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Insulin-like factor 3 (INSL3), initially described as a male hormone, is expressed in female reproductive organs during the estrous cycle and pregnancy but its function has not yet been established. This study explores the function of INSL3 in pregnant Saanen goats by characterizing the expression dynamics of INSL3 and its receptor, relaxin family peptide receptor 2 (RXFP2) and by demonstrating specific INSL3 binding in reproductive organs, using molecular and immunological approaches and ligand-receptor interaction assays. We demonstrate that the corpus luteum (CL) acts as both a source and target of INSL3 in pregnant goats, while extra-ovarian reproductive organs serve as additional INSL3 targets. The expression of INSL3 and RXFP2 in the CL reached maximum levels in middle pregnancy, followed by a decrease in late pregnancy; in contrast, RXFP2 expression levels in extra-ovarian reproductive organs were higher in the mammary glands but lower in the uterus, cervix and placenta and did not significantly change during pregnancy. The functional RXFP2 enabling INSL3 to bind was identified as an ~ 85 kDa protein in both the CL and mammary glands and localized in large and small luteal cells in the CL and in tubuloalveolar and ductal epithelial cells in the mammary glands. Additionally, INSL3 also bound to multiple cell types expressing RXFP2 in the uterus, cervix and placenta in a hormone-specific and saturable manner. These results provide evidence that an active intra- and extra-ovarian INSL3 hormone-receptor system operates during pregnancy in goats.

Accurate identification of the murine estrous cycle using vaginal exfoliative cytology is the initial and crucial step for controlled reproduction of this species. However, it is generally difficult to discriminate each stage of the cycle, and thus to select pro-estrous mice for mating. To increase the accuracy of identification of the pro-estrous stage, we re-evaluated the vaginal fold histology and modified the method of exfoliative cytology. Tissue fixation using methanol in Carnoy’s solution but not paraformaldehyde, combined with Alcian blue staining but not the conventional Giemsa staining, resulted in better manifestation of mucosal cell layers in the vaginal epithelium just above the keratinized layer. This mucous layer in the fold histology was found to form specifically in the pro-estrous and late di-estrous stages, and the mucous cells exfoliated in smear samples only in the pro-estrous stage. This novel method was found, by a blinded test, to increase the rate of accurate identification of the pro-estrous stage compared to the conventional method (80% vs 50%). Consistent with this finding, the mating experiment with “pro-estrous” females selected by the novel method revealed a significantly higher success rate than that with the conventional method (78.0% vs 47.5%). Thus, our study demonstrates vaginal exfoliative mucous cells as a better potential marker to detect the “receptive” state of female mice that leads to an improved success rate of mating.

Farnesoid X receptor (FXR) is mainly present in enterohepatic tissues and regulates cholesterol, lipid, and glucose homeostasis in coordination with target genes such as SHP and FABP6. Although FXR has been revealed to be expressed in reproductive tissues, FXR function and expression levels in the ovary remain unknown. In this study, we investigated FXR expression in mouse ovaries and its target genes in ovarian granulosa cells. In situ hybridization and immunohistochemical staining showed that FXR was mainly distributed in secondary and tertiary follicles. The agonist-induced activation of FXR in cultured granulosa cells induced the expression of SHP and FABP6, while siRNA targeting of FXR decreased CYP19a1 and HSD17b1 expression. Upon examination of the roles of SHP and FABP6 in granulosa cells, we found that SHP overexpression significantly decreased StAR, CYP11a1, and HSD3b gene expression. In addition, siRNA targeting of FABP6 decreased CYP19a1 and HSD17b1 expression, while FABP6 overexpression increased CYP19a1 expression. In conclusion, the present study demonstrates the presence of FXR signaling in the ovary and reveals that FXR signaling may have a role in function of granulosa cells.

The purpose of this study was to investigate effects of addition of lactoferrin on characteristics and functions of bovine epididymal, ejaculated, and frozen-thawed sperm. The addition of lactoferrin was significantly (p < .05) effective on increasing values of progressive motility, straightness, and linearity in caput epididymal sperm and values of motility in cauda epididymal sperm. When ejaculated sperm were incubated in capacitation medium, percentages of motile and progressively motile sperm decreased largely within the first period of 30 min, followed by only minor changes. However, the addition of lactoferrin significantly lessened the early decreases of these parameters and additionally promoted capacitation-dependent changes of chlortetracycline staining patterns (from F pattern to B pattern). In other experiments, when ejaculated sperm were exposed to oxidative stress with 100-µM H2 O2 , the addition of lactoferrin partially protected them from dysfunction of flagellar movement and loss of progressive movement. In final experiments with frozen-thawed samples incubated in the capacitation medium, the addition of lactoferrin effectively survived dying sperm and suppressed occurrence of sperm agglutination. These results may suggest biological and biotechnological potentials of lactoferrin for modulation of bovine sperm viability, motility, capacitation state, and preservation in vitro.

Accurate identification of the murine estrous cycle using vaginal exfoliative cytology is the initial and crucial step for controlled reproduction of this species. However, it is generally difficult to discriminate each stage of the cycle, and thus to select pro-estrous mice for mating. To increase the accuracy of identification of the pro-estrous stage, we re-evaluated the vaginal fold histology and modified the method of exfoliative cytology. Tissue fixation using methanol in Carnoy's solution but not paraformaldehyde, combined with Alcian blue staining but not the conventional Giemsa staining, resulted in better manifestation of mucosal cell layers in the vaginal epithelium just above the keratinized layer. This mucous layer in the fold histology was found to form specifically in the pro-estrous and late di-estrous stages, and the mucous cells exfoliated in smear samples only in the pro-estrous stage. This novel method was found, by a blinded test, to increase the rate of accurate identification of the pro-estrous stage compared to the conventional method (80% vs 50%). Consistent with this finding, the mating experiment with "pro-estrous" females selected by the novel method revealed a significantly higher success rate than that with the conventional method (78.0% vs 47.5%). Thus, our study demonstrates vaginal exfoliative mucous cells as a better potential marker to detect the "receptive" state of female mice that leads to an improved success rate of mating.

