DIFFERENTIAL MODULATION OF SHORT AND LONG-LATENCY SENSORY RESPONSES IN THE SI CORTEX BY IL-6

THE effects of topical application of interleukin-6 (IL-6) on the shor t and long latency evoked unit responses of the neurones in the primar y somatosensory (SI) cortex were determined quantitatively in anaesthe tized rats. IL-6 (0.01, 0.1, 1.0 units) significantly suppressed (-15. 13 +/- 3.4%) short latency afferent sensory responses, while it induce d profound facilitation (+464.74 +/- 132.7%) of long latency responses in a dose-dependent manner. IL-6-induced afferent modulations fully r ecovered by 60 min after drug administration. In control experiments, saline solution containing 0.2% bovine serum albumin, used as a vehicl e, did not affect afferent sensory transmission. Implications of these results are discussed with reference to the different somatosensory f unctions of short and long latency response components in the SI corte x.