The effects of hallucinogenic drugs on maze exploration in the rat over a 24 hour period

1. The variation with clock-hour in the behaviour of naive rats in a Y-maze has been recorded.2. The number of entries recorded was highest during the light period while the number of faecal boluses was highest during the dark period. Rearing showed a biphasic periodicity.3. The responses to LSD, mescaline and amphetamine also showed significant variation with clock-hour.4. In general, amphetamine, 1.25 mg/kg, increased the number of entries and the number of rears, the effect being greatest at the end of the light period. LSD, 100 mug/kg, and mescaline, 12.5 mg/kg, decreased the number of entries and the number of rears.5. All three drugs decreased the number of faecal boluses. The possible significance of these responses in terms of an effect on the emotional state of the animals is discussed.

The reflection of ejecting and retaining currents in the time-course of neuronal responses to microelectrophoretically applied drugs

The role of ejecting and retaining currents in determining the time-course of neuronal responses to microelectrophoretically applied drugs (acetylcholine, glutamate, noradrenaline, 5-hydroxytryptamine, and mescaline) was investigated. Comparing the parameters of excitatory responses to ejecting currents of successively increasing intensity, the following changes were observed: the response latency became progressively shorter, the plateau became higher, and the recovery time was prolonged. An increase in the intensity or duration of the pre-ejection retaining current resulted in the prolongation of the response latency and the latency to plateau, but did not alter the plateau itself. An increase in the intensity of the post-ejection retaining current reduced the recovery time of the response.