Fat and Fructose Consumption Affects Pre-pubertal Gilt Reproductive Tissues and Early Embryogenesis
Poole, Rebecca Kyle
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Infertility among women has become a growing issue in the world requiring a significant number of women to seek treatment by means of assisted reproductive technologies (ART). One suggested reason for the fertility issue is modern diet, leading to diseases such as obesity and type II diabetes. In this study, twenty gilts three weeks in age, were placed on one of five dietary treatments (n=4 gilts per treatment) containing 15% fat (FAT), 35% fructose (FRU), both fat and fructose (HFHF), or two different controls: one standard industry (IND) diet meant to result in optimal lean growth and a second diet to account for the reduced lysine (LYS) intake in the treatment diets. Two experiments were performed to assess the reproductive outcomes of pre-pubertal gilts consuming a high fat and/or high fructose diet and to demonstrate interactions between diet and infertility using pigs as a model. In the first experiment, follicular fluid was collected from these gilts and introduced into porcine in vitro maturation system to determine whether characteristics of the follicular fluid affect oocyte competence and embryo development. The follicular fluid of females consuming high fructose and fat diets did not alter nuclear maturation of oocytes (p>0.10). There were, however, detrimental effects on subsequent development of embryos, especially blastocyst formation, with the gilts having consumed the HFHF diet having reduced day 5 and 6 blastocysts formation when compared to the IVM follicular fluid free (FFF) group (p=0.03 and p=0.01, respectively). In regards to embryo quality, blastocysts from the FAT group had greater cell number when compared to all other groups. In the second experiment, the reproductive tissues; ovary, oviduct, and uterus were analyzed for genes of interest: estrogen receptor alpha (ESR1), estrogen receptor beta (ESR2), insulin like growth factor I (IGFI), insulin like growth factor I receptor (IGFIR), and growth differentiation factor 9 (GDF9). Resulting data was analyzed in three ways: 1) across all 5 treatments, 2) with gilts grouped by whether or not they consumed fat, or 3) with gilts grouped by whether or not they consumed fructose. There were no differences detected between individual treatments for ESR1 and ESR2. In the ovary samples, the fructose diets decreases ESR2 (p=0.05). Also, GDF9 ovarian expression tended to decrease with fructose consumption (p=0.07). Furthermore in the ovary, there was a positive correlation between ESR2 and GDF9 expression (r=0.92 and p<0.01). GDF9 expression was lower in the oviducts of gilts consuming fat diets when compared to non-fat diets (p=0.01). Neither IGFI nor IGFIR were altered in the reproductive tissues analyzed. Based on the results from both experiments, the consumption of fat and fructose alters both the developing embryo and gene expression in the reproductive tissues that support the growing embryo. Further investigation will provide more insight on the impact nutrition has on pre-pubertal reproductive development and subsequent fertility.
- Masters Theses