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J Neurosurg 65:825-833, 1986 Inhibition of dorsal-horn cell responses by stimulation of

Summary: J Neurosurg 65:825-833, 1986
Inhibition of dorsal-horn cell responses by stimulation of
the K611iker-Fuse nucleus
Department of Neurosurgery, State University of New York Health Science Center, Syracuse, New York
~" The K611iker-Fuse nucleus (KF) in the dorsolateral pons has been shown to be the major source of
catecholamine innervation of the spinal cord. This has important implications in terms of pain control
mechanisms, since catecholamine-mediated mechanisms are essential for the expression of opiate and other
varieties of antinociception. This study examines the effects of KF stimulation on responses of dorsal-horn
cells to innocuous and noxious cutaneous stimuli in anesthetized cats. Stimulation of the KF potently inhibits
the responses of dorsal-horn cells to both noxious and innocuous stimuli. The threshold for the inhibitory
effect is significantly lower for responses to noxious stimuli as opposed to innocuous stimuli. The inhibitory
effect is specific to the stimulus site, as evidenced by a marked decrease in the effect following small changes
in the position of the stimulating electrode in the brain stem. The latency of the effects indicates a bulbospinal
conduction velocity of 4 to 5 m]sec, which is much slower than usual reticulospinal effects and is consistent
with a catecholamine-mediated system. The dependence of KF-spinal inhibition on intact biogenic amines
was tested by depleting the animals of these amines with reserpine pretreatment. Depletion of biogenic amines
resulted in a significant decrease in the KF spinal inhibitory effects, suggesting their dependence on intact
noradrenergic stores. The results of these studies are consistent with the idea that the KF-spinal system plays
an important noradrenergic-dependent role in the brain-stem modulation of spinal processing of noxious,


Source: Apkarian, A. Vania - Department of Physiology, Northwestern University


Collections: Biology and Medicine