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Descending facilitatory modulation of a behavioral nociceptive response by stimulation in the adult rat anterior cingulate cortex
Author(s) -
Calejesan Amelita A.,
Kim Susan J.,
Zhuo Min
Publication year - 2000
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1053/eujp.1999.0158
Subject(s) - nociception , neuroscience , stimulation , rostral ventromedial medulla , periaqueductal gray , metabotropic glutamate receptor , chemistry , noxious stimulus , anterior cingulate cortex , reflex , psychology , glutamate receptor , hyperalgesia , central nervous system , receptor , midbrain , biochemistry , cognition
It is well documented that the descending endogenous analgesia system, including the periaqueductal gray (PAG) and the rostral ventral medulla (RVM), play an important role in modulation of nociceptive transmission and morphine‐ and cannabinoid‐produced analgesia. Neurons in the PAG receive inputs from different nuclei of higher structures, including the anterior cingulate cortex (ACC). However, it is unclear if stimulation of neurons in the ACC modulates spinal nociceptive transmission. The present study has examined the effects of electrical stimulation and chemical activation of metabotropic glutamate receptors (mGluRs) in the ACC on a spinal nociceptive tail‐flick (TF) reflex induced by noxious heating. Activation of the ACC at high intensities (up to 500 μA) of electrical stimulation did not produce any antinociceptive effect. Instead, at most sites within the ACC ( n = 36 of 41 sites), electrical stimulation produced significant facilitation of the TF reflex (i.e. decreases in TF latency). Chemical activation of mGluRs within the ACC also produced a facilitatory effect. Descending facilitation from the ACC apparently relays at the RVM. Electrical stimulation in the RVM produces a biphasic modulatory effect, showing facilitation at low intensities and inhibition at higher intensities. The present study provides evidence that activation of mGluRs within the ACC can facilitate spinal nociception. Copyright 2000 European Federation of Chapters of the International Association for the Study of Pain