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1.
In earlier in vitro experiments opioids affected steroidogenesis in porcine luteal and granulosa cells. The present studies were undertaken to examine the effects of FK 33-824 (opioid agonist) alone or in combination with LH, PRL or naloxone (NAL, opioid antagonist) on steroidogenesis in cultured porcine theca cells. Moreover, we have tested beta-endorphin-like immunoreactivity (beta-END-LI) concentrations in culture media under control conditions and following treatments of theca cells with LH, PRL, progesterone (P4), oestradiol (E2) or testosterone (T). FK 33-824 and NAL significantly increased P4 release by theca cells and inhibited stimulatory effect of LH on this steroid output. PRL-induced P4 secretion from the cells was blunted only by FK 33-824. Secretion of androstenedione (A4) and T was essentially elevated in the presence of FK 33-824 and this potentiation of both androgen release was completely abolished by PRL. NAL blocked stimulatory effect of the opioid agonist only in case of T. Secretion of oestradiol and oestrone was completely free from the influence of both the opioid agonist and antagonist. Pig theca cells were able to produce beta-END-LI but none of tested hormones (LH, PRL, P4, E2 and T alone or in combination) significantly affected this production. In conclusion, these data indicate that porcine theca cells may produce beta-END-LI and change their steroidogenesis in response to opioid peptides.  相似文献   

2.
The present studies were undertaken to examine the influence of mu (beta-endorphin, DAMGO, FK 33-824), delta (met-enkephalin, leu-enkephalin, DPLPE) and kappa opioid receptor agonists (dynorphin A, dynorphin B, U 50488) used at different doses (1-1000 nM) alone and in combination with LH (100 ng/ml) on steroidogenesis in porcine granulosa cells derived from large follicles. The effects of mu, delta and kappa receptor agonists on both basal and LH-induced progesterone (P4) secretion were negligible. Agonists of mu opioid receptors reduced basal androstenedione (A4), testosterone (T) and oestradiol (E2) release. Co-treatment with LH entirely abolished the inhibitory effect of these agonists on A4 and E2 secretion and resulted in an increase in T release. The addition of delta receptor agonists was followed by a decrease in basal A4, T and E2 secretion. The cells incubated in the presence of LH increased the androgen production and abrogated the inhibitory effect of delta agonists on E2 output. Basal A4, T and E2 release was also suppressed by kappa receptor agonists. The presence of LH in culture media extended the inhibitory effect of these opioids on E2 output and caused either abolition of the inhibitory influence of kappa agonists or even augmentation of both androgen release in response to the opioids. In conclusion, these data support the involvement of three major types of opioid receptors in the regulation of porcine granulosa cell steroidogenesis.  相似文献   

3.
Bone morphogenetic proteins (BMPs) are emerging as a family of proteins crucial in the regulation of fertility and ovulation rate. We have shown that porcine theca cells express BMP receptors, however, there is a paucity of information regarding the effect(s) of BMPs on theca cell function. The purpose of this study was to investigate the effects of BMP-2 and -6 on theca cells cultured under serum-free conditions in terms of steroidogenesis, cAMP release and proliferation. The study was further extended to determine whether BMP responses in theca cells are affected by the addition of granulosa cells to the culture system. Both BMPs suppressed progesterone and androstenedione synthesis by theca cells (P < 0.05) after 144 h in culture. Oestradiol synthesis was suppressed (P < 0.05) by BMP-2, but not BMP-6, and theca cell proliferation was stimulated (P < 0.05) by BMP-6, but not BMP-2, after 144 h in culture. Both BMP-2 and -6 inhibited cAMP release (P < 0.05) by theca cells. Furthermore, progesterone and androstenedione synthesis by co-cultured theca and granulosa cells were suppressed (P < 0.05) whereas cell proliferation was stimulated (P < 0.05). These results provide strong evidence for a functional BMP system in the porcine ovary and that theca cells are responsive to BMPs in terms of steroidogenesis and proliferation. BMP-2 and -6 may have a role as luteinisation inhibitors in this polyovular species.  相似文献   

