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

The functional role of the trigeminal system has been addressed in experiments on the cortical surface of alpha-chloralose anaesthetized cats. Application of calcitonin gene-related peptide (CGRP) caused a concentration-dependent increase in arteriolar calibre by 38 +/- 5% (n = 8) with an IC50 of 2 nM. Cerebral veins did not relax upon CGRP administration (n = 12). Substance P (SP) was less potent but showed dilatation of both arterioles (21 +/- 4%) and veins (16 +/- 4%). The cerebrovascular trigeminal system was investigated after chronic (14 days) surgical lesion of the trigeminal nerve with the concomitant disappearance of perivascular CGRP/SP immunoreactive nerves. The cortical arteriolar responses to subarachnoid microinjections of acidic (pH 6.8) and basic CSF (pH 7.6) as well as noradrenaline (10(-4) M), neuropeptide Y (10(-7) M), prostaglandin F2x (10(-6 M), barium chloride (10(-4) M), and autologous blood (5 microl) were examined in anaesthetized cats with lesions of the trigeminal nerve, and were compared with their effects in sham-operated animals. The magnitude of the vasodilator and vasoconstrictor responses to these agents was unaffected by trigeminal lesions. However, duration of the vasoconstriction produced by basic CSF, but not the vasodilitation to acidic CSF, was markedly prolonged by trigeminal lesions (from 0.8 +/- 0.1 min to 2.2 +/- 0.3 min, p < 0.01). Also, the vasoconstrictor responses to noradrenaline, prostaglandin F2x, barium chloride, and autologous blood were significantly prolonged, while the maximum contractile effect to each agent was similar in lesioned as in sham-operated controls. The effects of CGRP, SP, and neurokinin A (NKA) have been examined on isolated cerebral arteries in vitro. Different CGRP analogues induced a strong relaxation with no difference in Imax (85-96%) or pD2 values (8.65 - 9.12). NKA induced a stronger relaxation than SP (Imax: 33% and 13%, respectively). SP was more potent than NKA (pD2:8.7 and 7.7, respectively). Capsaicin, a substance which selectively causes the release of stored sensory neuropeptides (CGRP, SP, NKA), caused in vitro relaxation of precontracted arteries. This relaxation was not affected by the neurokinin blocker spantide, but shifted towards higher capsaicin concentrations by the CGRP antagonist (CGRP 8-37. Thus, in this preparation CGRP rather than a neurokinin (SP/NKA) is responsible for the capsaicin-induced dilatations.
Cephalalgia 1995 Oct
PMID:Modification of vasoconstrictor responses in cerebral blood vessels by lesioning of the trigeminal nerve: possible involvement of CGRP. 853 89

The vasomotor effects of calcitonin gene-related peptide (CGRP) analogues have been studied in circular segments of fresh human cerebral arteries obtained at neurosurgical operations using a sensitive in vitro system. Human alpha-CGRP, human beta-CGRP, rat alpha-CGRP and rat beta-CGRP induced strong and potent relaxation of precontracted circular vessel segments. The Imax (maximum relaxant effect) to human calcitonin was low and the pD2 (concentration for half maximum effect) 7.7 was much lower than that of CGRP. The CGRP-1, antagonist human alpha-CGRP8-37 blocked the response to human alpha-CGRP but not to human beta-CGRP, while the putative antagonist [Tyr]CGRP28-37 did not. Capsaicin (10(-15)-10(-8)M) caused relaxation of the cerebral arteries by 22% of precontraction. Pre-treatment with 10(-6)M human alpha-CGRP8-37 inhibited this relaxation. Human alpha-CGRP increased the cyclic AMP content of human cerebral arteries in a concentration-dependent manner. This increase in adenylyl cyclase activity was blocked by human alpha-CGRP8-37. The results suggest that CGRP-1 receptors coupled to adenylyl cyclase are present in human cerebral arteries.
Cephalalgia 1996 Aug
PMID:Calcitonin gene-related peptide is released from capsaicin-sensitive nerve fibres and induces vasodilatation of human cerebral arteries concomitant with activation of adenylyl cyclase. 886 58

Capsaicin, the most pungent ingredient in red peppers, has been used for centuries to remedy pain. Recently, its role has come under reinvestigation due to evidence that the drug acts selectively on a subpopulation of primary sensory neurons with a nociceptive function. These neurons, besides generating pain sensations, participate through an antidromic activation in the process known as neurogenic inflammation. The first exposure to capsaicin intensely activates these neurons in both senses (orthodromic: pain sensation; antidromic: local reddening, oedema etc.). After the first exposure, the neurons become insensitive to all further stimulation (including capsaicin itself). This evidence led to the proposal of capsaicin as a prototype of an agent producing selective analgesia. This perspective is radically different from previous 'folk medicine' cures, where the drug was used as a counter-irritating agent (i.e. for muscular pain). The new concept requires that capsaicin be repeatedly applied on the painful area to obtain the desensitisation of the sensory neurons. Following this idea, capsaicin has been used successfully in controlling pain in postherpetic neuralgia, diabetic neuropathy and other conditions of neuropathic pain. Furthermore, evidence indicates that capsaicin could also control the pain of osteoarthritis. Finally, repeated applications of the drug to the nasal mucosa result in the prevention of cluster headache attacks. On the basis of this evidence, capsaicin appears to be a promising prototype for obtaining selective analgesia in localised pain syndromes.
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PMID:Peppers and pain. The promise of capsaicin. 917 23

