Expression of Lymphangiogenic Vascular Endothelial Growth Factor Family Members in Bovine Corpus Luteum

The aim of this study was to evaluate mRNA expression, protein concentration and localization of the assumedly important lymphangiogenic factors VEGFC and VEGFD and the receptor FLT4 in bovine corpora lutea (CL) during different physiological stages. In experiment 1, CL were collected in a slaughterhouse and stages (days 1–2, 3–4, 5–7, 8–12, 13–16, >18) of oestrous cycle and month <3, 3–5, 6–7 and >8 of pregnancy. In experiment 2, prostaglandin F2α (PGF)‐induced luteolysis was performed in 30 cows, which were injected with PGF analogue on day 8–12 (mid‐luteal phase), and CL were collected before and 0.5, 2, 4, 12, 24, 48 and 64 h after PGF injection. The mRNA expression was characterized by RT‐qPCR. All three factors were clearly expressed and showed significant changes during different groups and periods examined in both experiments. Protein concentrations of VEGFD and FLT4 measured by ELISA were not detectable in early cyclic CL but increased to higher plateau levels during pregnancy. After PGF‐induced luteolysis FLT4 protein showed an increase within 2–24 h after the injection. FLT4 localization by immunohistochemistry in the cytoplasm of luteal cells was relatively weak in early CL. It increased in late CL and especially in CL during pregnancy. During pregnancy, a positive FLT4 staining in both the nucleus and cytoplasm of lymphatic endothelial cells in peripheral tissue was observed. In conclusion, our results lead to the assumption that lymphangiogenic factors are produced and regulated in CL and may be involved in mechanisms regulating CL function, especially during pregnancy.     

Actions of glucocorticoid and their regulatory mechanisms in the ovary

Glucocorticoid (G) directly modulates ovarian functions through binding to G receptor. The actions of G are both agonistic and antagonistic depending on the developmental stage of follicles and corpora lutea (CL). During follicular maturation, G suppresses follicular differentiation by downregulating expression of P450 aromatase and luteinizing hormone (LH) receptor in granulosa cells. During ovulation, G protects the ovulatory follicle from inflammatory damage and promotes luteinization, ensuring a smooth transition of the follicle to CL. Throughout life the ovary is exposed to periodic and sporadic waves of G. The Ovary appears to cope with this situation by locally modulating levels of active G. The primary regulatory mechanism consists of two isoforms of 11β‐hydroxysteroid dehydrogenase (11βHSD) that catalyze conversion between active and inactive G. During follicular maturation the levels of active G are suppressed by the dehydrogenase activity of 11βHSD, whereas during the ovulatory process, levels of active G are further increased by the oxo‐reductase activity of 11βHSD. The expression of these enzymes is under the control of gonadotrpins and local regulatory factors such as cytokines, allowing the mechanism to act in coordination with major reproductive events. Thus the G system is an integral part of ovarian physiology, which ensures that the ovary experiences only beneficial effects of G.     

Phytoestrogens and their metabolites inhibit the sensitivity of the bovine corpus luteum to luteotropic factors

The aim of this study was to examine whether active metabolites of phytoestrogens (equol and para-ethyl-phenol) inhibit sensitivity of bovine corpus luteum (CL) to luteinizing hormone (LH) and to auto/paracrine luteotropic factors (prostaglandin E2-PGE2 and prostaglandin F(2alpha)-PGF(2alpha)), and whether they influence pulsatile progesterone (P4) secretion by the bovine CL. In in vivo experiments, high levels of equol and para-ethyl-phenol were found in plasma and in the CL tissue of heifers and cows fed a soy bean diet (2.5 kg/animal/day), along with lower concentrations of P4 (P < 0.05). Both Prostaglandins (PG) and LH strongly stimulated P4 secretion in cultured pieces of CL that were collected from cows fed a standard diet (P < 0.01). There was no effect of PGs and LH on P4 stimulation in CLs obtained from cows fed a diet rich in soy bean. Finally, we examined whether active metabolites of phytoestrogens participated in regulation of pulsatile P4 secretion and LH-stimulated P4 secretion in vitro using a microdialysis system. Equol and para-ethyl-phenol had no effect on basic and pulsatile P4 secretion in CLs during 240 min of perfusion when compared to the control (P < 0.05). However, they inhibited LH-stimulated P4 secretion (P < 0.05). Phytoestrogens and their metabolites may disrupt CL function by inhibiting PG- and LH-stimulated P4 secretion.     

