Effect of Vasoactive Intestinal Polypeptide on Development of Migraine Headaches: A Randomized Clinical Trial

IMPORTANCE

Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptides (PACAPs) are structurally and functionally related, yet different in their migraine-inducing properties. It remains unclear whether the lack of migraine induction can be attributed to the only transient vasodilatory response after a 20-minute infusion of VIP.

OBJECTIVE

To determine whether a 2-hour infusion of VIP would provoke migraine attacks.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, double-blind, placebo-controlled, crossover study was conducted between May and September 2020 at the Danish Headache Center in Copenhagen, Denmark. Patients were eligible for inclusion if they were ages 18 to 40 years, weighed between 50 and 90 kg, had a diagnosis of migraine without aura as defined by the International Classification of Headache Disorders, and had a migraine frequency of 1 to 6 attacks per month.

INTERVENTIONS

Patients were randomly allocated to receive a 2-hour infusion of VIP or placebo on 2 different days.

MAIN OUTCOMES AND MEASURES

The primary end point was the difference in incidence of experimentally induced migraine attacks during the observational period (0-12 hours) between VIP and placebo.

RESULTS

Twenty-one patients (17 [81%] women and 4 [19%] men; mean [range] age, 25.9 [19-40] years) were recruited in the study. Fifteen patients (71%; 95% CI, 48%-89%) developed migraine attacks after VIP compared with 1 patient (5%; 95% CI, 0%-24%) who developed a migraine attack after placebo (P < .001). The VIP-induced migraine attacks mimicked patients' spontaneous attacks. The area under the curve (AUC) of headache intensity scores (0-12 hours), as well as the AUC of the superficial temporal artery diameter (0-180 minute) were significantly greater after VIP compared with placebo (AUC0-12h, P = .003; AUC0-180min, P < .001).

CONCLUSIONS AND RELEVANCE

A 2-hour infusion of VIP caused migraine attacks, suggesting an important role of VIP in migraine pathophysiology. VIP and its receptors could be potential targets for novel migraine drugs.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04260035.

Prognostic impacts of glucocorticoid treatment in patients with polymyalgia rheumatica and giant cell arteritis

Identifying comorbidities in polymyalgia rheumatica/giant cell arteritis (PMR/GCA) is crucial for patients' outcomes. The present study aimed to evaluate the impact of the inflammatory process and glucocorticoid treatment on aortic arterial stiffness and body composition in PMR/GCA. 77 patients with newly diagnosed PMR/GCA were treated with oral glucocorticoids and followed for 40 weeks. Aortic pulse wave velocity (PWV) was measured at baseline and during the follow-up period and compared to the results of temporal artery biopsy (TAB) and 18F-FDG PET/CT. Body composition was assessed by total body DXA at baseline and the end of the study. Of 77 patients (49 (63.6%) female, mean of age: (71.8 ± 8.0)), 64 (83.1%) had pure PMR, 10 (13.0%) concomitant PMR and GCA, and 3 (3.9%) pure GCA. Compared to baseline values, aortic PWV was initially decreased at week 16 (p = 0.010) and remained lower than baseline at week 28 (p = 0.002) and week 40 (p < 0.001), with no association with results of TAB and 18F-FDG PET/CT. Aortic PWV was significantly associated with age, male gender, left systolic and diastolic blood pressure, right diastolic blood pressure, and CRP. Total bone mineral content (BMC) was decreased in both genders (p < 0.001), while fat mass (FM) was significantly increased (p < 0.001). However, lean body mass did not significantly change during the study. Changes in FM were correlated with cumulative prednisolone dose (rho: 0.26, p = 0.031). Glucocorticoid treatment of patients with PMR/GCA had several prognostic impacts. Arterial stiffness was decreased due either to the treatment or a reduction in the inflammatory load. Additionally, treatment led to changes in body composition, including a decrease in BMC and FM excess.

Ligustrazine prevents basilar artery remodeling in two-kidney-two-clip renovascular hypertension rats via suppressing PI3K/Akt signaling

OBJECTIVE

In the present study, we used a two-kidney-two-clip (2k2c) stroke-prone renovascular hypertension rat model (RHRSP) to investigate the protective effects of ligustrazine (TMP) on cerebral arteries and to examine PI3K/Akt pathway behavior under this protection.

METHODS

The cerebral artery remodeling was induced by 2k2c-induced renovascular hypertension. Brain basilar artery tissues were isolated and their histological changes were detected through H&E and EVG staining, α-SMA IHC staining, and transmission electron microscopy at four, eight, and twelve weeks after 2k2c surgery, both with and without TMP treatment. Meanwhile, the ET-1, Ang II, and NO levels in basilar arteries and plasma were determined. Furthermore, the PTEN expression and the activation of PI3K/Akt in basilar artery tissues were detected through IHC and Western Blot. In addition, the primary basilar artery smooth muscle cells (BASMCs) were cultured and TMP protection of BASMCs stimulated with ET-1/Ang II in the presence or absence of insulin-like growth factor 1 (IGF-1) was determined.

RESULTS

TMP attenuated basilar artery remodeling, decreased ET-1 and Ang II levels and increased NO level in basilar arteries and plasma of RHRSP rats. Moreover, TMP reduced BASMCs proliferation upon ET-1/Ang II stimulation. We also found that TMP could effectively suppress the activation of PI3K/Akt in 2k2c-RHRSP rat basilar artery and ET-1/Ang II stimulated BASMCs. Most importantly, IGF-1, as an activator of PI3K/Akt, could damage the protective effect of TMP.

CONCLUSIONS

TMP exerts its protective effects and prevents basilar artery remodeling in RHRSP rats at least partly through the inhibition of PI3K/Akt pathway.

Effect of pituitary adenylate cyclase-activating polypeptide-27 on cerebral hemodynamics in healthy volunteers: A 3T MRI study

Pituitary adenylate cyclase-activating polypeptide (PACAP) has emerged as an important signaling peptide in migraine pathogenesis. Recently, we have shown that the less-abundant PACAP isoform, PACAP27, induced migraine and headache in patients equipotently to PACAP38. The present study examined the effect of PACAP27 on cerebral hemodynamics in healthy volunteers using high resolution magnetic resonance angiography (MRA). Eighteen healthy volunteers received infusion of PACAP27 (10 pmol/kg/min) or placebo over 20 min and were scanned repeatedly in fixed intervals for 5 h in a double-blind, randomized, placebo-controlled study. The circumference of extra-intracerebral arteries was measured and compared with PACAP38 data. We found significant dilation of middle meningeal artery (MMA) (p = 0.019), superficial temporal artery (p = 0.001) and external carotid artery (p = 0.039) after PACAP27 infusion compared to placebo. Whereas the middle cerebral artery (MCA) (p = 0.011) and internal carotid artery (ICA) (p_ICAcervical = 0.015, p_ICAcerebral = 0.019) were constricted. No effects on basilar artery (p = 0.708) and cavernous portion of ICA were found. Post hoc analyses revealed significant larger area under the curve for MMA after PACAP38 compared to PACAP27 (p = 0.033). We also found that PACAP27 induced headache in nine out of twelve (75%) volunteers and one (17%) after placebo. In conclusion, PACAP27 induced headache and dilated extracerebral arteries (>5 h) and slightly constricted MCA in healthy volunteers. Post hoc analysis of PACAP38 data compared with PACAP27 showed that PACAP isoforms dilates MMA with significantly different magnitude.

