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(70) EFFECT OF ANGIOTENSIN II AND RECEPTOR ANTAGONISTS ON PORCINE PREANTRAL OVARIAN FOLLICLES CULTURED IN SERUM-FREE MEDIA. Shuttleworth, Gail1,2, Broughton Pipkin, Fiona2, Hunter, Morag3, 1 AgResearch, Upper Hutt, NZ2 Division of Obstetrics and Gynaecology, Nottingham, UK3 Division of Animal Physiology, Sutton Bonington, UK ABSTRACT- The principal bioactive product of the renin-angiotensin system (RAS) is the octapeptide Angiotensin II (AngII). Previous studies from our laboratory have demonstrated that there are components of an active RAS within the porcine ovary (renin and both characterised AngII receptors: type 1 - AT1, type 2 - AT2). To test the putative role of AngII within the ovary, isolated preantral follicles (n=24 follicles per treatment) were cultured for 10 days in serum-free medium developed for porcine preantral follicle culture [Way++: Waymouth medium; 2 mg/l sodium pyruvate; 200 IU/ml penicillin; 200 mg/l streptomycin; 0.1% (w/v) BSA; 2.5 mg/l transferrin; 4 mg/l insulin; and 10 mg/l selenium; 10 mg/l FSH; 100 mg/l Long R3 IGF-1; 0.2 mM ascorbate] containing one of 4 concentrations of AngII (0mM, 10-12M, 10-10M or 10-8M). Follicles were morphologically assessed every 2 days, diameters measured and 0.5 ml culture medium removed and stored for steroid analysis and replaced with fresh equilibrated media. After culture, oocyte viability was tested using CFSD, and the number of viable granulosa cells determined by Neutral Red Assay. Results demonstrated a significant increase in follicle diameter (P<0.001), oestradiol (P<0.01), and progesterone (P<0.01) production over time. Although there was no significant effect of treatment, follicles cultured with 10-10M AngII resulted in the greatest percentage change in diameter. A second experiment (n=24 follicles per treatment, cultured for 10 days as before) compared the following additions to Way++: no further supplements, 10-10M AngII, 10-10M AngII plus 10-6M GR117289 (an AT1 antagonist), 10-10M AngII plus 10-6M PD123319 (an AT2 antagonist). There was a significant increase in follicle diameter with time in all cases (P<0.001). Although there was no significant effect of treatment, culture with PD123319 resulted in the greatest percentage change in follicle diameter. There was a significant increase (P<0.01) in progesterone secretion after treatment with GR117289. This indicates that AngII may have a role in preantral follicle development in the pig, and may act via both characterised receptor subtypes to affect growth (AT1) and progesterone (AT2) secretion. KEY WORDS: porcine, angiotensin II, ovarian follicle culture, receptor antagonist |
