The role of phosphoinositide-derived second messengers in oxytocin-stimulated prostaglandin F2α release from endometrium of pigs

The mechanism for prostaglandin (PG) F_2α release from pig endometrium after oxytocin (OT) treatment is unknown. OT may rapidly stimulate inositol (1,4,5)-trisphosphate (IP₃) and diacylglycerol (DAG) formation, consistent with the concept of rapid activation of a second-messenger system. In support of this hypothesis, endometrial IP₃ levels were increased (P < 0.05) within 0.5 min after treatment with 0.1 μM OT. In contrast, increased DAG formation was not detected after treatment with OT. However, similar to the stimulation of endometrial PGF_2α secretion observed after OT treatment (P < 0.001), PGF_2α release was increased (P < 0.01) after treatment with phorbol-12myristate-l3-acetate (PMA), which mimics DAG activation of protein kinase C. Further, stimulation of endometrial PGF_2α secretion did not result from cell death induced by PMA or OT because lactate dehydrogenase, a cytosolic marker of cellular integrity, did not leak into the medium after PMA or OT treatment. In contrast, 0.5% saponin (positive control for cell death and concomitant release of lactate dehydrogenase) increased PGF_2α secretion (P < 0.05) and lactate dehydrogenase release (P < 0.001). These results indicate that OT induces endometrial IP₃ production in a rapid manner indicative of a second-messenger system. The finding that increased DAG was not also detected after OT treatment may reflect rapid metabolism or compartmentalized production of DAG involved in the second-messenger stimulation of phospholipase C. The high background of DAG used in the biosynthesis of cellular lipids would obscure the rather small spatially localized changes in DAG levels resulting from the activation of phospholipase C. The finding that DAG was present at approximately 10 to 20-fold higher levels than IP₃ in resting cells was consistent with this conclusion.     

前列腺素F2α溶解黄体机制研究进展

前列腺素F     

Expression of matrix metalloproteinases in bovine luteal cells induced by prostaglandin F2α, interferon γ and tumor necrosis factor α

We recently demonstrated that luteal cells flow out from the ovary via lymphatic vessels during luteolysis. However, the regulatory mechanisms of the outflow of luteal cells are not known. Matrix metalloproteinases (MMPs) can degrade the extracellular matrix and basal membrane, and tissue inhibitors of matrix metalloproteinases (TIMPs) inhibit the activity of MMPs. To test the hypothesis that MMP expression in luteal cells is regulated by luteolytic factors, we investigated the effects of prostaglandin F2α (PGF), interferon γ (IFNG) and tumor necrosis factor α (TNF) on the mRNA expression of MMPs and TIMPs in cultured luteal cells. Luteal cells obtained from the CL at the mid-luteal stage (days 8–12 after ovulation) were cultured with PGF (0.01, 0.1, 1 μM), IFNG (0.05, 0.5, 5 nM) and TNF (0.05, 0.5, 0.5 nM) alone or in combination for 24 h. PGF and IFNG significantly increased the expression of MMP-1 mRNA. In addition, 1 μM PGF in combination with 5 nM IFNG stimulated MMP-1 and MMP-9 mRNA expression significantly more than either treatment alone. In contrast, IFNG significantly decreased the level of MMP-14 mRNA. The mRNA expression of TIMP-1, which preferentially inhibits MMP-1, was suppressed by 5 nM INFG. One μM PGF and 5 nM IFNG suppressed TIMP-2 mRNA expression. These results suggest a new role of MMPs: luteal MMPs stimulated by PGF and IFNG break down the extracellular matrix surrounding luteal cells, which accelerates detachment from the CL during luteolysis, providing an essential prerequisite for outflow of luteal cells from the CL to lymphatic vessels.     