The Effect of Propranolol on Glyceryltrinitrate-Induced Headache and Arterial Response

Prophylactic drug trials in migraine are long-lasting and expensive and require long-term toxicology information. A human migraine model would therefore be helpful in testing new drugs. Immediate headache and delayed migraine after glyceryltrinitrate (GTN) has been well characterized. We have recently shown that sodium valproate has prophylactic effect in the GTN model. Here we report our experience with propranolol in this model. Nineteen subjects with migraine without aura and 16 sex- and aged-matched healthy subjects were included in a two-centre randomized double-blind cross-over study. Fourteen migraine subjects and 14 healthy subjects completed the study and results from comparison of the 28 subjects are reported. Randomly propranolol 160 mg or placebo were each given daily for 14 days to both migraine and healthy subjects. A 20-min intravenous infusion of GTN 0.25 mg/kg per min was administered on a study day at the end of both pretreatment periods. Headache was registered for 12 h after GTN infusions. Its intensity was scored on a numerical verbal rating scale from 0 to 10. Fulfilment of International Headache Society (HIS) criteria was recorded for 24 h. Radial and superficial temporal artery diameters and blood velocity of both middle cerebral arteries were measured. All migraine subjects developed headache after GTN. No reduction of overall peak headache was found after propranolol (median 5, range 0-7) compared with placebo (median 5, range 0-10) ( P = 0.441). Eight of the 14 completing migraine subject developed IHS 1.1 migraine after GTN, two subjects on both days, three subjects only after placebo, and three subjects only after propranolol. No reduction of GTN-induced migraine was found after propranolol compared with placebo (5 vs. 5, P = 1.000). All healthy subjects developed headache after GTN. No reduction of overall peak headache was found after propranolol (median 2, range 1-5) compared with placebo (median 1, range 1-7) ( P = 0.315). Two subjects fulfilled IHS criteria 1.1 for migraine without aura after propranolol but not after placebo. The fulfilment was short lasting and did not require rescue medication. Headache after GTN was more pronounced in migraine subjects than in healthy subjects both with ( P = 0.003) and without pretreatment with propranolol ( P = 0.017). We found that 2 weeks of propranolol constricted the radial artery in healthy subjects but not in migraine subjects. GTN-induced vasodilatation abolished this difference. Mean maximum blood flow velocity in the middle cerebral artery was higher in healthy subjects than in migraine patients ( P = 0.003-0.033) and unaffected by propranolol. We observed no effect of propranolol on GTN-induced headache and migraine. This could indicate that GTN induces migraine at a deeper level of the pathophysiological cascade of migraine than the prophylactic effect of propranolol. Propranolol does not constrict cerebral arteries, which therefore cannot be part of its mechanism of action in migraine.

Steroid use is associated with clinically irrelevant biopsies in patients with suspected giant cell arteritis

Temporal artery biopsy (TAB) is the diagnostic gold standard for giant cell arteritis (GCA). GCA is treated by high-dose corticosteroids. In cases of high clinical suspicion, steroids may be administrated despite negative TAB, making TAB clinically irrelevant. We assessed the role of TAB in clinical decision-making in patients with suspected GCA and to identify factors associated with clinically irrelevant TAB. Charts of patients who underwent TAB from 2005 to 2010 were reviewed for clinical parameters potentially associated with GCA and clinically irrelevant TAB. We studied 143 patients with 99 negative (69%), 34 positive (24%), and 10 undefined (7%) TABs. Eventually 26 patients (18% of the entire cohort and 26% of the patients with a negative TAB) received steroid treatment for GCA despite negative TAB. The start of steroid treatment before TAB was associated with clinically irrelevant TABs. If clinical suspicion of GCA is high, a TAB can be considered clinically irrelevant.

Imatinib mesylate inhibits in vitro and ex vivo biological responses related to vascular occlusion in giant cell arteritis

OBJECTIVES

Ischaemic complications occur in 15-20% of patients with giant cell arteritis (GCA). The aim of our study was to explore the effect of mesenchymal growth factors expressed in GCA lesions on myointimal cell responses related to the development of intimal hyperplasia and vessel occlusion.

METHODS

We developed a method to obtain primary human temporal artery derived myointimal cells (HTAMCs) based on the culture of temporal artery sections on Matrigel.

RESULTS

Among the factors tested (platelet-derived growth factor (PDGF)-AB, fibroblast growth factor (FGF)-2, vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), transforming growth factor (TGF)beta, chemokine (C-C motif) ligand (CCL)2, interleukin (IL)6 and IL1beta), PDGF exhibited the strongest activity in inducing HTAMC proliferation and migration. As assessed by protein array, immunoassay and quantitative real-time reverse transcriptase (RT)-PCR, PDGF stimulated matrix proteins (collagen I, collagen III and fibronectin) as well as CCL2 and angiogenin production by HTAMCs. Imatinib mesylate inhibited PDGF-mediated activation of signalling pathways (Src, extracellular signal-regulated kinase (ERK) and Akt phosphorylation) related to cell motility and survival, efficiently resulting in inhibition of PDGF-induced HTAMC responses. Myointimal cell outgrowth from cultured temporal artery sections from patients with GCA, where multiple interactions take place, was also efficiently reduced by imatinib.

CONCLUSION

Among several mediators produced in GCA, PDGF has the highest vaso-occlusive potential. PDGF may also contribute to disease perpetuation by stimulating the production of angiogenic factors (angiogenin) and chemoattractants (CCL2). Imatinib mesylate strongly inhibits PDGF-mediated responses, suggesting a therapeutic potential to limit vascular occlusion and ischaemic complications in large vessel vasculitis.

5-Hydroxytryptamine-induced contraction of human temporal arteries coexpressing 5-HT2A receptors and wild-type or variant (Phe124Cys) 5-HT1B receptors: increased contribution of 5-HT1B receptors to the total contractile amplitude in arteries from Phe124Cys heterozygous individuals

OBJECTIVES

Expression studies of the rare Phe124Cys sequence variant of the human 5-HT1B receptor in HEK293 cells demonstrated that 5-hydroxytryptamine (5-HT) and sumatriptan had both three times higher binding affinity and agonist potency at the variant receptor than wild-type receptor. We examined whether in-vivo expression of the variant compared to the wild-type Phe/Phe genotype at codon 124 of the 5-HT1B receptor in human temporal arteries modifies their agonist-induced contraction.

METHODS

Rings of arteries, coexpressing 5-HT1B and 5-HT2A receptors, from 98 patients undergoing neurosurgery were set up to measure contraction. Blood sample genotyping was performed by PCR using a mutagenic primer which induces a NheI restriction site in the Cys but not in the Phe allele.

RESULTS

Three patients exhibited the Cys/Phe genotype, probably yielding coexpression of both the 124Phe and the 124Cys 5-HT1B receptors. In 95 Phe/Phe patients, exclusively the 124Phe receptor was expressed. The contractile potencies of 5-HT and sumatriptan were not significantly different in arteries from Cys/Phe or Phe/Phe individuals. The 5-HT1B receptor-selective antagonist SB224289 was five-fold more potent in blocking the effects of 5-HT in arteries from three Cys/Phe than from 30 Phe/Phe individuals (P < 0.03). The fraction of 5-HT effects via 5-HT1B receptors, related to the total contractile amplitude via 5-HT1B and 5-HT2A receptors, was enhanced from 0.42 +/- 0.03 in 88 Phe/Phe individuals to 0.75 +/- 0.10 in three Cys/Phe individuals (P < 0.05).

CONCLUSIONS

Although the potency of 5-HT1B receptor agonists does not differ between arteries from Phe/Phe and Cys/Phe individuals, the contribution of 5-HT1B receptors to the mediation of the effects of 5-HT is increased in Cys/Phe individuals.

Relationship between histological subtypes and clinical characteristics at presentation and outcome in biopsy-proven temporal arteritis

Temporal arteritis (TA) may offer major complications, whilst high dosage of prednisone may result in serious side effects. We tried to identify a subgroup of TA, which can be treated with a lower dosage of prednisone. Retrospectively, clinical and laboratory data were studied at presentation, as well as the outcome in 44 consecutive patients with biopsy-proven temporal arteritis. These data were related to three particular histological subgroups, (a) classical giant cell arteritis, (b) atypical arteritis, and (c) 'healed arteritis', defined according to Allsop and Gallagher (The American Journal of Surgical Pathology 5:317-332, 1981). At presentation in subgroup c, erythrocyte sedimentation rate was lower and the level of haemoglobin was higher than in the other two subgroups. During follow-up in the healed arteritis group, reactivation, recurrence, or early death were not observed, whilst prednisone dosage after 2 and 3 years was lower compared to subgroup b. Major complications (permanent blindness and cerebrovascular accident) were only observed in subgroups a and b. We believe that the healed arteritis subgroup represents a relatively benign subgroup with a mild clinical presentation and a good prognosis. Therefore, a much lower initial prednisone dosage (15 mg/day) is suggested for patients in subgroup c than in the other two subgroups (40-60 mg/day).

