PARENT SESSION
SLIDE SESSION 14: GROWTH FACTORS IN REPRODUCTIVE TISSUES
Chairs: Andrea Cupp, Barbara Vanderhyden, Wendy Ingman (Trainee)
Univ Ottawa-Lamoureaux 122
1:30 PM-3:30 PM

EFFECTS OF LEPTIN ON PORCINE OOCYTE MATURATION AND EMBRYO DEVELOPMENT IN VITRO.

Swain, Jason¹, Bormann, Charles ¹, Krisher, Rebecca ¹, ¹

ABSTRACT- Leptin is a 16 kDa protein secreted by mature adipocytes, which has been shown to affect normal reproductive function in several species. Interestingly, leptin and it's receptors have been found in a variety of reproductive structures, ranging from the oocyte and cumulus cells to the embryo. However, it's mode of action is unknown. The objective of this study was to determine the effects of leptin supplementation on porcine oocyte maturation and embryo development in vitro. Oocytes were collected from abattoir ovaries and matured in a defined TCM199 based medium for 45-47 h. Oocytes were fertilized in a modified tris-buffered medium (mTBM) for 5 h and presumptive zygotes cultured in NCSU23 for 146 h. In a 2 X 2 factorial design, oocytes were matured in the presence or absence of leptin (20 ng/ml) and subsequent embryos were cultured in the presence or absence of leptin (20ng/ml). Randomly selected oocytes were examined for nuclear maturation, embryos were examined for development and total blastocyst cell numbers counted. Developmental data were subjected to an arc sin transformation before analysis and are reported as a mean ± SEM. Data were analyzed with ANOVA and differences determined using the Bonferroni Multiple Comparison Test, P<0.05. Results indicate the presence of leptin during only embryo culture resulted in similar blastocyst development and cell numbers compared to controls (27%, 42.3 ± 2.6 and 29%, 44.0 ± 3.6, respectively). Blastocyst development and cell numbers resulting from leptin supplementation during only oocyte maturation were lower, but not significantly so compared to controls (22%, 38.3 ± 2.7). However, the presence of leptin during both oocyte maturation and embryo culture resulted in significantly lower rates of blastocyst development (13%) with similar blastocyst cell numbers (41.5 ± 4.3). The addition of leptin to oocyte maturation medium had no effect on completion of nuclear maturation (71%) compared to controls (67%). Decreased blastocyst development suggests leptin exerts negative effects on porcine embryo development through synergistic actions during oocyte maturation and embryo culture. One of these actions may be inhibition of cytoplasmic maturation.

KEY WORDS: porcine, oocyte, embryo, leptin