雌激素对奶牛输卵管上皮细胞前列腺素E2和F2α合成酶mRNA表达的影响

为了揭示雌激素(estrogen,E₂)对奶牛输卵管上皮细胞中前列腺素E₂合成酶(PGES)和前列腺素F_2α合成酶(PGFS)mRNA表达的影响,探讨E₂对奶牛输卵管生殖生理的调节作用,本试验采用了体外培养荷斯坦奶牛输卵管上皮细胞技术,分不同时间(0、2、4、8、16、24和48 h)和不同浓度(10^-12、10^-11、10^-10、10^-9 mol/L)添加雌激素E₂(以不加雌激素作空白对照),采用荧光定量PCR 技术检测PGES和PGFS mRNA表达。不同浓度的E₂或同一浓度不同刺激时间的E₂均能增加PGES的表达,但4 h浓度为10^-10 mol/L时与空白对照相比差异极显著(P<0.01),而PGFS在24 h添加浓度为10^-12 mol/L E₂时与空白对照相比差异极显著(P<0.01)。试验结果表明,E₂对培养的奶牛输卵管上皮细胞PGES和PGFS mRNA的表达有促进作用,说明雌激素E₂对前列腺素酶PGES和PGFS mRNA的表达具有调控作用。     

前列腺素F2α及其类似物氯前列烯醇在家畜繁殖中的应用

前列腺素F     

The effect of two different routes of administration of oxytocin on peripheral plasma prostaglandin F(2α) metabolite levels in early post-partum dairy cows

Various parenteral treatment forms of oxytocin, as often used under praxis circumstances, may act differently on contractility of the uterus during the first days of the puerperium. Various patterns of such induced uterotonic responses may lead to alterations in the emptying characteristics of the uterine lumen, thus influencing, as a late consequence, the process of involution. Therefore, this study was designed to test whether two different parenteral administration forms of oxytocin induce changes in peripheral plasma concentrations of 15-ketodihydro-prostaglandin F(2α) (PGF(2α) metabolite) in early post-partum cows. Between 13 and 15 h after uncomplicated calving, healthy dairy cows without retained foetal membranes were treated with 50 IU oxytocin, either intramuscularly (OT-IM group; n = 15) or intravenously (OT-IV group; n = 16). Saline solution was administered intramuscularly as controls (CON group; n = 15). Jugular blood samples were taken at 10-min intervals from 1 h before to 2 h after treatment. Plasma PGF(2α) metabolite levels were measured by radioimmunoassay. No significant differences in peripheral plasma PGF(2α) metabolite concentrations occurred in the OT-IM and CON groups, but mean values significantly increased in the OT-IV group, peaking at 20 min after treatment and reaching pre-treatment baseline values again at 120 min. Although the source of prostaglandins was not investigated in this study, our results suggest that exogenous oxytocin may enhance secretion of prostaglandins by the uterus during the first day after normal calving. These prostaglandins might contribute, by an endocrine or paracrine route, to the stimulation of myometrial contractility when exogenous oxytocin is given during this early post-partum stage.     

前列腺素F2α剂量依赖性对黄体溶解效果评价及其调控基因表达模式分析

本试验旨在探究不同剂量外源性PGF_2α对小鼠黄体(corpus luteum, CL)溶解效果的影响及其剂量依赖性关系。选用60只60日龄、体质量30～34 g雌性昆明小鼠随机分为6组,分别采用腹腔注射1,10,50,100,200μg PGF_2α。通过H.E染色法监测卵巢的形态学变化,ELISA法检测小鼠血清孕酮水平及利用qRT-PCR检测孕酮合成关键酶/细胞凋亡相关基因表达情况。结果显示,与对照组相比,不同剂量PGF_2α处理组中昆明小鼠的CL溶解效果为50μg组>10μg组>100μg组>1μg组>200μg组;CL功能性指征结果显示PGF_2α在50μg剂量范围内,小鼠体内P₄含量会随着PGF_2α处理剂量的增加而呈现递增趋势;而且,P₄合成关键酶基因检测结果显示StAR和3β-HSD表达量在PGF_2α注射剂量为50μg时呈现最低水平;同时,CL结构性指征检测结果发现此时促凋亡因子BAX...     