Cystic Degeneration in Porcine Ovaries - First Communication: Morphology of Cystic Ovaries, Interpretation of the Results

Contents: The morphological appearance of ovarian structures in 79 sows with ovarian cysts was examined. Sixty sows had been culled due to sterility; 19 sows had been repeatedly investigated clinically before slaughter. It was found that cystic ovaries without corpora lutea (CL) had the largest diameter and volume (151.3 cm³), in comparison to both cystic ovaries with CL (85.7 cm³) and normalovaries (16.9 cm³). The number of cysts on ovaries without corpora lutea was approximately twice as high as on the ovaries with CL (23.3 vs 12.1 cystslsow; p < 0.001). A combined form of degeneration consisting of large (> 1.5 cm in diameter) and small (1.5 em in diameter) cysts was found in 63% of the animals, whereas degeneration with only small cysts occured in 8% of the cases. Dark CL, interpreted as being functional, were mainly present in animals with up to 10 cysts per sow (24 out of 27 sows, p < 0.001); pale CL, interpreted as being weakly functional, were mainly found on ovaries with more than 10 cysts (19 out of 23 sows; p < 0.001). Based on macroscopical differentiation cyclic activity was found to be dependent to the number of cysts. Regular or irregular estrous cycles were observed in oligocystic animals (10 cysts/animal) with functional CL (58%). Up to 75% of the animals with pale or absent CL showed no estrous activity.     

The influence of trilostane on steroid hormone metabolism in canine adrenal glands and corpora lutea—an in vitro study

Trilostane is widely used to treat hyperadrenocorticism in dogs. Trilostane competitively inhibits the enzyme 3-beta hydroxysteroid dehydrogenase (3β-HSD), which converts pregnenolone (P5) to progesterone (P4) and dehydroepiandrosterone (DHEA) to androstendione (A4). Although trilostane is frequently used in dogs, the molecular mechanism underlying its effect on canine steroid hormone biosynthesis is still an enigma. Multiple enzymes of 3β–HSD have been found in humans, rats and mice and their presence might explain the contradictory results of studies on the effectiveness of trilostane. We therefore investigated the influence of trilostane on steroid hormone metabolism in dogs by means of an in vitro model. Canine adrenal glands from freshly euthanized dogs and corpora lutea (CL) were incubated with increasing doses of trilostane. Tritiated P5 or DHEA were used as substrates. The resulting radioactive metabolites were extracted, separated by thin layer chromatography and visualized by autoradiography. A wide variety of radioactive metabolites were formed in the adrenal glands and in the CL, indicating high metabolic activity in both tissues. In the adrenal cortex, trilostane influences the P5 metabolism in a dose- and time-dependent manner, while DHEA metabolism and metabolism of both hormones in the CL were unaffected. The results indicate for the first time that there might be more than one enzyme of 3β-HSD present in dogs and that trilostane selectively inhibits P5 conversion to P4 only in the adrenal gland.     

