The effect of N,N-Diisopropyltryptamine on modified acoustic startle reflex tasks

The psychedelic-related compound N,N-Diisopropyltryptamine (DiPT), unlike its structural relatives, has a behavioral effect in humans that is quite specific. DiPT induces altered pitch perception, such that the tone perceived is random but always in a lower frequency. To examine this unique drug the acoustic startle reflex (ASR) paradigms were used. The ASR is a reaction to a sudden stimulus which can be manipulated to express other behavioral phenomena (e.g., prepulse inhibition (PPI) and fear potentiated startle (FPS)). Habituation is a decrease in startle magnitude following repeated presentation of a startling stimulus. Because DiPT is thought to produce a pseudo-randomization of pitch perception, it was expected that DiPT-treated subjects would show little to no habituation. PPI can occur when a milder stimulus (for example, a low intensity tone) occurs prior to a startling stimulus and is marked by a reduction in startle magnitude. In this experiment, two prepulse stimuli (an 8 kHz and 12 kHz tone) were presented against an 8 kHz tone. It was expected that the 12 kHz tone would produce significantly more PPI than the 8 kHz tone, but that the 8 kHz tone would produce equal amounts of PPI in DiPT treated-subjects because these subjects presumably hear each tone differently. FPS is a paradigm which pairs a US with a CS, such that later presentations of the CS prior to a startling stimulus produce an exaggerated startle reflex. Unfortunately equipment malfunctions in this study precluded the use of the FPS data in analyses. Results from the other two tasks indicated DiPT treated subjects did not habituate, which may have been due to a lack of accurate frequency perception or due to the administration of a large dose of the drug. In the PPI task, no subjects showed increased PPI to the 12 kHz tone over the 8 kHz tone. However one notable finding did arise, the DiPT subjects had significantly lower startle magnitudes than all other groups. This may have been due to the administration of a large dose or a unique effect of a particular receptor, the Imidazoline 1 receptor. Together the results suggest DiPT doesn’t behave similar to its molecular relatives