Cisplatin (CP) is an extremely effective anticancer agent widely used to treat various cancer types, however, the potential side effects include testicular dysfunction. This study was to investigate, using a rat model of CP-induced testicular dysfunction, the protective effects of relaxin (RLN) against oxidative stress, testicular function, histological damage, spermatogenesis, germ-cell apoptosis, and sperm output, and to explore the usefulness of RLN as a potential protective drug for use with CP in chemotherapeutic treatments.Sprague-Dawley male rats were used, which were divided into three groups: sham control, CP, and CP + RLN. Porcine RLN (500 ng/h) or saline was infused for 5 days using an implanted osmotic mini-pump following intraperitoneal injection of CP (6 mg/kg). RLN dose was chosen based on previous studies showing that it resulted in serum relaxin levels comparable to those in rats at the middle of pregnancy. At 5 days after CP administration, samples were collected and assessment of testicular histopathology, germ-cell apoptosis, oxidative stress, lipid peroxidation, and sperm quality was performed as main measures.The testicular CP model showed reduced testis weight and significantly decreased spermatogenesis scores. Additionally, CP administration induced a 4.6-fold increase in the apoptotic index associated with a significant increase in oxidative stress and upregulation of pro-apoptoticThis study clearly indicates that RLN exerts a protective effect against CP-induced testicular damage through attenuation of oxidative stress and suppression of apoptosis. Our findings suggest RLN as a potentially efficacious drug for use with cisplatin chemotherapy in order to ameliorate CP-induced side effects and testicular injury adversely affecting spermatogenesis, sperm quality, and oxidative-stress parameters.Le cis platine (CP) est un agent anticancéreux extrêmement efficace largement utilisé pour traiter divers types de cancer. Parmi les effets secondaires potentiels associés aux traitements par CP on compte le dysfonctionnement des testicules. Le propos de ce manuscrit est d'étudier, à l'aide d'un modèle rat de dysfonctionnement testiculaire induit par la prise de CP, l’action protectrice de la relaxine (RLN) contre les effets délétères dus au CP lesquels incluent le stress oxydant, la perte de fonction testiculaire, les dommages histologiques au testicule, l'apoptose des cellules germinales et la baisse de la qualité des spermatozoïdes. L’objectif est d’explorer l'utilité de la RLN comme médicament protecteur potentiel à utiliser avec le CP dans les traitements chimiothérapeutiques.Des rats mâles Sprague-Dawley ont été utilisés. Trois groupes : contrôle, CP, et CP + RLN ont été comparés. Après une injection intrapéritonéale de CP (6mg/kg), de la RLN porcine (500 ng/h) ou du sérum physiologique a été perfusé pendant 5 jours en utilisant une mini-pompe osmotique implantée. La dose de RLN a été choisie en fonction d'études antérieures qui avaient montré qu'elle entraînait des taux sériques de RLN comparables à ceux de rats en milieu de la gestation. Cinq jours après l'administration de la CP, des échantillons ont été prélevés afin d’évaluer l'histopathologie, l'apoptose des cellules germinales, le stress oxydant, la peroxydation des lipides et les paramètres spermatiques.Le groupe CP a montré une réduction du poids des testicules et une diminution significative des scores de spermatogenèse. De plus, l'administration de CP a entraîné une augmentation de l’apoptose de 4,6 fois associée à une augmentation significative du stress oxydant, de la régulation à la hausse de la Caspase 3 pro-apoptotique et à la baisse de Bcl2 anti-apoptotique conduisantCette étude montre clairement que la RLN exerce un effet protecteur contre les lésions testiculaires par l'atténuation du stress oxydant et la suppression de l'apoptose induite par le CP. Nos résultats suggèrent que la RLN est un médicament potentiellement pertinent à utiliser afin de diminuer les effets secondaires induits par le CP sur la fonction testiculaire et sur les spermatozoïdes lors de la chimiothérapie cancéreuse.

Insulin-like factor 3 (INSL3) is essential for fetal testis descent, and has been implicated in the testicular and sperm functions in adult males; however, similar functions in domestic ruminants remain largely unknown. This study investigated the functional INSL3 hormone-receptor system in adult ruminant testes and spermatozoa, and explored its potential to diagnose the fertility of sires. Testes and spermatozoa were obtained from fertile bulls, rams and he-goats, whereas subfertile testes and spermatozoa were obtained only from bulls. As expected, INSL3 was visualized in Leydig cells, while we clearly demonstrated that the functional receptor, relaxin family peptide receptor 2 (RXFP2), enabling INSL3 to bind was identified in testicular germ cells and in the sperm equatorial segment of bulls, rams and he-goats. In comparison to fertile bulls, the percentage of INSL3- and RXFP2-expressing cells and their expression levels per cell were significantly reduced in the testes of subfertile bulls. In addition, the population of INSL3-binding spermatozoa was also significantly reduced in the semen of subfertile bulls. These results provide evidence for a functional INSL3 hormone-receptor system operating in ruminant testes and spermatozoa, and its potential to predict subfertility in sires.

Insulin-like factor 3 (INSL3), previously called relaxin-like factor, is essential for foetal testis descent and has been implicated in sperm production in adult males. This study investigated the role of INSL3 in sperm production by examining the effect of neutralising INSL3 by passive immunisation on testicular function and sperm output in boars. Six male Duroc boars were randomly assigned to passive immunisation and control groups (n = 3 each). The immunisation group was intravenously injected with an IgG fraction of anti-INSL3 antibody developed against the B domain of INSL3 at 2-week intervals from 21-40 weeks of age. The control group was treated with normal IgG in the same manner. Antibody administration reduced testis weight and caused a fourfold increase in the frequency of apoptotic germ cells, which was associated with upregulation of the pro-apoptotic caspase 3 and BAX, and downregulation of the anti-apoptotic XIAP and BCL2, and a substantial marked reduction in sperm concentration. Neutralising INSL3 delivered by passive immunisation reduced testis weight and sperm concentration by inducing germ cell apoptosis, suggesting that INSL3 acts as a germ cell survival/anti-apoptotic factor in the maintenance of sperm production.

Relaxin-like factor (RLF), now mainly known as insulin-like factor 3 (INSL3), is essential for testis descent during fetal development; however, its function in the adult testis is still being elucidated. As a major step toward understanding the as-yet-unknown function of INSL3 in boars, this study aimed to develop a time-resolved fluoroimmunoassay for boar INSL3, characterize the dynamics of INSL3 expression during development, and demonstrate the expression of the INSL3 hormone–receptor system in the testis. All samples were collected from Duroc boars. The sensitivity of the assay system established was 8.2 pg/well (164 pg/ml), and no cross-reactivity with other hormones, such as porcine relaxin, was observed. Circulating INSL3 was shown to increase progressively during development. INSL3 secreted from the Leydig cells was released not only into the blood circulation but also into the interstitial and seminiferous compartments in sufficient concentrations. A testicular fractionation study revealed that its receptorRXFP2transcripts were expressed mainly in testicular germ cells. In addition, INSL3 bound to the germ cell membranes in a hormone-specific and saturable manner. These results reveal that INSL3 secreted into the interstitial compartment from the Leydig cells is transported into the seminiferous compartments, where its receptorRXFP2is expressed mainly in the germ cells to which INSL3 binds, suggesting that INSL3 functions as a paracrine factor on seminiferous germ cells.

