Δ9) desaturase 1 (SCD1), apolipoprotein A1 (apoA1), fatty acid binding protein 2 (FABP2), 3-hydroxyl-3-methyl glutaryl-coenzyme A reductases (HMGCR), estrogen receptor α, β (ERα and β) mRNA were not affected by Kp-10 treatment. In line with hepatic mRNA abundance, hepatic SREBP1 protein content was significantly higher in H group. Although the mRNA expression was not altered, the content of ERα protein in liver was also significantly increased in H group. However, SREBP-2 protein content in liver was not changed by Kp-10 treatment. In conclusion, exogenous Kp-10 consecutive injections during juvenile stage significantly advanced the tempo of egg laying in quails, which was associated with the significant elevation in hepatic lipids synthesis and transport.

Effects of kisspeptin-10 on lipid metabolism in cultured chicken hepatocytes

Our previous studies showed that kisspeptin-10 (Kp-10) injected in vivo can markedly increase lipid anabolism in liver of quails. In order to investigate the direct effect of Kp-10 on lipid metabolism of hepatocytes in birds, cells were separated from embryos livers and cultured in vitro with 0, 100 and 1,000 nM Kp-10, respectively. The results showed that after 24 h treatment, cells viability was not affected by 100 nM Kp-10, but showed a mild decrease with 1,000 nM Kp-10 compared to the control cells. Based on the results of the cell viability, 100 nM dosage of Kp-10 was selected for the further study and analysis. Compared with control cells, total cholesterol (Tch) contents in 100 nM treated cells were increased by 51.23%, but did not reach statistical significance, while the level of triglyceride (TG), high density of lipoprotein-cholesterol (HDL-C) and low density of lipoprotein-cholesterol (LDL-C) were significantly increased. Real-time PCR results showed that ApoVLDL-II mRNA expression had a tendency to increase, genes including sterol regulatory element-binding protein-1 (SREBP-1), acetyl coenzyme A carboxylase α (ACCα), carnitine palmitoyltransferase 1 (CPT1), 3-hydroxyl-3-methylglutaryl-coenzyme A reductases (HMGCR) and stearyl coenzyme A dehydrogenase-1 (SCD1) mRNA in hepatocytes were significantly down-regulated by 100 nM Kp-10. However, contrary to its gene expression, SREBP-1 protein expression was significantly up-regulated by 100 nM Kp-10. Some of the significant correlations in mRNA expression were found between genes encoding hepatic factors or enzymes involved in lipid metabolism in liver of birds. These results indicate that Kp-10 stimulates lipid synthesis directly in primary cultured hepatocytes of chickens.

Looking for the bird Kiss: evolutionary scenario in sauropsids

Background

The neuropeptide Kiss and its receptor KissR are key-actors in the brain control of reproduction in mammals, where they are responsible for the stimulation of the activity of GnRH neurones. Investigation in other vertebrates revealed up to 3 Kiss and 4 KissR paralogs, originating from the two rounds of whole genome duplication in early vertebrates. In contrast, the absence of Kiss and KissR has been suggested in birds, as no homologs of these genes could be found in current genomic databases. This study aims at addressing the question of the existence, from an evolutionary perspective, of the Kisspeptin system in birds. It provides the first large-scale investigation of the Kisspeptin system in the sauropsid lineage, including ophidian, chelonian, crocodilian, and avian lineages.

Results

Sauropsid Kiss and KissR genes were predicted from multiple genome and transcriptome databases by TBLASTN. Phylogenetic and syntenic analyses were performed to classify predicted sauropsid Kiss and KissR genes and to re-construct the evolutionary scenarios of both gene families across the sauropsid radiation.

Genome search, phylogenetic and synteny analyses, demonstrated the presence of two Kiss genes (Kiss1 and Kiss2 types) and of two KissR genes (KissR1 and KissR4 types) in the sauropsid lineage. These four genes, also present in the mammalian lineage, would have been inherited from their common amniote ancestor. In contrast, synteny analyses supported that the other Kiss and KissR paralogs are missing in sauropsids as in mammals, indicating their absence in the amniote lineage. Among sauropsids, in the avian lineage, we demonstrated the existence of a Kiss2-like gene in three bird genomes. The divergence of these avian Kiss2-like sequences from those of other vertebrates, as well as their absence in the genomes of some other birds, revealed the processes of Kiss2 gene degeneration and loss in the avian lineage.

Conclusion

These findings contribute to trace back the evolutionary history of the Kisspeptin system in amniotes and sauropsids, and provide the first molecular evidence of the existence and fate of a Kiss gene in birds.

