The effects of buspirone, BMY-13805 and 1-(2-pyrimidinyl)-piperazine on cat spinal reflexes.

Buspirone and its analog BMY-13805, clinically effective anxiolytics and their metabolite, 1-PP, were tested on cat spinal reflexes. In the spinal preparation, the monosynaptic reflex and the dorsal root potential were not changed by buspirone, BMY-13805 or 1-PP. Significant changes in the dorsal root potential and monosynaptic reflex were seen after buspirone administration in the intact neuraxis preparation. Generally, these changes had a bimodal pattern, a significant change within 1 hr after buspirone administration, then a period of remittance, followed by a second significant change 3 or more hr later. They included increases in the dorsal root potential and the following changes in the conditioned monosynaptic reflex: an increase in excitatory postsynaptic potential, an increase in postsynaptic inhibition, and decreases in presynaptic inhibition. These data indicate that buspirone does not affect these reflexes directly, but alters supraspinal mechanisms that regulate spinal reflexes.