Relaxin-like factor (RLF), also called insulin-like peptide 3 (INSL3), is a member of the insulin/relaxin gene family and is produced by testicular Leydig cells. While the understanding of its effects is growing, very little is known about the structural and functional properties of native INSL3. Here, we demonstrate that native INSL3 isolated from goat testes is a single-chain structure with full biological activity, and is constitutively expressed and secreted by Leydig cells. Using a series of chromatography steps, native INSL3 was highly purified as a single 12-kDa peak as revealed by SDS-PAGE. MS/MS analysis provided 81% sequence coverage and revealed a distinct single-chain structure consisting of the B-, C-, and A-domains deduced previously from the INSL3 cDNA sequence. Moreover, the N-terminal peptide was six amino acid residues longer than predicted. Native INSL3 exhibited full bioactivity in HEK-293 cells expressing the receptor for INSL3. Immunoelectron microscopy and Western blot analysis revealed that INSL3 was secreted by Leydig cells through the constitutive pathway into blood and body fluids. We conclude, therefore, that goat INSL3 is constitutively secreted from Leydig cells as a B-C-A single-chain structure with full biological activity.

Insulin-like factor 3 (INSL3) is essential for fetal testis descent, and has been implicated in the testicular and sperm functions in adult males; however, similar functions in domestic ruminants remain largely unknown. This study investigated the functional INSL3 hormone-receptor system in adult ruminant testes and spermatozoa, and explored its potential to diagnose the fertility of sires. Testes and spermatozoa were obtained from fertile bulls, rams and he-goats, whereas subfertile testes and spermatozoa were obtained only from bulls. As expected, INSL3 was visualized in Leydig cells, while we clearly demonstrated that the functional receptor, relaxin family peptide receptor 2 (RXFP2), enabling INSL3 to bind was identified in testicular germ cells and in the sperm equatorial segment of bulls, rams and he-goats. In comparison to fertile bulls, the percentage of INSL3- and RXFP2-expressing cells and their expression levels per cell were significantly reduced in the testes of subfertile bulls. In addition, the population of INSL3-binding spermatozoa was also significantly reduced in the semen of subfertile bulls. These results provide evidence for a functional INSL3 hormone-receptor system operating in ruminant testes and spermatozoa, and its potential to predict subfertility in sires.

Relaxin-like factor (RLF), also known as insulin-like factor 3 (INSL3), is produced by testicular Leydig cells, but its specific receptor LGR8 (leucine-rich repeat family of G-protein-coupled receptor 8) has not been identified in goats. This study aimed to identify complementary DNA (cDNA) sequences of goat LGR8, and characterize the expression of both RLF and LGR8 in goat testes by RT-PCR and immunohistochemistry. Testes were collected from immature (3-month-old) and mature (24-month-old) Saanen goats, and partial cDNA sequences of the goat homologue of human LGR8 were identified. The sequence encoded a reduced peptide sequence of 167 amino acids, which corresponded to transmembrane regions 2 through 5, followed by the beginning of intracellular loop 3 of human LGR8. Expression of both LGR8 and RLF genes was drastically increased in mature testes compared with immature ones. Although RLF protein was restricted to Leydig cells, LGR8 protein was detected in both Leydig cells and seminiferous epithelial cells (possibly germ cells and Sertoli cells). These results reveal a possible existence of the RLF-LGR8 ligand-receptor system within the goat testis, suggesting that RLF may play a role in testicular function through LGR8 on Leydig cells and seminiferous epithelial cells in an autocrine and/or paracrine manner.

雄ヤギにおけるリラキシン関連因子（RLF）の生理機能を探るため，精巣でのRLFの局在と性成熟に伴う発現パターンを調べた．抗体はRLFのA鎖領域のペプチドを抗原としてウサギで作製し，特異性はWestern blotとOuchterlony法で評価した．免疫組織化学とWestern blotの結果，RLFはライディッヒ細胞で約12 kDaのタンパク質として翻訳されていた．RLF陽性を示すライディッヒ細胞の面積分率は生後3ヵ月齢までに2.2％まで一旦有意（P ＜ 0.05）に減少した後，春機発動期にあたる4ヵ月齢で再び有意（P ＜ 0.05）に増加して5.7％となり，成熟（6.7％）と変らないレベルに達した．これはWestern blotの結果と一致した．以上，ヤギでは精巣ライディッヒ細胞がRLFタンパク質の唯一の産生源で，その発現は性成熟に伴い増加することから，RLFの精巣機能への関与が示唆された．

In normal development, a limited number of cells in the proximal epiblast differentiate into germ cells. In this process, the interaction between primordial germ cells (PGCs) and surrounding somatic cells in the gonad is essential for germ cell development. In the present study, we demonstrated a novel method for inducing mouse embryonic stem cells (ESCs) to differentiate into PGCs using co-culture with undifferentiated gonadal cells or with their extracts. After embryoid bodies (EBs) formed, they were cultured for 10 days. Mvh and Dazla gene expressions increased to a peak, and also the number of Mvh-positive cells increased and were distributed in the peripheral region of EBs co-cultured with undifferentiated gonadal cells, whereas for EBs cultured in the medium supplemented with cell extracts, Mvh-positive cells were scattered within the EBs. Our results demonstrate that growth factors derived from undifferentiated gonadal cells may induce differentiation of ESCs into potential PGCs.

Vascular endothelial growth factor (VEGF) expression in granulosa cells is associated with the thecal vasculature growth during ovarian follicular development. We hypothesized that injection of VEGF gene fragments directly into the rat ovary would induce production of a large number of ovulatory follicles and that these follicles would ovulate. To test this hypothesis, we treated immature female rats with combinations of hormones and VEGF gene fragments. The animals were divided into two groups: one group received solution containing transfection reagents as a control (n= 5), while the other group received direct ovarian injection of VEGF gene fragments at 19 (n= 5), 21 (n= 5), 23 (n= 5), or 25 (n= 5) days after birth followed by i.p. administration of 20 IU equine chorionic gonadotropin (eCG) at the age of 26 days. Forty-eight hours after eCG injection, animals were given 20 IU human chorionic gonadotropin (hCG) i.p. and then the oocytes in both groups were counted. The maximum number of ovulated oocytes was obtained when the VEGF gene fragments were injected into the rat ovary at 21 days after birth. Histological examination revealed that the injection of VEGF gene fragments markedly increased the vascular density around the preovulatory follicles and also the number of these follicles. Our data provide the first reported evidence that most ovulatory follicles generated by injection of VEGF gene fragments are able to ovulate upon hCG treatment. These results demonstrate that injection of VEGF gene fragments directly into the ovary stimulates the development of antral follicles by inducing the formation of thecal vasculature in immature female rats.

