Enhanced proliferation and progesterone production by porcine granulosa cells cultured with pseudorabies virus growth factor (PRGF)

The objective of this research was to study possible interactions of pseudo rabies virus growth factor (PRGF) with ovarian tissue. Granulosa cells isol ated from porcine ovaries were cultured as monolayers for 6 days in a contr ol medium without PRGF and in medium supplemented with different doses of t his agent. Increased population density and change towards more fibroblasti c- like shape of cells cultured with 10(9) I.U PRGF was observed when compa red with control culture. The cells divided significantly faster during 6 days of culture under the i nfluence of 10(3), 10(4), 10(5), 10(6), 10(7), 10(8) and 10(9) I.U/ml of PR GF at a dose dependent manner. PRGF in a dose 10(9) I.U. added to cultured cells isolated from small and medium follicles did not influence progestero ne secretion. An increase of progesterone secretion under the influence of PRGF in all investigated days of cultures was observed in cells isolated fr om large preovulatory follicles. The marked increase in progesterone conten t in PRGF treated culture in doses of 0.5 x 10(7), 0.5 x 10(8), 0.5 x 109 I .U. was observed during 4 and 6 days of culture. The rise of progesterone content was not connected with increased number of secretory cells, but with a stimulation of production per cell. PRGF exert ed no visible effect on progesterone secretion by granulosa cells from smal l and medium follicles cultured for 6 days. The presented in vitro data provide evidence for a local action of PRGF in the follicle depending on the stage of follicular development and duration of exposure. Precise relevance of the interaction of PRGF with follicular d evelopment requires further study.