5-Methoxy-N:N-dimethyltryptamine, at a dose of 19 µm/kg, strongly disrupted the conditioned avoidance response in trained rats, more so than the known psychotomimetic tryptamines N:N-dimethyltryptamine, N:N-diethyltryptamine, and bufotenine at 25 µm/kg. LSD-25 produced a similar effect at 6 µm/kg. Because mammals have enzymes that can form 5-methoxy-N:N-dimethyltryptamine from serotonin, the authors suggest that abnormal tryptophan metabolism could lead to mental disturbance.
Injecting mescaline directly into an artery partially or completely paralyzes skeletal muscle in dogs. Mescaline and curare together enhance each other's muscle-depressing effects. After mescaline causes full blockade, the muscle still responds to direct electrical stimulation. In chronically denervated muscle, mescaline does not immediately reduce contractions. Adrenaline, potassium chloride, and prostigmine can counteract mescaline-induced paralysis. The paralyzing action of mescaline occurs at the neuromuscular junction.
Intravenous LSD-25 alters brain responses to visual stimuli in rabbits over many hours. Moderate doses (35 µg per animal) enhanced the size of electrically recorded cortical potentials for over six hours, with a triphasic pattern in amplitude over time. The drug also shortened the latency of these potentials by about 10%. LSD-25 markedly reduced the natural variability of both the amplitude and latency of the potentials for one to three hours after injection, indicating a stabilizing effect on neural responses.
In rats, the effect of serotonin (5-HT) and LSD on mortality after physical trauma depends on the route of administration. Intramuscular injection of 5-HT produced a multiphasic mortality curve: small doses increased mortality significantly above controls, mortality then fell to near-control levels as dose increased, and at a critical dose it rose again considerably above controls. Intravenous injection of 5-HT, LSD, or BOL at the doses used caused no significant difference in mortality compared to controls. However, an equimolar intravenous combination of 5-HT and LSD significantly increased mortality after trauma compared to 5-HT plus BOL or saline.