4.
The effects of a potent opioid peptide agonist [D-ala2-Phe4, Met(0)ol5-enkephalin (FK 33-824) on the magnitude of the oestradiol-induced LH surge and on basal plasma LH concentrations were examined in intact and chronically-ovariectomized ewes during the late-anoestrous period. In intact ewes, treatment with FK 33-824 (0.5 mg i.v. every 3 hr) for a 24 hr period commencing at the time of oestradiol-17 beta administration (25 micrograms i.m. bolus) was associated with non-significant 65% reduction in the peak plasma LH level observed and a significant (P less than 0.05) 58% reduction in the total amount of LH released during the surge (calculated from the area under the curve). Concurrent treatment with the opioid antagonist naloxone (10 mg i.v. every 3 hr) partially reversed this suppressive effect on the magnitude of the LH-surge. In ovariectomized ewes no significant effects on the oestradiol-induced LH surge of either FK 38-824 alone or FK 33-824 in combination with naloxone were observed. Administration of FK 33-824 at a 6-fold higher dose rate (0.5 mg every 30 min) failed to modify basal plasma LH concentration in intact ewes. In ovariectomized ewes, however, a significant (P less than 0.05) 25% fall in basal plasma LH was observed, an effect which was completely reversed by combined treatment with naloxone (10 mg every 30 min). These results support the conclusion that endogenous opioid peptides may contribute to the neuroendocrine mechanism through which oestradiol promotes a preovulatory-like surge in the anoestrous ewe.  相似文献   

5.
Prolactin (PRL) was found to have a stimulatory effect on adrenal steroidogenesis in vivo and in vitro in several species including pigs. PRL signal transduction pathways, however, in adrenocortical cells are poorly recognized. Therefore, the goal of this paper is to ascertain the involvement of protein kinase C (PKC) and tyrosine kinases in PRL signaling in porcine adrenal cortex. Adrenals were harvested from locally slaughtered mature gilts. Cortical cells were dispersed by sequential treatment with collagenase. The cells were seeded into 24-well culture plates at a density of 3×105/mL. Cells were incubated with or without PRL (500 ng/mL), ACTH (5 nM—a positive control), tyrosine kinase inhibitor—genistein (1; 2.5 or 5 μM), PKC inhibitor—sphingosine (20–1000 nM) and PKC activators—diacylglycerol (DiC8; 10–100 μM) and phorbol ester (PMA; 1–1000 nM). All incubations were performed for 8 h (95% air and 5% CO2, 37°C). PRL and ACTH (P<0.05) increased cortisol and androstenedione (A4) secretion. DiC8 and PMA mimicked the stimulatory effect of PRL. Sphingosine (P<0.05) suppressed basal and PRL-stimulated steroid secretion. Genistein inhibited (P<0.05) PRL-stimulated cortisol secretion and enhanced (P<0.05) basal and PRL-stimulated A4 secretion. Moreover, PKC activation was assessed by measuring the specific association of [3H]phorbol dibutyrate ([3H]PDBu) with adrenocortical cells after treatment with PRL or ionomycin (a positive control). PRL (within 2–3 min) and ionomycin (within 2–5 min) increased (P<0.05) specific binding of [3H]PDBu to the porcine adrenocortical cells. In addition, PRL did not augment the cortisol and A4 secretion by PKC-deficient adrenocortical cells. In conclusion, presented results support the hypothesis that PKC and tyrosine kinases are involved in PRL signaling in adrenocortical cells in pigs. Moreover, activation of PKC is associated with the increased secretion of cortisol and A4.  相似文献   

