CUTANEOUS NOXIOUS MECHANICAL SENSORY STIMULATION INCREASES EXTRACELLULAR RELEASE OF NORADRENALINE AND SEROTONIN IN THE CEREBRAL-CORTEX IN ANESTHETIZED RATS

The effects of noxious and innocuous mechanical stimulation of various segmental skin areas (face, forelimb or paw, back, hindlimb or paw) on extracellular noradrenaline (NA) and serotonin (5-HT) release in the parietal lobe of the cerebral cortex were examined in urethane-anesthetized rats, by means of the microdialysis technique. Pinching of a fore- or hindpaw for 5 min produced significant increases in NA and 5-HT release in the cerebral cortical extracellular space, whereas pinching of the face or buck or brushing of the face, forelimb, back or hindlimb produced no significant changes. These results demonstrate that cutaneous sensory stimulation can affect extracellular NA and 5-HT release in the cerebral cortex, and that the efficacy of the stimulation on cerebral cortical NA and 5-HT release is dependent on the sensory modality and the region of skin stimulated.