Expression and localization of extracellular matrix-degrading proteinases and their inhibitors in the bovine mammary gland during development, function, and involution

In degrading the extracellular matrix, matrix metalloproteinases (MMP) and the plasminogen activator (PA) system may play a critical role in extensive remodeling that occurs in the bovine mammary gland during development, lactation, and involution. Therefore, the aim of our study was to investigate the mRNA expression of MMP-1, MMP-2, MMP-14, MMP-19, tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, urokinase-type PA, tissue-type PA, urokinase-type PA receptor, and PA inhibitor-1 by quantitative PCR and to localize with immunohistochemistry MMP-1, MMP-2, MMP-14, and TIMP-2 proteins in the bovine mammary gland during pubertal mammogenesis, lactogenesis, galactopoiesis, and involution. Expression of mRNA for each of the studied factors was relatively lower during galactopoiesis and early involution but was markedly increased during mammogenesis and late involution, 2 stages in which tissue remodeling is especially pronounced. The localization of proteins for MMP-1, MMP-14, and TIMP-2 showed a similar trend with strong staining intensity in cytoplasm of mammary duct and alveolar epithelial cells during pubertal mammogenesis and late involution. Interestingly, MMP-2 protein was localized only in the cytoplasm of endothelial cells during late involution. Our study demonstrated clearly that expression of extracellular matrix-degrading proteinases coincides with a concomitant expression of their inhibitors. High expression levels of MMP, TIMP, and PA family members seem to be a typical feature of the nonlactating mammary gland.

Expression of Angiopoietin (ANPT)-1, ANPT-2 and their Receptors in Dominant Follicles during Periovulatory Period in GnRH-Treated Cow

Ovarian follicular vasculature is involved in follicular development and ovulation. Angiopoietin (ANPT)-Tie system is important for vascularization of the tissue surrounding the developing follicles and corpus luteum (CL). To determine how the expression of ANPT-1, ANPT-2 and their receptors in the follicles would be associated with the ovulatory process, the present study was conducted to examine mRNA expressions of ANPT-1, ANPT-2 and their receptors during the periovulatory phase in gonadotrophin-releasing hormone (GnRH)-treated cows. The ovaries were collected by transvaginal ovariectomy (n = 5, cows/group) and the follicles (n = 5, one follicle/cow) were classified into following groups: before GnRH administration [before luteinizing hormone (LH) surge]; 3-5 h after GnRH (during LH surge); 10 h after GnRH; 20 h after GnRH; 25 h after GnRH (peri-ovulation); and early CL (days 2-3). The mRNA expression was analysed by quantitative real-time PCR (rotor-gene 3000). Angiopoietin-1 expression rapidly decreased at 3-5 h and kept low level at 10 h after GnRH treatment compared with that before GnRH, and returned to the level before LH surge in the follicles >20 h after GnRH treatment. The levels of ANPT-2 mRNA decreased at 10 and 25 h after treatment compared with other periods. The ratio of ANPT-2/ANPT-1 (an index for destabilization of blood vessels) increased in the follicles at 3-5 h after GnRH treatment only. Both of Tie-1 and Tie-2 receptor expressions decreased in the follicles at 25 h after GnRH treatment. The results of the present study indicated that mRNA expressions of ANPT-1, ANPT-2 and their receptors changed in the bovine follicles during periovulatory period. These results suggest that angiopoietin-Tie system is associated with the initiation of vasculature of follicle that grows towards ovulation.

