Sucralose disrupts male fertility by damaging sperm and altering hormones in animal studies

Sucralose disrupts male fertility by damaging sperm and altering hormones in animal studies

A common artificial sweetener found in thousands of foods may threaten male fertility by disrupting hormones and damaging sperm, new research on rats shows.

In a study recently published in the journalEnvironmental health perspectivesResearchers examined the effects of sucralose exposure on male reproductive health.

Male infertility is a global health problem that affects 8% to 12% of couples and contributes to almost half of the world's infertility cases. Male infertility is influenced by hormonal, environmental and genetic factors that affect spermatogenesis and reproductive function. Diet and lifestyle changes, including increased intake of non-nitrous sweeteners (NNSS) and sugary drinks, are among such factors implicated in the increasing prevalence of infertility.

Sucralose, NNS, accounts for 30% of the sweetener market in the United States. Although sucralose has antibacterial properties and lower calories, there are emerging concerns about potential health risks and environmental duration. It is also a persistent contaminant in aquatic systems, with studies showing its consistent presence throughout the urban water cycle. The study highlights concerns about sucralose-6-acetate, a genotoxic byproduct of sucralose production and metabolism that may exacerbate health and environmental risks. Despite research into NNSS, data on potential links between sucralose and male infertility are limited.

About the study

In the present study, researchers evaluated the effects of sucralose on male reproductive health. Six-week-old male Sprague-Dawley (SD) rats were acclimatized under controlled conditions for one week and then randomized to one of four experimental groups. Sucralose was administered at 1.5 mg/kg, 15 mg/kg, 45 mg/kg, or 90 mg/kg for two months.

Controls received deionized water. Body weight was monitored weekly for eight weeks. At the end of the study, animals were euthanized and blood samples were collected for biochemical analysis. Organs such as liver, spleen, heart, testes, epididymis, and kidneys were harvested for histopathological evaluation.

The cauda epididymis was cut into pieces and kept briefly in culture medium, and the supernatant was used for sperm motility analysis. Sperm samples were subjected to Western blot analysis to evaluate DNA damage markers. Additionally, an enzyme-linked immunosorbent assay was used to measure follicle-stimulating hormone (FSH), luteinizing hormone (LH), and kissspeptin1 (Kiss1).

Chemiluminescence immunoassays were performed to measure serum testosterone, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Furthermore, mouse Sertoli cells (TM4) and Leydig cells (TM3) were treated with different concentrations of sucralose for 24–72 hours. These cells were subjected to intracellular reactive oxygen species (ROS), viability and Western blot analyses. To assess autophagy-lysosome dysfunction, researchers used bafilomycin A1, a compound that blocks lysosomal attempts and results in impaired fusion of autophagosomes and lysosomes.

The Kolmogorov-Smirnov test assessed data normality. Nonparametric tests were applied for data violating normality assumptions. A two-way analysis of variance was performed to assess the effects of sucralose and exposure duration. Group differences were compared using the Mann-Whitney U test or Student's t test.

Results

TM3 and TM4 cells exposed to different concentrations of sucralose (1 μm, 10 μm, 100 μm, 1000 μm and 10,000 μm) had significantly lower cell viability. The cells also showed higher levels of microtubule-associated protein 1A/1B light chain 3B, form II (LC3B-II) at 1000 or 10,000 μm and slightly lower p62 levels. These changes, combined with reduced cathepsin B (a lysosomal enzyme), indicate impaired autophagic degradation. After sucralose treatment, there was significantly lower expression of cathepsin B, indicating impaired lysosomal function.

ROS levels in TM3 and TM4 cells after sucralose exposure at 1 mM, 2.5 mm, 5 mm, 7.5 mm or 10 mM were significantly higher; Sucralose-treated cells also had increased nuclear factor erythroid 2-related factor 2 (Nrf2) expression and heme oxygenase 1 (HO-1) levels, indicating an increase in oxidative stress. Notably, exposed cells had a reduction in taste receptor type 1 1 (T1R3) protein expression.

Furthermore, coadministration with a known T1R3 antagonist (lactisol) suppressed T1R3 expression more than sucralose treatment alone. To further investigate the relevance of T1R3 modulation, rat pituitary adenoma cells (RC-4b/c) were treated with sucralose with or without lactisol cotreatment. This resulted in a significant reduction in LH levels in a dose-dependent manner. Lactisol co-treatment upset this suppression, particularly at lower sucralose levels.

SD rats exposed to sucralose showed no differences in body weight, AST or ALT levels, and cardiac and liver indices between groups. Although the appearance of reproductive organs was not remarkably different, exposed animals had significantly lower epididymal and testicular indices. Furthermore, rats showed a significant reduction in serum testosterone and LH levels as well as serum and testicular Kiss1 levels. KISS1, a key regulator of the hypothalamic-pituitary-gonadal (HPG) axis, is crucial for initiating puberty and maintaining reproductive hormone balance; Its suppression may directly contribute to impaired fertility.

Sucralose exposure also reduced protein levels of T1R3 in the testes. Exposed animals had abnormal sperm morphology (with coiled and curved tails) and lower sperm viability. Histological examination of the testes revealed changes in the seminous epithelium, including severe vacuolization, disrupted germ cell organization, and nuclear condensation.

DNA damage has also been observed in sperm, indicating cellular impairment. The testes of sucralose-exposed animals had higher levels of LC3B and lower levels of P62, indicating changes in autophagy. In addition, exposed animals had higher serum and testicular levels of malondialdehyde, indicating increased lipid peroxidation.

Conclusions

Together, sucralose exposure adversely affects male reproductive outcomes in rats by inducing oxidative stress, causing DNA damage, and disrupting autophagy. The study finds that in vitro doses (up to 10 mm) likely exceed typical human dietary exposure, justifying caution in extrapolating results to real-world intake levels.

The results highlight the need for careful evaluation of NNNS -NNS and call for better food safety regulations to mitigate potential risks. Additionally, the environmental durability of sucralose and its byproduct, sucralose-6-acetate, highlights broader environmental concerns.

Further studies are needed to investigate dose-response relationships, long-term effects and underlying molecular mechanisms to comprehensively delineate the adverse effects of sucralose.

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