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PubMed2004

Inter-digestive and post-prandial antro-pyloro-duodenal motor activity in humans: effect of 5-hydroxytryptamine 1 receptor agonism.

BACKGROUND: Little is known about the effect of 5-hydroxytryptamine 1 (5-HT(1)) receptor agonism on the co-ordinated motor activity of the gastric antrum, pylorus and duodenum under fasting and fed conditions. AIM: To evaluate the effect of sumatriptan, a 5-HT(1) agonist, on fasting and fed antro-pyloro-duodenal motility. METHODS: In study 1, antro-pyloro-duodenal motility was recorded for two phase IIIs of the migrating motor complex and then, following either a subcutaneous injection of sumatriptan 6 mg or saline control, for at least one additional phase III in 11 healthy volunteers (21-36 years). In study 2, the post-prandial motility was recorded for 3 h after either a subcutaneous injection of sumatriptan 6 mg or saline control in 10 healthy volunteers (18-36 years). RESULTS: Sumatriptan prolonged the migrating motor complex cycle (P = 0.009) by increasing the duration of phase II (P = 0.02) but not phases I and III. Post-prandially, sumatriptan reduced the activity index (P = 0.017) by reducing the frequency of co-ordinated motor activity involving the antrum and/or the duodenum (P < 0.05). CONCLUSION: 5-HT(1) receptor agonism increases the periodicity of the migrating motor complex and reduces the occurrence of post-prandial co-ordinated motor activity involving the gastric antrum, pylorus and duodenum.

Adolescent↗

PubMed1995

The in vivo pharmacological profile of a 5-HT1 receptor agonist, CP-122,288, a selective inhibitor of neurogenic inflammation.

1. The aim of the present study was to investigate the in vivo pharmacological profile of CP-122,288, an indole-derivative with a conformationally restricted N-methylpyrrolidinyl basic side chain in the C-3 position. This C-3 substituent structurally differentiates CP-122,288 from the 5-HT1D receptor agonist sumatriptan, which possesses an N,N-dimethylaminoethyl group. [Formula: see text] 2. When administered prior to electrical stimulation of the trigeminal ganglion, CP-122,288 (0.3-300 ng kg-1, i.v.) produced a dose-related inhibition of plasma protein extravasation in rat dura mater (minimum effective dose, MED, 3 ng kg-1 i.v., P < 0.05; maximal inhibition of plasma extravasation at 30 ng kg-1 i.v., P < 0.01). Sumatriptan produced a similar inhibition of plasma leakage in the dura, but at much higher dose levels (MED, 100 micrograms kg-1 i.v., P < 0.05). Thus, CP-122,288 is of the order of 10(4) fold more potent than sumatriptan. 3. At all doses tested, CP-122,288 did not inhibit plasma protein extravasation measured in extracranial tissues such as the lower lip, eyelid, and conjunctiva. 4. In a separate series of studies in the anaesthetized rat, CP-122,288 (0.003-3 micrograms kg-1 i.v.) produced no change in either heart rate or mean arterial blood pressure, thus demonstrating that doses of CP-122,288 which inhibit plasma protein leakage in rat dura, are devoid of hemodynamic effects. 5. Following a 5 min period of electrical stimulation of the trigeminal ganglion, a 20 min period of sustained neurogenically-driven plasma extravasation, occurring in the absence of electrical stimulation, was initiated. By administration of the compound 5 min after completing the phase of electrical stimulation, this protocol permitted the evaluation of the activity of CP-122,288 on an ongoing and established inflammatory event. CP-122,288 (30 and 300 ng kg-1, i.v., P < 0.01 and P < 0.05, respectively) produced a complete inhibition of plasma protein leakage which was consistent with its effects when administered prior to trigeminal ganglion stimulation. 6. In the anaesthetized dog, CP-122,288 and sumatriptan, at 1-300 micrograms kg-1, i.v., produced a dose-dependent reduction in carotid arterial blood flow and coronary arterial diameter. These data demonstrate that sumatriptan inhibits neurogenic inflammation in the rat (MED, 100 micrograms kg-1, i.v.), and produces vasoconstriction in the dog, over a similar dose-range. Interestingly, doses of CP-122,288 that inhibit neurogenic inflammation in rat dura mater (0.3-300 ng kg-1) were demonstrated to be devoid of vasoconstrictor activity in either the carotid or coronary vascular beds of dog. 7. These data demonstrate that in the rat, CP-122,288 is a highly potent and selective inhibitor of neurogenic inflammation in intracranial tissues, at doses which are devoid of vasoconstrictor activity in dog. Potentially, CP-122,288 may be of use for the acute treatment of migraine, without the risk of cardiovascular side-effects.