Morphology of Dromedary Camel Oocytes and their Ability to Spontaneous and Chemical Parthenogenetic Activation

The present work was conducted to examine (1) the morphology of dromedary cumulus-oocytes complexes (COCs), (2) to study the incidence of spontaneous development of oocytes in vivo and (3) to assess the ability of in vitro matured dromedary oocytes to chemical parthenogenetic activation compared with in vitro fertilized (IVF) oocytes. COCs were recovered from dromedary ovaries classified according to their morphology into six categories. Oocyte diameter was measured using eye piece micrometer. For chemical activation, COCs with at least three layers of cumulus-cells were in vitro matured (IVM) in TCM 199 + 10 microg/ml FSH + 10 IU hCG/ml + 10% FCS + 50 microg/ml gentamycin. COCs were incubated for 40 h at 38.5 degrees C under 5% CO2 in humidified air. After IVM, matured oocytes with first polar body (first Pb) were divided into two groups. Group 1: activated in 7% ethanol (E) for 5 min followed by culture in 2 mM 6-dimethylaminopurin (6-DMAP, E D, subgroup 1) or 10 microg/ml cycloheximide (CHX, E CHX, subgroup 2) for 3.5 h at 38.5 degrees C under 5% CO2. In group 2, oocytes were activated using 50 microM Ca A23187 (Ca A) for 5 min followed by culture in 2 mM 6-DMAP (Ca D, subgroup 3) or 10 microg/ml CHX(Ca CHX, subgroup 4) for 3.5 h at 38.5 degrees C under 5% CO2. For control group, IVM oocytes were fertilized using frozen-thawed camel spermatozoa separated by swim-up method then suspended in Fert-TALP medium supplemented with 6 mg/ml BSA (FAF) + 10 microg/ml heparin. In all groups, oocytes were in vitro cultured in SOFaa medium + 5% FCS and 5 microg/ml insulin + 50 microg/ml gentamycin. Cleavage rate and embryo development were checked on Days 2, 5 and 8. An average of 11.3 +/- 0.3 COCs were recovered/dromedary ovary. Categories 1 and 2 represented 33.1% and 34.8%, respectively, and were significantly higher (p < 0.01) than the other categories (19.1, 9.2 and 2.6% for categories 3-5, respectively). Category 6 (embryo-like structures) represented 1.2% of the recovered oocytes, staining of these embryo-like structures with orcien dye indicated the presence of divided cells with condensed nuclei. Dromedary oocytes averaged 166.2 +/- 2.6 microm in diameter with black cytoplasm. Chemical activation of IVM dromedary oocyte with first Pb in 7% ethanol or 50 microM Ca A followed by culture in 2 mM 6-DMAP showed significantly higher (p < 0.01) cleavage and developmental rates to the morula stage than oocytes activated using 7% ethanol or 50 microM Ca A followed by 10 microg/ml CHX or in vitro fertilized control group. Higher (p < 0.01) proportion of oocytes sequentially cultured in 10 microg/ml CHX or that in vitro fertilized were arrested at the 2-4-cell stage compared with that cultured in 6-DMAP.

Endocrine and cellular characteristics of corpora lutea from cows with a delayed post-ovulatory progesterone rise

The timing of the post-ovulatory progesterone rise is critical to the embryonic development and survival. The aim of this study was to determine the underlying causes of delayed post-ovulatory progesterone rises. Two groups of non-lactating dairy cows with early (n = 11) or late (n = 9) post-ovulatory progesterone rises were created by inducing luteolysis in the presence of either a large (> 10 mm) or small (< 10 mm) follicle, respectively. LH pulses were measured on days 4 (all cows) and 7 (n = 7, early; n = 5, late) (day 1= ovulation). The cows were slaughtered on day 5 (n = 4 each group) or 8 (n = 7, early; n = 5, late). Immunohistochemical analysis for endothelial cells (von Willebrand Factor, VWF), steroidogenic cells (3beta-HSD) and proliferation marker (Ki67) were performed. The basal progesterone production and LH responsiveness (0.001-100 ng/ml) of dispersed luteal cells was investigated. The luteal concentrations of FGF-2 and VEGF were measured by ELISA and RIA, respectively. There were no differences in LH pulse characteristics, area of VWF staining, proliferation index, steroidogenic cell characteristics, basal or LH-stimulated progesterone production by luteal cells between cows with an early or late progesterone rise (P > 0.10). However, the area of VWF staining increased from days 5 to 8, while the proliferation index decreased (P < 0.05). Furthermore, the luteal cells were more responsive to LH on day 8 (P < 0.01). Luteal concentrations of FGF-2 were higher on day 5 (P = 0.05), while VEGF was greater on day 8 (P < 0.01). In conclusion, we have clearly shown that LH support, degree of vascularization or luteal cell steroidogenic capacity were not the major factors responsible for inadequate secretion of progesterone by the developing bovine CL.