Expression of genes related to corticotropin production and glucocorticoid feedback in corticotroph adenomas of dogs with Cushing's disease

Cushing's disease caused by pituitary corticotroph adenoma is a common endocrine disease in dogs. A characteristic biochemical feature of corticotroph adenomas is their relative resistance to negative feedback by glucocorticoids. In this study, we examined gene expression related to adrenocorticotropic hormone (ACTH) production and secretion, and the negative feedback by glucocorticoids in canine corticotroph adenoma. We used resected corticotroph adenomas from 10 dogs with Cushing's disease. In order to investigate the alteration of gene expression between corticotroph adenoma and normal corticotrophic cells, ACTH-positive cells in the anterior lobe were microdissected using a laser-capture microdissection system, and mRNA levels of proopiomelanocortin (POMC), corticotropin releasing hormone receptor 1 (CRHR1), glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and 11 beta hydroxysteroid dehydrogenase (11HSD) type 1 and type 2 were determined using real-time RT-PCR. POMC, CRHR1, and 11HSD2 mRNA levels in corticotroph adenoma were greater than those in normal corticotrophic cells (POMC, 5.5-fold; CRHR1, 4.9-fold; 11HSD2, 4.2-fold, P<0.01, respectively). MR and 11HSD1 mRNA levels in corticotroph adenoma were lower than those in normal corticotrophic cells (MR, 2.2-fold; 11HSD1, 2.9-fold, P<0.01, respectively). GR mRNA levels did not differ between corticotroph adenoma and normal corticotrophic cells. Our results may help to understand the increased ACTH production and the resistance to negative feedback suppression by glucocorticoids in canine corticotroph adenomas. These changes in gene expression may have a role in the growth of canine corticotroph adenoma, and help elucidate the pathophysiology of dogs with Cushing's disease.     

橙皮苷对肉仔鸡生长性能、肌肉品质及肠道形态结构的影响

本试验旨在研究在肉仔鸡饲粮中添加不同水平的橙皮苷(HSD)对其生长性能、肌肉品质及肠道形态结构的影响.采用单因子完全随机试验设计,选取健康的、体重相近的1日龄爱拔益加(AA)肉鸡公雏288只,随机分为4组,每组6个重复,每个重复12只.饲粮中HSD的添加水平分别为0(对照组)、50(HSD 50组)、100(HSD 1...     

Potential role of hCG in apoptosis of human luteinized granulosa cells

The corpus luteum (CL) forms after ovulation and acts as a temporary endocrine gland that produces progesterone (P4), a hormone that is essential for implantation and maintenance of pregnancy in mammals. In pregnant women, human chorionic gonadotropin (hCG) secreted by the conceptus prevents luteolysis. hCG also increases the survival of cultured human luteinized granulosa cells (hLGCs). To clarify the maintenance mechanism of the human CL, we investigated the effects of hCG and P4 receptor antagonists, onapristone (OP) and RU486, on the viability of hLGCs. With the patients’ consent, hLGCs were isolated from follicular aspirates for in vitro fertilization. The cells were cultured with hCG (0.1, 1, 10, 100 IU/ml), OP (10, 25, 50, 100 μM), RU486 (100 μM), P4 (1, 10, 25, 50 μM) or some combination of the four for 24 h. Cell viability was significantly increased by hCG (100 IU/ml) and significantly decreased by OP (100 μM) compared with the control. Cells treated with hCG and OP together were significantly less viable than the control and OP-treated cells. The combined treatment also significantly increased CASP3 activity and cleaved CASP3 protein expression. Furthermore, P4 addition reversed the reduction in cell viability caused by the combination of hCG and OP treatment. The overall findings suggest that hCG cooperates with P4 to increase survival of hLGCs and to induce apoptosis when P4 action supported by hCG is attenuated in the human CL.     

Seasonal Changes in Luteal Progesterone Concentration and mRNA Expressions of Progesterone Synthesis-related Proteins in the Corpus Luteum of Mares

Although circulating progesterone (P(4)) levels tend to change with the season, little is known about the seasonal changes of P(4) synthesis-related proteins in the corpus luteum (CL) of mares. To examine these changes, seventy-four ovaries containing a CL were collected from Anglo-Norman mares at a local abattoir in Kumamoto, Japan (~N32°), five times during one year. The stages of the CLs were classified as early, mid and regressed by macroscopic observation of the CL and follicles. The mid CL, which had the highest P(4) concentration, was used to evaluate the seasonal changes in P(4) synthesis. The luteal P(4) concentration and mRNA expression of luteinizing hormone receptor (LHCGR) were lowest during early winter and highest during late winter. The mRNA expressions of steroidogenic acute regulatory protein (StAR), P450 cholesterol side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3β-HSD) were lowest during early winter and increased during late winter. These results suggest that P(4) synthesis in the CL is affected by the seasonal changes in the mRNA expressions of P(4) synthesis-related proteins in mares.     