Anesthesia↗

PubMed2002

Restoring migraine sufferers' ability to function normally: a comparison of rizatriptan and other triptans in randomized trials.

BACKGROUND: Many migraine patients are unable to function normally during a migraine attack. Assessments of treatment efficacy have tended to focus on migraine symptoms, rather than looking at functional impact. This study compared the efficacy of different oral triptans for restoring normal function in migraine sufferers. METHODS: Retrospective subgroup analysis of data from five randomized, placebo-controlled, double-blind clinical trials in which oral rizatriptan was directly compared with oral sumatriptan 100 mg (772 attacks), 50 mg (2,227 attacks), and 25 mg (1,182 attacks), naratriptan 2.5 mg (413 attacks), and zolmitriptan 2.5 mg (578 attacks) for the acute treatment of a moderate or severe migraine attack. Functional disability was evaluated by patients on a 4-grade scale ('normal', 'mild impairment', 'severe impairment', 'requires bedrest') at baseline and at 0.5, 1, 1.5, 2, 3 and 4 h after dosing. This analysis looked at the percentage of patients who had normal functional ability at 2 h, the last time point before escape medications were allowed, in the subgroup of patients who had some level of disability at baseline. RESULTS: Most patients in each trial and treatment group had some level of disability at baseline (range = 94-100%). At 2 h, more patients on rizatriptan 10 mg were able to function normally compared with sumatriptan 100 mg (39 vs. 32%, odds ratio = 1.4, p = 0.021), sumatriptan 50 mg (47 vs. 42%, odds ratio = 1.2, p = 0.033), sumatriptan 25 mg (48 vs. 36%, odds ratio = 1.7, p < 0.001), naratriptan 2.5 mg (39 vs. 22%, odds ratio = 2.5, p < 0.001), and zolmitriptan 2.5 mg (45 vs. 36%, odds ratio = 1.6, p = 0.008). CONCLUSION: In direct head-to-head comparative clinical trials, oral rizatriptan 10 mg enabled more migraine sufferers to function normally at 2 h after dosing than oral sumatriptan, naratriptan, and zolmitriptan.

Administration, Oral↗

PubMed2003

Clinical applications of new therapeutic deliveries in migraine.

A number of serotonin (5-HT)1B/1D agonists (triptans) are available worldwide for the treatment of migraine. The first-generation triptan, sumatriptan, was initially launched as an SC injection, which is fast-acting and consistently effective but relatively expensive and can be associated with adverse events in some patients. Sumatriptan was then launched as an oral tablet, shortly followed by the development of second-generation triptans that are now available in several formulations. Tablets are highly effective and convenient but may not be suitable in all migraine situations, e.g., migraine-associated nausea or vomiting and gastric disturbances. An intranasal route of administration appears to be an obvious way to deliver a migraine treatment and two triptans, sumatriptan and zolmitriptan, are available in nasal spray formulations. Sumatriptan offered the first nasal spray and has similar efficacy to the sumatriptan tablet, but the response is inconsistent and many patients cannot tolerate the unpleasant taste. The latest nasal spray, zolmitriptan, has produced exciting results in clinical studies and combines a rapid onset of action and consistently high response rates with a good tolerability profile. Early results from the author's clinic suggest that this promise is realized in clinical practice and that this combination of patient benefits makes zolmitriptan nasal spray an ideal way for patients to treat their migraine. With the introduction of zolmitriptan nasal spray, zolmitriptan is now available in three different formulations, enabling patients to tailor their treatment to the circumstances of the individual attack.

Administration, Intranasal↗

PubMed1999

Zolmitriptan.