BIBN4096BS and CGRP(8-37) antagonize the relaxant effects of alpha-CGRP more than those of beta-CGRP in human extracranial arteries

We hypothesize that dilatation of extracranial arteries during migraine could be caused by CGRP. We compared the relaxant effects of alpha-calcitonin gene-related peptide (alpha-CGRP) and beta-calcitonin gene-related peptide (beta-CGRP) and the antagonism by BIBN4096BS and CGRP(8-37) on rings of human temporal and occipital arteries precontracted with KCl. beta-CGRP relaxed temporal (-logEC50M = 8.1) and occipital arteries (-logEC50M = 7.6) with 19-fold and 29-fold lower potencies respectively than alpha-CGRP. Nearly maximal effective concentrations of alpha-CGRP (4 nM) and beta-CGRP (50 nM) caused stable relaxations of the temporal artery for 4 h without fading. BIBN4094BS antagonized the effects of alpha-CGRP (pK(B) = 10.1 and 9.9, respectively) more than beta-CGRP (pK(B) = 9.3 and 9.2 respectively) on both temporal and occipital arteries. CGRP(8-37) antagonized the effects of alpha-CGRP (pK(B) = 6.6 and 6.4 respectively) more than beta-CGRP (pK(B) = 5.7 and 5.5 respectively) on both temporal and occipital arteries. Antagonism of the relaxant effects of alpha-CGRP (4 nM) and beta-CGRP (50 nM) by BIBN4096BS (10 and 100 nM) was reversible for beta-CGRP, but irreversible for alpha-CGRP, 1 h after BIBN4096BS washout. We conclude that alpha-CGRP and beta-CGRP interact either at different binding sites of the same CGRP receptor system or all together with different receptor systems in human extracranial arteries. BIBN4096BS binds more firmly to the receptor activated by alpha-CGRP than to the receptor activated by beta-CGRP.

Progressive visual loss in a patient with presumed temporal arteritis despite treatment: how to make the diagnosis

Giant cell (temporal) arteritis is a severe potentially fatal systemic vasculitis characterized by focal involvement of the cranial arteries resulting in ischaemic arterial occlusion. The case is presented of a 75-year-old woman with presumed giant cell arteritis and normal bilateral temporal artery biopsies. Despite a seemingly adequate course of systemic steroid therapy, the patient developed sudden catastrophic vision loss. Cerebral angiography and ultrasonography were useful investigations to determine the most appropriate artery to biopsy to confirm the diagnosis of giant cell arteritis.

Endothelial and neuronal functions in cerebral and temporal arteries from monkeys fed a high-cholesterol diet

Modifications by hyperlipidemia of endothelium-dependent and -independent relaxations were evaluated in cerebral and temporal arteries from control and hyperlipidemic (high cholesterol-fed) monkeys. Histologically atherosclerotic lesions were not observed in either group. Relaxations induced by histamine, abolished by N(G)-nitro->L-arginine (>L-NA), were significantly potentiated in the hyperlipidemic monkey cerebral arteries, compared with those in the arteries from control monkeys. Treatment with superoxide dismutase did not affect the histamine-induced relaxation. Conversely, endothelium-dependent relaxations induced by A23187, Ca2+ ionophore, in cerebral arteries did not differ between control and hyperlipidemic monkeys. In temporal arteries, relaxations by acetylcholine and A23187 did not differ between control and hyperlipidemic monkeys. Endothelium-dependent and -independent relaxations by adenosine diphosphate in cerebral and temporal arteries were not affected by hyperlipidemia. Endothelium-independent relaxations by exogenously applied nitric oxide did not differ in the arteries from control and hyperlipidemic monkeys. Nicotine-induced relaxations in cerebral arteries, which were mediated with nitric oxide released from nitroxidergic (nitrergic) nerves, and the contractions caused by nicotine in temporal and mesenteric arteries treated with >L-NA did not differ between control and hyperlipidemic monkeys. It is concluded that long exposure to hyperlipidemia did not affect endothelial functions of monkey middle cerebral and temporal arteries but enhanced nitric oxide-mediated relaxations caused by histamine, possibly due to upregulation of endothelial histamine receptor-mediated functions in the cerebral arteries. The nitroxidergic (nitrergic) and adrenergic nerve functions do not seem to be affected by hyperlipidemia.

Cyclooxygenase inhibitors attenuate endothelin ET(B) receptor-mediated contraction in human temporal artery

It is well documented that endothelin ET(B) receptor-mediated contraction develops in artery segments incubated in culture and that the reaction is augmented by proinflammatory cytokines, but little is known of the mechanisms involved. Segments of human temporal artery were incubated in organ culture for 2 days in the absence or presence of interleukin-1 beta (IL-1 beta), with or without nonsteroidal anti-inflammatory drugs, glucocorticoids or a nitric oxide synthase inhibitor. Thereafter, contractions were induced by the selective endothelin ET(B) receptor agonist, sarafotoxin S6c. Acetylsalicylic acid, indomethacin, nimesulide and rofecoxib were all effective in eliminating the increase in endothelin ET(B) receptor-mediated contraction induced by interleukin-1 beta, but only indomethacin and rofecoxib significantly reduced the spontaneous development of this reaction in cultured arteries. Dexamethasone and methylprednisolone augmented the reaction, and the nitric oxide synthase inhibitor had no effect. The results clearly indicate a role for cyclooxygenase, most likely cyclooxygenase-2, in endothelin ET(B) receptor-mediated contraction in this preparation.

BIBN4096BS is a potent competitive antagonist of the relaxant effects of alpha-CGRP on human temporal artery: comparison with CGRP(8-37)

Release of CGRP during migraine may produce harmful dilatation of cranial arteries, thereby possibly causing pain. We have compared the antagonism by BIBN4096BS and CGRP(8-37) of the relaxant effects of alpha-CGRP on rings of human temporal artery. alpha-CGRP relaxed the arteries precontracted with 9 - 24 mM KCl (-logEC50=9.4) nearly as efficaciously as sodium nitroprusside (10 microM). BIBN4096BS (0.1 - 100 nM) antagonized the effects of alpha-CGRP in surmountable manner with slopes of Schild-plots not different from unity. -LogKB values of 10.1 and 10.4 were estimated for BIBN4096BS when administered before or during the KCl-contracture respectively. BIBN4096BS (1 microM) did not modify the relaxant effects of papaverine and sodium nitroprusside. CGRP(8-37) (1 - 10 microM) antagonized the effects of alpha-CGRP in a surmountable manner with slopes of Schild-plots not different from unity. -LogKB values of 6.6 and 6.7 were estimated for CGRP(8-37) administered before or during the KCl-contracture respectively. The high affinity of BIBN4096BS for CGRP receptors of human temporal artery makes it an excellent tool to explore the hypothesis of CGRP-evoked cerebral vasodilation in migraine.

Arterial wall production of cytokines in giant cell arteritis: results of a pilot study using human temporal artery cultures

BACKGROUND

Giant cell arteritis (GCA) is a subacute periarteritis predominantly affecting segments of the external carotids of elderly patients. Vasculitic lesions in GCA samples might be characterized by in situ production of cytokines mRNA, indicative of macrophage and T-cell activation. However, whether the cytokine production of vessels with arteritis differs from that of vessels exposed to inflammatory conditions that originate peripheral to the vessel remains unknown.