Expression of mRNAs for interleukin-4, interleukin-6 and their receptors in porcine corpus luteum during the estrous cycle

There is increasing evidence that inflammatory cytokines regulate corpus luteum (CL) function in many species. The purpose of the present study was to determine whether interleukin (IL)-4 and IL-6 are expressed in the porcine CL, and whether these cytokines influence porcine luteal steroidogenesis. The gene expressions of IL-4, IL-6 and their specific receptors were determined in the CL of Chinese Meishan pigs during the estrous cycle. Moreover, the effects of these cytokines on progesterone (P(4)), estradiol-17beta (E(2)) and prostaglandin (PG) F2alpha secretion by cultured luteal cells were investigated. IL-4 and IL-6 mRNAs were detected in the CL at all luteal stages. Furthermore, mRNAs of the receptors for IL-4 and IL-6 were clearly expressed in the CL throughout the estrous cycle. Real-time PCR analysis revealed that IL-6 receptor (IL-6R) mRNA expression was higher in the regressed CL (days 19-21 after ovulation) than in the CL at other stages (P<0.01). Exposure of cultured luteal cells obtained from mid-stage CL (days 8-11) to IL-6 (1-100 ng/ml), it inhibited P(4) and E(2) secretion by the cells (P<0.05). Although IL-4 (1-100 ng/ml) did not significantly alter P(4) secretion, it inhibited E(2) secretion by the cells (P<0.05). Neither IL-4 nor IL-6 had any effect on PGF2alpha secretion by the cells. These results suggest that IL-4 and IL-6 are locally produced in the porcine CL, and that they inhibit steroid production from luteal cells via their specific receptors. Collectively, both IL-4 and IL-6 may play roles in regulating porcine CL function throughout the estrous cycle.     

Characterization of certified Angus beef steaks from the round, loin, and chuck

Beef carcasses (n = 150) of A-maturity were selected randomly to determine baseline shear force and sensory panel ratings, assess variation in tenderness, and evaluate mean value differences between Certified Angus Beef (CAB), commodity Choice, and Select steaks. Three steaks were removed from the triceps brachii (TB), longissimus lumborum (LL), gluteus medius (GM), semimembranosus (SM), biceps femoris (BF), and quadriceps femoris complex (QF), and assigned to Warner-Bratzler shear (WBSF) and sensory panel analyses. As anticipated, marbling score and measured percentage of i.m. fat were greatest (P < 0.05) for CAB, intermediate (P < 0.05) for Choice, and least (P < 0.05) for Select carcasses. A muscle x quality level interaction (P < 0.05) was observed for WBSF values and sensory panel tenderness ratings. The TB, LL, GM, and BF steaks from CAB carcasses had lower (P < 0.05) WBSF than Select steaks from the same muscles. Even though WBSF values did not differ (P > 0.05) between CAB and Choice QF and TB steaks, the LL and GM steaks from CAB carcasses were more tender (P < 0.05) than Choice-grade LL and GM steaks. The TB from Select carcasses had higher (P < 0.05) WBSF values than TB steaks from CAB or Choice carcasses, but sensory panel ratings indicated that quality level showed little consistency among the GM, SM, BF, and QF. Trained sensory panelists rated CAB LL steaks more tender (P < 0.05) than LL steaks from Choice and Select carcasses, and Choice LL steaks were evaluated as more (P < 0.05) tender than those from Select carcasses. These results demonstrate that the influence of marbling on tenderness was more evident in muscles of middle meats than in end cuts, particularly in muscles of the round.     