Expression of prostaglandin F(2α) (PGF(2α)) receptor and its isoforms in the bovine corpus luteum during the estrous cycle and PGF(2α)-induced luteolysis

Prostaglandin F(2α) (PGF(2α)) induces luteolysis via a specific receptor, PTGFR. Although PTGFR mRNA expression in the bovine corpus luteum (CL) has been studied previously, changes in PTGFR protein and its localization are not fully understood during the life span of the CL. In addition to full-length PTGFR, several types of PTGFR isoforms, such as PTGFRα (type I) and PTGFRζ (type II), were reported in the bovine CL, suggesting isoform-specific luteal action. Full-length PTGFR mRNA in the bovine CL increased from the early to the mid-luteal phase and decreased during luteolysis, whereas PTGFR protein remained stable. PTGFR protein was localized to both luteal and endothelial cells and was expressed similarly during the life span of the CL. Like full-length PTGFR mRNA, PTGFRα and PTGFRζ mRNA also increased from the early to mid-luteal phases, and mRNA of PTGFRζ, but not PTGFRα, decreased in the regressing CL. During PGF(2α)-induced luteolysis, the mRNAs of full-length PTGFR, PTGFR,α and PTGFRζ decreased rapidly (from 5 or 15 min after PGF(2α) injection), but PTGFR protein decreased only 12 h later. Silencing full-length PTGFR using small interfering RNA prevented PGF(2α)-stimulated cyclooxygenase-2 (PTGS2) mRNA induction. By contrast, PGF(2α) could stimulate vascular endothelial growth factor A (VEGFA) mRNA even when full-length PTGFR was knocked down, thus suggesting that PGF(2α) may stimulate PTGS2 via full-length PTGFR, whereas VEGFA is stimulated via other PTGFR isoforms. Collectively, PTGFR protein was expressed continually in the bovine CL during the estrous cycle, implying that PGF(2α) could function throughout this period. Additionally, the bovine CL expresses different PTGFR isoforms, and thus PGF(2α) may have different effects when acting via full-length PTGFR or via PTGFR isoforms.     

Control of in vitro prostaglandin F2α and E2 synthesis by caruncular and allantochorionic tissues from cows that calved normally and those with retained fetal membranes

High concentrations of PGF_2α and PGE₂ are produced by the uterus during the early postpartum period in cows and may play an important role in both placental separation and uterine involution. In the present study, we have examined the hormonal and intracellular control mechanisms involved in PGF_2α and PGE₂ secretion by caruncular and allantochorionic tissue in vitro. Tissue explants, obtained about 6 hr postpartum from cows that delivered normally (NFM, n = 10) or cows with retained fetal membranes (RFM, n = 4), were incubated for 6 hr and PGF_2α and PGE₂ concentrations in the medium were determined by radioimmunoassay. Addition of oxytocin (100 μU/ml), platelet activating factor (PAF, 100 ng/ml) and epidermal growth factor (EGF, 100 ng/ml) had no effect on secretion of PGF_2α from the caruncle, but oxytocin and PAF did stimulate PGE₂. There was no difference between groups of cows. All three substances stimulated PGF_2α from the allantochorion of NFM, but not RFM, cows and stimulated PGE₂ secretion from the allantochorion of both groups of cows. Incubation of the tissues with cholera toxin (100 ng/ml), dibutyryl cyclic adenosine 3′,5′-monophosphate (dibutyryl cAMP, 1mM), calcium ionophore A23187 (5 μM) or phorbol ester 12-myristate-13 acetate (PMA, 100 nM) showed that PGF_2α secretion is essentially via the calcium-protein kinase C effector pathway. However, calcium-protein kinase C and cAMP second messenger systems appear to be involved in the secretion of PGE₂. Prostaglandin secretion was sensitive to cycloheximide in both caruncular and allantochorionic tissues, suggesting that protein synthesis may be involved. In conclusion, these data show that in vitro PGF_2α secretion can be modulated by the agonists used only in allantochorion and is essentially via the calcium-protein kinase C effector pathway. PGE₂ secretion can be modifified in both caruncular and allantochorion tissues and involves both inositol triphosphate-diacylglycerol and cAMP second messenger systems.     

Strategies to improve genomic predictions for 35 duck carcass traits in an F2 populationOA

Background Carcass traits are crucial for broiler ducks,but carcass traits can only be measured postmortem.Genomic selection(GS) is an effective approach in animal breeding to improve selection and reduce costs. However,the performance of genomic prediction in duck carcass traits remains largely unknown.Results In this study,we estimated the genetic parameters,performed GS using different models and marker densities,and compared the estimation performance between GS and conventional BLUP on 35 c...     

