Intravital, reversible, bilateral selective sulfide loading of the synaptic vesicle zinc in certain systems within the mammalian hippocampus can be produced, at least once daily, by exposure of animals to graded inhalation of H2S to the level of seizure followed by 15 sec apnea. Heavy sulfide loading during the first half hour after seizure, and then gradual disappearance of the sulfide from the synapses during the succeeding 2 hr, can be displayed in the mossy fiber system by Timm's silver-sulfide impregnation method modified to exclude all sulfide from the histological reagents. During most of the period of heavy sulfide loading rats, if given background sensory arousal, appear normal in their somatomotor and sensory activities and can be, for instance, memory tested on complex mazes. Hence, if such synaptic sulfide loading determines functional blocking, as von Euler has shown that it almost certainly does in acute electroanatomical experiments, this procedure furnishes a chemical ablation tool for behavioral investigations of the functions of the fascia dentata and hippocampus. © 1970.
McLardy, T. (1970). Intravital nontoxic sulfide loading of synaptic zinc in hippocampus. Experimental Neurology, 28(3), 416–419. https://doi.org/10.1016/0014-4886(70)90178-0