6.
Protein kinase C (PKC) activity was evaluated and the phosphorylation of its endogenous substrates was explored in fatty liver induced by administration of ethionine (an analogue of methionine) to cows in order to assess the relevance of PKC-dependent phosphorylation in the development of fatty liver. PKC activity was decreased in both the cytosolic and the total particulate fractions from fatty livers, compared to the corresponding fractions from control liver. The mode of activation by the PKC cofactors (1-oleoyl-2-acetyl-sn-glycerol, 12-O-tetradecanoylphorbol-13-acetate, phosphatidylserine and Ca2+) was similar in both control and fatty livers, suggesting a quantitative but not a qualitative change in PKC in fatty liver. At least three substrate proteins (34 kDa, 26 kDa and 19 kDa) were found in the cytosolic fraction and their phosphorylation was reduced in fatty liver. These results suggest that impairment of the signal transduction pathway mediated by PKC is involved in the pathogenesis of fatty liver in cows.Abbreviations ATP adenosine triphosphate - EGTA ethylene glycol bis(-aminoethylether)-N,N,N,N-tetraacetic acid - NEFA non-esterified fatty acid - OAG 1-oleoyl-2-acetyl-sn-glycerol - PKC protein kinase C - PS phosphatidylserine - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - TG triglyceride - TPA 12-O-tetradecanoylphorbol-13-acetate  相似文献   

7.
Structural luteolysis occurs by apoptosis of luteal cells. The present study examined the effects of activators of well-characterized second messengers on Fas and caspase-3 mRNA expression and on P4 production in luteal cells in order to trace the pro- and anti-apoptotic factors in the bovine corpus luteum (CL). Cultured bovine mid luteal cells were treated for 24 h with a cyclic AMP analogue (8-bromo cyclic AMP; 8br-cAMP; 2.5 mM), a protein kinase C (PKC) activator (phorbol 12-myristate 13-acetate; PMA; 10 microM), or calcium ionophore (A23187; 10 microM). Fas and caspase-3 mRNA expression was inhibited by 8br-cAMP and PMA but was increased by A23187 (P<0.05). In addition, P4 production by bovine luteal cells was stimulated by 8br-cAMP and PMA, whereas it was inhibited by A23187, compared with untreated controls (P<0.05). The overall results suggest that cAMP and PKC suppress apoptosis in bovine luteal cells through inhibition of Fas and caspase-3 mRNA expression and through stimulation of P4 production. Therefore, substances that activate cAMP or PKC may act as survival factors in the bovine CL. Furthermore, substances that mobilize Ca2+ may act as apoptotic factors by stimulating Fas and caspase-3 expression in the bovine luteal cells.  相似文献   

8.
As major fuels for the small intestinal mucosa, dietary amino acids (AA) are catabolized in the mitochondria and serve as sources of energy production. The present study was conducted to investigate AA metabolism that supply cell energy and the underlying signaling pathways in porcine enterocytes. Intestinal porcine epithelial cells (IPEC-J2) were treated with different concentrations of AA, inhibitor, or agonist of mammalian target of rapamycin complex 1 (mTORC1) and adenosine monophosphate activated protein kinase (AMPK), and mitochondrial respiration was monitored. The results showed that AA treatments resulted in enhanced mitochondrial respiration, increased intracellular content of pyruvic acid and lactic acid, and increased hormone-sensitive lipase mRNA expression. Meanwhile, decreased citrate synthase, isocitrate dehydrogenase alpha, and carnitine palmitoyltransferase 1 mRNA expression were also observed. We found that AA treatments increased the protein levels of phosphorylated mammalian target of rapamycin (p-mTOR), phosphorylated-p70 ribosomal protein S6 kinase, and phosphorylated-4E-binding protein 1. What is more, the protein levels of phosphorylated AMPK α (p-AMPKα) and nicotinamide adenine dinucleotide (NAD)-dependent protein deacetylase sirtuin-1 (SIRT1) were decreased by AA treatments in a time depending manner. Mitochondrial bioenergetics and the production of tricarboxylic acid cycle intermediates were decreased upon inhibition of mTORC1 or AMPK. Moreover, AMPK activation could up-regulate the mRNA expressions of inhibitor of nuclear factor kappa-B kinase subunit beta (Ikbkβ), integrin-linked protein kinase (ILK), unconventional myosin-Ic (Myo1c), ribosomal protein S6 kinase beta-2 (RPS6Kβ2), and vascular endothelial growth factor (VEGF)-β, which are downstream effectors of mammalian target of rapamycin (mTOR). The mRNA expressions of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta isoform (PIK3CD) and 5′-AMP-activated protein kinase subunit gamma-1 (PRKAG1), which are upstream regulators of mTOR, were also up-regulated by AMPK activation. On the other hand, AMPK activation also down-regulated FK506-binding protein 1A (FKBP1A), serine/threonine-protein phosphatase 2A 55 kDa regulatory subunit B beta isoform, phosphatase and tensin homolog (PTEN), and unc-51 like autophagy activating kinase 1 (Ulk1), which are up-stream regulators of mTORC1. Taken together, these data indicated that AA regulated cellular energy metabolism through mTOR and AMPK pathway in porcine enterocytes. These results demonstrated interactions of AMPK and mTORC1 pathways in AA catabolism and energy metabolism in intestinal mucosa cells of piglets, and also provided reference for using AA to remedy human intestinal diseases.  相似文献   

