Substance P released endogenously by high-intensity sensory stimulation potentiates purinergic inhibition of nociceptive dorsal horn neurons induced by peripheral vibration.
To investigate the interaction at the spinal level of endogenously released substance P with the effects of endogenously released adenosine, extracellular single-unit activity was recorded from dorsal horn neurons in the anesthetized cat. Vibration to the skin inhibited on-going activity of nociceptive neurons; 20 mg/kg caffeine reversibly blocked this inhibition, indicating mediation via adenosine receptors. In half of the cases, this inhibition was potentiated by iontophoretic application of substance P. High-intensity electrical stimulation to a sensory nerve produced excitation which was blocked by an NK-1 (substance P) receptor antagonist, implicating an endogenous neurokinin. When electrical stimulation preceded the vibrational stimulus, the inhibitory effect of vibration was potentiated. Thus, we suggest that endogenous substance P may potentiate the inhibitory response to endogenous adenosine. The results have important implications for integration of inputs from different sensory modalities, especially as they relate to nociception and pain.
De Koninck
Y
Y
Department of Physiology, McGill University, Montréal, Québec, Canada.
Salter
M W
MW
Henry
J L
JL
D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology*; D002415:Cats; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D018698:Glutamic Acid / Q000494:pharmacology; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007478:Iontophoresis; D009474:Neurons / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D012867:Skin / Q000294:innervation; D013116:Spinal Cord / Q000502:physiology*; D013373:Substance P / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology*; D013997:Time Factors; D014732:Vibration
D001713:Biphenyl Compounds; D006993:Hypnotics and Sedatives; D013373:Substance P; D002110:Caffeine; D018698:Glutamic Acid; C066892:CP 96345