The effects of sesame oil and different doses of estradiol on testicular structure, sperm parameters, and chromatin integrity in old mice

Abstract

Objective: Studies of the effects of estrogens on the male reproductive system have emphasized the role of these hormones in male fertility. Sesame oil has many phytoestrogenic compounds and may improve male fertility. This study investigated the effects of sesame oil and different concentrations of estrogen on sperm parameters and DNA integrity in male mice.Methods: Twenty old NMRI (The Naval Medical Research Institute) male mice (40 weeks; weight, 30–35 g) were treated with sesame oil or different concentrations of estrogen (estradiol, 1 and 10 μL/kg/ day) or received no treatment (controls). After 35 days, sperm parameters and DNA integrity were assessed and analyzed.Results: Sperm count, progressive motility, and morphology were decreased in the group that received 10 μL/kg of estradiol. A remarkably lower percentage of DNA fragmentation and protamine deficiency were detected in the group that received 1 μL/kg of estradiol. In the groups that received sesame oil and 1 μL/kg of estradiol, the numbers of spermatogonia and Leydig cells were higher than in controls. The combination of sesame oil and 1 μL/kg of estradiol led to improved sperm parameters and chromatin and testicular structure.Conclusion: Based on this study, consumption of sesame oil and a low concentration of estradiol may improve testicular function in older mice.

The association between serum estradiol levels and sperm DNA integrity

“…This would be in line with a reduction in sperm DNA fragmentation reported in mice treated with low levels of estradiol (Mohammadzadeh et al, 2021), possibly due to either the antioxidant effect mentioned (Hamden et al, 2008) or due to positive effects on the sperm DNA condensation and packaging (Cacciola et al, 2013). Such a mechanism would corroborate the emerging role of estrogens in the function of germ cells (Correia et al, 2015) and also associations reported between levels of estradiol and decreased sperm DNA fragmentation in two previous human studies (Meeker et al, 2008;Richthoff et al, 2002).…”

“…Since an elevated BMI may be associated with higher estradiol levels (Kahn & Brannigan, 2017 ; MacDonald et al, 2010 ; Vermeulen et al, 2002 ), and since estrogens are reported to play an essential role in the production and maturation of spermatozoa (Carreau & Hess, 2010 ; Dostalova et al, 2017 ) as well as to protect testicular cells against oxidative damage (Hamden et al, 2008 ), we speculated that lower sperm DNA fragmentation in the overweight men (Bandel et al, 2015 ) could be due to higher levels of estradiol. This would be in line with a reduction in sperm DNA fragmentation reported in mice treated with low levels of estradiol (Mohammadzadeh et al, 2021 ), possibly due to either the antioxidant effect mentioned (Hamden et al, 2008 ) or due to positive effects on the sperm DNA condensation and packaging (Cacciola et al, 2013 ). Such a mechanism would corroborate the emerging role of estrogens in the function of germ cells (Correia et al, 2015 ) and also associations reported between levels of estradiol and decreased sperm DNA fragmentation in two previous human studies (Meeker et al, 2008 ; Richthoff et al, 2002 ).…”

Sperm Chromatin Status and DNA Fragmentation in Mouse Species with Divergent Mating Systems

“…Finally, the three mouse species examined here exhibited 0.4-1.2% positively stained sperm (either completely or partially stained) with chromomycin A3, indicative of defective protamination [61], as opposed to the laboratory mouse, which exhibited values of ~3% [48,57]. In contrast, in other studies, cauda epididymal mouse sperm stained with chromomycin A3 revealed higher values (~10-20% stained) [45][46][47]. The ability of these staining methods to identify alterations in chromatin status is demonstrated by higher percentages of stained mouse sperm under different conditions, such as treatment with estrogens (30%) [46], oxidative stress, age (30-70%) [47], and protamine 1 (90%) or protamine 2 deficiencies (30%) [48].…”

“…In contrast, in other studies, cauda epididymal mouse sperm stained with chromomycin A3 revealed higher values (~10-20% stained) [45][46][47]. The ability of these staining methods to identify alterations in chromatin status is demonstrated by higher percentages of stained mouse sperm under different conditions, such as treatment with estrogens (30%) [46], oxidative stress, age (30-70%) [47], and protamine 1 (90%) or protamine 2 deficiencies (30%) [48]. In comparison to other species, alterations in chromatin status in the mouse are rather low; studies of human, bull, boar, dog, and cat sperm revealed higher proportions of spermatozoa with defects in sperm chromatin compaction [39,42,55,[62][63][64][65].…”

“…Some contradictory results have been reported using these methods in both species, especially with regard to associations with other sperm traits and fertility, which probably originate from the diversity of methods used. Studies in other species are limited, but some attention has been given to the mouse model to examine, for instance, the effect on chromatin status of anti-estrogens [45], estrogens [46], lack of antioxidant protection [47], defects in protamine expression [48], or protamine transport into the nucleus [49].…”