*Zolmitriptan (Zomig) is an antimigraine drug similar to sumatriptan.*The clinical file mainly comprises placebo-controlled, dose-finding studies recommending an optimal oral dose of 2.5 mg.*Zolmitriptan has been compared with sumatriptan in a trial that showed no difference in efficacy. In particular, the recurrence rate of headache after initial relief was not lower on zolmitriptan than on sumatriptan.*The safety profile of zolmitriptan is similar to that of sumatriptan. The contraindications relating to a history of cardiovascular disease must be respected because of the vasoconstrictive effect of the drug.*Zolmitriptan has the same drug interactions as sumatriptan. Zolmitriptan should not be used during migraine attacks by patients using propranolol.

Drug Interactions↗

PubMed2003

Stimulation of the calcitonin gene-related peptide enhancer by mitogen-activated protein kinases and repression by an antimigraine drug in trigeminal ganglia neurons.

Calcitonin gene-related peptide (CGRP) is involved in the underlying pathophysiology of all vascular headaches, including migraines. Elevated levels of CGRP during migraine are restored to normal coincident with headache relief after treatment with the antimigraine drug sumatriptan. We have used primary cultures of trigeminal neurons under conditions simulating migraine pathology and therapy to study the mechanisms controlling the CGRP promoter. Using reporter genes in transient transfection assays, we demonstrate that an 18 bp enhancer containing a helix-loop-helix element is both necessary and sufficient for full promoter activity. NGF treatment and cotransfection with an upstream activator of the extracellular signal-regulated MAP kinases (MAPKs) activated the enhancer. Treatment with sumatriptan repressed NGF- and MAPK-stimulated CGRP promoter activity. Repression was also observed using a synthetic MAPK-responsive reporter gene. Sumatriptan regulation of CGRP gene expression did not couple to a G(i)/G(o) pathway, but rather caused a prolonged increase in intracellular calcium. The importance of the prolonged calcium signal in repression of MAPK activity was demonstrated by using the ionophore ionomycin to mimic sumatriptan action. We propose that activation of MAPK pathways may increase CGRP gene expression during migraine, and that sumatriptan can diametrically oppose that activation via a prolonged elevation of intracellular calcium.

Animals↗

PubMed1998

The 5-HT1-like receptors mediating inhibition of sympathetic vasopressor outflow in the pithed rat: operational correlation with the 5-HT1A, 5-HT1B and 5-HT1D subtypes.

1. It has been suggested that the inhibition of sympathetically-induced vasopressor responses produced by 5-hydroxytryptamine (5-HT) in pithed rats is mediated by 5-HT1-like receptors. The present study has re-analysed this suggestion with regard to the classification schemes recently proposed by the NC-IUPHAR subcommittee on 5-HT receptors. 2. Intravenous (i.v.) continuous infusions of 5-HT and the 5-HT1 receptor agonists, 8-OH-DPAT (5-HT1A), indorenate (5-HT1A), CP 93,129 (5-HT1B) and sumatriptan (5-HT(1B/1D)), resulted in a dose-dependent inhibition of sympathetically-induced vasopressor responses. 3. The sympatho-inhibitory responses induced by 5-HT, 8-OH-DPAT, indorenate, CP 93,129 or sumatriptan were analysed before and after i.v. treatment with blocking doses of the putative 5-HT receptor antagonists, WAY 100635 (5-HT1A), cyanopindolol (5-HT(1A/1B)) or GR 127935 (5-HT(1B/1D)). Thus, after WAY 100635, the responses to 5-HT and indorenate, but not to 8-OH-DPAT, CP 93,129 and sumatriptan, were blocked. After cyanopindolol, the responses to 5-HT, indorenate and CP 93,129 were abolished, whilst those to 8-OH-DPAT and sumatriptan (except at the lowest frequency of stimulation) remained unaltered. In contrast, after GR 127935, the responses to 5-HT, CP 93,129 and sumatriptan, but not to 8-OH-DPAT and indorenate, were abolished. 4. In additional experiments, the inhibition induced by 5-HT was not modified after 5-HT7 receptor blocking doses of mesulergine. 5. The above results suggest that the 5-HT1-like receptors, which inhibit the sympathetic vasopressor outflow in pithed rats, display the pharmacological profile of the 5-HT1A, 5-HT1B and 5-HT1D, but not that of 5-HT7, receptors.

