The present study aimed to study the effect of acute oxidative stress on serum isoenzyme expression and protein profile induced by acute paraquat (PQ) toxicity in female rats. The protective role of α-lipoic acid (LA) administration has been challenged. Acute paraquat toxicity was induced by administration of 1/4 LD50 in adult female wistar rats. α-Lipoic acid was orally supplemented 2 h prior PQ administration at a dose equivalent to 10 mg/100 g body weight. Isoenzyme expression of serum enzymes, namely MDH, ACP, G6PDH, ASAT and EST, as well as serum protein patterns were determined 24 h post administration. The present data revealed a significant rise in total serum activity of MDH, ACP and ASAT but insignificant change in total activity of G6PDH and EST in PQ group versus the control group. Fractional activities of serum isoenzymes exhibited the same trend as that demonstrated in serum total activity except in case of EST. α-LA administration exhibited a high protective effect against the changes in both total and fractional activities of serum ACP and ASAT but a considerable protection in case of MDH. The present investigation supports the idea that the estimation of the fractional rather than the total activity of an enzyme is more reliable in reflecting the molecular consequences of acute oxidative stress. The present data has also exposed a wide-range variation in serum protein patterns duo to PQ and/or lipoic acid treatment, which indirectly reflects a parallel variation in the process of gene expression and/or proteolytic activity.
Key words: acute oxidative stress, acute paraquat toxicity, α-lipoic acid, isoenzyme expression of serum MDH, ACP, G6PDH, ASAT, EST, serum protein patterns
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