Localization of Vascular Endothelial Growth Factor (VEGF) and its Receptors VEGFR-1 and VEGFR-2 in Bovine Placentomes from Implantation Until Term

Interactions of vascular endothelial growth factor (VEGF) with its receptors VEGFR-1 and VEGFR-2 promoting angiogenesis have been described in placentation of human, mink and pig. The bovine placenta is multiplex, villous and synepitheliochorial due to migratory trophoblast giant cells (TGC). To determine the role of VEGF in bovine implantation and placentation, placentomes and interplacentomal areas from 33 cows from early implantation until near term were evaluated by immunohistochemistry. VEGF immunoreactivity was detected in fetal and maternal blood vessel tissues during implantation and throughout gestation, and in preimplantatory trophoblast cells and uterine epithelium. After implantation the immunoreaction was confined to TGC and uterine epithelium. An antibody against bovine VEGF revealed a strong reactivity in the stroma of maternal caruncular septa in early and mid-gestation, which distinctly decreased near term. In interplacentomal areas, VEGF was found in luminal and glandular epithelia as well as in trophoblast, with distinctly higher reactivity in giant cells. VEGFR-1 was observed in trophoblast and uterine epithelium around implantation. Later, in definite placentomes, VEGFR-1 was localized in TGC near the chorionic plate and in maternal endothelial cells in the center of the placentome. VEGFR-1 and VEGFR-2 were co-localized in uterine epithelium and trophoblast as well as in blood vessel tissue and uterine glands. The presence of VEGF, VEGFR-1 and VEGFR-2 at the feto-maternal interface and in vasculature indicates that in the bovine VEGF may have (1) classic functions in angiogenesis and vascular permeability, (2) growth factor properties, facilitating feto-maternal exchange via paracrine action, (3) chemotactic activity on capillary endothelium, and (4) an autocrine influence on TGC migratory activity.

Localization of Fibroblast Growth Factor I (Acid Fibroblast Growth Factor) and Its mRNA in the Bovine Mammary Gland During Mammogenesis, Lactation and Involution

Growth factors are involved in development and function of the mammary gland. The aim of this study was the localization of fibroblast growth factor 1 (FGF-1) and its mRNA in the bovine mammary gland during different developmental and functional stages. Mammary tissue was obtained from German Brown Swiss cows (n = 23) during defined stages of mammogenesis (before and during pregnancy), lactogenesis, peak lactation and involution. The distribution of FGF-1 mRNA was studied using non-radioactive in situ hybridization, the corresponding FGF-protein was analysed using immunohistochemistry [avidin-biotin peroxidase complex (ABC)-method]. A moderate to distinct staining for FGF-mRNA was found in the epithelium of ducts and developing alveoli during mammogenesis. Post-partum at the same cellular locations, a considerable amount of FGF-1 mRNA, was seen that decreased during lactation. Also during early involution clear staining for FGF-mRNA could still be observed. Immunoreactive FGF-1 was found in considerable concentration in the epithelium of the mammary gland in heifers. The staining intensity generally decreased somewhat during mammogenesis and lactation, but could be always clearly demonstrated in the secretory epithelial cells of alveoli and glandular ducts. Also during the first day after the end of milking, the epithelium displayed a moderate to distinct epithelial immunostaining. Notably, After 4 weeks of involution, in many alveoli a shedding of the FGF-1 positive luminal cell layer was found. In our localization studies, no strict correlation between FGF-1 mRNA and its corresponding protein was found. The various reasons for this finding are discussed.