The Effect of Dose and Type of Cloprostenol on the Luteolytic Response of Dairy Cattle during the Ovsynch Protocol under Different Oestrous Cycle and Physiological Characteristics

The objective of this study was to characterize the effect of dose and type of cloprostenol (CLO) on the luteolytic response of dairy cattle during the Ovsynch protocol under different oestrus cycle and physiological characteristics. Twelve non‐lactating dairy cows and 111 lactating dairy cows were used in three experiments. In Experiment I, cows were synchronized so that they had only a 5.5‐ to 6‐day‐old corpus luteum (CL) at the time of the prostaglandin F_2α (PGF_2α) treatment of Ovsynch. In Experiment II, cows were synchronized so that they had at least a CL of approximately 14 days old at the time of PGF_2α treatment and an accessory CL if they had responded to the first GnRH of Ovsynch. Furthermore, in each experiment, cows received either a standard or a double dose of d‐CLO as the luteolytic treatment. In Experiment III, lactating cows were blocked by parity and assigned to one of three luteolytic treatments during Ovsynch: 500 μg d,l‐CLO, 150 or 300 μg of d‐CLO. In Experiment I, the dose of d‐CLO had an effect (p = 0.08) on the percentage of cows with full luteolysis, but not in Experiment II (p > 0.1). More cows in Experiment II had full luteolysis than did cows of Experiment I (87% vs 58%, respectively; p = 0.007). In Experiment III, 87.1%, 84.4% and 86.2% lactating dairy cows had full luteolysis and 37.8%, 36.8% and 36.1% of cows became pregnant after treatment with 500 μg d,l‐CLO, 150 or 300 μg of d‐CLO, respectively (p > 0.05).     

Is nutritional anestrus precipitated by subfunctional corpora lutea in beef cows?

Thirty-four multiparous, lactating, cyclic beef cows which calved in moderate body condition were used to determine effects of restricted nutrition on corpus luteum (CL) development and endocrine status. At 78 d postpartum, six cows were assigned to a control (CON) diet (26.0 Mcal ME), fed to increase bodyweight (BW) and body condition score (BCS), and the remaining 28 cows were fed to lose BW and BCS on a restricted (RES) diet (14.0 Mcal ME). Following a 40-d adjustment period on respective diets, estrous cycles were synchronized and cows bled daily for determination of progesterone (P4), luteinizing hormone (LH) and insulin (INS) beginning at the synchronized estrus. Ultrasonography was used to determine the ovulatory follicle and CL development. Control cows were maintained for one estrous cycle and were ovariectomized on day 11 of their second cycle. Ten cows on restricted diet (RES-C) continued to form a functional CL (P4 > 1.5 ng/ml at day 10 of an estrous cycle) through as many as 5 cycles, after which observations were discontinued. Fourteen cows on restricted diet (RES-A) were ovariectomized on day 11 of a cycle when a CL was identified by ultrasonography, but was subfunctional (P4 < 1.5 ng/ml on day 10 of that cycle). Four additional RES-A cows which had subfunctional CL were not ovariectomized but were bled for an additional 25 d. At ovariectomy, CL and ovarian weights were collected. Luteal tissue was prepared for evaluation of P4 synthesis, LH responsiveness in vitro, and for determination of P4 content and total LH receptors. Bodyweight and BCS increased in CON cows; whereas, RES cows lost BW and BCS (P < .05). In the cycle prior to ovariectomy, serum P4 and LH were not different in 18 RES-A cows which developed subfunctional CL in comparison to CON cows. Four RES-A cows not ovariectomized but bled for an additional 25 d neither exhibited estrus, ovulated, nor had P4 concentrations greater than .3 ng/ml. Serum INS was lower in RES-A cows during the cycle prior to ovariectomy than in CON cows (P < .05). During the 11-d period prior to ovariectomy, mean serum P4 and INS were lower in RES-A cows than in CON cows (P < .05); however, serum LH was not different. Furthermore, CL and ovarian weights, P4 content of CL, secretion of P4 by luteal tissue in response to LH in vitro and LH receptor number were not different between CON and RES-A cows. In conclusion, nutritional anestrus may be preceded by the formation of a CL with lower steroidogenic output in vivo. However, luteal tissue, collected from RES-A cows, did not appear to be subfunctional during in vitro incubation when substrate availability and gonadotropin support were equal between diets.     

