THE ACTION OF MEPHENESIN AND OTHER INTERNEURON DEPRESSANTS ON THE BRAIN STEM

¹ Department of Anatomy, School of Medicine, University of California, Los Angeles 24, California
² Department of Pharmacology, University of Illinois College of Medicine, Chicago 12, Illinois

A method has been devised for the study of the levels of the neuraxis at which drugs act and of the differential sensitivity of interneurons to certain compounds.

The polysynaptic linguomandibular reflex has been shown to be very sensitive to the depressant action of mephenesin and 6-methyl-2-aminobenzothiazole.

Polysynaptic motor pathways altering reflex activity were depressed by the compounds both at brain stem and spinal levels while monosynaptic arcs were totally resistant.

In contrast to atrolactamide which selectively depressed polysynaptic pathways originating at the level of the caudate nucleus, mephenesin did not appear selectively to depress polysynaptic pathways originating from higher levels in the central nervous system.