Disruption of taste aversion learning by pentylenetetrazol.

Rats were taught an aversion to a sucrose taste cue (CS) by pairing it with lithium chloride-induced toxicosis (UCS). The CS-UCS interval was 30 min. Animals were injected with pentylenetetrazol (PTZ) (50 mg/kg at 0, 15, 25, 28 or 30 min after the CS in an attempt to disrupt taste aversion learning. Only animals given PTZ 30 min after the CS (simultaneously with the UCS) showed a significant learning deficit. However, learning deficits were also observed in individual animals in groups given PTZ at 15, 25 and 28 min. As lithium salts may produce seizures and abnormal electroencephalographic activity, it is suggested that the neurophysiological consequences of PTZ administration may interact with those of LiCl, causing a greater amnesic effect than PTZ by itself. The resulting interference with the memory trace is probably affecting either the neural engram underlying the CS or the associative bond between the CS and UCS. Evidence was also found that PTZ could act as a UCS with which to establish a mild taste aversion.