9.
1-(5-Isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), a potent and selective inhibitor of protein kinase C (PKC), inhibited PHA-stimulated bovine peripheral blood mononuclear cell (PBMC) proliferation, interleukin-2 (IL-2) production, and cytosolic PKC activity without affecting the cell viabilities. Presence of exogenous cytokines, such as purified human IL-2 or recombinant bovine IL-2 (rbovIL-2), reversed the H-7 inhibitory effects on PHA-stimulated PBMC proliferation. We conclude that the PKC enzyme plays an important role as a second messenger in bovine PBMC proliferation in the early stages of cell activation.  相似文献   

10.
Porcine corpora lutea (CL) fail to show a luteolytic response to prostaglandin-F-2α (PGF-2α) (ie, luteolytic sensitivity, or LS) until ∼day 13 of the estrous cycle. In view of the importance of protein kinase C (PRKC) in PGF-2α signal transduction, it was hypothesized that limiting levels of 1 or more PRKC isoforms may explain the lack of LS before day 13. This hypothesis was tested by examining expression of mRNA and protein, and the cellular localization patterns of the 11 PRKC isoforms throughout the porcine estrous cycle, to determine whether PRKC expression correlates with and thus may be associated with the control of the acquisition of LS in the pig. The expression patterns show that for most PRKC isoforms (ie, PRKC alpha, beta 1, beta 2, delta, epsilon, theta, iota, and zeta), mRNA was maximally expressed on day 7 or day 10 (protein kinase D1 only) of the cycle, whereas PRKCs gamma, eta, and lambda were unchanged. At the protein level, only PRKC epsilon (PRKCE) significantly changed during the estrous cycle and was elevated on day 13 (versus days 4, 7, and 15; P < 0.05). By immunofluoresence, most PRKC isoforms, including PRKCE, were localized to steroidogenic large luteal cells (LLC) and small (nonendothelial cell) luteal cell subtypes (SLC). In conclusion, since the increase in PRKCE protein expression (day 13) occurred coincidentally with the onset of LS (≥day 12), these results support a potential role for PRKCE in control of the acquisition of LS in the pig.  相似文献   

11.
We have previously reported that treatment of hen granulosa cells with the tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate (PMA), or the diacylglycerol analog, 1-oleoyl-2-acetylglycerol (OAG), attenuates the steroidogenic response to luteinizing hormone (LH) at sites both prior and distal to the formation of cyclic 3',5'-adenosine monophosphate (cAMP). The present study was designed to determine the site(s) of inhibition within the steroidogenic pathway by evaluating the effects of OAG and PMA on key enzyme systems involved in hen granulosa cell steroidogenesis: adenylyl cyclase, phosphodiesterase, the cholesterol-side-chain-cleavage (CSCC) complex and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD). The adenylyl cyclase activator, forskolin (0.1 mM), stimulated a 3.3-fold increase in granulosa cell cAMP formation, and this increase was inhibited by the presence of OAG (2.5, 25 and 63 microM) in a dose-dependent manner. By contrast, a 1.8-fold increase in cAMP accumulation induced by the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX; 1.0 mM), was not altered by OAG at any dose (2.5, 25 and 63 microM). Inclusion of 25-hydroxycholesterol (2500 ng/tube) in the incubation medium in the presence of 1.0 microM cyanoketone resulted in a 10-fold increase in pregnenolone production. Increasing concentrations of OAG (2.5, 25 and 63 microM) caused a dose-dependent suppression of the conversion of 25-hydroxycholesterol to pregnenolone. On the other hand, granulosa cells incubated with 200 ng/tube pregnenolone increased progesterone production 100-fold, but this increase was not inhibited by either PMA (3.2, 32, 8.1 and 162 nM) or OAG (2.5, 25 and 63 microM). The results indicate that activation of protein kinase C can suppress the function of at least two key enzymes involved in hen granulosa cell steroidogenesis. Inhibition of adenylyl cyclase greatly reduces the steroidogenic response of granulosa cells to endocrine factors that act via increasing levels of cAMP (i.e. LH). Furthermore, a reduction in CSCC activity limits the availability of precursor required for progesterone production. These data provide additional evidence of a role for protein kinase C in modulating ovarian function in the domestic hen.  相似文献   

