Cordycepin, an Active Constituent of Nutrient Powerhouse and Potential Medicinal Mushroom Cordyceps militaris Linn., Ameliorates Age-Related Testicular Dysfunction in Rats

Abstract

Age-related male sexual dysfunction covers a wide variety of issues, together with spermatogenic and testicular impairment. In the present work, the effects of cordycepin (COR), an active constituent of a nutrient powerhouse Cordyceps militaris Linn, on senile testicular dysfunction in rats was investigated. The sperm kinematics, antioxidant enzymes, spermatogenic factors, sex hormone receptors, histone deacetylating sirtuin 1 (SIRT1), and autophagy-related mammalian target of rapamycin complex 1 (mTORC1) expression in aged rat testes were evaluated. Sprague Dawley rats were divided into young control (2-month-old; YC), aged control (12-month-old; AC), and aged plus COR-treated groups (5 (COR-5), 10 (COR-10), and 20 (COR-20) mg/kg). The AC group showed reduced sperm kinematics and altered testicular histomorphology compared with the YC group (p < 0.05). However, compared with the AC group, the COR-treated group exhibited improved sperm motility, progressiveness, and average path/straight line velocity (p < 0.05-0.01). Alterations in spermatogenesis-related protein and mRNA expression were significantly ameliorated (p < 0.05) in the COR-20 group compared with the AC group. The altered histone deacetylating SIRT1 and autophagy-related mTORC1 molecular expression in aged rats were restored in the COR-20 group (p < 0.05). In conclusion, the results suggest that COR holds immense nutritional potential and therapeutic value in ameliorating age-related male sexual dysfunctions.

Keywords: Cordycepin; SIRT1; antioxidant; mTORC1; sex hormone receptors; spermatogenesis.

Figure 1

Chemical structure, histological analysis, Johnsen’s scores, and seminiferous tubule size in aged rat testes. (A) Cordycepin structure. (B) Representative images of tubular cross sections of testis: (a) young control rats YC, (b) vehicle-treated aged rats AC, (c) COR 5 mg/kg treated aged rats, (d) COR 10 mg/kg treated aged rats, and (e) COR 20 mg/kg treated aged rats. Sections were stained with hematoxylin and eosin (H&E). The images are typical of those obtained in five independent experiments. Scale bar = 45 μM and magnification = 200x. (C) Johnsen’s score. (D) Tubular size (µM). The results are expressed as mean ± SEM (n = 10). ^# p < 0.05 compared with YC group and ^* p < 0.05 compared with AC group. COR, cordycepin; LC, Leydig cell; ST, Sertoli cell; SG, spermatogonia; SC, spermatocyte; SM, spermatid; SP, spermatozoa.

Figure 2

Effect of COR on the spermatogenesis parameters in aged rats. (A) Percentage of tubules with sperm, (B) sperm count per tubule, (C) Sertoli number, (D) germ cell count, and (E) Sertoli cell index. ^# p < 0.05 compared with YC group and ^* p < 0.05 compared with AC group. YC, young rats; AC, aged rats; COR, cordycepin.

Figure 3

Effect of COR on the expression levels of sex hormone receptors. (A) Protein expression of AR, FSHR, and LHR. (B) Relative expression levels (fold) in three independent experiments normalized to β-actin. (C) The mRNA expression of AR, FSHR, and LHR. (D) Relative expression levels (fold) in three independent experiments normalized to that of GAPDH. ^# p < 0.05 compared with YC group and ^* p < 0.05 compared with the AC group. AR, androgen receptor; LHR, luteinizing hormone receptor; FSHR, follicle-stimulating hormone receptor; YC, young rat group; AC, aged rat group; COR-20, cordycepin (20 mg/kg) treated AC group; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.

Figure 4

Effect of COR on expression levels of antioxidant enzymes in rat testes. (A) Protein expression of GPx4, GSTm5, and PRx4. (B) Relative expression levels (fold) in three independent experiments normalized to β-actin. (C) The mRNA expression of GPx4, GSTm5, and PRx4. (D) Relative expression levels (fold) in three independent experiments normalized to that of GAPDH. ^# p < 0.05 compared with YC group and ^* p < 0.05 compared with AC group. YC, young rat group; AC, aged group; COR-20, cordycepin (20 mg/kg) treated AC group; PRx4, peroxiredoxin-4; GSTm5, glutathione S-transferase mu 5; GPx4, glutathione peroxidase 4; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.

Figure 5

Effect of COR on expression of key biomolecules involved in spermatogenesis. (A) Protein expression of CREB-1, nectin-2, and inhibin-α. (B) Relative expression levels (fold) in three independent experiments normalized to β-actin. (C) The mRNA expression of CREB-1, nectin-2, and inhibin-α. (D) Relative expression levels (fold) in three independent experiments normalized to that of GAPDH. ^# p < 0.05 compared with YC group and ^* p < 0.05 compared with the AC group. YC, young rat group; AC, aged rat group; COR-20, cordycepin (20 mg/kg) treated AC group; CREB-1, cyclic adenosine monophosphate (cAMP) responsive element binding protein; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.

Figure 6

Effect of COR on protein expression levels of mTOR and SIRT1in testis tissue. (A) Protein expression of mTOR and SIRT1. (B) Relative expression levels (fold) in three independent experiments normalized to β-actin. (C) The mRNA expression of mTOR and SIRT1. (D) Relative expression levels (fold) in three independent experiments normalized to GAPDH. ^# p < 0.05, compared with YC group and ^* p < 0.05 compared with the AC group. YC, young rat group; AC, aged rat group; COR-20, cordycepin (20 mg/kg) treated AC group; mTOR, growth-related mammalian target of rapamycin; SIRT1, silent mating type information regulation 2 homolog; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.