The effect of successive administrations of charcoal-treated porcine follicular fluid (CTPFF) on ovulation in rabbits was examined.
In group 1, fifteen does mated after receiving 15 injections of 5 ml of CTPFF at 8-hour intervals (treatment A) or 10 injections of 4 ml at 12-hour intervals (treatment B) showed completely suppressed ovulation. Control does which were treated with saline solution ovulated (20% of does in control A and 33% in control B). Non-ovulatect does treated with CTPFF showed a decrease in large follicles (> 1.5 mm size in diameter) 4 days post coitum. Vulvar swelling and coloration receded 1 day (treatment A) and 2 days (treatment B) after the beginning of CTPFF treatments. Follicle-stimulating-hormone (FSH) concentrations in peripheral blood werc examined by radioimmunoassay, but no samples had detectable levels during the treated period in CTPFF groups. But elevation in FSH levels was noted in 4 does in treated groups after treatments.
In group 2, 6 does which had received 10 injections of 4 ml of CTPFF at 12-hour intervals were given 10 IU of hCG, resulting in ovulations in 50%. The same dose of hCG caused ovulation in 75% of control animals (8 does). The number of ovulations was significantly lower in the CTPFF groups than in controls (p < 0.01). Numbers of large follicles were fewer in ovaries of treated non-ovulated does than that in controls 4 days post coitum. Vulvas became smaller and more faded from treatment with CTPFF, also.
In group 3, 15 IU of hCG was used for ovulation induction in 6 does which were treated with CTPFF in the same manner as group 2. This gave rise to ovulation in all does in both treated and control (7 does) groups. However, the number of ovulations was significantly lower in the CTPFF gro~tpt han in the controls (p < 0.01). The appearance of the vulva showed a trend similar to that in groups 1 and 2. But the number of large follicles in ovulated does did not vary at 7 days after the end of CTPFF treatments between treated and control groups. This indicates that follicular development which is inhibited by CTPFF treatments may be resumed by a rebound phenomenon in FSH levels.
It is concluded that successive injections of CTPFF for sevcral days affected ovulation in our rabbits, not only reducing the number of does which ovulated, but also the number of ovulations in does which were caused to ovulate by administration of hCG.