12.
The expression of protein kinase C (PKC) was studied in the bovine retina by immunohistochemical analysis. Western blot analysis showed that PKC isoforms, including alpha, betaI, delta and theta, were detected in the bovine retina. By immunohistochemistry, both PKC alpha and betaI were expressed in all retinal layers, with an intense localization of both PKC alpha and betaI detected in bipolar cells in the inner nuclear cell layer and in some glial cells in ganglion cell layers. The immunoreactivity of both PKC delta and theta was quite weak in the retinal layers, compared with that of PKC alpha and betaI. These findings suggest that both conventional and novel PKCs are differentially expressed in the bovine retina.  相似文献   

13.
The aim of this study was to determine the ability of corticotropin-releasing hormone (CRH), lysine vasopressin (LVP), oxytocin (OT), and angiotensin II (AII) to stimulate adrenocorticotropin (ACTH) secretion from porcine anterior pituitary (AP) cells in vitro and to evaluate the role of protein kinase C (PKC) in the interaction between CRH and LVP. In this study, porcine AP cells were enzymatically and mechanically dispersed, cultured (150,000 cells/well) for 4 d, and then challenged with doses of various neuropeptides for 3 hr. CRH (10−7−10−10 M) was the most potent of the peptides tested in stimulating ACTH release from porcine AP cells. In fact, none of the other peptides consistently affected ACTH concentrations relative to basal levels. However, LVP potentiated CRH action, even though by itself, it failed to stimulate ACTH production. Neither OT or AII potentiated CRH-stimulated ACTH release from porcine AP cells. To determine whether the interaction between CRH and LVP was regulated partially by the protein Kinase C (PKC) pathway, we challenged AP cells in a 30-min incubation with 10−7 M staurosporine (ST), a treatment predicted to decrease PKC activity. Then, cells were washed and challenged with 10−9 M LVP, 10−9 M CRH, and 10−9 M CRH + LVP. Treatment with ST decreased (P < 0.05) CRH + LVP-stimulated ACTH release. To further demonstrate an interaction between protein kinase A (PKA) and PKC transduction pathways in the observed synergism between CRH and LVP to enhance ACTH secretion, we also challenged AP cells with 10−7 M phorbol 12, 13-myristate acetate (PMA) and 5 μM forskolin (FOR) for 3 hr. This treatment was predicted to enhance PKA and PKC activities, respectively, and thereby enhance ACTH concentrations. Challenging cells with FOR + PMA enhanced (P < 0.001) ACTH release above basal concentrations, but more important, it increased (P < 0.001) ACTH concentration above that elicited by either drug given alone. Taken together, our in vitro studies support the conclusion that CRH is the principal regulator of ACTH secretion in the pig. In contrast to the results in most other species evaluated, vasopressin alone did not affect ACTH release. However, LVP can enhance the effectiveness of CRH in releasing ACTH, and this enhancement appears to rely, at least in part, on the activation of the PKC signal transduction pathway.  相似文献   

14.
蛋白激酶C（PKC）是一个广泛分布在真核细胞中的丝氨酸/苏氨酸蛋白激酶家族。它在卵母细胞的生发泡破裂（GVBD）、染色体凝集、MⅠ期纺锤体组装和第一极体排放等过程中起着重要的调节作用。PKC的活性变化调节着GVBD的发生，GVBD标志着第1次减数分裂的启动。PKC活性在卵母细胞成熟过程中逐渐升高，在第1次减数分裂中/后期转变时活性下降，使卵母细胞得以释放出第一极体，至此卵母细胞完成第1次减数分裂进入第2次减数分裂。作者就PKC在卵母细胞第1次减数分裂成熟过程中的作用综述如下。  相似文献   