Fibroblast Growth Factor (FGF)-1, FGF2, FGF7 and FGF Receptors are Uniformly Expressed in Trophoblast Giant Cells During Restricted Trophoblast Invasion in Cows

The bovine placenta is characterized by a limited invasion of trophoblast giant cells (TGC). In contrast to mononuclear trophoblast cells (MTC), TGC are non-polarized cells, which migrate and fuse with single uterine epithelial cells throughout gestation. Fibroblast growth factors (FGF) were shown to be associated with the migratory activity of cells, cell differentiation and angiogenesis, and due to its localization in trophoblast cells were proposed as important regulating factors in hemochorial placentae of rodents and humans, and the (syn)epitheliochorial placenta of pig and sheep. Since migrating bovine TGC are of epithelial origin, but exhibit similarities to mesenchymal cells we hypothesize that the restricted trophoblast invasion in cattle is characterized by a specific FGF expression pattern. Therefore, the spatiotemporal expression of specific FGF factor:receptor pairs, either acting on cells of mesenchymal origin or on epithelial cells was examined in bovine placental tissues throughout gestation and prepartum by immunohistochemistry, semiquantitative RT-PCR and in situ hybridization. FGF1 protein was found in trophoblast, caruncular epithelium (CE) and stroma (CS), stroma of chorionic villi (SCV), and in fetal and maternal blood vessels. FGF2 signals dominated in maternal vascular endothelia (VE), immature TGC, and MTC, whereas staining in other cell types was clearly weaker. FGF7 protein was detected in fetal and maternal blood vessel as well as in immature TGC and MTC predominantly at the chorionic plate. FGFR immunoreaction was localized in immature TGC, MTC, and to a clearly lesser extent in CS, CE and fetal and maternal blood vessels. Mature TGC stained negatively for all examined factors and FGFR. The corresponding mRNAs specific for FGF1, -2, -7, total FGFR, and FGFR2 isoforms IIIb and IIIc were colocalized in immature TGC, whereas hybridization was substantially lower in CE and absent in CS, SCV and mature TGC throughout gestation, but switched to CS and VE immediately prepartum. Semiquantitative RT-PCR revealed higher mRNA levels for FGF1, FGFR, and FGFR2IIIc in cotyledons compared to caruncles (p<0.05), whereas it was the opposite with FGF2 (p<0.001). FGF7 and FGFR2IIIb mRNA levels did not differ between caruncles and cotyledons. Significant changes (p<0.05) of mRNA levels related to gestational age were found for FGF1 and FGFR2IIIc, but not for FGF2, -7, total FGFR, and FGFR2IIIb. The specific localization of all examined FGF family members in TGC suggests that TGC, apart from their classical function as producers of hormonal products, play other important roles in the regulation of bovine placentomal growth, differentiation and angiogenesis.

Boar contact does not induce oxytocin release during the period of embryo migration in sows

Nine multiparous cyclic sows with permanent jugular catheters were introduced to a boar at day 10 (n = 9) or 11 (n = 5) after ovulation to study the effect on oxytocin (OT) release. If it occurs, the release of OT might play a role in embryo migration which occurs around this time, by stimulating uterine contractions. Blood samples were taken before introduction of the boar and at 2-min intervals up to 10 min after boar introduction. On average, OT levels after boar introduction were not higher than before. In only three out of the 14 occasions of boar introduction, a rise in OT level was observed that was higher than two times the standard deviation above base level. However, even on these occasions OT levels were far below the range normally observed during other events where exogenous stimuli cause OT release, such as boar introduction during estrus and suckling during lactation. We conclude that boar contact around day 10 of the estrous cycle does not induce a biologically significant OT release in sows.

Angiogenese-Gentherapie mit AdVEGF165- Eine Art „Delay“ für Lappenplastiken?