We developed an in situ hybridization method for detecting relaxin mRNA in the porcine corpus luteum (CL) by employing a non-radioactive probe and microwave fixation. We subsequently examined the expression and cellular patterns of relaxin mRNA in the CL during pregnancy and then evaluated whether relaxin mRNA was a factor limiting hormone production by the CL. Digoxigenin (DIG)-labeled RNA probes complementary to porcine relaxin mRNA were produced by in vitro transcription. The specificity was validated by showing, by Northern analysis, that the anti-sense probe hybridized to a 1.0-kb relaxin transcript in the CL. Microwave fixation (2-min irradiation in a conventional microwave oven) combined with DIG-labeled cRNA probes allowed precise and reliable analysis of relaxin mRNA, with superior retention of the mRNA and a higher resolving power. Application of this method to the porcine CL during pregnancy demonstrated that the relaxin mRNA level per cell and the percentage of mRNA-expressing cells increased as gestation progressed, with a marked decline near term. Northern analysis revealed the cellular pattern of relaxin mRNA localization, showing that the increase of relaxin mRNA with advancing pregnancy was attributable to an increase of both the cellular mRNA level and the percentage of mRNA-expressing cells. The present findings, taken together with known relaxin levels in the CL, reveal that changes of relaxin mRNA are correlated with changes of the hormone in the CL during pregnancy, suggesting that the relaxin level is determined by the amount of mRNA available for translation.

Vascular endothelial growth factor (VEGF) is an important angiogenic factor in the ovary, but the localization of VEGF in the ovary of neonatal animals is poorly understood. A clear understanding of the relationship between the formation of the thecal layer and the cell-specific expression of the VEGF system during follicular development in the neonatal ovary is still lacking. Immature female Wistar-Imamichi rats used in this study were killed by decapitation 5, 7, 9 and 11 days after birth, and their ovaries were removed and subjected to histological and immunohistochemical observation. The number of primordial follicles had decreased in the ovaries at day 11 compared with that at day 5. The number of secondary follicles significantly increased with age. In the morphological observation of secondary follicles, we found that the theca layer (70 µm in diameter of follicles) began to form at day 9 and was completely formed at day 11. An endothelial cell marker, CD31, VEGF and Flk-1 were located in the stromal tissues in the ovaries on each day examined after birth. In particular, in the ovaries at day 9 and day 11, when the secondary follicles appeared, CD31, VEGF and Flk-1 were expressed in the theca layer. Flt-1 was expressed in the oocytes of the ovaries at day 5 and day 7, and the sites of its expression changed to stromal and thecal tissues at day 9 and day 11. In conclusion, we provide the first evidence that the theca layer of secondary follicles begin to form at day 9 after birth and that VEGF and Flk-1 may be able to stimulate the differentiation of stromal-interstitial cells into thecal cells and the formation of the thecal vasculature in the neonatal rat ovaries, suggesting that the VEGF system may be involved in the formation of the thecal layer and vasculature during folliculogenesis in the neonatal rat.

SummaryIn the present study, we examined the preimplantation and postimplantation development of rat tetraploid embryos produced by electrofusion of 2-cell-stage embryos. Developmental rate of tetraploid embryos to morula or blastocyst stage was 93% (56/60) and similar to that found in diploid embryos (95%, 55/58). After embryo transfer, rat tetraploid embryos showed implantation and survived until day 8 of pregnancy, however the conceptuses were aberrant on day 9. In mouse, tetraploid embryos have the ability to support the development of blastomeres that cannot develop independently. As shown in the present study, a pair of diploid blastomeres from the rat 8-cell-stage embryo degenerated immediately after implantation. Therefore, we examined whether rat tetraploid embryos have the ability to support the development of 2/8 blastomeres. We produced chimeric rat embryos in which a pair of diploid blastomeres from an 8-cell-stage green fluorescent protein negative (GFP−) embryo was aggregated with three tetraploid blastomeres from 4-cell GFP-positive (GFP+) embryos. The developmental rate of rat 2n(GFP−) ↔ 4n(GFP+) embryos to the morula or blastocyst stages was 93% (109/117) and was similar to that found for 2n(GFP−) ↔ 2n(GFP+) embryos (100%, 51/51). After embryo transfer, 2n(GFP−) ↔ 4n(GFP+) conceptuses were examined on day 14 of pregnancy, the developmental rate to fetus was quite low (4%, 4/109) and they were all aberrant and smaller than 2n(GFP−) ↔ 2n(GFP+) conceptuses, whereas immunohistochemical analysis showed no staining for GFP in fetuses. Our results suggest that rat tetraploid embryos are able to prolong the development of diploid blastomeres that cannot develop independently, although postimplantation development was incomplete.

Successful production of offspring by somatic cell nuclear transfer (SCNT) is affected by the nature of the donor cells used. The purpose of this study was to determine whether characteristic changes induced in donor cells by culture conditions influenced gene expression patterns in the resultant SCNT embryos. Rabbit granulosa cells (rGC) were cultured under different conditions, either with or without hCG, and the two derivative cell types obtained (named respectively cGC+ and cGC−) were used as donor cells for SCNT. There were characteristic differences between fresh rGC and the two derivative cell types: p450scc expression and progesterone secretion were both higher in cGC+ than in cGC−; expression of bmp4 and fgfr2 was decreased in cGC+ and cGC− compared with rGC; and cGC+ and cGC− cell types gained collagenIV expression. Use of fresh rGC, or cGC+ and cGC− derivative cells, did not alter either the developmental potencies of SCNT oocytes or cell numbers at the blastocyst stage. The expression patterns of four genes (bmp4, fgfr2, gata4, oct3/4) in SCNT embryos and in fertilized embryos were analyzed by quantitative RT-PCR. We found that oct3/4 was expressed in all embryos. The expression patterns of the other three genes showed considerable variation between the different types of embryo: bmp4 was found in most fertilized embryos but only some of rGC and none of cGC+ and cGC− derived SCNT embryos; fgfr2 was present in fertilized embryos but was present in some rGC and cGC− NT embryos and in all cGC+ NT embryos; gata4 was not expressed in fertilized embryos but was present in a few rGC and cGC+ NT embryos and in most cGC− NT embryos. Our results suggest that the gene expression patterns in SCNT embryos derived from granulosa donor cells are affected by characteristic changes to the cells during in vitro culture.