METHODS

We investigated cytokine and soluble receptor cytokine production in blood samples and cultures of human temporal arteries from 22 consecutive patients (mean age 77 +/- 6 years) further investigated for possible diagnosis of GCA: 7 patients had GCA and 15 had neither GCA nor vasculitis but had other inflammatory, infectious, or malignant diseases (controls). The production of cytokines and soluble cytokine receptors in the supernatants of cultures of 3-mm segments of temporal artery specimens, before and after lipopolysaccharide (LPS) stimulation (10 ng/ml and 10 microg/ml) and in serum, was quantified using sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Cytokine production by temporal arteries increased significantly and in a dose-dependent manner (p <.01) after LPS stimulation in all patients studied, suggesting that the system is methodologically functional. Despite a large interindividual variation, we found similar differences in cytokine production before and after stimulation by 10 ng/ml and 10 microg/ml LPS between both groups: temporal arteries of GCA patients produced more interleukin (IL)-1beta (p <.05) and IFNgamma (nonsignificant) and less tumor necrosis factor (TNF)alpha (p <.05) and IL-6 (nonsignificant) than temporal arteries of controls. The levels of TNFalpha (p <.05) and IL-6 soluble receptor (p <.05) were significantly lower in GCA patients as compared with controls in blood samples, whereas levels of cytokines in temporal artery and in blood samples were not significantly correlated at the individual level in both groups.

CONCLUSIONS

The present pilot study, which requires further confirmation on a larger number of well-defined patients with GCA, suggests that a specific arterial cytokine production profile might exist in GCA (high IL-1beta +/- IFNgamma and low TNFalpha), addresses the question of the mechanisms by which IL-1beta and TNFalpha might be differentially regulated at the level of the arterial cell wall, and supports the view that cultures of the temporal artery might be an interesting tool for evaluating the role of cytokines in GCA pathogenesis.

5-HT1B-receptors and vascular reactivity in human isolated blood vessels: assessment of the potential craniovascular selectivity of sumatriptan

AIMS

5-HT1B-receptor mediated vasoconstriction of cranial arteries is a potential mechanism by which 5-HT1B/1D-receptor agonists such as sumatriptan produce their antimigraine effects. 5-HT1B-receptors exist in other blood vessels which may give rise to unwanted vascular effects. Therefore we examined the distribution of 5-HT1B-receptor immunoreactivity (i.r.) in human blood vessels (including target and nontarget vessels) and confirmed the functionality of this receptor protein, by comparing the vasoconstrictor effects of sumatriptan and 5-HT (the endogenous ligand) in isolated vessels.

METHODS

Blood vessels (middle meningeal, pial, temporal and uterine arteries and saphenous veins) were obtained from surgical patients (with consent). Sections of the vessels were prepared for routine immunohistochemical studies using specific 5-HT1B- and 5-HT1D-receptor antibodies. For functional studies, ring segments of the vessels were mounted in organ baths for isometric tension recording.

RESULTS

5-HT1B-receptor i.r. was detected on the smooth muscle layer in middle meningeal, pial and uterine arteries and in saphenous vein and sumatriptan produced contractions in these vessels with potency values (mean pEC50) of 7.00, 7.08, 6.44 and 6.61, respectively, the magnitude of contraction was greatest in the cranial arteries with Emax values of 100.7, 60.3, 23.0 and 35.9%, respectively (expressed as a percentage of the reference agonist 45 mm KCl). 5-HT1B-receptor i.r. was not detected in temporal artery and sumatriptan had no effect in this artery. 5-HT1D-receptor i.r. was not detected in any of the vessels studied.

CONCLUSIONS

Sumatriptan can evoke vasoconstriction in antimigraine target vessels and also in nontarget vessels through an action at 5-HT1B-rcceptors. Sumatriptan acts preferentially to cause contraction in human cranial arteries compared with the other blood vessels we examined and this effect is likely to be shared by other drugs of this class.

[Color duplex ultrasound of the temporal artery: replacement for biopsy in temporal arteritis]

The diagnosis of temporal arteritis (TA) is generally confirmed by biopsy. To investigate the diagnostic accuracy of color duplex sonography (CDS), both temporal arteries of 20 patients with suspected TA were prospectively insonated prior to biopsy. Detection of >or=1 hypoechogenic perivascular halo was used as CDS criterion, a temporal artery biopsy and the criteria of the American College of Rheumatology (ACR) as references. The frequency of halo disappearance after 3 months of steroid therapy was also studied. CDS showed TA in 6, biopsy in 12 and ACR criteria in 15 patients. CDS sensitivity was 50 and 40%, and specificity 100%, using the biopsy and the ACR criteria, respectively. After 3 months of steroid treatment, 1 patient still showed halos. In conclusion, detection of halos confirms, whereas the absence of halos does not exclude the diagnosis of TA suggesting that ultrasound may replace biopsy in single patients with typical clinical signs and symptoms and a halo.

Vascular effects of the new anti-migraine agent almotriptan on human cranial and peripheral arteries

This paper describes the vascular effects of almotriptan in comparison with sumatriptan in human vessels and tissues in vitro. The contractile properties of almotriptan and sumatriptan were evaluated in vitro in the following arteries: meningeal, temporal, basilar, internal carotid, ophthalmic, pulmonary and coronary. In addition, the effects of almotriptan on the pulmonary vein and on bronchial tissues were studied. Almotriptan showed selectivity of action for migraine-related arteries (i.e. contractile EC(50) of 30 and 700 nm for meningeal and temporal arteries, respectively), whereas the effect on arteries supplying blood to the brain was lower. The contractile effect of almotriptan was lower than that of sumatriptan in pulmonary arteries, whereas in bronchial preparations no clinically relevant contractile responses were observed for either almotriptan or sumatriptan. In ophthalmic arteries the contractile effects of almotriptan and sumatriptan were similar, whereas lower contractile effects were obtained with almotriptan than with sumatriptan in coronary arteries.

Cytokine enhancement of endothelin ET(B) receptor-mediated contraction in human temporal artery

Segments of human temporal artery were incubated in organ culture for 2 days in the absence or presence of cytokines. Thereafter, contractions were induced by the selective endothelin ET(B) receptor agonist sarafotoxin S6c, a peptide that does not induce contraction in fresh human temporal artery. Interleukin-1beta was most potent in increasing the sarafotoxin-induced contraction in cultured segments. Tumour necrosis factor (TNF)-alpha increased the magnitude of contraction to a similar degree, but at a higher dose. A significant increase was also induced by interferon-gamma, but not by interleukin-6 at the concentrations used. The results suggest that endothelin ET(B) receptor-mediated contraction can be enhanced by pro-inflammatory cytokines in a concentration-dependent manner, and this may have relevance for pathophysiological conditions where inflammation and vasoactivity are important.

Vascular effects of 5-HT1B/1D-receptor agonists in patients with migraine headaches

OBJECTIVES

Second-generation triptans are believed to have fewer cardiovascular effects than sumatriptan. This was investigated in vivo by comparing the vascular effects of equipotent therapeutic dosages of selective 5-HT1B/1D-receptor agonists.

METHODS

Sixteen patients with migraine headaches completed a double-blind, placebo-controlled, four-way crossover study. With ultrasonography and applanation tonometry used 1.5 hours after the oral intake of sumatriptan (50 mg), rizatriptan (10 mg), zolmitriptan (2.5 mg), or placebo arterial vessel wall properties, blood flow and pressure waveforms were measured in common carotid, brachial, and temporal arteries. At the brachial artery, flow-induced vasodilation (an endothelium-dependent process) was evaluated, and blood pressures were recorded.

RESULTS

Mean arterial pressure, 91 +/- 2 mm Hg after placebo, increased (P < .05) by 4% to 6% after administration of each triptan. Each active treatment decreased (P < .001) both brachial and carotid artery diameter. Isobaric compliance of the brachial artery, 0.077 +/- 0.010 mm2/kPa after placebo, decreased (P < .01) by 11% +/- 8%, 11% +/- 11%, and 23% +/- 7% after administration of sumatriptan, rizatriptan, and zolmitriptan, respectively. Isobaric compliance of the carotid artery was 1.31 +/- 0.10 mm2/kPa after placebo (no change). Zolmitriptan was the only triptan that decreased temporal artery diameter significantly (by 12% +/- 3%, P < .001). The resistance of the temporal artery vascular bed increased after administration of sumatriptan (by 26% +/- 11%, P < .05) and zolmitriptan (by 40% +/- 9%, P = .001). Flow-induced vasodilation was unaffected.

