Cadmium (Cd) is a non-essential heavy metal that is highly toxic to testicle. Selenium (Se) is known to possess antagonistic effects against Cd toxicity, yet the precise mechanisms through which Se counteracts Cd-induced testicular damage in chickens through Nuclear factor erythroid 2-related factor 2/Heme oxygenase-1 (Nrf2/HO-1) signaling pathway, oxidative stress (OS), apoptosis, and inflammation remained unclear. In the present study, the experimental model of chicken testis was established by incorporating CdCl 2 and Na 2 SeO 3 into the dietary intake. After 60 days, chickens from each group were euthanized, and testicular and serum samples were subsequently collected. Ultrastructural assessment revealed that Se supplementation significantly mitigated the testicular damage induced by Cd. Se effectively suppressed the Cd-induced elevation in ROS, MDA, and H 2 O 2 levels, while also preventing the downregulation of CAT, GSH, and T-AOC levels. Furthermore, Se administration ameliorated the reduction in the expression levels of Nrf2, HO-1, and Bcl-2 induced by Cd, and counteracted the overexpression of Caspase-3, Bax, Cyt-c, and Caspase-9, TNF-α, IL-2, IL-6, and IL-1β. Meanwhile, immunofluorescence data demonstrated that Se attenuated the Cd-induced decrease in Nrf2 and HO-1 expression and the upregulation of IL-6 expression. In conclusion, this study elucidated that Se might mitigate Cd-induced oxidative stress in chicken testicles through the stimulation of the Nrf2/HO-1 signaling pathway, thereby inhibiting apoptosis and inflammation, and was beneficial in reducing Cd-induced testicular injury.
The optimized fixative for testis is still controversial. This study investigated the effects of Modified Davidson’s Fluid (mDF), 4% Paraformaldehyde (4% PFA), and Bouin’s Fluid (BF) fixatives on chicken testes in normal/cadmium (Cd) feeding groups using hematoxylin and eosin (HE), immunohistochemistry (IHC), and Terminal Transferase dUTP Nick End Labeling (TUNEL) staining. Compared to the mDF, we established that the testes fixed with 4% PFA and BF in the normal group had severe shrinkage in tubular and interstitial compartments. Moreover, compared with 4% PFA, the number of GATA4-positive Sertoli cells/mm 2 reduced by 67.61% in mDF and 80.57% in BF for one seminiferous tubule . The TUNEL assay illustrated that more positive cells/mm 2 in mDF group (28.47 ± 11.38) than in 4% PFA (10.49 ± 7.89). In Cd-treated testes, mDF showed more morphological details than 4% PFA and BF. In contrast, the number of GATA4-positive Sertoli cells/mm 2 of 4% PFA was higher than that of mDF by 65.78% and BF by 64.80% in a seminiferous tubule. The number of TUNEL positive cells/mm 2 in mDF (272.60 ± 34.41) were higher than in 4% PFA (175.91 ± 19.87). These results suggest that mDF fixative is suitable for normal and Cd-treated testis fixation for HE and TUNEL staining in chicken, whereas 4% PFA fixative is better for IHC examination.
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