The effect of myelin basic protein (MBP) on the bioelectric activity of spinal cord and cerebellar neurones.

The effects of myelin basic protein (MBP) on the ventral root response in rat spinal cord in situ and on the spontaneous bioelectric activity of cultured rat Purkinje cells were investigated. Injection of 2 or 4 microl MBP (10(-4) M/l) into the motoneurone pool reduced the ventral root response to dorsal root stimulation. The depression was long-lasting (30-50 min) and partially reversible. At 5 x 10(-6) M/l MBP abolished the spontaneous activity of most cultured Purkinje cells, an effect which was not blocked by haloperidol, propranolol, phenoxybenzamine and bicuculline. The EC(50) for the depression was 4 + or - 1 x 10(-6) M/l.