Investigation of the effects of high fructose corn syrup consumption on puberty transition and sexual behavior in male rats

In recent years, the use of High-Fructose Corn Syrup (HFCS) as a sweetener in the food industry has increased significantly. Along with this increase, many studies have been conducted arguing that it may be responsible for the high incidence of metabolic diseases. However, the effects of HFCS consumption on pubertal maturation, sexual behavior, and the reproductive system are not fully known. The purpose of the present thesis was to investigate the effects of HFCS consumption on pubertal maturation, sexual behavior, and the reproductive system. The experimental work of the thesis consisted of 3 stages; In the first stage, efforts were made to understand the effects of HFCS on the transition to puberty (HFCS-1). The male animals to be used in this stage of the study were selected when they were 21 days old (weaning period). They were divided into Control and HFCS-55 (15% diluted, 55% fructose content administered for an average of 30 days) Groups (n=10 each group). Enzyme Linked ImmunoSorbent Assay (ELISA) was used for reproductive hormone levels (Testosterone, Estrogen, Luteinizing Hormone (LH), Follicle-Stimulating Hormone(FSH) ) in the parameters of the transition of animals to puberty, serum, and brain tissue samples, and gene analyzes (Kiss1, KiSS1R, RFRP3) were performed by PCR. In the second stage of experimental work, the effects of HFCS consumption on the reproductive system in adult male rats with sexual behavior (HFCS-2) were examined. At this stage, 20 male rats were divided into 2 groups Control and HFCS-55 (15% diluted, 55% fructose content applied daily for an average of 56 days) groups (n=10 each group). In the third stage of the experimental study, the animals were taken at 21 days of age (weaning period) and fed with HFCS until they reached sexual maturity (HFCS-3). At this stage, 20 male rats were divided into 2 groups Control and HFCS-55 (15% diluted, 55% fructose content applied daily for an average of 86 days) Groups (n=10 in each group). At the end of the second and third stages of this experimental study, all animals underwent a Sexual Behavior Test (SBT) and a Sexual Incentive Motivation Test (SIMT). The animals were then decapitated and RT-PCR gene analyses were made in serum and brain tissue samples and reproductive hormone levels were determined by ELISA. In the HFCS-1 protocol, it was observed that the consumption of HFCS delayed puberty when compared to control animals. It was also found that HFCS application increased serum estrogen, LH, and FSH levels at significant levels compared to the Control Group. Kiss and KiSS1R gene expression was significantly increased in the Arcuate Nucleus (ARC) region when compared to the Control Group. In the HFCS-2 protocol, it was found that the female spent less time in the entire end zone adjacent to the female (end zone) and the female approach zones with SIMT when compared to the control after the application of the YFCS-2 protocol. On the other hand, it was found in CDT that consumption of HFCS significantly increased the Mount Latency (ML) and Ejaculation Latency (EL) and significantly decreased the Mating Rate (MR) and Sexual Activity Index (SAI). It was also found that serum estrogen, LH, and FSH levels increased significantly. Kiss and KiSS1R gene expression was significantly increased in the ARC region compared to the control group. In the HFCS-3 protocol, it wasobserved that the application of HFCS prolonged the first sexual behavior day and increased the weight of the first sexual behavior at significant levels. It was found with SIMT that the female test animal significantly reduced the time spent in the Approach Zone and End Zone. In SBT, on the other hand, it was also found that HFCS consumption increased EL and decreased Ejaculation Frequency (EF), DO, and CAI at significant levels. As a result, it was observed that HFCS delayed the transition to puberty and sexual maturation by causing hypogonadism and altering serum hormone levels, affecting sexual motivation and behaviors negatively. Our findings require further investigation of the links between HFCS consumption and male reproductive system disorders in animal models.