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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current theories propose that the primary dysfunction in migraine occurs within the CNS and that this evokes changes in blood vessels within pain-producing intracranial meningeal structures that give rise to headache pain. Migraine is now thought of as a neurovascular disorder. It has been proposed that genetic abnormalities may be responsible for altering the response threshold to migraine specific trigger factors in the brain of a migraineur compared to a normal individual. The exact nature of the central dysfunction that is produced in migraineurs is still not clear and may involve spreading depression-like phenomena and activation of brain stem monoaminergic nuclei that are part of the central autonomic, vascular and pain control centers. It is generally thought that local vasodilatation of intracranial extracerebral blood vessels and a consequent stimulation of surrounding trigeminal sensory nervous pain pathways is a key mechanism underlying the generation of headache pain associated with migraine. This activation of the 'trigeminovascular system' is thought to cause the release of vasoactive sensory neuropeptides, especially CGRP, that increase the pain response. The activated trigeminal nerves convey nociceptive information to central neurons in the brain stem trigeminal sensory nuclei that in turn relay the pain signals to higher centers where headache pain is perceived. It has been hypothesized that these central neurons may become sensitized as a migraine attack progresses. The 'triptan' anti-migraine agents (e.g. sumatriptan, rizatriptan, zolmitriptan naratriptan) are serotonergic agonists that have been shown to act selectively by causing vasoconstriction through 5-HT1B receptors that are expressed in human intracranial arteries and by inhibiting nociceptive transmission through an action at 5-HT1D receptors on peripheral trigeminal sensory nerve terminals in the meninges and central terminals in brain stem sensory nuclei. These three complementary sites of action underlie the clinical effectiveness of the 5-HT1B/1D agonists against migraine headache pain and its associated symptoms.
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PMID:Pathophysiology of migraine--new insights. 1056 28

Migraine attacks can be provoked by administration of nitroglycerin, suggesting a role for nitric oxide (NO). The fact that release of the neuropeptide CGRP from trigeminal sensory nerves occurs during the pain phase of migraine and that NO can augment transmitter release prompted us to study CGRP release from the in situ dura mater in guinea pig skulls. Release of CGRP by capsaicin or by high potassium concentration was concentration-dependent and counteracted in calcium-free medium. The anti-migraine compound, sumatriptan, inhibited CGRP release via the 5-HT1-receptor. The NO donors, nitroglycerin, sodium nitroprusside and S-nitroso-N-acetylpenicillamine did not influence CGRP release, alone or together with the stimulants. We concluded that the skull preparation is well suited for scrutinizing CGRP release from dura mater. The fact that sumatriptan inhibits CGRP release as in migraine patients suggests a use for the present preparation in headache research.
Cephalalgia 2000 Nov
PMID:Release of calcitonin gene-related peptide (CGRP) from guinea pig dura mater in vitro is inhibited by sumatriptan but unaffected by nitric oxide. 1116 15

Sumatriptan succinate (SMT) was a highly specific 5-HT1-receptor agonist. It showed high affinity only for 5-HT but no affinity for other neurotransmitter receptors such as muscarinic, dopamine D1, D2, adrenergic alpha 1, alpha 2, and beta. Furthermore, it was highly selective for 5-HT1B/1D-receptor and showed no affinity for 5-HT2 and 5-HT3 receptors. SMT contracted isolated cranial arteries such as basilar, midcerebral, temporal arteries and large arteries in the dura matter, but did not contract coronary, femoral, mesenteric and other arteries. Reflecting these results, SMT induced vasoconstriction of carotid artery, but produced practically no contractile responses in the other arteries mentioned above in anaesthetized animals. These pharmacological characteristics of SMT were different from those of ergot alkaloids, current anti-migraine drugs, which contracted coronary, femoral and other arteries as well. SMT inhibited neurotransmitter release, including CGRP, from trigeminal nerve terminals. Consequently protein extravasation induced by CGRP was inhibited and neurogenic inflammation could be suppressed. It was believed that SMT showed its anti-migraine activity through cranial vasoconstriction via 5-HT1B/1D receptors, since it did not show any analgesic activities. Its clinical efficacy on migraine and cluster headache had been already confirmed in about 100 western countries. Its efficacy was also shown by open trials and placebo controlled double blind tests in Japan.
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PMID:[Anti-migraine drug sumatriptan succinate, a 5-HT1B/1D-receptor agonist]. 1143 16

