1alpha, 25-dihydroxyvitamin D3 prevents DNA damage and restores antioxidant enzymes in rat hepatocarcinogenesis induced by diethylnitrosamine and promoted by phenobarbital

Abstract

Aim: To investigate the chemopreventive effects of 1alpha, 25-dihydroxyvitamin D(3) in diethylnitrosamine induced, phenobarbital promoted rat hepatocarcinogenesis.

Methods: The rats were randomly divided into 6 different groups (A-F). Groups A, C and E rats received a single intraperitoneal (i.p.) injection of diethylnitrosamine (DEN) at a dose of 200 mg/kg body mass in 9 g/L NaCl solution at 4 wk of age, while group B served as normal vehicle control received normal saline once. After a brief recovery of 2 wk, all the DEN treated rats were given phenobarbital (PB) at 0.5 g/L daily in the basal diet till wk 20. Group A was DEN control. Treatment of 1alpha, 25-(OH)2D3 in group C was started 4 wk prior to DEN injection and continued thereafter till wk 20 at a dose of 0.3 microg/100 microL propylene glycol per one single dose (os) twice a week. Group E received the treatment of 1alpha, 25-(OH)2D3 at the same dose mentioned as above for 15 wk. The rats in group D and F received 1alpha, 25-(OH)2D3 alone as in group C without DEN injection.

Results: The comet assay showed statistically higher mean values for length to width ratios (L: W) of DNA mass and tailed cells (P<0.01; P<0.01 respectively) in DEN treated rats as compared to their normal controls. Continuous supplementation of 1alpha, 25-dihydroxyvitaminD2 showed a significant (P<0.01) decrease in L:W ratio of DNA mass tailed cells. Furthermore, 1alpha, 25-(OH)2D3 supplementations elevated the super oxide dismutase (SOD) activity, hepatic malondialdehyde (MDA) level, reduced glutathione (GSH) and glutathione S-transferase (GST) activity (P<0.01, P<0.05, P<0.05 and P<0.05 respectively). As an endpoint marker histological changes were observed to establish the chemopreventive effects of 1alpha, 25-dihydroxyvitaminD2.

Conclusion: Supplementations of 1alpha, 25-(OH)2D3 has a marked protection against hepatic nodulogenesis, antioxidant enzymes and DNA damages in DEN induced rat hepatocarcinogenesis promoted by phenobarbital.

Figure 1

Basic experimental protocol.

Figure 4

Shows the section of the rat liver (group A) showing abnormal hepatic architecture after a single i.p. Injection of DEN (200 mg/kg b.m.) (HE × 325).

Figure 5

Shows the thin section of normal rat liver untreated (group B) showing hepatocellular architecture (HE × 325).

Figure 6

Shows section of rat liver (group C) initiated with DEN and supplemented with 1α, 25(OH)₂D₃ [0.3 μg/100 μL propylene glycol per os twice a week for 20 wk] showing almost normal hepatic architecture (HE × 325).

Figure 2

Box-and-whisker plot of the distribution of DNA damage treated with 1alpha, 25(OH)₂D₃ in DEN induced rat hepatocarcinogenesis promoted by phenobarbital.

Figure 3

Tailed cells (%) in hepatic cells of rats treated with 1alpha, 25(OH)₂D₃ in DEN induced rat hepatocarcinogenesis promoted by phenobarbital.