CHELATION OF ZINC BY DIETHYLDITHIOCARBAMATE FACILITATES BURSTING INDUCED BY MIXED ANTIDROMIC PLUS ORTHODROMIC ACTIVATION OF MOSSY FIBERS IN HIPPOCAMPAL SLICES

The effect of chelation of zinc by diethyldithiocarbamate (DEDTC) on bursting of CA3 pyramidal cells induced by mixed antidromic plus orthodromic activation of mossy fibers (MP) in hippocampal slices was studied. Slices perfused in artificial cerebrospinal fluid (ACSF) with high (2.5 mM) Ca2+ rarely exhibited triggered bursting following a series of stimulus trains similar to those used in kindling. In contrast, slices perfused with DEDTC (0.1 mM) in ACSF and subsequently perfused with ACSF alone prior to initiating the stimulus trains exhibited robust triggered bursting following the stimulus trains. However, if slices perfused with ACSF containing DEDTC were then perfused with ACSF containing zinc chloride (0.5 muM) followed by ACSF alone, triggered bursting was not induced subsequent to delivering stimulus trains. It is concluded that release of zinc from the mossy fibers induced by tetanic stimulation serves to obtund bursting in CA3 pyramidal cells.