Estradiol Effects on Secretagogue-Induced Prolactin Release: Disparity in Responses to Sulpiride,Exercise, Epinephrine,Prostaglandin-F2α, and Thyrotropin-Releasing Hormone

Three experiments were conducted (1) to assess the effects of estradiol pretreatment on the prolactin response to various secretagogues, and (2) to determine whether elevated plasma thyroxine concentrations altered the prolactin responses to those secretagogues. Geldings were available and were used because their prolactin and luteinizing hormone responses to estradiol and dopamine antagonists are known to be similar to those in seasonally anovulatory mares. In the first experiment, performed in summer, estradiol cypionate (ECP; 100 mg) treatment of geldings increased (P = .07) plasma prolactin concentrations before the onset of exercise, and repeated exercise bouts stimulated (P < .001) plasma prolactin concentrations after each bout; there was no interaction with estradiol pretreatment. Epinephrine injection (5 μg/kg of body weight) did not alter prolactin concentrations. Prostaglandin-F_2α administration (10 mg Lutalyse) stimulated (P < .001) prolactin concentrations, but there was no interaction with ECP pretreatment. Sulpiride administration (0.1 mg/kg of body weight) stimulated (P < .001) prolactin concentrations, and there was a greater (P = .038) response in ECP-treated geldings relative to controls. In the second experiment, performed in winter, ECP (50 mg) pretreatment of geldings before 21 days of daily thyrotropin-releasing hormone (TRH; 1.5 mg) injections did not alter prolactin secretion (P > .1); TRH stimulated prolactin secretion only after the very first injection. In the third experiment (performed in July), pretreatment of geldings with 50 mg of thyroxine in biodegradable particles (day 0) raised (P < .001) plasma thyroxine concentrations in plasma for the duration of the experiment, but had no effect on the prolactin responses to two exercise bouts on day 5, to an injection of prostaglandin-F_2α on day 9, or to an injection of sulpiride on day 13. The previously reported stimulation of plasma prolactin concentrations by estradiol pretreatment and subsequent sulpiride administration in mares, as evidenced herein in geldings, does not occur when prolactin is stimulated by exercise, prostaglandin-F_2α, or TRH. The practical impact of these data is that stimulation of prolactin concentrations after ECP treatment in winter, in an effort to stimulate ovarian activity in seasonally anovulatory mares, is likely limited to dopamine antagonists. Results of the third experiment indicate that TRH is not likely the mediator in the prolactin response to exercise or prostaglandin-F_2α injection.     

Conditional knockout of brca1/2 and p53 in mouse ovarian surface epithelium: Do they play a role in ovarian carcinogenesis?

Alterations of genes are known to be critical for the induction of tumorigenesis, but the mechanism of ovarian carcinogenesis is little understood and remains to be elucidated. In this study, we investigated the roles of brca1, brca2 and p53 genes in the development of ovarian cancer using conditional knockout mice generated by a Cre-loxP recombinant system. Following the application of recombinant adenovirus expressing Cre in vitro, the proliferation of ovarian surface epithelium (OSE) was increased. For instance, a significant increase in cell growth was observed in OSE cells in vitro by conditional knockout isolated from the mice bearing concurrent floxed copies of brca1 and brca2/p53. However, the proliferative effect of the ovarian cells was not observed in concurrent brca1/brca2 or p53 knockout mice in vivo, indicating that we could not observe the direct evidence of the involvement of brca1, brca2, and p53 in ovarian carcinogenesis. Since morphological changes including tumor formation were not observed in mice bearing floxed copies of concurrent brca1/brca2 or p53, the inactivation of brca1/2 or p53 is not sufficient for the induction of tumor formation. Taken together, these results suggest that the deficiency of these genes may not be involved directly in the mechanism of ovarian carcinogenesis.     

Heat stress in pigs and broilers:role of gut dysbiosis in the impairment of the gut-liver axis and restoration of these effects by probiotics,prebiotics and synbioticsOA

Heat stress is one of the most challenging stressors for animal production due to high economic losses resulting from impaired animal’s productivity,health and welfare.Despite the fact that all farm animal species are susceptible to heat stress,birds and pigs are particularly sensitive to heat stress due to either lacking or non-functional sweat glands.Convincing evidence in the literature exists that gut dysbiosis,a term used to describe a perturbation of commensal gut microbiota,develops in br...