Studies of the physiological action of follistatin in the porcine ovary
Abstract (Summary)To investigate the physiologicai action of follistatin in the swine ovary a recombinant porcine follistatin (rpFS) with apparent molecular weights of 39,46,48, and 50 Da was expressed and characterized. The rpFS crossreacted with antibodies against native porcine follistatin and with activin A. One rpFS isotype was purified by monoclonal antibody affinity chromatography (rp-305 a.a. FS). In porcine granulosa ce11 cultures, rp-305 a-a. FS suppressed estradiol-17P accumulation (EDSo= 0.9 pg/ml) independent of activin. Gilts were vaccinated against rpFS to detennine the effect of follistatin immunoneutralization on litter size or ovulation rate. In Experirnent 1, fortyseven gilts were vaccinated four tirnes with rpFS (FS n=23) or with a control vaccine (CTL n=24). The naturally matured, cycling gilts were bred and piglet numbers were recorded at farrowing. FS vaccination did not increase total litter size. However, grouping by low ( < 1:400 n=16) or high anti-follistatin antibody titer (>1:400 n=7) responses showed an increased litter size in gilts with a high titer (total piglets: FS high titer = 13.0 + 0.8; FS low titer = 10.8 +0.6; CTL 11.4 + 0.5; p = 0.08). In Experiment 2, sixty-nine gilts were vaccinated three times with rpFS (n=35) or CTL (n=34) vaccines. The gilts were induced and synchronized into estrus using PG600, PGFr, and boar exposure; cycling gilts received a fourth vaccination. Reproductive tracts were collected two weeks after the second observed estrus (FS n = 14, CTL n = 15). FS vaccination did not increase the number of corpora lutea (FS=13.2 +0.5, Cm = 14.5 + 0.7) or corpora albicantia (FS = 12.1 + 1.9, CTL = 12.3 + 2.0), but appeared to effect normal ovarian morphology increasing the number of blood-filled follicles and corpora lutea. In conclusion, rp-305 a.& FS appears to negatively affect estradiol accumulation in vitro. Vaccination against follistatin in naturdly cycling gilts enhanced Iitter size. Follistath vaccination of phmacologically induced gilts did not increase ovulation rate, but biological effects were apparent suggesting that pharrnacological induction of estrus may have confounded the follistatin vaccination treatment. .-. III 1am grateful for the guidance and support of rny supervisor, Dr. Bernard Laarveld. Dr. Mark Redmond was critical in initiating my entrance into graduate studies and provided me with a lot of support. The other members of rny advisory cornmittee Drs. Vikram Misra, Norman Rawlings, Jorge Chedrese, and Iain Christison gave me valuable comments and assistance throughout my program. Appreciation is extended to Dr. Jorge Chedrese for providing valuable laboratory space for the in vitro biological assays, Dr. Jacek Kowalski for providing the heat shock expression vector system, and Dr. Bob Baker for statistical advice. The support of al1 present and past members of the Animal Biotechnology Centre has been wonderful. 1 would have been lost without the animal assistance given by Blair Goldade and the RIA guidance of Charlotte Hampton. Thank you to everyone for making Our laboratory a fun and well-organized work environment. Financial support for my research was provided by grants to Drs. Laarveld and Redmond through the Saskatchewan Agncultural Development Fund and the National Science and Engineering Research Council of Canada. 1 am very grateful to the University of Saskatchewan for the persona1 funding which has allowed me to study at this facility. Finally, 1 would like to thank my brothers and al1 of my fnends, especially Mike, who helped keep me sane and aware of the fact that there is life after graduate studies.
Source Type:Master's Thesis
Date of Publication:01/01/1999