A regular tissue functioning requires the adequate supply of oxygen and nutrient via blood vessels. The sequences of formation and maturation of vessels are initiated and maintained by different growth factors. The VEGF growth factor plays an exceptional role in these mechanisms. The creation of sublethal ischemia as an angiogenic stimulus known as "Delay" is a well established procedure in plastic surgery, although the underlying molecular biological mechanisms still remain unknown. The important role of VEGF and its regulation depending on oxygen pressure suggest a strong connection between this growth factor and the delay phenomenon. The VEGF concentration in skin and underlying muscle was measured in overdimensioned random pattern flaps on 32 male Sprague-Dawley rats after either VEGF gene therapy or circumcision without elevation of the flap and compared to controls. Additional random pattern flaps were raised seven days post gene therapy or delay. The effect on the flap perfusion was measured postoperatively using Indocyanine green Laser Fluoroscopy and the size of the surviving and necrotic areas of the flaps were analysed. The skin of the random pattern flaps showed both in the Delay group and in the VEGF gene therapy group a significantly elevated VEGF concentration compared to the controls. The underlying rectus abdominis muscle showed no significant differences in VEGF concentration between the groups. The flap perfusion postoperatively was significantly increased solely in the VEGF gene therapy group. The analysis of the surviving area of the flaps showed a significant increase over the controls in the gene therapy group. The Delay procedure results in a significantly and locally raised concentration of the VEGF growth factor. The gene therapeutical use of this growth factor allows us to raise flap perfusion and to reduce necrosis. Both VEGF gene therapy and Delay seem to promote similar mechanisms whereas the gene therapy produced superior results in this setting.

Ovarian function in ruminants

The purpose of this overview is to highlight important steps of ovarian regulation during follicle development, ovulation and the life span of corpus luteum (CL) in ruminants. The ovarian cycle is central to reproductive function. It is characterized by repeating patterns of cellular proliferation, differentiation and transformation that encompass follicular development and ovulation as well as the formation, function and regression of the CL. In the first part, the importance and regulation of final follicle growth and especially of angiogenesis and blood flow during folliculogenesis, dominant follicle development and CL formation are described. Our results underline the importance of growth factors especially of insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) for development and completion of a dense network of capillaries (angiogenesis) during follicle growth and CL formation. In the second part, the regulation of CL function by endocrine/paracrine and autocrine acting regulators is discussed. There is evidence that besides the main endocrine hormones luteinizing hormone (LH) and growth hormone (GH) local regulators as growth factors, peptides, steroids and prostaglandins are important modulators of luteal function. During early CL development until midluteal stage oxytocin (OT), prostaglandins and progesterone (P) itself stimulate luteal cell proliferation and function supported by the luteotropic action of a number of growth factors. The still high mRNA expression, protein concentration and localization of VEGF, FGF and IGF family members in the cytoplasm of luteal cells during midluteal stage suggest that they play pivotal role in the maintenance (survival) of this endocrine tissue. The major function of the CL is to secrete P. Progesterone itself regulates the length of the estrous cycle via influencing the timing of the luteolytic PGF2alpha signal from the endometrium. At the end of a nonfertile cycle, the regression of CL commences, steroidogenic capacity is lost (functional luteolysis), cell death is initiated, and tissue involution as well as resorption occurs within a few days (structural luteolysis). The cascade of mediators during luteolysis is very complex and still awaits elucidation. Evidence is given for participation of blood flow, inflammatory cytokines, vasoactive peptides (angiotensin II and endothelin-1), and decrease of the classical luteotropic mediators.

Expression pattern of fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) system members in bovine corpus luteum endothelial cells during treatment with FGF-2, VEGF or oestradiol

