Effects of vitamin C on the formation of aflatoxin B₁-DNA adduct in rat livers treated with radiation and aflatoxin B₁

Vitamin C가 방사선과 Aflatoxin B₁을 처리한 흰쥐의 간세포에서 Aflatoxin B₁-DNA Adduct 형성에 미치는 영향

The objective of this study was to examine the effects of vitamin C on the formation of aflatoxin $B_1$ ($AFB_1$)-DNA adduct and $AFB_1$-induing cellular oxidative damage in rat livers treated with radiation and $AFB_1$. Six-week-old male Sprague-Dawley rats were randomly divided into five groups: the control group, the $AFB_1$-treated group, the group treated with $AFB_1$ and vitamin C, the group treated with X-ray and $AFB_1$, and the group treated with X-ray and $AFB_1$ with vitamin C. On the first day of the experiment, only one dose of X-rays was exposed to the entire liver at 1,500 cGy. Next, vitamin C was injected at 10 mg/kg body weight via intraperitoneal injection, followed an hour later by the administration of 0.4 mg/kg of $AFB_1$ via intraperitoneal injection. These treatments were administered every three days for 15 days. On the 16th day, the animals were sacrificed. The $AFB_1$ contents of the rat sera were determined via indirect competitive ELISA. In the quantitative analysis of $AFB_1$ in the rat sera via ELISA, $5.17{\pm}0.34ng/mL$ of $AFB_1$ was detected in the $AFB_1$-treated groups, but the amount decreased more significantly to $3.23{\pm}0.76ng/mL$ in the groups treated with $AFB_1$ and vitamin C (p<0.01) than in the $AFB_1$-treated groups. The effect of vitamin C on $AFB_1$-DNA adduct formation was determined via ELISA. The values of $AFB_1$-DNA adduct formation were $9.38{\pm}0.41ng/mL$ in the $AFB_1$-treated groups, but the amount decreased more significantly to $5.28{\pm}0.32ng/mL$ in the groups treated with $AFB_1$ and vitamin C (p<0.01) than in the $AFB_1$-treated groups. Immunohistochemistry revealed that the accumulation of the $AFB_1$ was not observed in the normal liver tissue (G1). The $AFB_1$-positive materials were observed in the central vein and the portal vein of the liver tissue from the $AFB_1$(G2) treatment or the X-ray and $AFB_1$(G4) co-treatment, but the $AFB_1$-positive materials were observed weakly in the group treated with vitamin C (G3 and G5). These results indicate that vitamin C had ameliorating effects on the $AFB_1$ accumulation of liver tissue.

본 연구는 흰쥐에게 $AFB_1$을 투여하거나 방사선과 $AFB_1$을 병합처리함으로 유발된 흰쥐의 간세포에서의 $AFB_1$-DNA 부가체의 형성과 세포의 산화적 손상에 대한 vitamin C의 효과를 조사하기 위하여 수행되었다. X-ray 조사는 실험기간 내 단 1회로 실험사육기간 1일에 조사 하였고 X-ray 조사 후 vitamin C를 투여하였으며 vitamin C 투여 1시간 후 $AFB_1$을 투여하였다. Vitamin C와 $AFB_1$은 모두 복강투여로 실험 사육 첫 일부터 1회 시작하여 3일에 한번씩, 5회 반복 투였으며 실험동물 사육기간은 총 15일로 하였다. ELISA에 의한 흰쥐의 혈청 내 $AFB_1$ 잔여 농도는 $AFB_1$ 단독 투여군에서 $5.17{\pm}0.34ng/mL$이었으나 여기에 vitamin C 혼합 투여군에서는 $3.23{\pm}0.76ng/ml$가 검출되었다. 간세포의 $AFB_1$-DNA adduct 농도는 $AFB_1$ 단독 투여군에서는 $9.38{\pm}0.41ng/mL$이었으며 2군에 vitamin C를 함께 투여한 3군에서는 $5.28{\pm}0.32ng/ml$로 나타나 2군에 비해 유의적으로(p<0.001) 44% 감소한 양상을 나타내었다. 한편 X선 조사와 $AFB_1$ 병합처리한 4군에 비해 4군에 vitamin C를 투여한 5군에서 혈청 내 $AFB_1$ 함량과 간세포의 $AFB_1$-DNA adduct 함량이 다소 감소하였으나 유의적인 차이는 없었다. 또한 면역조직화학적 관찰에서 $AFB_1$ 단독 투여군에서는 중심정맥과 혈관주변에서 $AFB_1$ 축적이 관찰되었는데 이러한 현상은 vitamin C를 혼합 투여함으로써 중심정맥과 혈관 주변의 갈색 침전이 현저하게 감소한 것으로 나타났다. 그러나 X선 조사와 $AFB_1$ 병합 처리한 군에서는 그 정도가 약했다.