Macrophages are essential in cleaning up apoptotic debris during follicular atresia. However, the key factors of this process are still unclear. In the present study, we evaluated CD44 mRNA, CD44 protein, and CD44 antigen glycosylation on macrophages during follicular atresia in the pig. Atresia was classified into five stages: stage I, healthy follicles; stage II, early atretic follicles having apoptotic granulosa cells with an unclear basement membrane; stage III, progressing atretic follicles having apoptotic granulosa cells completely diffused from the basement membrane; stage IV, late atretic follicles with increasing lysosomal activity; and stage V, disintegrated atretic follicles having collapsed theca cells and strong lysosomal activity. Immunohistological analysis showed that macrophages expressing CD44 invaded the inside of stage III follicles, accompanied by a collapse of basement membrane. Semiquantitative RT-PCR showed that only mRNA of the CD44 standard isoform (CD44s) was present in inner cells of follicles, and not any CD44 variant isoform (CD44v) mRNAs. The amount of CD44s mRNA was increased at stage III. Western blot and lectin blot analyses showed that CD44 was markedly expressed at stage III and glycosylated with polylactosamine at the same time. After macrophages invaded atretic follicles at stages III-V, the CD44 expressed on macrophages was glycosylated with polylactosamine. The lysosomal activity began to increase at stage IV, and reached the highest level at stage V. Increased CD44s protein and posttranslational modification of CD44 with polylactosamine on macrophages from stage III could be involved in the cleaning up apoptotic granulosa cells.

Porcine relaxin is a peptide hormone belonging to the insulin super family that has a variety of biological functions. The present experiment was designed to investigate the effects of relaxin on sperm function and on in vitro fertilization (IVF) of porcine oocytes. Porcine spermatozoa were washed, swum-up, and incubated for 1-4 h in mTALP medium supplemented with 0, 20 or 50 ng/ml porcine relaxin. Motility was determined by observing the type of forward movement of the spermatozoa, and acrosome status was evaluated by applying the triple staining technique. Immature oocytes were aspirated from antral follicles and matured in IVM medium (modified NCSU-37). Matured oocytes were co-cultured with spermatozoa in IVF medium (mTALP) supplemented with 0, 5, 10, 15 or 20 ng/ml relaxin. After 6 h of sperm-oocyte co-incubation, putative zygotes were cultured for 18 h in oocyte culture medium NCSU-37 and then assessed for the rates of monospermy, polyspermy, and male pronucleus formation after acetic orcein staining. Relaxin improved (P

Connexin 43 (Cx43)-mediated gap junctional communication in granulosa cells is crucial for germ line development and postnatal folliculogenesis. We previously showed that follicle-stimulating hormone (FSH) promoted phosphorylation of Cx43 in rat primary granulosa cells. We further identified Ser365, Ser368, Ser369, and Ser373 in the carboxy-terminal tail as the major sites of phosphorylation by FSH, and found that the phosphorylation of these residues was essential for channel activity. In this study, we investigated the protein kinase(s) responsible for FSH-induced phosphorylation. H89, a cyclic AMP-dependent protein kinase (PKA) inhibitor, inhibited FSH-induced phosphorylation both in vivo and in vitro, whereas PD98059, a mitogen-activated protein kinase kinase (MEK) inhibitor, had little effect on the phosphorylation level. Ca2+-dependent protein kinase (PKC) appeared to negatively regulate phosphorylation. Phosphopeptide mapping with or without H89 treatment indicated that PKA could be responsible for phosphorylation of the four serine residues. In addition, the purified catalytic subunit of PKA could phosphorylate the recombinant C-terminal region of Cx43, but not the variant in which all four serine residues were substituted with alanine. These results suggest that FSH positively regulates Cx43-mediated channel formation and activity through phosphorylation of specific sites by PKA.

When the nucleus in G0/G1 phase is transferred to an enucleated oocyte by nuclear transfer (NT), its nuclear envelope is broken, followed by condensation of chromosome structure by maturation promoting factor (MPF). This morphological remodeling of the transferred interphase nucleus seems to be essential for subsequent development of NT embryos. In this study, we treated porcine NT embryos with caffeine, which has been reported to increase MPF activity, to keep their MPF level high during NT. When 2.5 mM caffeine was added to the handling medium, the proportion of NT embryos showing condensed chromosome increased significantly (P < 0.05). In NT embryos treated with caffeine, the activity of p34cdc2 kinase was significantly (P < 0.05) higher than in those without caffeine at 3 h post-injection. In addition, the rate of development to the blastocyst stage after activation was significantly (P < 0.05) higher in NT embryos treated with caffeine. These results indicate that caffeine treatment can increase not only the rate of chromosome condensation but also the developmental rate to the blastocyst stage of porcine NT embryos. This action is most likely due to the support/increase of MPF activity throughout the process of NT.

To improve the feasibility of nylon-mesh holder for vitrification of bovine cumulus-oocytes complexes (GV-COCs) having germinal vesicle, this study was conducted to demonstrate effects of sugars and protocol of exposure in vitrification on subsequent in vitro maturation, ultrastructural changes, and in vitro development in bovine immature oocytes after cryopreservation using nylon mesh. Before vitrification, GV-COCs were exposed to the cryoprotectant, which was composed of 40% (v/v) ethylene glycol, 18% (w/v) Ficoll-70, and 0.3 M sucrose (EFS40) or 0.3 M trehalose (EFT40), either by single step or in a stepwise way. The maturation rates in the stepwise exposure with EFS40 or EFT40 were significantly higher (P < 0.05) compared with the corresponding rates in the single step. In the stepwise exposure, few abnormalities were observed compared with the single-step exposure, where most oocytes showed a highly vacuolated cytoplasm with many ruptured mitochondria. Cleavage rates in fertilized oocytes previously exposed stepwise to EFS40 or EFT40 were significantly higher than those exposed by the single-step procedure. The cleaved embryos derived from the stepwise exposure to EFS40 developed to blastocysts. After transfer of blastocysts derived from vitrified GV oocytes, a female calf was born. These results indicate that vitrification of large numbers of bovine GV-COCs using a nylon-mesh holder accompanied with stepwise exposure minimizes structural damage in organelles, resulting in yield of viable blastocysts following in vitro embryo production.

In the present study, we examined a novel lipid removal method, centrifugation in solutions made hypertonic by adding 0.27 M sugar. This allowed the lipid to be extruded and removed without the loss of active mitochondria or extra cytoplasm. The type of sugar influenced the proportion of oocytes that could be stratified by centrifugation. Glucose induced the highest extrusion rate of lipid droplets. After vitrification the rates of survival, germinal vesicle breakdown and metaphase II were 30, 26, and 7%, respectively, for lipid-removed GV oocytes; this was significantly higher (P

To address the role of follicular angiogenesis in the determination of ovulatory follicles and the effects of different vascular endothelial growth factor (VEGF) isoforms on follicular angiogenesis and development, mature female rats were treated with an angiogenic inhibitor (TNP-470), and also with VEGF 120 or 164 at different dosages (0.4, 0.8, 4.0 or 8.0 microg/kg body weight) for 3 days during the estrous cycle. Ovarian follicular angiogenesis, the population of large follicles and ovulation were examined. VEGF 120 (0.8 microg/kg) and 164 (8.0 microg/kg) treatments stimulated follicular angiogenesis in the theca interna layer, while TNP-470 treatment showed severe depression of follicular angiogenesis, and completely inhibited ovulation. After administration of VEGF 120 or 164, the number of healthy preovulatory follicles and ovulated oocytes increased significantly, concomitantly with a decrease in the number of atretic preovulatory follicles. The oocytes ovulated had normal fertilizability and developed to term with the same litter size as in the control rats. Our findings suggest that follicular angiogenesis may be a determinant of follicular development during the periovulatory phase, and that VEGF isoforms may play different important roles in regulating follicular angiogenesis.

