Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams1

Abstract

The objective of this study was to evaluate the reproductive toxicity of gossypol and the possible counteracting effect of selenium supplementation in rams. Twenty-five mature crossbred (Barki × Rahamni) rams were randomly divided into 5 equal groups. The first group served as a control (no gossypol in diet). The second and third groups received diets containing free gossypol of 9 and 14 mg·kg(-1) BW·d(-1)(low level and high level of gossypol), respectively. The fourth and fifth groups received the same diets given to the second and third groups, respectively, with an oral administration of 1 mg selenium (as sodium selenite) daily for each animal. Results showed reductions in ejaculate volume (P = 0.028), percentage of dead sperm (P = 0.003), total functional sperm fraction (P < 0.001), and blood serum concentration of testosterone (P < 0.001) in the presence of both levels of gossypol inclusion. Furthermore, high level of gossypol reduced forward motility (P < 0.001) and semen initial fructose concentration (P = 0.002) and increased abnormal-head sperm (P = 0.003) and blood serum concentration of triiodothyronine (P = 0.006). Regardless of selenium supplementation, increasing level of free gossypol in diet resulted in a significant decrease in the percentage of forward motility (P = 0.037) and significant increases in the mean values of sperm concentration (P < 0.001), total sperm output (P = 0.002), percentage of total abnormal sperm (P = 0.058), and abnormal-head sperm (P = 0.016). On the other hand, regardless of levels of gossypol inclusion, selenium supplementation resulted in significant increases in libido (P < 0.001), mean values of ejaculate volume (P < 0.001), percentage of forward motility (P = 0.019), total sperm output (P < 0.001), total functional sperm fraction (P < 0.001), semen initial fructose concentration (P = 0.031), and blood serum concentrations of both testosterone and triiodothyronine (P < 0.001). In conclusion, free gossypol in diet induced adverse effects on semen quality in rams, but selenium supplementation successfully counteracts most of the hazardous effects of gossypol on semen characteristics.

Gossypol Promotes Degeneration of Ovarian Follicles in Rats

“…Reduced T3 levels were also observed in rabbits, but this reduction was reverted when dosing was discontinued [10]. However, gossypol dosing resulted in increased T3 serum levels without affecting T4 in rats [40] and sheep [41]. The thyrotropic cells in the pituitary gland, which specializes in TSH synthesis and secretion, showed hypertrophy, hyperplasia, and degranulation after gossypol acetate dosing in rats [42].…”

Gossypol Toxicity from Cottonseed Products

“…Gossypol also affects thyroidal metabolism [68, 97–100]. Some studies with male [98] and female [99] rats showed decreased blood concentrations of T4 and T3 after dosing with gossypol.…”

“…Some studies with male [98] and female [99] rats showed decreased blood concentrations of T4 and T3 after dosing with gossypol. On the other hand, gossypol dosing resulted in increased T3 serum concentrations without affecting T4 in rats [97] and sheep [68]. The histopathological evaluation of thyroid glands from male rats dosed with gossypol revealed follicular degeneration and atrophy [98].…”

Gestational form of Selenium in Free-Choice Mineral Mixes Affects Transcriptome Profiles of the Neonatal Calf Testis, Including those of Steroidogenic and Spermatogenic Pathways

“…It is well known that a deficiency of Se will reduce rates of growth [2], immune responses [3,4], and fertility, including reduced biosynthesis of testosterone by the testis and increased frequency of abnormalities in mature spermatozoa [5][6][7]. In boars and turkey toms, it is reported the form of Se supplemented to an animal's diet affects semen quality and male fertility [8,9], and the addition of Se to the diet of gossypol-treated rams [10] or cadmium-exposed rats [11,12] will reverse the negative effect of these toxins on serum testosterone and sperm motility. Effects on the testis are due, in part, to the high sensitivity of this organ to the generation of reactive oxygen species (ROS), requiring high levels of Se for selenoprotein-mediated redox balance [13].…”