Differential Expression of Serum LDH Isozymes in the Fish Labeo rohita as a Function of the Pesticide Carbamate

Lactate dehydrogenase LDH (E.C. 3.1.1.27) is one of the chief enzymes of carbohydrate metabolism which catalyses the oxidation of lactate and reduction to pyruvate in glycolysis. It is a dimeric molecule consisting of two separate loci which code for A and B sub- units of the enzyme. The A and B sub- units associate to form 5 tetrameric isozymes (A4, A3B1, A2B2, A3B1 and B4). Isozymes are multiple forms of single enzyme which have different isoelectric points and therefore they can be separated electrophoretically. Following the treatment of carbamate there was an induction of oxidative stress in the experimental fish which is one of the mechanisms of action of carbamate. There were 3 bands in the control fish having LDH A (55.6%) (LDH A' absent), LDH B (31.3%) and LDH B' (13.1%). Following the treatment of carbamate, there was a differential percentage in increase or decrease of different serum isozymes of LDH in the fish, Labeo rohita. It was interesting to observe that following the treatment of carbamate, the B subunits increase till 96h in contrast to the treatment of methyl parathion where the A subunit increased during 24h as earlier reported by Ray & Sinha in 2016. The physiological and biochemical significance are reported herein for the first time.