Luteal vascularity and embryo dynamics in mares during early gestation: Effect of age and endometrial degeneration

The present study characterized the luteal status and the dynamic of the conceptus during the first 20 days of gestation in mares with different ages and degrees of endometrial degeneration. Total area of the corpus luteum (CL), luteal vascularity, CL area with blood signals, progesterone concentrations (P4), embryonic vesicle diameter, number of embryonic location changes, embryonic fixation position and uterine contractility were evaluated. In Experiment 1, mares ≤6 years of age (Young group, 5.6 ± 0.2 years, n = 7 mares) and mares ≥15 years of age (Old group, 17.2 ± 0.9 years, n = 6 mares) were used to investigate the effect of age. In Experiment 2, the luteal and embryonic parameters were compared between mares with minimal (Mild group, endometrial category I, n = 9 mares) and severe (Severe group, endometrial category III, n = 7 mares) endometrial degeneration. The Old and Severe groups had greater (p ≤ 0.04) total CL area and reduced luteal vascularity (p ≤ 0.04) than the Young and Mild groups, respectively. However, P4 levels and CL area with blood signals were similar (p ≥ 0.8) between the groups. A negative effect of age (p < 0.01), but not of endometrial degeneration (p = 0.6), was found for the embryonic vesicle diameter. The conceptus mobility was high (p > 0.1) until day 14 of gestation in the Severe group, while a reduced number of changes of the embryo location was detected earlier (p < 0.05) in the Old group. In conclusion, the newly formed CL of aged mares and mares with severe endometrial degeneration suffered a structural remodelling to safeguard the local blood supply and the continuous P4 output during early gestation. Moreover, an earlier reduction of the embryonic mobility and a delayed development of the conceptus were associated with advanced age, regardless of the degree of endometrial degeneration.     

Effects of in utero and lactational exposure to the no-observed-adverse-effect level (NOAEL) dose of the neonicotinoid clothianidin on the reproductive organs of female mice

Recently, developmental exposure to clothianidin (CLO) has been shown to cause reproductive toxicity in male mice, but the effects in female mice remain to be clarified. Pregnant C57BL/6N mice were given a no-observed-adverse-effect-level (NOAEL) dose of CLO until weaning. We then examined ovaries of 3- or 10-week-old female offspring. In the CLO-administered group, morphological changes, a decrease in the immunoreactivity of the antioxidant enzyme glutathione peroxidase 4 (GPx4), and activation of genes in the steroid hormone biosynthesis pathway were observed in 3-week-old mice, and decreases of GPx4 immunoreactivity, 17OH-progesterone and corticosterone levels were observed in 10-week-old mice, along with high rates of infanticide and severe neglect, providing new evidence that developmental exposure to CLO affects juvenile and adult mice differently.     

Relation of reproductive performances and rectal palpation for luteum function of heifers 7 days after estrus