Trigeminal neurogenic inflammation is one explanation for the development of vascular migraine. The triggers for this inflammation and pain are not well understood, but are probably vasoactive components acting on the blood vessel wall. Migraine-related inner ear symptoms like phonophobia, tinnitus, fluctuation in hearing perception and increased noise sensitivity provide indirect evidence that cochlear blood vessels are also affected by basilar artery migraine. The purpose of this investigation was to determine if a functional connection exists between the cochlea and the basilar artery. Neuronally mediated permeability changes in the cochlea and basilar artery were measured by colloidal silver and Evans Blue extravasation, following orthodromic and antidromic stimulation of the trigeminal ganglion innervating the cochlea. Capsaicin and electrical stimulation induced both dose- and time-dependent plasma extravasation of colloidal silver and Evans Blue from the basilar artery and anterior inferior cerebellar artery. Both orthodromic and antidromic activation of trigeminal sensory fibers also induced cochlear vascular permeability changes and significant quantitative differences between the treated and control groups in spectrophotometric assays. These results characterize a vasoactive connection between the cochlea and vertebro-basilar system through the trigeminal sensory neurons. We propose that vertigo, tinnitus and hearing deficits associated with basilar migraine could arise by excitation of the trigeminal nerve fibers in the cochlea, resulting in local plasma extravasation. In addition, cochlear "dysfunction" may also trigger basilar and cluster headache by afferent input to the trigeminal system.
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PMID:Capsaicin stimulation of the cochlea and electric stimulation of the trigeminal ganglion mediate vascular permeability in cochlear and vertebro-basilar arteries: a potential cause of inner ear dysfunction in headache. 1131

We report a case of fatal intoxication with 2% viscous lidocaine. A 18 month old infant was admitted after malaise and cardiorespiratory arrest at home. He was resuscitated, then seizures appeared before arrival at the hospital. Treatment was symptomatic, including cardiorespiratory resuscitation and administration of anticonvulsants. Identification of lidocaine and its metabolite monoethylglycinexylidide (MEGX) MEGX was performed after organic extraction by High Performance Liquid Chromatography (HPLC) with Diode Array Detection (DAD); the serum concentrations, determined by Fluorescence Polarisation Immuno Assay (FPIA), were: 1.1 micrograms/ml for lidocaine and 0.94 microgram/ml for MEGX (H + 7) and 0.30 microgram/ml for the lidocaine (Day + 1). Neurotoxic manifestations appear at lower concentrations than cardiotoxic symptoms which are correlated with plasma levels of lidocaine. The toxic symptoms begin with headache, hallucinations, seizure, coma, respiratory arrest and circulatory collapse. The toxic symptoms can persist even after the decrease of lidocaine concentration under therapeutic levels. There is no antidote and acute lidocaine toxicity is managed with supportive therapy (diazepam for seizures, intubation, chronotropic agents). Considering the gravity of these poisonings which remain rare, the 2% viscous lidocaine prescription is forbidden for children under 6 years old.
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PMID:[Fatal intoxication after accidental ingestion of viscous 2% lidocaine in a young child]. 1197 45

In order to investigate the c-fos response within the trigeminal nucleus caudalis (Sp5C) after noxious meningeal stimulation, capsaicin (0.25, 0.5, 1 and 5 nmol) was administered intracisternally in urethane (1 g/kg) and alpha-chloralose (20 mg/kg) anaesthetized male mice. Capsaicin induced a robust and dose-dependent c-fos-like immunoreactivity (c-fos LI) within Sp5C. C-fos LI was observed within laminae I and II of the entire brain stem from the area postrema to C2 level, being maximum at the decussatio pyramidum level. The area postrema, solitary tract, medullary and lateral reticular nuclei were also labelled. The 5-hydroxytryptamine(1B/1D/1F) receptor agonist sumatriptan (0.01, 0.1, 1 and 10 mg/kg), administered intraperitoneally 15 min before capsaicin stimulation (1 nmol), decreased the c-fos response within Sp5C, but not within solitary tract. The novel specific 5-hydroxytryptamine1F agonist LY 344864 (0.1 and 1 mg/kg, i.p.) significantly decreased the c-fos LI within the Sp5C as well. These findings suggest that intracisternally administered capsaicin activates the trigeminovascular system and that the pain neurotransmission can be modulated by 5-hydroxytryptamine(1B/1D/1F) receptors in mice. Thus, the availability of this model in mice, taken together with the possibility of altering the expression of specific genes in this species, may help to investigate further the importance of distinct proteins in the neurotransmission of cephalic pain.
Cephalalgia 2002 Jun
PMID:5-Hydroxytryptamine(1B/1D) and 5-hydroxytryptamine1F receptors inhibit capsaicin-induced c-fos immunoreactivity within mouse trigeminal nucleus caudalis. 1211 Jan 14

