Impact of Ultraviolet C Radiation on Male Fertility in Rats: Suppression of Autophagy, Stimulation of Gonadotropin-Inhibiting Hormone, and Alteration of miRNAs

Abstract

While ultraviolet C (UVC) radiation has beneficial applications, it can also pose risks to living organisms. Nevertheless, a detailed assessment of UVC radiation's effects on mammalian male reproductive physiology, including the underlying mechanisms and potential protective strategies, has not yet been accomplished. This study aimed to examine the critical roles of oxidative stress, autophagy, reproductive hormonal axis, and microRNAs in UVC-induced reproductive challenges in male rats. Semen, biochemical, molecular, and in silico analyses revealed significant dysregulation of testicular steroidogenesis, impaired spermatogenesis, deteriorated sperm quality, and altered reproductive hormonal profiles, which ultimately lead to a decline in fertility in male rats exposed to UVC radiation. Our data indicated that the suppression of autophagy, stimulation of gonadotropin-inhibiting hormone (GnIH), and alteration of microRNAs serve as key mediators of UVC-induced stress effects in mammalian reproduction, potentially contributing to male infertility. Targeting these pathways, particularly through pretreatment with hesperidin (HES), offers a promising strategy to counteract UVC-induced male infertility. In conclusion, the present findings emphasize the importance of understanding the molecular mechanisms behind UVC-induced male infertility and offer valuable insights into the protective mechanisms and prospective role of HES in safeguarding male reproductive health.

Keywords: hesperidin; male fertility; miR-137-3p; miR-20a-5p; molecular docking; oxidative stress.

Figure 1

Effects of UVC irradiation, alone or in combination with hesperidin, on testicular weight (A) and gonadosomatic index (B) in male rats. Rats exposed to total body irradiation with low or high doses of artificial UVC for 8 h/day for 8 consecutive weeks showed a dose-dependent reduction in testicular weight and Gonadosomatic Index. HES alleviates the decrease of testicular weight and gonadosomatic index caused by UVC radiation. A gross morphology photograph of rat testicles is shown above the bar charts. Data are expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 2

Effects of UVC irradiation, alone or in combination with HES, on the rat spermiogram. Sperm quality parameters: (A) sperm count, (B) live sperm%, (C) abnormal sperm%, and (D–F) sperm motility%. Data are expressed as mean ± SE from six rats per group. Statistically significant at **** p < 0.0001, *** p < 0.001, * p < 0.05.

Figure 3

Sperm-related morphological abnormalities of rats exposed to UVC radiation. Photographs of different types of sperm abnormalities were assessed in eosin–nigrosin stained smears and viewed under the oil-immersion objective of a light microscope. Spermatozoa in all photographs are shown at ×100 magnification.

Figure 4

Effects of UVC irradiation, alone or in combination with HES, on oxidative stress biomarkers in male rat testes. Oxidative stress biomarkers, namely, (A) malondialdehyde (MDA), (B) superoxide dismutase (SOD), and (C) total antioxidant capacity (TAC), were evaluated and are represented as mean ± SE. For each group, (n = 6). Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 5

Effects of UVC irradiation, alone or in combination with HES, on serum levels of reproductive hormones in male rats. The levels of (A) luteinizing hormone (LH), (B) follicle stimulating hormone (FSH), and (C) testosterone were determined in the sera of control and UVC-irradiated rats with or without HES treatment. Values represent the mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 6

Effects of UVC irradiation, alone or in combination with HES, on the expression levels of reproductive-related genes in the hypothalamus of male rats. Rats exposed to total body irradiation with low or high doses of artificial UVC for 8 h/day for 8 consecutive weeks showed dose-dependent substantial changes in the hypothalamic gene expression of (A) gonadotropin-inhibiting hormone (GnIH), (B) kisspeptin-1receptor (Kiss1r), and (C) gonadotropin-releasing hormone (GnRH). HES significantly reversed the effects caused by exposure to UVC radiation. Data are expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 7

Effects of UVC irradiation, alone or in combination with HES, on the expression levels of reproductive-related genes in the pituitary glands of male rats. Rats exposed to total body irradiation with low or high doses of artificial UVC for 8 h/day for 8 consecutive weeks showed dose-dependent substantial changes in the pituitary gene expression of (A) gonadotropin-releasing hormone receptor (GnRHr), (B) follicle-stimulate hormone β1 (FSHβ1), and (C) luteinizing hormone β1 (LHβ1). HES significantly mitigates the effects caused by exposure to UVC radiation. Data are expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 8

Effects of UVC irradiation, alone or in combination with HES, on the expression of steroidogenic enzymes in testicles of male rats. Expression levels of testicular steroidogenic genes (A) steroidogenic acute regulatory (StAR), (B) hydroxysteroid dehydrogenase-3-beta 17 (HSD17B3), (C) cytochrome P450 family 11 subfamily A member 1 (CYP11A1), (D) cytochrome P450 family 17 subfamily A member 1 (CYP17A1), and (E) cytochrome P450 family 19 subfamily A member 1 (CYP19A1) were evaluated using real-time PCR analysis in control and UVC-irradiated rats with or without HES pretreatment. Data are expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 9

Effects of UVC irradiation, alone or in combination with HES, on testicular autophagy-related gene expression in male rats. Expression of autophagy-related genes [(A) mammalian target of rapamycin (mTOR), (B) Beclin1, and (C) microtubule-associated protein-light chain 3 II (LC3II)] were examined using real-time PCR analysis in testes of control and UVC-irradiated rats, with or without HES pretreatment. Data are expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01.

Figure 10

Effects of UVC irradiation alone or in combination with HES on the gene expression of miR- 20a and miR-137-3p and their potential targets in male rats. Bioinformatic predictions of SQSTM1/p62 and Kiss1 regulation by miRNAs. (A,F) Schematic representation of predicted binding sites for miR-137-3p and miR-20-5p in rat 3’UTR of Kiss1 gene and SQSTM1/p62, respectively. Seed regions of miR-20-5p and miR-137-3p are highlighted in red (A and F). Expression of hypothalamic and testic-ular miR-137-3p (B,D) and its target Kiss1 (C,E), as well as testicular miR-20-5p (G) and its target SQSTM1/p62 (H) were examined using real-time PCR analyses in control and UVC-irradiated rats with or without HES pretreatment. Data is expressed as mean ± SE from six rats per group. Asterisks indicate a statistically significant difference: **** p < 0.0001, *** p < 0.001, ** p < 0.01, * p < 0.05.

Figure 11

Molecular docking studies of HES against reproductive and autophagic receptors in male rats. Docking studies were conducted on the active sites of six target receptor proteins [(I) GnRHr, (II) LHr, (III) FSHr, (IV) Kiss1r, (V) mTORC1r, and (VI) SQSTM/p62] with HES: (A) 3D images showing the binding affinity of HES with each receptor; (B) 3D images showing the binding pockets between HES and each receptor; (C) 3D images showing the types of interactions between HES and the receptor protein residues; and (D) 2D images showing different types of bonds and interactions between HES and the assessed receptor protein.