CONCLUSIONS

Selective 5-HT1B/1D-receptor agonists induce vasoconstriction and decrease compliance of conduit arteries. These effects are more pronounced at muscular (temporal, brachial) compared with elastic (carotid) arteries. Resistance is only increased at the temporal artery vascular bed, suggesting cranioselectivity for resistance vessels. Endothelial function is not differently affected by any of the triptans tested.

Induction of nitrate tolerance is not a useful treatment in cluster headache

The aims of the present study were to investigate whether induction of nitrate tolerance is a useful treatment in cluster headache and to correlate any changes in attack frequency of cluster headache and nitrate-induced headache to the vascular adaptation during continuous nitrate administration. The results were compared to results obtained from studies of nitrate tolerance in healthy subjects.

MATERIALS AND METHODS

5-isosorbide-mononitrate (5-ISMN) 30 mg was administered orally three times daily for 4 weeks in nine sufferers of chronic cluster headache in a double-blind, randomized placebo-controlled cross-over design. Blood velocity in the middle cerebral artery was measured with transcranial Doppler and the diameters of the temporal and radial arteries were measured with high frequency ultrasound. The haemodynamic data were compared to changes in the frequency of cluster headache attacks and interval headaches over time.

RESULTS

Tolerance was complete within 24 h in the middle cerebral arteries and after 7 days in the symptomatic temporal artery, while tolerance of the radial artery was not observed within this period. The time profiles of tolerance were almost identical to the time profiles observed in healthy subjects. A close temporal association between the disappearance of nitrate-induced headache and tolerance of the temporal artery was observed but tolerance had no effect on cluster headache attack frequency.

CONCLUSIONS

Induction of tolerance to nitrates cannot be used to treat cluster headache. If pain is related to arterial dilatation the results point to extracerebral rather than cerebral arteries as the site of nociception. However, other peripheral and central pain-modulating effects of nitric oxide, the time courses of which are unknown, should also be taken into consideration.

Interleukin-1beta potentiates endothelin ET(B) receptor-mediated contraction in cultured segments of human temporal artery

Segments of human temporal artery were placed in organ culture for up to 4 days and examined for endothelin ET(B) receptor activity in the presence and absence of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) by in vitro pharmacology and reverse transcriptase-polymerase chain reaction (RT-PCR). The contractile effect of prostaglandin F2alpha (used as a reference), was not significantly altered by culture or IL-1beta. However, the selective ET(B) agonist sarafotoxin S6c induced no contraction in fresh arteries, but marked contraction after culture. Both maximal contraction and potency to sarafotoxin S6c were increased in segments incubated with IL-1beta . The contraction was sensitive to BQ 788 (ET(B) antagonist), but not FR 139317 (ET(A) antagonist). Actinomycin D abolished the contraction, whereas only the cytokine-induced increase in contraction was inhibited by cycloheximide. ET(A) and ET(B) receptor mRNAs were detected in all arteries; predominantly for the ET(A) receptor in fresh arteries, and for the ET(B) receptor after culture. However, there was no change in the ET(A)/ET(B) receptor mRNA ratio after treatment with IL-1beta. This suggests de novo synthesis of contractile ET(B) receptors after organ culture and that IL- 1beta may further stimulate translation of the mRNA to active receptors. The results raise the possibility that contractile ET(B) receptors may be implicated in disease states with inflammatory processes.

Increased endothelin ETB contractile activity in cultured segments of human temporal artery

Contractions induced by endothelin-1, endothelin-3 and the selective ETB agonist, sarafotoxin S6c, were studied in segments of human temporal artery. The results in fresh arteries were compared with those obtained after 1 or 4 days in organ culture, and with the specific ETA antagonist FR 139,317, the specific, mixed antagonist bosentan, or the specific ETB antagonist, BQ 788. Sarafotoxin S6c induced no contractile activity in fresh artery segments, but elicited marked contractions after culture. This contraction was only slightly inhibited by FR 139,317, but was abolished by BQ 788. Contractions induced by endothelin-1 were antagonized by FR 139,317 and bosentan, but not by BQ 788. Organ culture did not change the overall pattern, but all concentration-response curves were shifted leftwards. Contractions induced by endothelin-3 were abolished by all antagonists in fresh arteries, but some activity was restored after organ culture. Sensitivity to endothelin-3 was markedly increased. The results suggest a change in endothelin receptors during organ culture, resulting in a marked increase in contractile ETB activity, and possibly some increase in ETA activity. Such changes illustrate the complexity of endothelin responses in this vascular bed.

5-HT1B receptor-mediated contractions in human temporal artery: evidence from selective antagonists and 5-HT receptor mRNA expression

1. In the human temporal artery both 5-HT1-like and 5-HT2A receptors mediate the contractile effects of 5-hydroxytryptamine (5-HT) and we have suggested that the 5-HT1-like receptors resemble more closely recombinant 5-HT1B than 5-HT1D receptors. To investigate further which subtype is involved, we investigated the blockade of 5-HT-induced contractions by the 5-HT1B-selective antagonist SB-224289 (2,3,6,7-tetrahydro-1'-methyl-5-[2-methyl-4'[(5-methyl-1,2,4-oxadiazole- 3-yl) biphenyl-4-yl] carbonyl] furo[2,3-f]indole-3-spiro-4'-piperidine oxalate) and the 5-HT1D-selective antagonist BRL-15572 (1-phenyl-3[4-3-chlorophenyl piperazin-1-yl] phenylpropan-2-ol). We also used RT-PCR to search for the mRNA of 5-HT1B, 5-HT1D and other 5-HT receptors. 2. The contractile effects of 5-HT in temporal artery rings were partially antagonized by SB-224289 (20, 200 nM) (apparent KB = 1 nM) and ketanserin (1 microM) but not by BRL-15572 (500 nM). 3. Sumatriptan evoked contractions (EC50, 170 nM) that were resistant to blockade by BRL-15572 (500 nM) but antagonized by SB-224289 (20, 200 nM). 4. The potency of 5-HT (EC50) was estimated to be 94 nM for the ketanserin-sensitive receptor and 34 nM for the SB-224289-sensitive receptor. The fraction of maximal 5-HT response mediated through SB-224289-sensitive receptors was 0.20-0.67, the remainder being mediated through ketanserin-sensitive receptors. 5. We detected arterial receptor mRNA for the following receptors (incidence): 5-HT1B (8/8), 5-HT1D (2/8), 5-HT1F (0/4), 5-HT2A (0/8) 5-HT2B (0/8), 5-HT2C (0/8), 5-HT4 (4/8) and 5-HT7 (4/8). 6. We conclude that the ketanserin-resistant fraction of the 5-HT effects and the effects of sumatriptan are mediated by 5-HT1B receptors. The lack of antagonism by BRL-15572 rules out 5-HT1D receptors as mediators of the contractile effects of 5-HT and sumatriptan.

Role of endothelium and nitric oxide in histamine-induced responses in human cranial arteries and detection of mRNA encoding H1- and H2-receptors by RT-PCR

