The neurotoxicity of zinc sulfate in the rat hippocampus and cell death reduction by verapamil

Abstract

The neurotoxic and convulsant effects of zinc have been shown in several reports. In this study the density of pyramidal neurons was investigated in hippocampus after intracortical injections of zinc sulfate. Rats were divided into three groups. Zinc sulfate (500 ?g/kg) was injected into the left hippocampus (near the Bregma) in first group. Zinc sulfate (500 ?g/kg) and verapamil (1 mg/kg) were injected to the same region into the left hippocampus in the second group and an identical volume of saline (2 ?l, %0.9) was given to the same region in third group as control group. After one-week observation, animals were perfused intracardially with neutral formalin (%10) under deep anaesthesia. The serial hippocampal sections were stained with the hematoxylen-eosine. The pyramidal neurons in the dorsal hippocampus were counted under light microscope (with 400 x magnification). The density of pyramidal cell was found in control, zinc and zinc + verapamil 112.48 ± 4.58/mm, 35.12 ± 1.35/mm, 93.90 ± 2.06/mm as respectively. The present results provide direct evidence that zinc might be a relatively potent neurotoxic in the central nervous system. Therefore it can be concluded that verapamil as a calcium antagonist decreased the central neural loss which is caused by zinc sulfate, by preventing calcium into the cell.