Co-induction of regenerative DNA, proteins and glucose-6-phosphatase activity after treatment of partially hepatectomized rats with nigerian light crude oil.

ABSTRACT

The effect(s) of two doses of Light Crude Oil (LCO) on the concentrations of regenerative DNA, total protein and glucose-6-phosphatase activity, as molecular indices of potential carcinogenicity was determined in liver homogenates of partially-hepatectomized and non-hepatectomized (normal) rat liver. Rats were treated with intraperitoneal injection at six hours, and sacrificed twenty-four hours post-partial hepatectomy (pph); control rats were partially hepatectomized but not treated; while reference rats (with normal liver) were non-hepatectomized and not treated. Regenerative DNA was partially purified from liver homogenates and quantified by the diphenylamine method; total protein concentration was determined directly in the homogenates by the Biuret method; and glucose-6-phosphatase activity by a modification of the Fiske-Subbarow method. Results showed a 21.5% increase in glucose-6-phosphatase activity in partially-hepatectomized rat liver over non-hepatectomized controls, 59.3% and 9.8% increases in total homogenate protein concentration at 2.5 and 5.0ml/kg body weight (bw) LCO respectively; 68.2% and 46.0% increases in glucose-6-phosphatase activity at 2.5 and 5.0 ml/kg bw over the control, respectively. Increases in partially-purified regenerative DNA concentrations also occurred at 13.7% and 20.5% over the controls at 2.5 and 5.0 ml/kg bw, respectively. Nigerian light crude oil (LCO) apparently induced increases in both regenerative DNA and protein syntheses at the first wave of synthesis (24hrs. pph) at the two dose levels tested, while also inducing increases in the bio-transformation by, or perhaps synthesis of, microsomes (cytochrome P450 and 448 detoxification enzymes) as judged by the increased level of the marker enzyme glucose-6-phosphatase. These results may shed more light on the probable molecular mechanism of LCO's potential carcinogenicity and/or toxicity.