Dose response and time course effects of N,N-dimethyltryptamine on disruption of rat shuttlebox avoidance.

N,N-Dimethyltryptamine (DMT) was given (ip) in different doses (0.25, 0.5, 1.0, 2.0, 4.0, 8.0 mg/kg) in a randomized order to a group of ten rats (Fisher 344/Mai) who were trained to a high, stable base line of conditioned avoidance responding in the shuttlebox. DMT produced dose-dependent disruptive effects, as a sigmoid function, with 1.0 mg/kg the minimal dose causing disruption and progressively more disruption with increasing doses, reaching a plateau at the highest dose. The disruptive effects were time-related, with onset and peak 8 min after injection, gradual decline thereafter, and disappearance by about 25-30 min. Both the threshold dose and time course for the disruptive effects correspond closely to what has been previously reported for DMT's psychological effects in humans.