Diagnosis of corpus luteum (CL) function by rectal palpation (RP) has been widely used for recipient selection of embryo transfer (ET), a technology essential for genetic improvements in cattle. To examine the accuracy of RP diagnosis method, the relationship between RP‐based CL function and reproductive performance was compared in this study. In Experiment 1, CL of Holstein heifers on day 7 after estrus was classified into functional or hypoplastic by RP, and the results were compared with ultrasonographic (US) images and plasma progesterone (P4) levels. As a result, heifers with functional CL judged by RP had a mean maximum CL diameter of 20.1 ± 3.1 mm on US and a mean P4 concentration of 8.1 ± 2.3 ng/mL. These values were significantly greater than those of heifers with hypoplastic CL (12.4 ± 5.4 mm, 4.0 ± 2.8 ng/mL) (P < 0.001). In Experiment 2, the length of the estrus cycle was examined between functional CL and hypoplastic CL. The rate of heifers with a normal estrus cycle length with 18–25 days was significantly lower with hypoplastic CL than with functional CL (16/24 vs. 43/46, P < 0.01). In Experiment 3, 543 inseminated heifers were similarly classified by CL function by RP 7 days after estrus. The heifers with functional CL showed higher pregnancy rate compared with the heifers with hypoplastic CL (75.2 vs. 47.9%, P < 0.0001). Finally, the CL function of 66 heifers was examined by RP on day 7 post‐estrus, and ET was performed in 49 (74.2%) heifers with functional CL. As a result, 27 (55.1%) of them became pregnant. Taken together, these results reconfirm that RP on day 7 after estrus is useful for selection of heifers with functional CL.     

The metastatic potential of canine mammary tumours can be assessed by mRNA expression analysis of connective tissue modulators

Metastases are the crucial factor for the prognosis of canine mammary tumours (CMTs). In women, the peptide hormone relaxin is linked with metastatic breast cancer. Therefore, the impact of relaxin and its receptors on matrix metalloproteinase (MMP) expression, metastatic disease and survival was analysed using qRT‐PCR and immunohistochemistry of CMT samples from 59 bitches. The expression of relaxin and its receptor RXFP1 (relaxin family peptide receptor 1) was discovered on gene and protein levels. Intratumoural relaxin mRNA expression and relaxin plasma levels had no prognostic value. High mRNA levels RXFP1 were an independent marker of metastatic potential, with a more than 15‐fold risk increase, and a predictor for shorter survival. Also, MMP‐2 expression was associated with early death because of CMT. The mRNA expressions of relaxin, RXFP1 and MMP‐2 were positively correlated indicating a common pathogenetic linkage. Thus, RXFP1 is proposed as a new early marker of metastatic potential in CMT and a possible therapeutic target.     

Expression of insulin-like growth factor binding protein (IGFBP)-3, and the effects of IGFBP-2 and -3 in the bovine corpus luteum.

The present study was conducted to gain insight into the insulin-like growth factor (IGF) system in the bovine corpus luteum (CL). Specific aims were to measure the levels of IGF binding protein-3 (IGFBP-3) and RNA encoding IGFBP-3 in the CL throughout diestrus, and to investigate the effects of IGFBP-2 and -3 on IGF-I-stimulated progesterone (P4) production and IGF-I-receptor binding. Bovine CL were collected from a local abattoir and classified according to stage of diestrus based on anatomical characteristics. Corpora lutea from early, mid and late diestrus were each analyzed for the presence of IGFBP-3 by ligand blot analysis, and for RNA encoding IGFBP-3 by Northern blot analysis. Dissociated cells from mid-cycle CL were treated with IGF-I, IGFBP-2 or -3, or a combination of IGF-I and IGFBP-2 or -3. The effect of IGFBP-2 and IGFBP-3 on [(125)I] IGF-I binding to its receptor on CL plasma membranes also was investigated. IGFBP-3 protein and RNA expression were higher in early CL, compared to mid or late CL (p < 0.05). IGF-I stimulated P4 production in a dose-dependant manner (p < 0.05). IGFBP-2 and -3 blocked the stimulatory effect of IGF-I on P4 production (p < 0.05). Both IGFBP-2 and -3 inhibited [(125)I]-IGF-I binding to its receptor in a dose-dependant manner. These results demonstrate that IGFBP-3 protein and RNA are expressed predominantly during early diestrus in the bovine CL. Moreover, both IGFBP-2 and -3 can modulate IGF-I actions in the CL by interfering with binding of IGF-I to its receptor.