15.
Oxidized(OX)-low density lipoprotein (LDL) inhibits steroidogenesis by luteal cells (LC) from regressing porcine CL. The present study was designed to investigate the mechanism of inhibition by determining whether OX-LDL inhibits basal and agonist-stimulated cAMP production in regressing LC. Collagenase-dispersed porcine LC (n = 7 animals, estrous cycle Day 12-15) were cultured (2.5 x 10(5) cells/0.5 ml) in serum-free DMEM/Hams F-12 in duplicate wells at 37 degrees C. Approximately 18 hr after plating, media were replaced and LC were immediately treated with human LDL (0, 25, or 100 microg/ml) or OX-LDL (25 or 100 microg/ml). LC were incubated for 2 hr before addition of isobutylmethylxanthine (IBMX) to inhibit phosphodiesterase activity, immediately followed by hCG (100 ng/ml), cholera toxin (CT; 0.1 microM), forskolin (FS; 50 microM), or no further treatment (controls). LC were incubated for an additional 90 min. After removal of culture media, cells were extracted with 0.1 N HCl. Cell extracts were assayed for cAMP by enzyme immunoassay (EIA). HCG, CT, and FS increased (P < 0.05) cAMP production approximately four-, 10-, and 25-fold, respectively, relative to controls. OX-LDL (25 and 100 microg/ml) inhibited (P < 0.05) cAMP production by unstimulated, hCG-, and CT-stimulated LC, but not that by FS-stimulated LC. The highest concentration of OX-LDL (100 microg/ml) reduced cAMP formation by 39.8 +/- 6.6%, 44.7 +/- 10.5%, and 67.7 +/- 4.5% in unstimulated, hCG-, and CT-stimulated LC, respectively. In contrast, unmodified LDL (25 and 100 microg/ml) did not alter cAMP production. We conclude that OX-LDL can interfere with the cAMP signaling pathway in regressing luteal cells by acting at sites proximal to adenylate cyclase activation.  相似文献   

16.
Protein kinase (PK) C activity in the liver of cattle with fatty liver syndrome was evaluated and compared with that in liver of healthy cattle. The PKC activities in cytosolic and particulate fractions were reduced in fatty livers, compared with those in livers from healthy cattle. The decrease of PKC activity was more distinct in cytosolic (P = 0.0016) than particulate (P = 0.069) fractions. Protein kinase activities other than PKC were not substantially changed. Seemingly, PKC was involved in the pathogenesis of fatty liver syndrome in cattle.  相似文献   

17.
OBJECTIVE: To determine the effects of the protein kinase C (PKC) inhibitor, Ro-31-8220, on agonist-induced constriction of laminar arteries and veins obtained from horses. SAMPLE POPULATION: Laminar arteries and veins obtained from 8 adult mixed-breed horses. PROCEDURES: Laminar arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Concentration-response curves were then obtained for the vasoconstrictor agonists phenylephrine, 5-hydroxytryptamine, prostaglandin F(2), and endothelin-1. All responses were measured with or without the addition of Ro-31-8220 (3 microM). RESULTS: Laminar veins were more sensitive to vasoconstrictor agonists than laminar arteries, and incubation of laminar veins with Ro-31-8220 resulted in significantly smaller agonist-induced contractile responses for all agonists tested. In contrast, Ro-31-8220 had no effect on agonist-induced contractile responses of laminar arteries. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the study were consistent with activation of PKC being confined to agonist-induced contraction of laminar veins isolated from the laminar dermis of horses. Consequently, the possible involvement of PKC in the venoconstriction observed during the development of laminitis is worthy of further investigation.  相似文献   