Animals↗

PubMed2001

Oral almotriptan in the treatment of migraine: safety and tolerability.

OBJECTIVE: To summarize safety and tolerability data on orally administered almotriptan from premarketing clinical trials. BACKGROUND: Almotriptan is a new 5-HT1B/1D receptor agonist similar to sumatriptan in mode of action and therapeutic efficacy. In addition, the safety and tolerability profile of almotriptan has been demonstrated in a number of controlled clinical trials. Sumatriptan is generally safe and well tolerated; however, in controlled clinical trials, it has been associated with chest symptoms (pressure, warmth, and other unpleasant sensations) with an incidence of 3% to 5%. DESIGN: Three phase 1 dose-finding and pharmacokinetic studies in healthy men and women volunteers were reviewed to assess the safety and tolerability of oral almotriptan at single doses ranging from 2 to 200 mg. The objective of one study was to evaluate cardiovascular safety. Two phase 2 trials assessed the safety and tolerability of single doses of 2 to 150 mg in migraine (n=911). Two phase 3 trials assessed the safety and tolerability of a single 12.5-mg oral dose after three attacks (n=910) and repeated doses of 12.5 mg for multiple attacks over the long term (n=747). All studies were conducted in Europe. Data from the United States is currently being analyzed and will be published at a later date. RESULTS: In phase 2 and 3 trials comprising more than 2500 patients with migraine and 15 000 attacks, adverse events were infrequent and mild. The most common events-dizziness, nausea and vomiting, headache, fatigue, paresthesia, and drowsiness-were reported in fewer than 3% of patients. At the recommended therapeutic dose of 12.5 mg, the adverse events profile was not statistically different from placebo. The incidence of chest symptoms was 0.2% in the phase 3 trials. The long-term safety and tolerability profile after treatment of more than 10 000 attacks was similar to that following the single-dose studies. In all clinical trials, almotriptan demonstrated a very favorable adverse event profile, particularly with respect to nonischemic-related chest symptoms. CONCLUSIONS: Almotriptan was safe and well tolerated in nearly all adult patients with migraine, with and without aura, enrolled in these studies. The incidence of chest symptoms in preclinical studies was substantially lower than that reported for sumatriptan in premarketing studies, indicating that almotriptan may be better tolerated than sumatriptan at clinically anticipated doses. However, any potential difference in cardiovascular safety between almotriptan and sumatriptan cannot be determined or inferred from this data. Cardiovascular risk profiles for all drugs within this class (triptans) should be considered similar. Only extensive postmarketing data, not currently available, can potentially change this recommendation.

Administration, Oral↗

PubMed2001

Eletriptan.

Eletriptan (Relpax, Pfizer) is one of a group of anti-migraine medications commonly referred to as 'triptans'. It is a potent serotonin agonist at the 5-HT(1B/1D) receptor and is indicated for the acute treatment of migraine headaches. Eletriptan is administered orally. It is rapidly absorbed and has a bioavailability of 50% compared to 14% for sumatriptan. The relatively high lipophilicity of eletriptan compared to sumatriptan may explain its faster oral absorption and shorter time to onset of action. Results from comparative studies between oral eletriptan and sumatriptan indicate that eletriptan 80 mg was superior to sumatriptan 100 mg in onset of action, headache response rate, pain free response rate and relief of associated migraine symptoms at the 1 or 2 h time intervals. Although there was a modest increase in adverse events with eletriptan 80 mg than with sumatriptan 100 mg, eletriptan received a high patient acceptability rating (84%).

Clinical Trials as Topic↗

PubMed1993

Dual coupling of cloned human 5-hydroxytryptamine1D alpha and 5-hydroxytryptamine1D beta receptors stably expressed in murine fibroblasts: inhibition of adenylate cyclase and elevation of intracellular calcium concentrations via pertussis toxin-sensitive G protein(s).