CGRP is a potent vasodilator that has been shown to have a physiological and/or pathological role in neurogenic inflammation, headaches including migraine, thermal injury, circulatory shock, pregnancy and menopause, hypertension and heart failure and is known to be cardioprotective. CGRP is also a positive inotrope and increases heart rate. Clinical trials have shown beneficial effects of the vasodilatory action of CGRP in hypertension, angina, heart failure, Raynaud's disease and venous stasis ulcers. However, the clinical potential of CGRP is limited as it has to be given by infusion and is quickly broken down. Oral long acting CGRP-mimetics may have potential in disorders in which CGRP has been shown to be beneficial. CGRP-mimetics include capsaicin/vanilloid receptor agonists and gene transfer of an adenoviral vector that encodes prepro-CGRP. CGRP inhibitors have therapeutic potential in conditions in which excessive CGRP-mediated vasodilatation is present; neurogenic inflammation, migraine and other headaches, thermal injury, circulatory shock and flushing in menopause. CGRP inhibitors include capsaicin, antagonists at capsaicin/vanilloid receptors, civamide, CGRP receptor antagonists and 5-HT1D-receptor agonists. Drugs that are 5-HT1D-receptor agonists, the 'triptans' are already commonly used in migraine and the first small molecule CGRP antagonist, BIBN4096BS, is under clinical investigation for the treatment of migraine.
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PMID:Migraine and beyond: cardiovascular therapeutic potential for CGRP modulators. 1177 40

The purpose of this study was to use intravital microscopy to determine the effect of a selective adenosine A1 receptor agonist, GR79236 (1, 3 and 10 microg/kg i.v.), on neurogenic dural blood vessel dilation in anaesthetized rats. Vasodilation was evoked either by electrical stimulation of perivascular trigeminal nerves or by intravenous CGRP. GR79236 (1-10 microg/kg i.v.) caused a dose-dependent inhibition of neurogenic vasodilation, but had no significant effect on dural vasodilation caused by CGRP. GR79236 (1-3 microg/kg i.v.) had no effect on basal dural vessel diameter, but caused transient dose-dependant bradycardia and hypotension. Bradycardia was more prolonged following 10 microg/kg i.v. GR79236. Pre-treatment with the adenosine A1 receptor antagonist DPCPX (1 mg/kg i.v.) prevented the inhibitory effect of GR79236 (10 microg/kg i.v.) on neurogenic vasodilation as well as GR79236-induced bradycardia and hypotension. These data suggest that the inhibition of neurogenic vasodilation by GR79236 is mediated via the activation of prejunctional adenosine A1 receptors. Provided the systemic cardiovascular effects could be limited, such a mechanism may offer a novel approach to migraine therapy.
Cephalalgia 2002 May
PMID:Study of an adenosine A1 receptor agonist on trigeminally evoked dural blood vessel dilation in the anaesthetized rat. 1210 87

5-HT1D (but not 5-HT1B)-receptor immunoreactivity (i.r.) can be detected on trigeminal fibres within the spinal trigeminal tract of the human brainstem. The present study used immunohistochemical and morphometric techniques to determine the proportions of trigeminal fibres expressing substance P, CGRP or 5-HT1D-receptor immunoreactivities. Co-localization studies between 5-HT1D-receptor and substance P- or CGRP-i.r. were also performed. Brainstem material was obtained with consent (four donors) and the total number of immunoreactive fibres within the trigeminal tract was estimated using random field sampling. A greater proportion of fibres (>1 microm diameter) expressed CGRP-i.r. (80 +/- 6%) compared with substance P-i.r. (46 +/- 7%) or 5-HT1D-receptor-i.r. (25 +/- 1%). 5-HT1D-receptor-i.r. was co-localized on some CGRP- or substance P-i.r. fibres. This suggests that 5-HT1D-receptors can regulate the release of CGRP and substance P and may be relevant to the clinical effectiveness of 5-HT1B/1D-receptor agonists in the treatment of migraine and other cranial pain syndromes.
Cephalalgia 2002 Jul
PMID:An immunocytochemical investigation of human trigeminal nucleus caudalis: CGRP, substance P and 5-HT1D-receptor immunoreactivities are expressed by trigeminal sensory fibres. 1213 41

The shared anatomical and physiological substrate for headache syndromes is the neural innervation of the cranial circulation. Evidence suggests, that the observed dilatation of vessels in trigeminal pain is not inherent to a specific headache syndrome but rather a feature of the physiology of the trigeminal neural innervation of the cranial circulation. Moreover, the impact of vascular changes for the generation of headaches remains elusive. The trigeminal nerve innervates blood vessels within ipsilateral meninges. Upon activation neuropeptides such as CGRP are released. Blockade of both the trigeminal nerve system and neuropeptides are crucial targets for headache alleviating drugs. While these mechanisms are well known the events within and outside the CNS which initiate headaches are poorly understood. This article will review the anatomy and physiology of the trigeminovascular system which demand renewed consideration of the neural influences in many primary headaches.
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PMID:[What is needed to develop a headache? Anatomical and pathophysiological implications]. 1525 41

