Feed-forward inhibition: a novel cellular mechanism for the analgesic effect of substance P.
Substance P (SP) is a neuropeptide well known for its contribution to pain transmission in the spinal cord, however, less is known about the possible modulatory effects of SP. A new study by Gu and colleagues, published in Molecular Pain (2005, 1:20), describes its potential role in feed-forward inhibition in lamina V of the dorsal horn of the spinal cord. This inhibition seems to function through a direct excitation of GABAergic interneurons by substance P released from primary afferent fibers and has a distinct temporal phase of action from the well-described glutamate-dependent feed-forward inhibition. It is believed that through this inhibition, substance P can balance nociceptive output from the spinal cord.
Wu
Long-Jun
LJ
Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, Medical Science Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada. longjun.wu@utoronto.ca
Xu
Hui
H
Ko
Shanelle W
SW
Yoshimura
Megumu
M
Zhuo
Min
M
D000344:Afferent Pathways / Q000378:metabolism; D000818:Animals; D006801:Humans; D009433:Neural Inhibition / Q000502:physiology*; D009619:Nociceptors / Q000378:metabolism; D010146:Pain / Q000378:metabolism*; D020671:Posterior Horn Cells / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D018040:Receptors, Neurokinin-1 / Q000378:metabolism; D013126:Spinal Nerve Roots; D013373:Substance P / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*
D018040:Receptors, Neurokinin-1; D013373:Substance P