Role of the platelet-activating factor and its receptor in the proliferative regulation of bovine ovarian granulosa cells.
Proliferation of granulosa cells and their withdrawal from the cell cycle may regulate follicular ovulation. Antagonists of platelet-activating factor (PAF) and its receptor (PAFr) inhibit follicle rupture.


OBJECTIVE
Thus, PAF and PAFr may be involved in proliferative regulation of granulosa cells; however, expression of PAFr in these cells is unknown.


METHODS
The aim of this study was to investigate the presence of PAFr and the effect of PAF on proliferation of cultured bovine granulosa cells using real-time polymerase chain reaction to assay steady-state level of mRNA, immunocytochemistry to quantify PAFr protein and proliferating cell nuclear antigen protein by flow cytometry.


RESULTS
We found that granulosa cells express PAFr transcripts and protein. PAF presence did not change the concentration of PAFr mRNA or PAFr protein. Granulosa cells responded to PAF doses of 10 and 50 nm with increasing proportions of cells entering G0/G1 phase, as well as a significant expansion of total cell numbers. Rise in G0/G1-phase cells was accompanied by a decline in proliferating cell nuclear antigen protein expression, and these effects could be suspended by simultaneous PAFr blockage. The results provide clear evidence for expression of PAFr in bovine granulosa cells and its functional involvement in PAF/PAFr-mediated stimulation of cell recruitment.


CONCLUSIONS
PAF antagonists are suggested to disturb this regulative activity of PAF and to contribute in this way to blockage of ovulation.
Viergutz
T
T
Department of Reproductive Biology, Research Institute of the Biology for Farm Animals, Dummerstorf, Germany. viergutz@fbn-dummerstorf.de
Löhrke
B
B
D000818:Animals; D002417:Cattle; D002452:Cell Count; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D006107:Granulosa Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000378:metabolism* / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D004247:DNA