Reproductive neuropeptides: prevalence of GnRH and KNDy neural signalling components in a model avian, gallus gallus

Diverse external and internal environmental factors are integrated in the hypothalamus to regulate the reproductive system. This is mediated through the pulsatile secretion of GnRH into the portal system to stimulate pituitary gonadotrophin secretion, which in turn regulates gonadal function. A single subpopulation of neurones termed 'KNDy neurones' located in the hypothalamic arcuate nucleus co-localise kisspeptin (Kiss), neurokinin B (NKB) and dynorphin (Dyn) and are responsive to negative feedback effects of sex steroids. The co-ordinated secretion from KNDy neurones appears to modulate the pulsatile release of GnRH, acting as a proximate pacemaker. This review briefly describes the neuropeptidergic control of reproduction in the avian class, highlighting the status of reproductive neuropeptide signalling systems homologous to those found in mammalian genomes. Genes encoding the GnRH system are complete in the chicken with similar roles to the mammalian counterparts, whereas genes encoding Kiss signalling components appear missing in the avian lineage, indicating a differing set of hypothalamic signals controlling avian reproduction. Gene sequences encoding both NKB and Dyn signalling components are present in the chicken genome, but expression analysis and functional studies remain to be completed. The focus of this article is to describe the avian complement of neuropeptidergic reproductive hormones and provide insights into the putative mechanisms that regulate reproduction in birds. These postulations highlight differences in reproductive strategies of birds in terms of gonadal steroid feedback systems, integration of metabolic signals and seasonality. Also included are propositions of KNDy neuropeptide gene silencing and plasticity in utilisation of these neuropeptides during avian evolution.

The role of thyroid hormones in regulation of chicken ovarian steroidogenesis

In all vertebrates, including birds, the normal development of the ovary and ovarian follicles is under the regulatory influence of hormones produced by the reproductive axis. In recent years, it has become clear that in birds an adequate level of thyroid hormones (THs), i.e. thyroxine (T4) and triiodothyronine (T3), in blood circulation is of primary importance for normal female reproductive functions. In avian species, characterized by seasonal reproduction, THs are involved in the photoperiodic regulation of reproduction acting at the mediobasal hypothalamus. In domestic fowl, where the seasonality of reproduction has been eliminated, the role of THs in ovarian function is not fully elucidated. Recent studies have revealed that ovarian follicles of the laying hen express mRNAs of TH nuclear receptors (TRα and TRβ0) as well as integrin (αVβ3) plasma membrane receptors, indicating genomic and nongenomic action of THs in the chicken ovary. In vivo experiments carried out on laying hens have showed that the bolus injection of T3 decreases levels of luteinizing hormone (LH) and estradiol (E2) in blood, and a hyperthyroid state evoked by administration of T3 for few days diminishes LH, E2 and progesterone (P4) levels, reduces the weight of the ovary, induces atresia of preovulatory follicles and eventually causes stoppage of egg laying. In vitro studies have demonstrated that T3 decreases E2 secretion from white nonhierarchical follicles and the theca layer of yellow preovulatory follicles, while on the other hand, it elevates P4 production from the granulosa layer of these follicles. These effects have been associated with steroidogenic enzyme expression and cyclic AMP synthesis. This review summarizes the current knowledge concerning the role of THs in regulation of steroidogenesis in chicken ovarian follicles.

Analysis of the expression of neurokinin B, kisspeptin, and their cognate receptors NK3R and KISS1R in the human female genital tract

OBJECTIVE

To investigate the presence of neurokinin B (NKB)/NK(3) receptor (NK(3)R) and kisspeptin/KISS1 receptor (KISS1R) messenger RNA (mRNA) and proteins throughout the human female genital tract.

DESIGN

In vitro study.

SETTING

Academic research laboratories and academic hospitals.

PATIENT(S)

Fifteen reproductive-age women and 16 postmenopausal women provided fresh samples of uterus, ovary, or oviduct, and 12 women provided archival samples of endometrium or oviduct.

INTERVENTION(S)

Fresh and archival samples of uterus, ovary, and oviduct obtained from reproductive-age and postmenopausal women.

MAIN OUTCOME MEASURE(S)

Results of reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry to investigate the pattern of expression of NKB/NK(3)R and kisspeptin/KISS1R in target tissues.

RESULT(S)

Expression of the genes encoding NKB (TAC3) and NK(3)R (TACR3), and kisspeptin (KISS1) and its receptor (KISS1R) was found in the uterus, ovary, and oviduct. Both NKB and NK(3)R immunoreactivity was detected in the endometrium, the oviduct, and the ovary, with marked expression in endometrial and oviductal epithelial cells, where intense coexpression of kisspeptin and KISS1R was also detected. Positive staining for NKB and NK(3)R was found in the myometrium where, in contrast, kisspeptin and KISS1R were absent.

CONCLUSION(S)

NKB/NK(3)R and kisspeptin/KISS1R are present in female peripheral reproductive tissues with colocalization of both systems in some non-neuronal cell populations of the human female genital tract. Our findings are compatible with a potential modulatory role of NKB and kisspeptin at peripheral reproductive tissues.