Nano-Curcumin Prevents Copper Reproductive Toxicity by Attenuating Oxidative Stress and Inflammation and Improving Nrf2/HO-1 Signaling and Pituitary-Gonadal Axis in Male Rats

Abstract

Copper is essential for several cellular processes and is an important catalytic factor for many proteins. However, excess copper can provoke oxidative stress and reproductive toxicity. This study evaluated the effect of liposomal nano-curcumin (N-CUR) and CUR on testicular oxidative injury, inflammation, and apoptosis, and altered steroidogenesis and Nrf2/HO-1 signaling induced by copper sulfate (CuSO4). Rats received CuSO4 and N-CUR or CUR via oral gavage for 7 days. CuSO4 induced histopathological changes and altered pituitary-gonadal axis manifested by decreased serum gonadotropins and testosterone. Testicular steroidogenesis genes (StAR, 3β-HSD, CYP17A1, and 17β-HSD) and androgen receptor (AR) were downregulated in rats that received CuSO4. N-CUR and CUR prevented testicular tissue injury, increased circulating FSH, LH, and testosterone, and upregulated testicular steroidogenesis genes and AR. Additionally, N-CUR and CUR decreased testicular MDA, NO, NF-κB, iNOS, TNF-α, Bax, and caspase-3 while enhanced Bcl-2, Nrf2, and the antioxidants GSH, HO-1, SOD, and catalase. In conclusion, N-CUR and CUR prevented CuSO4-induced reproductive toxicity in male rats by suppressing oxidative injury and inflammatory response and boosting steroidogenesis, sex hormones, and Nrf2/HO-1 signaling. N-CUR was more effective in ameliorating tissue injury, oxidative stress, inflammation, and apoptosis and enhancing steroidogenesis and Nrf2/HO-1 than the native form.

Keywords: copper sulfate; curcumin; oxidative stress; reproductive toxicity; steroidogenesis.

Figure 1

N-CUR and CUR enhance the pituitary-gonadal axis in Cu-intoxicated rats. CUR, N-CUR, and DFO increased serum (A) LH, (B) FSH, and (C) testosterone in rats that received CuSO₄. Data are mean ± SEM, (n = 8). * p < 0.05 and *** p < 0.001 versus Control. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 versus CuSO₄.

Figure 2

N-CUR and CUR prevent Cu-induced testicular tissue injury. Photomicrographs of H&E-stained sections in the testis of (A,B) control rats showing normal histological architecture, (C,D) Cu-intoxicated rats showing degenerative changes and loss of spermatogenic series, and spermatozoa, and (E–J) Cu-intoxicated rats treated with DFO (E,F), CUR (G,H), and N-CUR (I,J) showing normal seminiferous tubules with spermatogonia, primary spermatocytes, spermatids, and spermatozoa. (×200: A,C,G,E,I. ×400: B,D,F,H,J).

Figure 3

N-CUR and CUR upregulate steroidogenesis and AR in Cu-intoxicated rats. Treatment with DFO, CUR, and N-CUR increased (A) StAR, (B) 3β-HSD, (C) CYP17A1, and (D) 17β-HSD mRNA abundance, and (E) AR protein expression. Data are mean ± SEM, (n = 8). *** p < 0.001 versus Control and ^### p < 0.001 versus CuSO₄.

Figure 4

N-CUR and CUR attenuate testicular oxidative stress in Cu-intoxicated rats. Treatment with DFO, CUR, and N-CUR decreased (A) MDA and (B) NO and increased (C) GSH, (D) SOD, and (E) CAT. Data are mean ± SEM, (n = 8). ** p < 0.01 and *** p < 0.001 versus Control, and ^### p < 0.001 versus CuSO₄.

Figure 5

N-CUR and CUR upregulate Nrf2/HO-1 signaling in Cu-intoxicated rats. (A–C) Treatment with DFO, CUR, and N-CUR increased testicular Nrf2 and HO-1 protein levels. Data are mean ± SEM, (n = 8). ** p < 0.01 and *** p < 0.001 versus Control, and ^### p < 0.001 versus CuSO₄.

Figure 6

N-CUR and CUR mitigate testicular inflammation in Cu-intoxicated rats. CUR, N-CUR, and DFO decreased (A) NF-κB p65 and (B) iNOS mRNA abundance, and (C) TNF-α protein. Data are mean ± SEM, (n = 8). * p < 0.05, ** p < 0.01 and *** p < 0.001 versus Control, and ^### p < 0.001 versus CuSO₄.

Figure 7

N-CUR and CUR prevent testicular apoptosis in Cu-intoxicated rats. CUR, N-CUR, and DFO downregulated (A) Bax and (B) caspase-3, and upregulated (C) Bcl-2 and (D) PCNA in the testis of rats. Data are mean ± SEM, (n = 8). * p < 0.05, ** p < 0.01 and *** p < 0.001 versus Control, and ^### p < 0.001 versus CuSO₄.