1. Histamine induces relaxation of human cranial arteries. Studies have revealed that the relaxant histamine H1-receptor predominates in human cerebral and the H2-receptor in temporal arteries, while H1- and H2-receptors are of equal importance in the middle meningeal artery. The purpose of the present study was to examine the role of the endothelium and nitric oxide in histamine-induced responses and to show the presence of mRNA encoding H1- and H2-receptors in human cranial arteries. 2. Electrophoresis of polymerase chain reaction (PCR) products from human cerebral, middle meningeal and temporal arteries, demonstrated products corresponding to mRNA encoding both H1- and H2-receptors in arteries with and without endothelium. The amplified PCR products were sequenced and showed 100% homology with the published sequences of these histamine receptors. 3. A sensitive in vitro system was used to study vasomotor responses to histamine. In precontracted cerebral, middle meningeal and temporal arteries with and without endothelium, histamine caused a concentration-dependent relaxation with Imax values between 87% and 81% and pIC50 values between 8.14 and 7.15. In arteries without endothelium the histamine-induced relaxation was significantly less potent (Imax values between 87% and 66% and pIC50 values between 7.01 and 6.67) than in cranial arteries with an intact endothelium. 4. This addition of histamine to arteries without endothelium and pretreated with the histamine H2-antagonist, cimetidine (10(-5) M), caused a concentration-dependent contraction of the cranial arteries with Emax values between 86% and 29% and pEC50 values between 7.53 and 6.77. This contraction was blocked by the histamine H1-receptor antagonist, mepyramine (10(-7) M), and even turned into a relaxation with Imax values between 84% and 14% and pIC50 values between 7.42 and 5.86. 5. The nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 3 x 10(-5) M) significantly inhibited the relaxant response to histamine in cerebral and temporal arteries (pIC50 values between 7.43 and 7.13). The combined treatment with L-NAME (3 x 10(-5) M) and cimetidine (10(-5) M) caused a further displacement of the concentration-response curve (pIC50 values between 7.14 and 6.57) and decreased the maximum relaxant responses in all three cranial arteries (Imax values between 62% and 39%). 6. In conclusion, this is the first study which show mRNA encoding histamine H1- and H2-receptors in human cranial arteries. The results indicate that histamine-induced relaxation of human cranial arteries is partially mediated via an endothelial H1-receptor coupled to the production of nitric oxide and partially via a H2-receptor associated with the smooth muscle cells. In addition, there is evidence for a contractile H1-receptor in the smooth muscle cells in these arteries.

alpha-Thrombin upregulates G alpha i3 in human vascular endothelial cells

BACKGROUND AND PURPOSE

During thrombosis, alpha-thrombin becomes sequestered by fibrin and the subendothelial basement membrane, and it is available to interact with the vasculature over prolonged periods. In this study, we investigated the long-term effect of alpha-thrombin on G alpha i3 and G alpha s levels in human vascular endothelial cells (EC). Because obesity is associated with changes in receptor signaling in many animal models, we also explored the influence of this clinical risk factor.

METHODS

Primary cultures of human EC were exposed to alpha-thrombin for 16 hours, and immunologically detectable G alpha i3 and G alpha s levels were measured.

RESULTS

alpha-Thrombin (100 nmol/L) increased G alpha i3 levels in EC derived from the cerebral microvasculature and superficial temporal artery (4.2 +/- 1.2-fold and 2.8 +/- 0.32-fold, respectively) but had no significant effect on EC derived from omental artery (P > .6) or from the superficial temporal artery of obese (body mass index > or = 28 kg/m2) patients (P > .4). The expression of G alpha s was unchanged in all cell types (P > or = .1). Two other circulating peptides, vasoactive intestinal peptide and endothelin-1, failed to alter the expression of either G protein in EC from the cerebral microvasculature, further demonstrating the specificity of the alpha-thrombin effect. However, thrombin receptor activating protein-14 mimicked the alpha-thrombin response and increased G alpha i3 in EC derived from the cerebral microvasculature and superficial temporal artery.

CONCLUSIONS

We conclude that alpha-thrombin increases G alpha i3 expression in some EC through activation of its tethered liganded receptor. Obesity appears to suppress this action of alpha-thrombin.

Participation of 5-HT1-like and 5-HT2A receptors in the contraction of human temporal artery by 5-hydroxytryptamine and related drugs

1. We investigated the hypothesis that, as in some other large human arteries, 5-HT-induced contraction of the temporal artery is mediated through two co-existing receptor populations, 5-HT1-like- and 5-HT2A. Temporal arterial segments were obtained from patients undergoing brain surgery and rings prepared set up to contract with 5-HT and related agents. Fractions of maximal 5-HT responses mediated through 5-HT1-like and 5-HT2A receptors, f1 and f2 = 1-f1, were estimated by use of the 5-HT2A-selective antagonist ketanserin. 2. In rings with intact endothelium 5-HT evoked contractions with a -log EC50, M of 7.0. Ketanserin (10-1000 nM) antagonized part of the 5-HT-induced contractions. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M of 6.9 and f1 of 0.17 (100 nM ketanserin) and -log EC50, M of 6.4 and f1 of 0.20 (1000 nM ketanserin). 3. In rings with endothelial function attenuated by enzymatic treatment, 5-HT caused contractions with a -log EC50, M of 7.2 that were partially blocked by ketanserin. Ketanserin-resistant components of 5-HT-induced contractions were found with -log EC50, M 7.4 and f1 of 0.16 (100 nM ketanserin) and -log EC50, M of 7.5 and f1 of 0.14 (1000 nM ketanserin). 4. The ketanserin-resistant component of 5-HT-evoked contraction was blocked by methiothepin (100-1000 nM) consistent with mediation through 5-HT1-like receptors. 5. In rings with intact endothelium the 5-HT1-like-selective agonist, sumatriptan, caused small contractions with a -log EC50, M of 6.5 and intrinsic activity of 0.21 with respect to 5-HT that were resistant to blockade by 1000 nM ketanserin but antagonized by 100 nM methiothepin. 6. In rings with intact endothelium the 5-HT2A receptor partial agonist SK&F 103829 (2,3,4,5-tetrahydro-8[methyl sulphonyl]-1H3-benzazepin-7-ol methensulphonate) contracted rings with a -log EC50, M of 5.0 and an intrinsic activity of 0.49 with respect to 5-HT; the effects were antagonized by ketanserin 1000 nM. 7. We conclude that 80-86% of the maximum 5-HT-evoked contraction of human temporal artery is mediated through 5-HT2A receptors, the remainder through 5-HT1-like-receptors, regardless of whether or not endothelium is functional. The 5-HT1-like-receptors are more likely to be 5-HT1D beta receptors than 5-HT1D alpha receptors and sumatriptan is a full agonist for these receptors. As found in arteries of other species, SK&F 103829 is a partial agonist for 5-HT2A receptors of human temporal artery.

In-office temporal artery biopsy

Biopsy is essential in the diagnosis of temporal arteritis. Temporal artery biopsy done in the office has many advantages. Patients tolerate the procedure well with little anxiety. There is greater convenience for the patient and ease of scheduling for the referring physician. It can be done promptly and is far more cost-effective than performing the procedure in a surgical center or hospital. Finally, and perhaps most importantly, because the in-office procedure is safe, more convenient, less stressful, and less expensive, clinicians are more likely to obtain a temporal artery biopsy when the diagnosis of temporal arteritis is even a remote possibility. Contrariwise, there is evidence to indicate that many cases of temporal arteritis are not diagnosed because of reluctance to schedule a biopsy. The ophthalmologist is in a unique position to provide help in the diagnosis and follow-up care of the patient with suspected temporal arteritis. Ophthalmologists are familiar with the disease, its treatment, and particularly its ocular manifestations. In addition to the baseline ophthalmic examination to help reveal subclinical pathology, ophthalmologists can evaluate the patient as subsequent visual complaints arise. Finally, by offering a convenient biopsy procedure, the diagnosis can be accurately and promptly confirmed.

Invasive aspergillosis. A complication of treatment of temporal arteritis

Temporal arteritis is a systemic necrotizing vasculitis for which the only effective treatment is systemic corticosteroids. A review of the literature suggests that there is a significant mortality rate in untreated patients but that those patients who receive adequate corticosteroid treatment rarely experience a reduced life expectancy. I had the opportunity to evaluate a patient with temporal arteritis who eventually died from disseminated aspergillosis 6 weeks after beginning corticosteroid treatment. A high index of suspicion for infections with opportunistic organisms should be maintained in patients with temporal arteritis receiving corticosteroids.

Histamine actions in dog retinal central arteries as compared to those in middle cerebral and temporal arteries

PURPOSE

Mechanisms underlying the relaxant response to histamine were compared in isolated dog retinal arteries (branch of internal and external carotid arteries), middle cerebral arteries (branch of internal carotid artery) and superficial temporal arteries (branch of external carotid artery).

METHODS

Changes in the isometric tension of helical strips of the arteries with and without the endothelium were recorded.