Angiogenic factors can induce the perifollicular capillary network in the theca interna that shows marked changes in and around the preovulatory luteinizing hormone (LH) surge. To get more information on their functional crosstalk, the aim of the present study was to investigate the manner of mRNA expression of vascular endothelial growth factors (VEGFs) 120, 164, angiopoietin (Ang)-1, Ang-2 and their specific receptors during the periovulatory phase. We used an established equine and human chorionic gonadotropins (eCG/hCG)-derived experimental model capable of stimulating naturally occurring follicular maturation, ovulation and corpus luteum (CL) formation. On day 28 postpartum, immature female rats were administrated s.c. with 10 IU of eCG to promote follicular development, followed 48 hr later by i.p. administration of 20 IU of hCG. Ovaries were dissected at 0, 6, 12, 18 and 24 hr after hCG treatment, and were obtained on day 30 in the untreated control. After induction of follicular growth by the eCG treatment, each mRNA expression of VEGF 120, VEGF 164, Neuropilin-1 and Flt-1 significantly increased. The peaks in mRNA expressions of VEGF120 and VEGF164 were both found at 18 hr after hCG treatment. Flk-1 mRNA expression maintained up to 6 hr after hCG treatment, and then decreased at 12, 18 and 24 hr after hCG treatment. Ang-2 mRNA expression increased in the ovaries at 6 and 12 hr after hCG treatment. Tie-2 mRNA expression decreased at 24 hr after the treatment of gonadotropins. Our findings suggest that ovarian vascular formation during the periovulatory period including preovulatory follicles, ovulation and CL formation may develop via crosstalk of the VEGF-Flt-1 and Ang-Tie2 systems.

Component engineering is important for the development of implantable-type rotary blood pumps (RP). The authors are conducting elementary development of an implantable artificial heart. A sensor system detects information in the living body. An automatic control system performs the drive control. Energy is provided by a transcutaneous energy transmission system (TETS). Various artificial hearts are being created. Miniaturization resulting from an increase in operating frequency is planned. A vibrating flow pump (VFP) has a reduced size of pumping chamber because of the high-speed reciprocating movement. Undulation pump ventricular assist devices (UPVAD) are small, lightweight rotary pumps. VFPs are useful in the medical treatment of multiple organ failure (MOF). UPVADs are planned to be permanent-use RPs. The purposes of these two artificial hearts differ, although they have a common component. The authors are developing TETS by using amorphous fibers, making efficient power transmission possible. Control information input from a micro or nano sensor is realized. A control algorithm has been developed and baroreflex control has been successful. Artificial heart development, fully exploiting component engineering, continues.

In the present study, we examined the developmental ability of enucleated zygotes, MII oocytes, and parthenogenetically activated oocytes at pronuclear stages (parthenogenetic PNs) as recipient cytoplasm for rat embryonic cell nuclear transfer. Enucleated zygotes as recipient cytoplasm receiving two-cell nuclei allowed development to blastocysts, whereas the development of embryos reconstituted with MII oocytes and parthenogenetic PNs was arrested at the two-cell stage. Previous observations in rat two-cell embryos suggested that the distribution of microtubules is involved in two-cell arrest. Therefore, we also examined the distribution of microtubules using immunofluorescence. At the two-cell stage after nuclear transfer into enucleated zygotes, microtubules were distributed homogeneously in the cytoplasm during interphase, and normal mitotic spindles were observed in cleaving embryos from the two- to four-cell stage. In contrast, embryos reconstituted with MII oocytes and parthenogenetic PNs showed aberrant microtubule organization. In enucleated zygotes, fibrous microtubules were distributed homogeneously in the cytoplasm. In contrast, dense microtubules were localized at the subcortical area in the cytoplasm and strong immunofluorescence intensity was observed at the plasma membrane, while very weak intensity was detected in the central part of enucleated MII oocytes. In enucleated parthenogenetic PNs, high-density and fibrous microtubules were distributed in the subcortical and central areas, respectively. Pre-enucleated parthenogenetic PNs also showed lower intensity of microtubule immunofluorescence in the central cytoplasm than zygotes. In conclusion, the results of the present study showed that zygote cytoplasm is better as recipient than MII oocyte and parthenogenetic PNs for rat two-cell embryonic cell nuclear transfer to develop beyond four-cell stage. Furthermore, microtubule organization is involved in the development of reconstituted embryos to overcome the two-cell arrest. Mol. Reprod. Dev. 68: 313–318, 2004. © 2004 Wiley-Liss, Inc.

The present study was undertaken to determine optimal conditions for parthenogenetic activation and subsequent development of rat oocytes. Oocytes from immature Wistar-Imamichi (WI) and Sprague Dawley (SD) rats were activated by electrical stimulation in combination with 6-dimethylaminopurine (6-DMAP) to assess whether different rat strains display different responses to activation treatment. Since the cleavage rates of activated oocytes were significantly higher in WI than SD strain rats, WI rats were used for the subsequent experiments to determine the effects of post-hCG time, culture duration, different activation protocols (electrical stimulation with 6-DMAP or ionomycin with 6-DMAP) and osmolarity of the activation medium on the activation and subsequent development of WI rat oocytes. For oocytes activated by electrical stimulation combined with 6-DMAP, the percentages of oocytes that were activated and that developed to blastocysts were higher when oocytes were collected at 18-20 h than at any other time points after hCG injection (16, 22-24 h). Culturing for 2-6 h before activation treatment markedly decreased the percentage of activated oocytes that developed to beyond the four-cell stage. There were no differences in the percentages of oocytes with pronuclear formation and subsequent development to the two-cell and blastocyst stages between oocytes that were activated by electrical stimulation or ionomycin, both followed by 6-DMAP treatment. Activation of oocytes by ionomycin and 6-DMAP, both in low osmolarity media (246 mOsM), markedly increased the cleavage rates and percentages of high quality blastocysts (71%). The optimal conditions determined in the present study with simplified activation protocols and high efficiency of activation and subsequent development of WI rat oocytes will be helpful for further research involving nuclear transfer in the rat.