The development of the corpus luteum (CL) is accompanied by very active angiogenesis. We hypothesize that during this process endothelial cells (EC) are under the control of several angiogenic factors and steroids. The aim of this study was to examine the expression of the angiogenic growth factor systems - fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) - in EC derived from the bovine CL. Endothelial cells were cultured in serum-free medium and treated for 24 h with different concentrations of oestradiol (range from 10(-13) to 10(-5) mol/l), VEGF or FGF-2 (1, 10 and 100 ng/ml, respectively) and compared with untreated controls. Cells were harvested, total RNA extracted and subjected to semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Treatment with oestradiol or FGF-2 stimulated the expression of FGF-2, but VEGF treatment showed no effect on the FGF-2 expression. FGF-2 or VEGF treatment resulted in an up-regulation of the FGF receptor (FGFR) mRNA. However, no FGF-1 expression was detected in EC. For the VEGF system, treatment with FGF-2, VEGF or oestradiol did not affect VEGF expression. However, the presence of FGF-2 in the medium up-regulated the expression of both VEGF receptors (VEGFR-1 and VEGFR-2), whereas oestradiol or VEGF treatment showed no effect on the expression of these receptors. Our results reveal that functional angiogenic growth factor systems were expressed in vitro in bovine EC derived from the CL. This suggests that the angiogenic FGF and VEGF system members were regulated by FGF or VEGF, but not by oestradiol-17beta.

Effect of dietary beta-carotene on the early embryonic development and uterine fluid composition of gilts

The role of beta-carotene in reproduction was investigated in gilts assigned to three dietary supplementations: VA (4000 IU vitamin A); VA + VA (4000 IU + 8300 IU); VA + BC (4000 IU + 100 mg beta-carotene) per kg diet for 14 weeks. Gilts were slaughtered at day 12 of gestation. In the VA + BC group, number of corpora lutea was lowest, but the number of embryos was greatest, resulting in a non-significant decreased prenatal mortality (p<0.07). The proportion of less developed spherical and tubular embryos compared with filamentous was greatest in the VA + BC group (p<0.01). No differences were observed for vitamin A and retinal binding protein (RBP) in the uterine fluid. When animals were grouped according to the development of blastocysts, vitamin A and RBP levels were higher in the VA + BC group with only filamentous embryos (p<0.01). This indicates that the supplementation of beta-carotene to gilts might affect embryonic losses possibly because of slower alterations in the uterine environment, resulting in a higher and less variable number of embryos, despite an apparently more heterogeneous development.

AdVEGF165gene transfer increases survival in overdimensioned skin flaps

BACKGROUND

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. VEGF A also plays an important role in wound healing of the skin by promoting angiogenesis and by stimulating blood vessel growth. Therefore we tested the hypothesis that flap survival could be increased by the preoperative injection of AdVEGF(165).

METHODS

We studied the effect of AdVEGF(165) in an overdimensioned ischemic random-pattern-flap model in the rat (n = 50) with a length-to-width ratio of 4 : 1. VEGF cDNA was administered in two concentrations of 5 x 10(8) plaque-forming units (pfU) and 1 x 10(9) pfU using a recombinant adenoviral vector. Recombinant virus was injected subdermally 7, 3 or 0 days prior to flap harvest for the lower concentration and 7 days prior for the higher concentration. Flap survival and necrosis were observed at day 7, the day the animals were sacrificed.

RESULTS

Adenoviral gene transfer with VEGF(165) 3 and 7 days before flap harvest showed a significantly increased flap survival of 50% together with a significantly reduced necrosis (p < 0.01). Injection using a titer of 1 x 10(9) pfU 7 days prior to surgery increased flap survival even more, though failing to reach statistical significance compared to the lower concentration. VEGF protein concentration in the injected skin was significantly higher than in controls (p < 0.01). Flap perfusion was increased as well, demonstrated by indocyanine green (ICG) fluoroscopy (p < 0.001).

CONCLUSIONS

Our results confirm the important role of VEGF(165) on angiogenesis in ischemic flaps. Indeed by injecting VEGF(165) at 3 to 7 days preoperatively in a concentration of 1 x 10(9) pfU our data show that length-to-width ratio for random-pattern-flaps could be increased from 2 : 1 to 3 : 1 and therefore may allow a wider range of applications of this simple flap technique.

