Antinociceptive system
Nociceptive system has a functional antipode -
antinociceptive system, which controls the activity of the nociceptive system
structures.
Antinociceptive system consists of a variety of
nerve structures belonging to different departments and organizations CNS
levels ranging from afferent inputs in the spinal cord and cerebral cortex
ending. Each relay switch in the nociceptive system has its own control unit
for the active constituent of nociceptive neurons. Nociceptive and
antinociceptive systems form a common system of pain sensitivity, which
determines the nature of nociceptive signaling, measure its perception and the
reaction to it.
Antinociceptive system plays an essential role in
the mechanisms of prevention and elimination of pathological pain. Joining the
reaction at nociceptive stimuli, it weakens the upward flow of nociceptive
stimulation and the intensity of pain, so pain is under control and does not
acquire pathological character. If any of the activities antinociceptive system
nociceptive stimuli of small intensity even cause excessive pain. This effect
takes place, for example, congenital or acquired deficiency antinociceptive
mechanisms of the spinal cord, in particular when failure "gating
control", in violation of the excitation by the thick fibers, activating
this control, with injuries, infectious lesions of the central nervous system
and so on.
In cases of failure antinociceptive system, it
must be additional and special activation. The latter is carried out in various
ways. Effective anti-nociceptive direct electrical stimulation of the brain
structures that can cause suppression of even severe pathological pain. Many
analgesics, including opioids exert their effect not only by a direct downward
pressure on nociceptive neurons and blockade of excitatory synaptic
transmission, but also via activation of antinociceptive system structures.
Through activation of antinociceptive system function and non-pharmacological means
of suppression of pain (eg, acupuncture). Electrical stimulation of thick
fibers, activating "gating control" and other mechanisms of
antinociceptive system, used clinically to suppress many kinds of pain, in
particular peripheral origin.
However hyperactivation antinociceptive system may
lead to inadequate hypoalgesia and even profound suppression of pain
sensitivity. These effects occur in the formation of structures in
antinociceptive generator system. Hysterical loss of pain sensitivity, analgesia
occurs in severe stress and some psychoses, it is also associated with
increased activity of antinociceptive system.
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