The effect of methamphetamine on auditory system was studied on guinea pigs by estimating Pinna reflex thoresholds and ABR wave changes.
Methamphetamine was administered intraperitoneally to guinea pigs, and the time course of Pinna reflex threshold, latencies of waves of I, II, III, and IV, and interpeak latencies of wave I to IV, of wave I to III, and of wave III to IV of the ABR were measured respectively.
The results were as follows;
1. The decrease of Pinna reflex threshold was the greatest at 30 and 66 minutes after the administration of methamphetamine.
2. The wave latencies of ABR were decreased up to 240 minutes after the administration, and the decrease of interpeak latencies of ABR was similar to the decrease of wave latencies. But, the amplitude and the threshold revealed no significant differences before and after administration of methamphetamine.
These results suggest that methamphetamine has the effect of decreasing latencies of firings in both the spiral ganglion and the midbrain auditory tract. In other words, methamphetamine effects pheripheral system (spiral ganglion) as well as the central nervous system generally regarded as an effector organ.
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