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.

The expression of the IGF family and GH receptor in the bovine mammary gland.

To study the involvement of the IGFs in mammary development and lactation of the cow, the temporal expressions of IGF-I and -II, its receptor type 1 (IGFR-1), IGF-binding proteins (IGFBPs)-1 to -6 and GH receptor (GHR) mRNA were examined. This was carried out for different stages of mammogenesis, lactogenesis, galactopoiesis and involution in the bovine mammary gland of 26 animals. Furthermore, IGF-I was localised by immunohistochemistry. The highest mRNA concentrations for IGF-I were detected in the mammary tissue of late pregnant heifers (days 255-272) and significantly lower expression was detected during lactogenesis and galactopoiesis. Immunohistochemistry of IGF-I revealed only a weak staining in the epithelium of the ducts during mammogenesis. The epithelium of the alveoli were negative during mammogenesis, lactogenesis and galactopoiesis but displayed distinct IGF-I activity during involution. In the stroma a distinct staining of the cytoplasm of adipocytes and of vascular smooth muscle cells was observed. A certain percentage of fibroblasts (usually 20-30%) were also immunopositive. In contrast, highest expression for IGFR-1 was detected during galactopoiesis and involution. The lowest mRNA concentration for IGFR-1 was found during pregnancy (days 194-213). In general, the expression of IGF-II was not regulated during mammogenesis and lactation, but decreased during involution. The mRNA for the six binding proteins was detected in the bovine mammary gland. The dominant binding proteins were IGFBP-3 and -5. The highest expression of IGFBP-3 was observed during mid-pregnancy and the lowest during late lactation, involution and in non-pregnant heifers. The mRNA for IGFBP-5 increased during late mammogenesis and lactogenesis followed by a decrease thereafter. In general, the mRNA concentrations for IGFBP-2, -4 and -6 were barely detectable during all stages. In contrast, the expression for IGFBP-1 was upregulated in the mammary gland of virgin heifers and increased around the onset of lactation. mRNA for GHR was found during all stages examined without outstanding fluctuations. In conclusion, locally produced IGF-I and -II may mediate mammogenesis. The high mammary IGFR-1 mRNA during lactation suggests a role for peripheral IGF-I in maintenance of lactation. The role of IGFBPs in the mammary gland needs further evaluation.

Insulin-like and fibroblast growth factors and their receptors are differentially expressed in the oviducts of the common marmoset monkey (Callithrix jacchus) during the ovulatory cycle.

It is suggested that growth factors support the process of maturation and differentiation in the mammalian oviduct. Fibroblast growth factors (FGF) and insulin-like growth factors (IGF) are possible influences on these processes. The present study describes for the first time the expression of FGF-1 and -2 and their receptors as well as IGF-1 and -2 and the corresponding IGF receptor type 1 in the oviduct of the New World monkey Callithrix jacchus. Because of the limited RNA yields from oviducts, reverse transcription-polymerase chain reaction (RT-PCR) was performed to estimate expression levels. Expression patterns were found to be similar for all examined growth factors and receptors: the highest mRNA contents were obtained at the late proliferative and early to midsecretory phases, compared with lower levels during the early proliferative phase. Elevated amounts of these RNAs were correlated with high serum estradiol but not with progesterone concentrations. Each PCR product showed a high degree of homology (> 92%) to the known human sequences. Immunohistochemical analysis indicated greater specific staining for FGF-1 and -2 and IGF-1 before ovulation on the luminal epithelial surface of marmoset oviducts in comparison to the other cycle phases. Differences in staining intensity were not observed between the ampulla and isthmus. In summary, the marmoset oviduct expresses all components of functional FGF and IGF systems, thus suggesting auto-/paracrine effects of these growth factors within the primate oviduct, possibly under the control of estrogenic hormones.