Determination of diazinon's toxicity degree and evaluation its effecton some Enzymatic indices in Huso huso

In present study, it was determinated LC50 96-h and toxicity degree of diazinon in Huso huso, then were evaluated effects of sub-lethal concentrations on tow general enzymatic indices including Alanine and Aspartate aminotransferase of plasma and one specific enzymatic index including tissue AChE enzyme. The median lethal concentration, lowest observed effect concentration and maximum allowable toxicant concentration was measured 5.47, 4.28 and 0.54 mg.L-1, respectively. Also, diazinon according by amount of LC50 was classified in “moderate toxicity degree” for this sturgeon. The test results showed that with increasing sub-lethal concentrations of diazinon in water, AST and ALT enzyme activity in experimental fish were increased, Thus, a direct relationship seen between the concentration of diazinon with the public indices. However, increased concentrations of diazinon, causing a decrease in cholinesterase activity in both brain and muscle tissues. In other words, inhibition of AChE is directly related to the concentration of pesticide.The diazinon pesticide concentrations for non-target specieses which were ineffective and allowable according to the lethal test can lead to their enzymatic indicies of serum and AChE responses.