Although immunoassayable relaxin has been detected in human and boar seminal plasma, there is no evidence suggesting the existence of immunoreactive relaxin in the seminal plasma of other domestic animals. The first objective of this study was to determine whether immunoreactive relaxin was present in the seminal plasma of bulls, rams and he-goats. In addition, the correlation of immunoreactive relaxin with sperm motility as an index for predicting the fertilizing ability of bull sires was investigated. Semen with normal sperm motility was collected from bulls, rams and he-goats, and the relaxin immunoreactivity of the semen samples was measured using a time-resolved fluoroimmunoassay (TR-FIA) for porcine relaxin that we developed. The presence of relaxin immunoreactivity was demonstrated in seminal plasma from bulls, rams and he-goats. The level of immunoreactive relaxin in seminal plasma was the highest in bulls followed by humans, rams, boars and he-goats in that order, when relaxin levels in boar and human semen having normal sperm motility were also assayed under the same conditions. When the correlation between the seminal plasma level of immunoreactive relaxin and sperm motility was examined in bull semen samples as an index for predicting fertilizing ability, it was found that the relaxin level was significantly correlated with the percentage of spermatozoa showing the most intensive motility (r = 0.64, p < 0.05). These results indicate that immunoreactive relaxin is widely found in the seminal plasma of domestic animals and that measuring the relaxin concentration of seminal plasma may be useful to identify subfertile sires or predict the fertility potential of individual sires.

The purpose of this study was to evaluate the viability and subsequent developmental ability of murine germinal vesicle (GV) oocytes ultrarapidly vitrified after step-wise exposure to cryoprotectants (CPAs). Oocytes were transferred to a vitrification solution composed of 15% ethylene glycol, 15% dimethyl sulfoxide and 0.5 M sucrose in a direct manner (non-preequilibrium) or in a step-wise manner (single-, two-, or ten-step preequilibrium). After ultrarapid vitrification and storage in liquid nitrogen, the oocytes were thawed, washed by diluting the CPAs in five steps, and then subjected to in vitro maturation, fertilization and culture. In the non-preequilibrium group, the rates of post-thawed oocytes surviving, maturing to metaphase-II, developing to blastocysts and to hatching/hatched blastocysts were 91.8, 87.1, 15.9 and 2.3%, respectively. In the single- and two-step groups, the corresponding rates were 97.0-98.2%, 92.2-95.0%, 22.0-29.4% and 8.8-15.6%, whereas in the ten-step group they were 98.2, 91.8, 38.6 and 22.8%, respectively. In the non-vitrified control group, the rates of oocytes maturing to metaphase-II, developing to blastocysts and to hatching/hatched blastocysts were 90.2, 75.2 and 51.5%, respectively. The present study shows that the ultrarapid vitrification of murine GV oocytes by a step-wise manner involving 10 steps preequilibrium may have an advantage in maintaining the viability and subsequent production of blastocysts.

The interaction between angiogenic factors and related receptors is closely associated with follicular angiogenesis. The present study was performed to determine the relationships between the capillary network and mRNA expression of several angiogenic factors and related receptors during porcine follicular development. Ovaries in gilts were collected 72 h after eCG (1250 IU) treatment for histological observation. Granulosa cells and thecal tissues in small (diameter, 5 mm) individual follicles were collected for detection of mRNA expression of vascular endothelial growth factor (VEGF) 120, VEGF 164, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) in granulosa cells and fms-like tyrosine kinase (Flt-1), fetal liver kinase (Flk-1) or the murine homologue of kinase domain region (KDR), bFGF receptor (bFGF-R), and EGF receptor (EGF-R) in thecal tissue by semiquantitative reverse transcription-polymerase chain reaction. The eCG treatment resulted in the emergence of healthy preovulatory follicles (diameter, >6.0 mm) that possessed more capillaries in the thecal cell layer and a significant increase in the percentage of atretic follicles of 1.0-2.9 mm in diameter. The number of capillaries in the thecal cell layer increased significantly in healthy follicles larger than 3 mm in diameter in the eCG group compared with those in controls. The expression of VEGF 120, VEGF 164, and bFGF mRNAs increased in granulosa cells of medium and large follicles from ovaries of prepubertal gilts after eCG treatment. The Flt-1, Flk-1/KDR, and bFGF-R mRNA expression increased in theca cells of medium and large follicles after eCG treatment. The expression of EGF mRNA increased in granulosa cells of small, medium, and large follicles from ovaries after eCG treatment, but the mRNA expression of EGF-R in thecal tissue did not change. These data indicate that preovulatory follicles possessed a larger capillary network and expressed more mRNAs of angiogenic factors in granulosa cells and related receptors in thecal tissue. We concluded that VEGF 120, VEGF 164, bFGF, and EGF may be greatly involved in the angiogenic process of follicular development in prepubertal gilts with eCG treatment.

Hyaluronic acid-binding proteins (HABPs) are necessary for expansion of the cumulus-oocyte complex (COC) during oocyte maturation. In this study, to obtain the detailed information of HABPs during cumulus expansion, we examined the expression of HABPs in porcine COCs during in vitro maturation (IVM). After maturation culture, proteins were extracted from porcine COCs and separated by SDS-PAGE and then transferred to polyvinylidene fluoride membranes. After transfer, the membranes were subjected to ligand blotting with biotinylated hyaluronic acid (bHA) or fluorescein isothiocyanate-labeled hyaluronic acid (FITC-HA). Furthermore, the extracted proteins were subjected to immunoprecipitation, Western blotting, and immunofluorescence analysis to dissect the HABPs. Ligand blotting with FITC-HA could detect HABPs. Using this ligand-blotting method, 13 and 14 bands of HABPs were detected in porcine COCs after 0 and 48 h in culture, respectively. Of these, the level of expression of 85-kDa HABP increased with cumulus expansion during IVM and was newly detected after culture. Immunoprecipitation, Western blotting, and immunofluorescent analysis confirmed that the 85-kDa HABP corresponded to CD44 and that it existed on/in the membrane of cumulus cells. The present results indicated that HABP expressed in porcine COCs during IVM, particularly CD44, may form a network of the matrices in the extracellular space of the oocyte with cumulus expansion during IVM.

The present study was performed to establish a rat cell line from blastocysts and to examine the developmental ability of nuclear transfer embryos reconstituted from the established cells and cumulus cells with enucleated mature oocytes. No colonies of embryo-derived cells were observed when morulae were cultured. In contrast, 89% and 40% of the attached embryos formed colonies when blastocysts and hatched blastocysts were cultured, respectively. When the colonies were subcultured in the absence of feeder cells, a cell line with round cell morphology was obtained. This cell morphology was stable up to at least passage 23. The percentage of these embryo-derived cells at G0/G1 was increased when cells were cultured in medium with 0.5% FCS for 48 and 72 h. Ninety-three percent of fresh, non-cultured cumulus cells were at G0/G1. The percentages of reconstructed embryos survival (44-48%), and developed to the 2-cell stage (35%), were significantly higher when the nuclei of cumulus cells were used than when the nuclei of blastocyst-derived cells were used (29% and 3%). The results of the present study indicate that a rat cell line can be established from blastocysts and maintained in vitro for a long period, and that reconstructed embryos obtained by transferring the blastocyst-derived cell nuclei into enucleated oocytes have poorer development potential than those obtained using cumulus cell nuclei. No reconstructed embryos developed beyond the 2-cell stage in vitro.

