Inhibition of formalin-induced responses of spinal dorsal horn neurons by stimulation of lateral reticular nucleus in rats.

ABSTRACT

The effects of stimulation of the lateral reticular nucleus (LRN) on responses of spinal dorsal horn neurons produced by formalin (5%, 50 microliters, sc) were investigated. In 12 out of 19 neurons tested, formalin induced 2 distinct phases of response. The first phase was initiated immediately after the injection of formalin and lasted for 3-8 min. The second phase started gradually 20-35 min after administration of formalin and lasted 30-65 min. Both phases of the response were inhibited by LRN stimulation.