Diminished nociceptive response in mice following immunization with neurokinins.

Female BALB/C mice were immunized with various neuropeptides and later tested on a hot plate apparatus for responses to nociceptive stimuli. Animals immunized with substance P, neurokinin B (NKB) or fragments of either peptide were found to spend significantly longer periods of time on the hot plate than controls. Subjects treated with substance K (NKA), its N-terminal fragment or neuropeptide Y were not different from controls. Finally, mice injected with histamine or the EXON-4-related peptide were also found to exhibit delayed responses in this test situation. These results suggest roles for SP, NKB, EXON-4-related peptide and histamine in sensory processing and transmission.