Substance P released endogenously by high-intensity sensory stimulation potentiates purinergic inhibition of nociceptive dorsal horn neurons induced by peripheral vibration.

Publication Type:

Journal Article


Neurosci Lett, Volume 176, Issue 1, p.128-32 (1994)


Animals, Biphenyl Compounds, Caffeine, Cats, Electric Stimulation, Electrophysiology, Glutamic Acid, Hypnotics and Sedatives, Iontophoresis, Neurons, Peripheral Nerves, Skin, Spinal Cord, Substance P, Time Factors, Vibration


<p>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.</p>

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