Effect of intracerebroventricular injection of norepinephrine and serotonin on somatosensory evoked potentials in rabbits

The components of somatosensory evoked potentials (SEP), P7, N9, P12, and N15, were recorded from dura mater before and after intracerebroventricular injection (icv) of monoamines. The peak latencies of P12 and N15 were prolonged and the amplitudes of P12 and N15 were decreased following icv norepinephrine (NE) 1 microgram.microliter-1 and serotonin (5-HT) 1 microgram.microliter-1. Generally, P12 and N15 restored to normal 1-2 h after icv NE and 5-HT. Dopamine (DA) 1 microgram.microliter-1, however, did not show any significant effect on SEP. Tolazoline (Tol) 2.5 micrograms.microliters-1 markedly potentiated the inhibitory effect of NE, but propranolol (Pro) 1 microgram.microliter-1 weakened the effect of NE on SEP. These results indicated that icv NE and 5-HT exerted an inhibitory effect on the somatosensory afferent function from thalamus to cortex and/or intercortical areas and alpha-adrenoceptor had an influence on the inhibitory effect of NE