RESULTS

Histamine produced concentration-related biphasic (phasic and sustained) relaxations in retinal arterial strips contracted partially with prostaglandin (PG)F2 alpha. Relaxations induced by histamine were not dependent on the endothelium. Treatment with cimetidine attenuated the sustained relaxation, whereas chlorpheniramine or indomethacin depressed the phasic relaxation. In addition, the phasic relaxant response to histamine was attenuated by tranylcypromine, a PGI2 synthesis inhibitor. In contrast, the amine-induced relaxant responses in dog middle cerebral arterial branch and temporal arteries were markedly suppressed by cimetidine alone.

CONCLUSIONS

In dog retinal arteries, the phasic relaxation caused by histamine is mediated by PGI2 in association with activation of the H1 receptor subtype in subendothelial tissues, possibly smooth muscle, and the sustained relaxation is evoked by direct stimulation of the H2 receptor subtype in smooth muscle. The histamine-induced relaxation in temporal and distal middle cerebral arteries is associated solely with a stimulation of H2 receptors in smooth muscle.

Nitroglycerin-induced headache is not dependent on histamine release: support for a direct nociceptive action of nitric oxide

The molecular mechanisms of migraine pain have not yet been clarified. Monoamine and the peptide neurotransmitters involved in neurogenic inflammation do not cause significant head pain. Our previous studies of glyceryl trinitrate (GTN) and histamine-induced headaches have suggested that nitric oxide (NO) is the causative molecule in migraine pain. We furthermore suggest that substances capable of inducing experimental vascular headache do so via a common mediator which is NO. Finally, it is suggested that drugs exert their antimigraine activity by inhibiting NO or subsequent steps in the cascade of intracellular reactions triggered by NO. These novel observations change current views on vascular headache mechanisms and the importance of NO as an initiator of the migraine attacks dictates new approaches to the pharmacological treatment of migraine and other vascular headaches.

Spontaneous and 5HT-induced cyclic contractions in superficial temporal arteries from chronic and episodic cluster headache patients

Superficial temporal arteries (STAs) are abnormally dilated in the painful side during cluster headache (CH) attacks. We have assessed the possible dysfunction of these arteries by comparing in vitro the reactivity of STAs removed from the painful side of CH patients during a cluster of attacks with that of STAs from patients free of CH. The responses to KCl and norepinephrine (NE) of both types of arteries were similar. Serotonin (5HT) induced a classical dose-dependent constriction in arteries from non-CH patients, but systematically triggered rhythmic contractions in arteries from episodic CH patients. Arteries from chronic CH patients also showed spontaneous rhythmic contractions. In both cases, this activity was stopped by calcitonin gene-related peptide (CGRP) but, even in the presence of CGRP, it could be restored by low concentrations of 5HT. Thus, 5HT, unlike NA, can trigger rythmic activity in STAs of CH patients and may play a major role in CH through abnormal smooth muscle cell reactivity.

Endothelin-A receptors mediate contraction in human cerebral, meningeal and temporal arteries

Endothelin-1 (ET-1), an endothelium-derived vasoconstrictor peptide, produced strong contractions in human cerebral, meningeal and temporal arteries. The isopeptides ET-2 and ET-3 also showed potent constrictor activity; however, ET-3 was less potent. The selective ETA receptor antagonist FR 139317 mediated a shift to the right of the concentration-response curve of ET-1. These results suggest that the powerful constriction elicited by the endothelin-isopeptides in cerebral, meningeal and temporal arteries is mediated through ETA receptors.

Mechanism underlying substance P-induced relaxation in dog isolated superficial temporal arteries

1. In helical strips of dog superficial temporal arteries with intact endothelium, substance P elicited a concentration-related relaxation with an EC50 of 2.8 (2.4-3.2) x 10(-10) M. 2. The relaxant response to the peptide in low concentrations (1-4 x 10(-10) M) sufficient to produce approximately half maximal relaxation was not inhibited by indomethacin, but was markedly suppressed by NG-nitro-L-arginine (L-NOARG), a nitric oxide (NO) synthase inhibitor, and by endothelium denudation. 3. High concentration (10(-7) M) of substance P produced marked relaxations in endothelium-intact strips. Removal of the endothelium attenuated the relaxation, and indomethacin or tranylcypromine suppressed the endothelium-independent relaxation. In indomethacin-treated strips with intact endothelium, L-NOARG attenuated but did not abolish the relaxation. The residual, L-NOARG-resistant relaxation was not significantly inhibited by ouabain, glibenclamide or tetraethylammonium. 4. Substance P (10(-7) M) increased the levels of cyclic GMP and cyclic AMP. The increase in cyclic GMP was abolished by endothelium denudation and treatment with L-NOARG, whereas the cyclic AMP increment was abolished by indomethacin. 5. Three different mechanisms may be involved in the substance P-induced relaxation: (1) an endothelium-dependent relaxation mediated by the release of NO from the endothelium, resulting in an increase of cyclic GMP (low and high concentrations of the peptide); (2) an endothelium-independent relaxation in association with cyclic AMP increment caused by prostaglandin I2 released from subendothelial tissues (high concentration), and (3) another endothelium-dependent relaxation possibly mediated by unidentified mediator(s) released from the endothelium (high concentration).

Nitric oxide synthase-immunoreactive nerve fibers in dog cerebral and peripheral arteries

Nitric oxide synthase (NOS)-immunoreactive fibers innervating the dog arterial wall were histochemically determined by the use of NOS antiserum. NOS-immunoreactive fibers were consistently found in every arterial wall examined. In a whole-mount preparation, NOS-positive fibers were detectable in the small pial artery having a diameter of about 100 microns as well as the proximal middle cerebral artery. Further detailed analyses in thin cryostat sections indicated that in middle cerebral, basilar, temporal, mesenteric and femoral arteries, fine NOS-positive fibers were detected in outer zones of the media in addition to many thicker fibers in the adventitia. However, in the coronary artery, many thick fibers were situated in the adventitia, and fine NOS-positive fibers were not found in the media. Injection of ethanol to the pterygopalatine ganglion markedly decreased or abolished the NOS immunoreactivity in nerve cells and fibers and abolished the innervation of NOS-positive fibers in the wall of middle cerebral artery of the ipsilateral side. Together with findings in our previous publications concerning the functional role of nitroxidergic nerve in the control of arterial tone, we conclude that perivascular nerves containing NOS are crucial in eliciting the neurally induced, NO-mediated arterial relaxation.

Responses to perivascular nerve stimulation of distal temporal arteries from dogs and monkeys

In helical strips of dog distal superficial temporal artery denuded of endothelium and partially contracted with prostaglandin F2 alpha (PGF2 alpha), nicotine produced a moderate relaxation preceded by no contraction or a slight contraction. The contraction was less than that observed in proximal arterial strips obtained from the same dogs and was abolished by alpha-adrenoceptor antagonists. Relaxations under alpha-receptor blockade were greater in the distal than in the proximal arteries. Treatment with NG-nitro-L-arginine (L-NA), a nitric oxide (NO) synthase inhibitor, abolished the relaxation caused by nicotine and transmural electrical stimulation (5 Hz for 40 s), the response being reversed by L- but not by D-arginine. In monkey temporal arteries of the distal and proximal portions treated with alpha-antagonists, nicotine produced similar magnitudes of relaxation, which were abolished by treatment with the NO synthase inhibitor. Vasodilator nerves appear to play an important role in regulation of small arterial tone; noradrenergic vasoconstrictor function is less and vasodilator nerve function is more evident in dog distal arteries than in dog proximal arteries. The neurally induced relaxation in dog and monkey distal temporal arteries is postulated to be mediated by NO derived from nerves.

