INTRODUCTION
Migraine is one of the most common
neurological disorders. It is described by
unilateral throbbing headaches with or
without aura, and characterised by
attacks. The current global prevalence
of migraine is 10%. It is more common
among women and between the ages of 25
and 55. Approximately 6–8% of men and
16–18% of women in America are estimated
to suffer from migraine.
Acupuncture is a method of treatment
that has been used for thousands of years
for a range of conditions. It is a treatment
modality frequently employed in migraine
and is known to be effective. The mechanism
by which it exhibits its effect has not
yet been fully clarified, and various
mechanisms have been proposed. It has
been suggested that the needles stimulate A
delta fibres, closing the ‘pain gates’ in the
CNS so pain is not perceived since the
stimuli fail to reach the thalamus. The
mechanisms of the analgesic effects of acupuncture
involve endogenous opioids
(β-endorphin, encephalin, endomorphin,
dynorphin) as well as serotonin.
It has been suggested that pain in
migraine occurs as a result of vasodilation
in the intracranial vessels or release of
vasoactive peptides as a result of activation
of the perivascular fibres of the trigeminal
nerve. An increase in the concentration
and activity of matrix metalloproteinase
(MMP) in the pathogenesis of migraine
has recently been proposed. MMPs are
neutral proteases responsible for the proteolytic
activity of extracellular matrix proteins.
An increase in MMP production is
known to result in tissue injury and inflammation.
Structures constituting the blood
barrier in the brain contain extracellular
matrix molecules, the substrate for MMPs
(particularly MMP-2 and MMP-9). With
increased MMP activity, the permeability
of the blood–brain barrier is compromised,
and headache occurs with pain-sensitive
meningeal structures being affected.
The proteolytic activities of MMPs
released in the form of inactive zymogens
are inhibited by specific tissue inhibitors
(TIMP). Studies have shown increases in
favour of MMP in the MMP/TIMP ratio in migraine. Studies have also shown that acupuncture
reduces MMP expression in some inflammatory diseases,
such as osteoarthritis.
This study investigated the effect of acupuncture
therapy on levels and activation of MMP-2, a pathological
increase in which has been shown to compromise
the blood–brain barrier, in patients with migraine.