Regulation of Corpus Luteum Function in Cattle - an Overview

The corpus luteum (CL) is a transient reproductive gland that produces progesterone (P), required for the establishment and maintenance of pregnancy. Although the regulation of bovine luteal function has been studied for several decades, many of the regulatory mechanisms involved are incompletely understood. We are far from understanding how these complex mechanisms function in unison. The purpose of this overview is to stress important steps of regulation during the lifetime of CL. In the first part, the importance and regulation of angiogenesis and blood flow during CL formation is described. The results underline the importance of growth factors especially of vascular endothelial growth factor A (VEGF A) and basic fibroblast growth factor (FGF-2) for development and completion of a dense network of capillaries. In the second part, the regulation of function by endocrine/paracrine- and autocrine-acting regulators is discussed. There is now more evidence that besides the main endocrine hormones LH and GH local regulators as growth factors, peptides, steroids and prostaglandins are important modulators of luteal function. During early CL development until mid-luteal stage oxytocin, prostaglandins and P itself stimulate luteal cell proliferation and function supported by the luteotropic action of a number of growth factors. The still high mRNA expression, protein concentration and localization of growth factors [VEGF, FGF-1, FGF-2, insulin-like growth factors (IGFs)] in the cytoplasm of luteal cells during mid-luteal stage suggest maintenance (survival) functions for growth factors. In the absence of pregnancy regression (luteolysis) of CL occurs. Progesterone itself regulates the length of the oestrous cycle by influencing the timing of the luteolytic signal prostaglandin F2alpha (PGF2alpha) from the endometrium. The cascade of mediators afterwards is very complex and still not well-elucidated. Evidence is given for participation of blood flow, inflammatory cytokines, vasoactive peptides (angiotensin II and endothelin-1), reactive oxygen species, angiogenic growth factors (VEGFs, FGFs, IGFs) and decrease of the classical luteotropic components as LH-R, GH-R, P450(scc) and 3beta-HSD. Despite of differences in methodology and interpretations, progress has been made and will continue to be made.

Involvement of Pro-Inflammatory Cytokines, Mediators of Inflammation, and Basic Fibroblast Growth Factor in Prostaglandin F2α-Induced Luteolysis in Bovine Corpus Luteum1

The process of luteolysis requires very subtly modulated coordination of different factors and regulation systems. Immune cells and cytokines were shown to be relevant for bovine luteolysis. The aim of this study was to investigate the detailed pattern of mRNA expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNFalpha), TNF receptor type 1 (TNF-R1), interleukin 1beta (IL-1beta), and interferon gamma (IFNgamma), and of the inducible nitric oxide synthase (iNOS) and the basic fibroblast growth factor (FGF-2) during prostaglandin (PG) F(2alpha)-induced luteolysis in the bovine corpus luteum (CL). In addition, the mRNA expression for the LH-receptor (LH-R) and the steroidogenic enzyme p450scc was determined. Cows in the midluteal phase (Days 8-12) were injected with the PGF(2alpha) analogue cloprostenol, and CL were collected by transvaginal ovariectomy before and 2, 4, 12, 48, and 64 h after PGF(2alpha) injection. Conventional and real-time reverse transcription polymerase chain reaction RT-PCR (LightCycler) using SYBR Green I detection were employed to determine the mRNA expression for the investigated factors. All cytokines were significantly up-regulated during induced luteolysis. LH-R and p450scc mRNA were down-regulated (P < 0.05) during structural luteolysis (after 12 h), and p450scc in addition at 2 h after PGF(2alpha) (P < 0.05). FGF-2 expression increased (P < 0.001) during functional luteolysis (until 12 h after PGF(2alpha)) and diminished thereafter. The mRNA expression for iNOS decreased (P < 0.05) after induction of luteolysis. In conclusion, cytokines may be involved not only in structural but also in functional luteolysis and the deprivation of luteal survival factors, leading to a situation where apoptosis can occur. FGF-2 may participate in the suppression of cytokine-induced iNOS mRNA expression and in the prevention of an inflammatory reaction in the surrounding tissues.