Neurogenic and non-neurogenic relaxations caused by nicotine in isolated dog superficial temporal artery

Nicotine produced a transient contraction followed by biphasic (rapid and slow) relaxations in dog superficial temporal arterial strips denuded of the endothelium. The responses to nicotine were abolished by treatment with hexamethonium. The nicotine-induced contraction was abolished by phentolamine and potentiated by NG-nitro-L-arginine (L-NA), a nitric oxide synthase inhibitor. The slowly developing relaxation was markedly suppressed by indomethacin and tranylcypromine, a prostaglandin I2 synthetase inhibitor, whereas the rapid relaxation was abolished by L-NA. The inhibitory effect of L-NA was reversed by L-, but not D-, arginine. NG-nitro-D-arginine had no effect. Transmural electrical stimulation elicited a transient relaxation in phentolamine-treated arteries. The relaxation was not influenced by indomethacin but was abolished by L-NA and tetrodotoxin. Nicotine increased intracellular cyclic AMP and cyclic GMP in the endothelium-denuded arteries. The increment of cyclic AMP was inhibited by indomethacin but not by L-NA, whereas that of cyclic GMP was not influenced by indomethacin but was abolished by L-NA. It may be concluded that nicotine stimulates the adrenergic and nitroxidergic nerves innervating the temporal arterial wall, resulting in a contraction and a rapidly developing relaxation, respectively; the latter is mediated by cyclic GMP. Potentiation by the nitric oxide synthase inhibitor of the contractile response to nicotine is expected to be a suppression of the relaxation mediated by the nerve-derived nitric oxide. Slow relaxations caused by nicotine appear to be associated with the elevation of cyclic AMP produced possibly by prostaglandin I2, which is released from subendothelial, non-neuronal tissues.

Low concentrations of lithium and cyclooxygenase inhibitors enhance endothelin-1 (ET-1)-induced contractions in human temporal artery, but not in porcine ophthalmic artery

Endothelins are a recently discovered group of potent vasoconstrictor peptides synthesized by endothelial cells and other tissues in various species, which seem to participate in the regulation of vascular tonus. Abnormalities in vasoactivity in the head may be an important event in headache pathophysiology, although the mechanisms responsible for such constrictions and/or dilations are not known. The endothelium and its constrictor peptide, endothelin, may play a key role in such mechanisms. Of the various drugs used in the treatment of headache, lithium is an accepted treatment for cluster headache, and indomethacin is the drug of choice for the associated condition chronic paroxysmal hemicrania. The mechanism of action of these drugs in these headaches is not known. Due to the possible involvement of endothelin in headache disorders, the objective of this study was to verify the effects of lithium and cyclooxygenase inhibitors (indomethacin, acetylsalicylic acid and naproxen) on endothelin-1 (ET-1)-induced contractions in isolated human temporal arteries and porcine ophthalmic arteries. It was found that all drugs increased the (ET-1)-induced contractions in human temporal arteries. Conversely, there were no significant changes induced by the drugs in porcine ophthalmic arteries. These results are consistent with the variation of activity often seen in different vascular beds and between species. The potential importance of such reactions for the understanding of vascular changes putatively involved in headache development and treatment is discussed.

Sumatriptan is a potent vasoconstrictor of human dural arteries via a 5-HT1-like receptor

The action of sumatriptan, putatively a selective 5-HT1D or 5-HT1-like receptor agonist which is effective in the treatment of migraine, has been studied on fresh human dural (middle meningeal) arteries. In low concentrations (10(-8)-10(-7) M) it was found to be a significantly stronger vasoconstrictor of dural arteries compared to cerebral and temporal arteries. However, its potency was less than that of 5-HT. The sumatriptan-induced vasoconstriction was antagonized by methiothepin (10(-9)-10(-8) M), but not by ketanserin (10(-7) M). The observations suggest that the sumatriptan-induced contraction of the dural artery is mediated via activation of 5-HT1D or 5-HT1-like receptors, whereas it does not appear to activate the 5-HT2 receptors.

N-acetylcysteine enhances nitroglycerin-induced headache and cranial arterial responses

The effects of N-acetylcysteine, a sulfhydryl group donor, on nitroglycerin-induced headache and dilation of temporal and radial arteries were investigated in 11 healthy volunteers. Nitroglycerin, 0.06 microgram/kg/min, was infused for 20 minutes immediately after and 120 minutes after pretreatment with N-acetylcysteine (100 mg/kg) or placebo. Arterial diameters were measured with high frequency ultrasound, and pain was scored by use of a previously evaluated 10-point scale. Plasma levels of free (n = 2) and total (n = 11) N-acetylcysteine were determined. N-Acetylcysteine potentiated the headache response (median headache score, 3 versus 1), and the headache retained its vascular characteristics. Temporal artery dilation was also potentiated by N-acetylcysteine, 139% +/- 3% versus 127% +/- 3% of baseline, whereas the radial artery was unaffected. The potentiation was most pronounced after the first nitroglycerin infusion (12% versus 4.5% compared with placebo). A prolonged dilation of the temporal artery was observed only after the first nitroglycerin infusion, when high levels of N-acetylcysteine were present.

Distribution and effects of neuropeptide Y, vasoactive intestinal peptide, substance P, and calcitonin gene-related peptide in human middle meningeal arteries: comparison with cerebral and temporal arteries

A sparse to moderate supply of nerve fibers containing neuropeptide Y-like immunoreactivity (NPY-LI), vasoactive intestinal polypeptide (VIP-LI), substance P (SP-LI), and calcitonin gene-related peptide (CGRP-LI) was demonstrated in the walls of human middle meningeal arteries. Comparison with similar studies on human cerebral and temporal arteries indicated a similar distribution and density. The immunoreactive material in all three arterial regions was characterized by reversed-phase high pressure liquid chromatography (HPLC) and radioimmunoassay (RIA). The major peak of NPY-LI, VIP-LI, SP-LI, and CGRP-LI in each extract eluted approximately with the same elution volume as that of the corresponding synthetic analogues. The concentration of NPY in the middle meningeal arteries was lower as compared to the temporal arteries. Low concentrations of SP-LI and CGRP-LI were found in the middle meningeal arteries as compared to the cerebral arteries. In isolated ring segments of human middle meningeal and cerebral arteries, NPY caused vasoconstriction but did not potentiate the contractile response of noradrenaline. In the temporal artery, NPY did not induce contraction but potentiated the vasoconstrictor response to noradrenaline. Vasoactive intestinal polypeptide, peptide histidine methionine-27, SP, neurokinin A, and CGRP relaxed all three types of cephalic arteries. The peptide effects were not antagonized by propranolol, atropine, or cimetidine. Comparison of the responses to VIP and SP of vessels from the different regions showed a similar pattern of reactivity. The response to SP was slightly (p less than 0.05) more potent, whereas the responses to CGRP were less potent in the middle meningeal as compared to that in cerebral (p less than 0.005) vessels.

Dose-dependent headache response and dilatation of limb and extracranial arteries after three doses of 5-isosorbide-mononitrate

The aim of the present study was to compare the ability of different doses of isosorbide-5-mononitrate (5-ISMN) to cause dilatation of medium sized and small arteries, and to examine the intensity and duration of any headache produced. Ten healthy volunteers each received 3 doses of 5-ISMN and placebo on separate days. The diameters of the radial and superficial temporal arteries were repeatedly measured with high frequency ultrasound and pain was scored using a 10 point verbal scale. A clear dose-relationship was found for plasma concentrations and headache, and for changes in the diameter of the temporal artery, but not for the radial artery. It is concluded that headache after 5-ISMN is caused by arterial dilatation or by mechanisms responsible for the arterial dilatation. Ultrasound monitoring of arterial diameters is an important and sensitive tool in the evaluation of nitrates and other vasodilators.

Histamine receptors in the isolated human middle meningeal artery. A comparison with cerebral and temporal arteries

The subtypes of histamine receptors mediating dilatation of human meningeal arteries have been tested in vitro, using "selective" antagonists, and compared with cerebral and temporal arteries previously examined. Dilatory responses were tested after preconstriction with prostaglandin F2 alpha. Both mepyramine and cimetidine caused a parallel shift to the right of the histamine concentration-response curve, suggesting the presence of both H1- and H2-receptors. Combined treatment with mepyramine and cimetidine caused further displacement of the concentration-response curve to the right. Schild analysis indicated pA2 values of 6.3 for cimetidine and 9.8 for mepyramine in situations of near complete blockade of either of the receptors. Both H1- and H2-receptors seem of importance for the histamine-induced dilatation in meningeal arteries and neither appear to dominate. The data considered in conjunction with our previous findings support the finding that experimental histamine-induced headache due to vasodilatation is intracranial of origin.