18.
Granulosa cells play important roles in the regulation of ovarian functions. Phospholipase C is crucial in several signalling pathways and could participate in the molecular mechanisms of cell proliferation, differentiation and ageing. The objective of this study was to identify the effects of phospholipase C on the steroidogenesis of oestradiol and progesterone in porcine granulosa cells cultured in vitro. Inhibitor U73122 or activator m‐3M3FBS of phospholipase C was added to the in vitro medium of porcine granulosa cells, respectively. The secretion of oestradiol decreased after 2 hr, 8 hr, 12 hr, 24 hr and 48 hr of treatment with 500 nM U73122 (p < .05) and decreased after 2 hr of treatment in the 500 nM m‐3M3FBS addition group (p < .05). The secretion of progesterone increased after 4 hr of treatment with 500 nM U73122 (p < .05) and increased after 2 hr and 8 hr of treatment in the 500 nM m‐3M3FBS addition group (p < .05). The ratio of oestradiol to progesterone decreased at each time point, except 8 hr after the addition of 500 nM U73122 (p < .05). The ratio of oestradiol to progesterone decreased after 2 hr (p < .05) of treatment with 500 nM m‐3M3FBS. In genes that regulate the synthesis of oestradiol or progesterone, the mRNA expression of CYP11A1 was markedly increased (p < .05), and the mRNA expression of other genes did not change significantly in the U73122 treatment group, while the addition of m‐3M3FBS did not change those genes significantly despite the contrary trend. Our results demonstrated that phospholipase C can be a potential target to stimulate the secretion of oestradiol and suppress progesterone secretion in porcine granulosa cells cultured in vitro, which shed light on a novel biological function of phospholipase C in porcine granulosa cells.  相似文献   

19.
Cyclic gilts (96 +/- 1 kg) were used to determine the effect of active immunization against growth hormone-releasing factor GRF(1-29)-NH2 on concentrations of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Gilts were immunized against GRF conjugated to human serum albumin (GRF-HSA, n = 5) or HSA alone at 180 d of age (wk 0). Booster doses were administered at wk 9 and 13. Seven days after the second booster (wk 14), blood samples were collected at 15-min intervals for 6 h before feeding and 30, 60, 120, 180 and 240 min after feeding. Eight days after the second booster, all gilts were administered a GRF analog, [desNH2Tyr1,Ala15]-GRF(1-29)-NH2, followed by an opioid agonist, FK33-824. Blood samples were collected at 15-min intervals from -30 to 240 min after injection. Immunization against GRF-HSA resulted in antibody titers, expressed as dilution required to bind 50% of [125I]GRF, ranging from 1:11,000 to 1:60,000 (wk 11 and 14); binding was not detectable or was less than 50% at 1:100 in HSA gilts (P less than .05). Episodic release of GH was abolished by immunization against GRF-HSA (P less than .05). Mean GH was decreased (P less than .07), but basal GH concentrations were not altered (P greater than .15) by immunization against GRF-HSA. Serum concentrations of IGF-1 were similar at wk 0, but concentrations were lower in GRF-HSA than in HSA gilts (P less than .05) at wk 14.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Compared with adipose tissue from other mammals, porcine adipose tissue has stringent specificity for stimulation of lipolysis by analogs of norepinephrine. This study was to ascertain whether the specificity for control was reflected in the concentration of tissue cyclic AMP (cAMP). Adipose tissue slices were incubated and concentrations of tissue cAMP and free fatty acids (FA) released to the medium were measured. It was necessary to include theophylline in the incubation medium to be able to measure changes in cAMP concentration. Fatty acid release and cAMP production were increased most effectively by the beta-adrenergic agonists; isoproterenol, fenoterol, dobutamine and the mixed alpha- + beta-adrenergic agonist, epinephrine. Isoproterenol-stimulated FA and cAMP production both inhibited by the beta-adrenergic antagonist, propranolol. There was no evidence for alpha 2-adrenergic inhibition of lipolysis in porcine adipose tissue because clonidine (alpha 2-adrenergic agonist) did not lower isoproterenol-induced FA or cAMP levels and phentolamine, an alpha-adrenergic antagonist, did not increase epinephrine-stimulated FA release or cAMP generation. These results imply that the stringent specificity observed for stimulation of swine adipose tissue lipolysis resides in the beta-adrenergic receptor coupled to cAMP production.  相似文献   

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