In the past months significant new data have been published in the field of headache and migraine. With the publication of the second and revised version of the classification of headache disorders, new entities such as chronic migraine have been introduced. Moreover, the repertoire of drugs available for the treatment of migraine has changed as well. Whereas ergot derivatives have been almost completely taken off the market, seven triptans in 23 different preparations are now available and allow the physician to customize the treatment of acute attacks. CGRP antagonists, a completely new generation of anti-migraine compounds for the treatment of acute attacks, have now been tested successfully in clinical trials. For the prophylaxis of migraine, several agents that had been well established for decades have recently been taken off the market too, but new agents such as topiramate, which possesses different modes of action, have been tested successfully and are now available for the prophylaxis of migraine. The following review will summarize the newest developments in acute therapy and prophylactic treatment of migraine.
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PMID:[Faster, higher, further. Current thinking on acute and prophylactic treatment of migraine]. 1532 86

BIBN4096BS is a CGRP-antagonist effective in the treatment of migraine. Blocking the receptor of a strong vasodilator involves a theoretical risk of causing cerebral vasoconstriction, a probability not previously investigated with BIBN4096BS. Seven healthy volunteers completed this double-blinded placebo-controlled crossover study. The volunteers received randomly 10 min infusions of either placebo, 2.5 mg or 10 mg of BIBN4096BS on 3 separate days. Transcranial Doppler was used to measure the middle cerebral artery blood flow velocity (V(MCA)); global and regional cerebral blood flow (rCBF(MCA)) was measured by 133-Xenon inhalation SPECT. The diameter of the temporal and radial artery was measured by high-resolution ultrasound. Systemic haemodynamics and partial pressure of CO(2) (P(et)CO(2)), and adverse events were monitored regularly. BIBN4096BS had no influence on global or regional cerebral blood flow, or on the blood flow velocity in the middle cerebral artery. There was no effect on systemic haemodynamics and adverse events were minor. We conclude that there is no effect of CGRP-receptor blockade on the cerebral or systemic circulation in humans. Circulating CGRP is therefore not likely to exert a vasodilatory activity in the resting state and the use of BIBN4096BS for acute migraine seems to be without risk of cerebral vasoactivity. These data suggest that BIBN4096BS is the first specific antimigraine drug without vasoactive effect.
Cephalalgia 2005 Feb
PMID:The CGRP-antagonist, BIBN4096BS does not affect cerebral or systemic haemodynamics in healthy volunteers. 1565 51

Neuropeptide release and the expression of c-fos like immunoreactivity (c-fos LI) within trigeminal nucleus caudalis neurons (TNC) are activation markers of the trigeminal nerve system. Glyceryltrinitrate (GTN) is believed to stimulate the trigeminal nerve system, thereby causing headache. We examined the effects of a 30 min NO-donor infusion on CGRP release in jugular vein blood and c-fos LI within TNC of the rat. GTN (2 and 50 microg/kg/min) or NONOate infusion (25 nmol/kg/min) did not cause any CGRP release during and shortly after infusion, whereas administration of capsaicin resulted in strongly increased CGRP levels. GTN infusion (2 microg/kg/min for 30 min) did not lead to enhanced c-fos LI after 2 h and 4 h, whereas capsaicin infusion caused a time- and dose-dependent expression of c-fos LI within laminae I and II of the TNC. Surprisingly, GTN attenuated capsaicin-induced c-fos expression by 64%. The nitric oxide synthase (NOS) inhibitor L-NAME (5 and 50 mg/kg) reduced capsaicin-induced c-fos LI dose dependently (reduction by 13% and 59%). We conclude that GTN may lead to headaches by mechanisms independent of CGRP release from trigeminal nerve fibres. GTN doses comparable to those used in humans did not activate or sensitize the trigeminal nerve system. Both GTN and L-NAME reduced capsaicin-induced c-fos LI. This is most likely due to a feedback inhibition of nitric oxide synthases, which indicates that the c-fos response to capsaicin within TNC is mediated by NO dependent mechanisms.
Cephalalgia 2005 Mar
PMID:CGRP release and c-fos expression within trigeminal nucleus caudalis of the rat following glyceryltrinitrate infusion. 1568 99


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