Lead-exposed increase in movement behavior and brain lipid peroxidation in fish

Lipid peroxides formation and motor activity were studied in fish under lead exposure for a period of 30 days. The in vitro studies of lead exposure were also performed in fish brain homogenates. Spontaneous motor activity of fish was affected by lead exposure (50 microg/L). The behaviors were increased in fish during the first three days with jerky movements and then as spontaneous movements between 16 and 30 days of lead exposure. Lipid peroxidation, which is measured as thiobarbituric acid reactive species, was increased by 52% on 15 days and 156% on 30 days of lead exposure (50 microg/L). The effects of lead exposure (50 microg) were also observed in in vitro fish brain homogenates (1 mL, 5% w/v) alone, in presence of pro-oxidant system (as iron 100 microg) or anti-oxidant system (as alpha-tocopherol, 100 microg). Steady state increments of lipid peroxidation were apparent up to the concentration of 40 microg of lead treatment in brain homogenates, which subsequently attained a plateau up to the treatment of 100 microg lead. Lead at the concentration of 50 microg promoted lipid peroxidation by 225%. Iron-induced lipid peroxidation was 135% as compared to control. Lead neurotoxicity was further aggravated by iron by 33%, while the combined impact was 476% higher when compared with the control (i.e., untreated brain homogenates). Alpha-tocopherol reduced the levels of lipid peroxidation by 31%. Moreover, treatment of alpha-tocopherol also suppressed the lead neurotoxicity by 53%. These findings suggest that lead intoxication increases spontaneous motor activity and lipid peroxides in brain of fish in chronic exposure. I, therefore, speculate that presence of iron may accentuate lead neurotoxicity, while on the other hand, treatment with biological anti-oxidant alpha-tocopherol may provide relief from lead neurotoxicity.