PT - JOURNAL ARTICLE AU - Swaran J. S. Flora AU - Geetu Saxena AU - Ashish Mehta TI - Reversal of Lead-Induced Neuronal Apoptosis by Chelation Treatment in Rats: Role of Reactive Oxygen Species and Intracellular Ca<sup>2+</sup> AID - 10.1124/jpet.107.121996 DP - 2007 Jul 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 108--116 VI - 322 IP - 1 4099 - http://jpet.aspetjournals.org/content/322/1/108.short 4100 - http://jpet.aspetjournals.org/content/322/1/108.full SO - J Pharmacol Exp Ther2007 Jul 01; 322 AB - Lead, a ubiquitous and potent neurotoxicant causes several neurophysiological and behavioral alterations. Toxic properties of lead have been attributed to its capability to mimic calcium and alter calcium homeostasis. In this study, we have addressed the following issues: 1) whether chelation therapy could circumvent the altered Ca2+ homeostasis and prevent neuronal death in chronic lead-intoxicated rats, 2) whether chelation therapy could revert altered biochemical and behavioral changes, 3) whether combinational therapy using two different chelating agents was more advantageous over monotherapy in lead-treated rats, and 4) what could be the mechanism of neuronal apoptosis. Results indicated that lead caused a significant increase in reactive oxygen species, neuronal nitric-oxide synthetase, and intracellular free calcium levels along with altered behavioral abnormalities in locomotor activity, exploratory behavior, learning, and memory that were supported by changes in neurotransmitter levels. A fall in membrane potential, release of cytochrome c, and altered bcl2/bax ratio indicated mitochondrial-dependent apoptosis. Most of these alterations reverted toward normal level following combination therapy over monotherapy with calcium disodium EDTA (CaNa2EDTA) or monoisoamyl meso-2,3-dimercaptosuccinic acid (MiADMSA). It could be concluded from our present results that combined therapy with CaNa2EDTA and MiADMSA might be a better treatment protocol than monotherapy with these chelators in lead-induced neurological disorders. We for the first time report the role of Ca2+ in regulating neurological dystrophy caused by chronic lead exposure in rats and its recovery with a two-course treatment regime of mono or combination therapy. The American Society for Pharmacology and Experimental Therapeutics