We previously reported that thyroxine (T4) treatment significantly improved follicular development and increased the number of eggs ovulated in immature hypothyroid infertile rdw rats in the presence of gonadotrophins. The present study was conducted to determine whether (1) infertile rdw rats would respond to repeated stimulation with gonadotrophins, and whether (2) T4 treatment would increase the total number of ovulated eggs in an individual rat induced to ovulate up to three consecutive times at intervals of about 30 days. eCG was repeatedly given from the immature stage on postnatal day 28 and then at day of metestrus in the mature stage at intervals of about 30 days, followed by hCG 54 h later in rdw and normal rats, both of which were also given T4 (T4-rdw and T4-Normal), and in normal rats without T4 treatment (Normal). The results indicate that there were no significant differences in the weights of ovaries at any age tested among T4-rdw, T4-Normal and Normal. The number of eggs ovulated in the first treatment was significantly higher than in subsequent treatments in the same group (P

Relaxin-like factor (RLF), generally known as insulin-like factor 3 (INSL3), is essential for testis descent during fetal development. However, its role in adult males is not fully understood. We investigate the function of INSL3 in male Saanen goats by identifying cell types expressing its receptor, relaxin/insulin-like family peptide receptor (RXFP)2 and by characterizing the developmental expression pattern of INSL3 and RXFP2 and the binding of INSL3 to target cells in the male reproductive system. A highly specific RXFP2 antibody that co-localizes with an anti-FLAG antibody in HEK-293 cells recognizes RXFP2-transcript-expressing cells in the testis. INSL3 and RXFP2 mRNA expression is upregulated in the testis, starting from puberty. INSL3 mRNA and protein expression has been detected in Leydig cells, whereas RXFP2 mRNA and protein localize to Leydig cells, to meiotic and post-meiotic germ cells and to the epithelium and smooth muscle of the cauda epididymis and vas deferens. INSL3 binds to all of these tissues and cell types, with the exception of Leydig cells, in a hormone-specific and saturable manner. These results provide evidence for a functional intra- and extra-testicular INSL3 ligand-receptor system in adult male goats.

This study investigated the possibility of the presence of specific receptor for relaxin-like factor (RLF)/insulin-like peptide 3 (INSL3) in boar testes. While RLF/INSL3 was produced by Leydig cells in the boar testis, its own receptor RXFP2 was expressed mainly in meiotic and post-meiotic germ cells, but not in Leydig cells, suggesting the existence of RLF/INSL3-RXFP2 signaling in germ cells of boars.

Vitrification of oocytes and embryos has recently been improved using new physical supports such as electron microscope (EM) grids, open-pulled straws, and cryoloops. However, the number of samples per container was restricted in each of these methods. In the present study, to develop a novel simple technique for vitrification of large quantities of oocytes or embryos, we examined vitrification of large quantities of immature bovine oocytes using nylon mesh as a novel container. As many as 65 oocyte-cumulus cell complexes could be placed on nylon mesh for vitrification compared with 15 per EM grid. Recovery rates were higher when using nylon mesh than EM grids, while fertilization and development rates were not different. These results indicated that vitrification using nylon mesh is useful and offers a new way to cryopreserve large numbers of oocytes.

Summary Ejaculates from 10 mature fertile large white Yorkshire boars were used to examine the correlation between immunoreactive relaxin levels in seminal plasma and sperm motility characteristics. Seminal plasma levels of immunoreactive relaxin were measured by a timeresolved fluoroimmunoassay (TR-FIA). Motility characteristics were assessed using a CellSoft computer-assisted digital image analysis system. The mean a SD level of immunoreactive relaxin in seminal plasma was 2.61 a 0.62 ng/mL. When the correlation between seminal plasma levels of immunoreactive relaxin and parameters of sperm movement was examined, it was found that relaxin levels were significantly correlated with the percentage of motile spermatozoa (ra 0.687, p < 0.05), curvilinear velocity (ra 0.745, p < 0.05), straight line velocity (ra 0.651, p < 0.05), mean amplitude of lateral head displacement (mean ALH) (ra 0.844, p < 0.01) and the maximum amplitude of lateral head displacement (max ALH) (ra 0.830, p < 0.01), but not with linearity, beatcross frequency, or percentage of circular cells. Among these parameters, seminal plasma levels of immunoreactive relaxin showed the strongest correlation with the ALH parameter related to fertilizing ability. These results indicate that immunoreactive relaxin in boar semen may be necessary not only for normal sperm motility but also for normal fertility, suggesting that determination of the profile of immunoreactive relaxin in ejaculates may have value as a potential marker for predicting sperm fertilizing ability of boars.

The purpose of this investigation was to examine whether boar spermatozoa possess specific binding sites for relaxin and to examine what effects relaxin actually exerts on their motility characteristics. Boar spermatozoa were collected from cauda epididymides. For the relaxin binding study, washed cauda epididymal spermatozoa were smeared on glass slides, and specific sites that bind relaxin were identified by sequential application of a biotinylated relaxin probe, antibiotine immunoglobulin G conjugated to 1 nm colloidal gold, and silver for signal amplification. For the motility characteristics study, cauda epididymal spermatozoa were diluted 300-fold in modified KRB + 2% cauda epididymal fluid (approximately 1 × 10 7 cell/ml). After preincubation for 30 min at 37 C in a CO2 incubator, the sperm aliquots were placed in culture dishes covered with mineral oil and mixed with porcine relaxin. The concentrations of relaxin and spermatozoa in the aliquot were 100 ng/ml and 5 × 106 cells/ml, respectively. The aliquots were incubated for a certain defined period under the same conditions. After 30, 60, 90 and 120 min of incubation, sperm motility was recorded using a videotape recorder. As an evaluation of motility characteristics, the percent motility, grade of forward progression and velocity were examined. The results of the relaxin binding study demonstrated that relaxin bound with specificity to the midpiece and tail. In addition, bindings were visible at the acrosome cap and neck of the head. The results of the motility study which examined the effects of relaxin on the motility characteristics of boar sperm showed that relaxin did not cause a significant alteration in percent motility, but it improved forward progression. Relaxin treatment for 90 min produced a significant 1.4-fold enhancement in sperm velocity compared to that of control. These results suggest that relaxin activates sperm motility through a specific receptor.