The potential for exposure to neurotoxicants in Lebanon is high, especially in the absence of strict control and regulatory measures in workplaces. Children working in mechanical and other trade workshops are at significant risk of exposure to organic solvents and as a result at significant risk to develop clinical and subclinical signs of neurotoxicity. This study investigated the association between exposure to solvents and neurobehavioral performance of 10-17 years old working children in comparison to groups of non-exposed working children and non-exposed children at school. A convenience cross-sectional sample of 100 working children (10-17 years) exposed to organic solvents at work, a positive control of 100 non-solvent exposed working children, and a negative control of 100 non-working, non-exposed school children were recruited to the study. The exposed and non-exposed groups were, as far as possible, frequency matched on geographic location of residence and on age. Neurotoxic effects were assessed through a questionnaire and the child's performance on a battery of neurobehavioral tests, which were specifically selected for a non-English speaking population and were tailored to assess the specific modalities of the central nervous system commonly known to be affected by the neurotoxicants identified. Children in the non-exposed groups (working and non-working) performed better than the working exposed group on reaction speed for the choice reaction time, symbol-digit and dual task tracking tests, but accuracy of performance was not affected on these tests. Children in the working exposed group also complained of more headaches, loss of concentration, memory deficits and higher irritability. This study identifies an association between exposure to solvents and lower neurobehavioral performance. Response speed appears to be particularly affected in solvent exposed working children.
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PMID:Evidence of neurotoxicity in working children in Lebanon. 1290 87

Cluster headache is characterized by typical autonomic dysfunctions including facial and intracranial vascular disturbances. Both the trigeminal and the cranial parasympathetic systems may be involved in mediating these dysfunctions. An experimental model was developed in the rat to measure changes in lacrimation and intracranial blood flow following noxious chemical stimulation of facial mucosa. Blood flow was monitored in arteries of the exposed cranial dura mater and the parietal cortex using laser Doppler flowmetry. Capsaicin (0.01-1 mm) applied to oral or nasal mucosa induced increases in dural and cortical blood flow and provoked lacrimation. These responses were blocked by systemic pre-administration of hexamethonium chloride (20 mg/kg). The evoked increases in dural blood flow were also abolished by topical pre-administration of atropine (1 mm) and [Lys1, Pro2,5, Arg3,4, Tyr6]-VIP (0.1 mm), a vasoactive intestinal polypeptide (VIP) antagonist, onto the exposed dura mater. We conclude that noxious stimulation of facial mucosa increases intracranial blood flow and lacrimation via a trigemino-parasympathetic reflex. The blood flow responses seem to be mediated by the release of acetylcholine and VIP within the meninges. Similar mechanisms may be involved in the pathogenesis of cluster headache.
Cephalalgia 2004 Mar
PMID:Noxious chemical stimulation of rat facial mucosa increases intracranial blood flow through a trigemino-parasympathetic reflex--an experimental model for vascular dysfunctions in cluster headache. 1500 14

Snakebite is an environmental hazard associated with significant morbidity and mortality. We report a case series of venomous snakebites in a military operational area of north India. Of 33 cases of snake bites presenting to the military hospital, 21 patients were envenomated. The median age of patients was 24 years; all were men. All of the envenomations were neurotoxic in nature. Abdominal pain (91%), headache (86%), dysphagia (86%), ptosis (77%), diplopia (72%), blurred vision (72%), dyspnea (67%), and vomiting (62%) were the predominant clinical presentation. Polyvalent AntiSnakeVenom (ASV) [mean 180 ml; range 90-320 ml] was given to all patients with systemic manifestations, and repeated as needed. Eleven (52%) patients received neostigmine with glycopyrrolate to counter cholinergic effects. Two patients were given ventilatory support. The average time of recovery from envenomation was 16 hours after administration of ASV. All patients recovered without sequelae. Soldiers during military exercise are vulnerable to snakebites. Neurotoxic snakebites predominate in our study and usually present with autonomic features along with headache, abdominal pain, ptosis, diplopia and dysphasia. Preventive measures to minimize snake bites and planned treatment regimens should be emphasized among medical and military personnel deployed in the field operations.
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PMID:Clinical profile of venomous snake bites in north Indian Military Hospital. 1956 85

Capsaicin, the main ingredient responsible for the hot pungent taste of chilli peppers, is an alkaloid found in the Capsicum family. Capsaicin was traditionally used for muscular pain, headaches, to improve circulation and for its gastrointestinal protective effects. It was also commonly added to herbal formulations because it acts as a catalyst for other herbs and aids in their absorption. In addition, capsaicin and other capsaicinoid compounds showed strong evidence of having promising potential in the fight against many types of cancer. The mechanism of action of capsaicin has been extensively studied over the past decade. It has been established that capsaicin binds to the transient receptor potential vanilloid 1 receptor which was expressed predominantly by sensory neurons. And many analogues of capsaicin have been synthesized and evaluated for diverse bioactivities. In this review, we will attempt to summarize the biology and structure-activity relationship of capsaicinoids.
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PMID:Capsaicin and its analogues: structure-activity relationship study. 2362 37


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