The Prophylactic Effect of Vitamin C and Vitamin B12 against Ultraviolet-C-Induced Hepatotoxicity in Male Rats

Abstract

Ultraviolet C (UVC) devices are an effective means of disinfecting surfaces and protecting medical tools against various microbes, including coronavirus. Overexposure to UVC can induce oxidative stress, damage the genetic material, and harm biological systems. This study investigated the prophylactic efficacy of vitamin C and B12 against hepatotoxicity in UVC-intoxicated rats. Rats were irradiated with UVC (725.76, 967.68, and 1048.36 J/cm²) for 2 weeks. The rats were pretreated with the aforementioned antioxidants for two months before UVC irradiation. The prophylactic effect of vitamins against UVC hepatotoxicity was evaluated by monitoring the alteration of liver enzyme activities, antioxidant status, apoptotic and inflammatory markers, DNA fragmentation, and histological and ultrastructural alterations. Rats exposed to UVC showed a significant increase in liver enzymes, oxidant-antioxidant balance disruption, and increased hepatic inflammatory markers (TNF-α, IL-1β, iNOS, and IDO-1). Additionally, obvious over-expression of activated caspase-3 protein and DNA fragmentation were detected. Histological and ultrastructural examinations verified the biochemical findings. Co-treatment with vitamins ameliorated the deviated parameters to variable degrees. In conclusion, vitamin C could alleviate UVC-induced hepatotoxicity more than vitamin B12 by diminishing oxidative stress, inflammation, and DNA damage. This study could provide a reference for the clinical practice of vitamin C and B12 as radioprotective for workers in UVC disinfectant areas.

Keywords: DNA fragmentation; UVC radiation; antioxidants; apoptosis; caspase-3; inflammatory markers; ultrastructural examination.

Figure 1

The effects of UVC irradiation, vitamin C, and vitamin B12 on serum parameters. (a) ALT activity, (b) AST activity, (c) total protein level, (d) albumin level, (e) total cholesterol level and (f) triglycerides level. Values are presented as means ± SD of ten rats. One-way analysis of variance (ANOVA) was utilized, followed by a post hoc test (Tukey) for pairwise comparisons. *: Statistically significant compared to the control group at p ≤ 0.05. #: Statistically significant compared to the corresponding UVC group at p ≤ 0.05.

Figure 2

The effect of UVC irradiation, vitamin C, and vitamin B12 on hepatic oxidative stress parameters. (a) MDA level, (b) SOD activity and (c) GSH level. Values are provided as means ± SD of ten rats. One-way analysis of variance (ANOVA) was utilized, followed by a post hoc test (Tukey) for pairwise comparisons. *: Statistically significant compared to the control group at p ≤ 0.05. #: Statistically significant compared to the corresponding UVC group at p ≤ 0.05.

Figure 2

The effect of UVC irradiation, vitamin C, and vitamin B12 on hepatic oxidative stress parameters. (a) MDA level, (b) SOD activity and (c) GSH level. Values are provided as means ± SD of ten rats. One-way analysis of variance (ANOVA) was utilized, followed by a post hoc test (Tukey) for pairwise comparisons. *: Statistically significant compared to the control group at p ≤ 0.05. #: Statistically significant compared to the corresponding UVC group at p ≤ 0.05.

Figure 3

The effect of UVC irradiation, vitamin C, and B12 on hepatic IL-1β (a), TNF-α (b), iNOS (c), and IDO-1 (d) gene expression levels. Values are identified as means ± SD of four rats. One-way analysis of variance (ANOVA) was performed, then a post hoc test (Tukey) for pairwise comparisons. *: Statistically significant compared to the control group at p ≤ 0.05. #: Statistically significant compared to the corresponding UVC group at p ≤ 0.05.

Figure 4

The effect of UVC irradiation, vitamin C, and B12 on (a) the hepatic caspase-3 level and (b) genomic DNA fragmentation in ethidium bromide-stained agarose gel. Blue symbols illustrate bands of DNA fragmentation. Values are given as means ± SD of four rats. One-way analysis of variance (ANOVA) was utilized, then the post hoc test (Tukey) for pairwise comparisons. *: Statistically significant compared to the control group at p ≤ 0.05. #: Statistically significant compared to the corresponding UVC group at p ≤ 0.05.

Figure 5

Histopathological evaluations of the hepatic tissues of control and UVC-irradiated rats. (a): Section of a control rat showing polygonal-shaped hepatocytes with centrally located nuclei (N), sinusoid (S), central vein (V), and Kupffer cells (arrow). (b,c): Vitamin-C- and vitamin-B12-treated rats showing normal hepatic architecture with vesicular nuclei (N) and Kupffer cells (arrows) lining the sinusoids (S). (d): Section of the liver of a rat exposed to a low dose of UVC showing normal nuclei (N) of hepatocytes and Kupffer cells (arrow) lining the sinusoids (S). (e,f): A section of the livers of rats exposed to mild and high UVC showed vacuolized hepatocyte cytoplasm (arrows) and congested portal vein (*); arrowheads point to hyperplasia in the wall of the bile ductulus, H&E, ×400.

Figure 6

Histopathological evaluations of the hepatic tissues of vitamin-C- and vitamin-B12-pretreated rats. (a–c): Sections of the livers of rats pretreated with vitamin C and exposed to low, mild, and high UVC doses, respectively, showing normal nuclei (N) of hepatocytes and Kupffer cells (arrows) lining the sinusoids (S); arrowheads point to hyperplasia in the portal vein. (d–f): Sections of the livers of rats pretreated with vitamin B12 exposed to low, mild, and high UVC doses showing normal nuclei (N) of hepatocytes, vacuolized cytoplasm in some hepatocytes (arrows), and arrowheads pointing to bi-nucleated hepatocytes, H&E, ×400.

Figure 7

Electron micrographs of the hepatic tissues of control and UVC-irradiated rats. (a–c): Electron micrographs of liver sections of control rats and rats treated with vitamin C and vitamin B12, showing sections of rounded-shaped nuclei (N) of hepatocytes, nucleoli, mitochondria (M), cisternae of the rough endoplasmic reticulum (rER), glycogen particles (g), and small lysosomes (arrowheads). (d): Electron micrograph of livers of rats exposed to low UVC showing an irregular nuclear outline of the nuclear envelope nucleus (arrow), mitochondria (M), glycogen content (g); the arrowhead points to small lysosomes; (e–h): Electron micrographs of livers of rats exposed to mild and high UVC showing pyknotic nuclei (N), vacuolized mitochondria (M), glycogen content (g), short membranes of rER; microvilli in the bile canaliculi (↑) (×10,000).

Figure 8

Electron micrographs of livers of rats pretreated with vitamin C and vitamin B12 and exposed to low, mild, and high doses of UVC. (a–f): The nuclei (N) of hepatocytes that maintain their normal cellular boundaries, euchromatic nucleus (*), large-sized nucleoli (arrowheads), mitochondria (M), short, flattened cisternae of rER, Kupffer cell (K), active Golgi bodies (arrows), proliferated smooth ER (sER), and small areas of glycogen (g) (×10,000).

Figure 9

An illustration of the experimental design groups.