Modification of the effects of LSD-25, d-amphetamine and tryptamine on electrically evoked responses in the visual system by methiothepin and octoclothepin.

LSD-25 (32 microgram/kg), d-amphetamine (3.2 mg/kg), and tryptamine (320 to 3200 microgram/kg) given intravenously depressed the response recorded in the visual cortex to electrical stimulation of the optic chiasm of the chloralose anesthetized cat. Relatively large doses of 1 mg/kg of the dibenzothiepin derivatives, methiothepin and octoclothepin, antagonized the depressant effects of both LSD-25 and tryptamine to a greater degree than d-amphetamine.