The second messenger coupling of cloned human 5-hydroxytryptamine (5-HT)1D alpha and 5-HT1D beta receptors stably expressed in murine fibroblasts (LM (tk-)) was investigated. Clonal cell lines expressing similar receptor densities (Bmax = 750-950 fmol/mg) were used in this study. 5-HT (EC50 = 1.5-2.0 nM) and sumatriptan (EC50 = 6-14 nM), a selective 5-HT1D agonist, produced dose-dependent inhibition of forskolin-stimulated cAMP accumulation in intact cells transfected with the 5-HT1D alpha or 5-HT1D beta receptor gene. The maximal inhibitory responses elicited by these agonists were slightly greater with the 5-HT1D alpha receptor (approximately 90%) than the 5-HT1D beta receptor (approximately 80%). 5-HT (EC50 = 1.7-2.4 nM) and sumatriptan (EC50 = 8-18 nM) also evoked dose-dependent elevations in intracellular calcium concentrations ([Ca2+]i), with EC50 values that were indistinguishable from those for inhibition of forskolin-stimulated cAMP accumulation. Cells expressing 5-HT1D beta receptors displayed significantly larger 5-HT-induced increases in [Ca2+]i than did cells expressing 5-HT1D alpha receptors (206 nM versus 114 nm increase; p < 0.01). Dose-dependent elevations in inositol phosphates (IP) were also observed after application of 5-HT (EC50 = 29-54 nM) or sumatriptan (EC50 = 73-481 nM); the maximal increases in IP accumulation were modest (51-69%) for both 5-HT1D subtypes. In contrast to the cAMP and calcium responses, the concentration-response curves for IP accumulation were shifted to the right at least 10-fold. Methiothepin, a nonselective 5-HT1 antagonist, competitively antagonized the cAMP response, yielding an apparent dissociation constant (Kb) of 3-4 nM for the 5-HT1D receptors. Methiothepin (10 microM) significantly reduced the elevations in [Ca2+]i (> 90%) and IP (> 75%) evoked by saturating concentrations (1 microM) of agonists. All three functional responses were significantly attenuated (> 90%) by pretreatment with 100 ng/ml pertussis toxin. The sumatriptan-induced elevation of [Ca2+]i via activation of the 5-HT1D subtypes may provide a molecular mechanism of action by which sumatriptan could directly constrict cerebral blood vessels and alleviate migraine symptoms.

Adenylate Cyclase Toxin↗

PubMed1996

Alniditan, a new 5-hydroxytryptamine1D agonist and migraine-abortive agent: ligand-binding properties of human 5-hydroxytryptamine1D alpha, human 5-hydroxytryptamine1D beta, and calf 5-hydroxytryptamine1D receptors investigated with [3H]5-hydroxytryptamine and [3H]alniditan.

Alniditan is a new migraine-abortive agent. It is a benzopyran derivative and therefore structurally unrelated to sumatriptan and other indole-derivatives and to ergoline derivatives. The action of sumatriptan is thought to be mediated by 5-hydroxytryptamine (5-HT)1D-type receptors. We investigated the receptor-binding profile in vitro of alniditan compared with sumatriptan and dihydroergotamine for 28 neurotransmitter receptor subtypes, several receptors for peptides and lipid-derived factors, ion channel-binding sites, and monoamine transporters. Alniditan revealed nanomolar affinity for calf substantia nigra 5-HT1D and for cloned h5-HT1D alpha, h5-HT1D beta and h5-HT1A receptors (Ki = 0.8, 0.4, 1.1, and 3.8 nM, respectively). Alniditan was more potent than sumatriptan at 5-HT1D-type and 5-HT1A receptors. Alniditan showed moderate-to-low or no affinity for other investigated receptors; sumatriptan showed additional binding to 5-HT1F receptors. Dihydroergotamine had a much broader profile with high affinity for several 5-HT, adrenergic and dopaminergic receptors. In signal transduction assays using cells expressing recombinant h5-HT1D alpha, h5-HT1D beta, or h5-HT1A receptors, alniditan (like 5-HT) was a full agonist for inhibition of stimulated adenylyl cyclase (IC50 = 1.1, 1.3, and 74 nM, respectively, for alniditan). Therefore, in functional assays, the potency of alniditan was much higher at 5-HT1D receptors than at 5-HT1A receptors. We further compared the properties of [3H]alniditan, as a new radioligand for 5-HT1D-type receptors, with those of [3H]5-HT in membrane preparations of calf substantia nigra, C6 glioma cells expressing h5-HT1D alpha, and L929 cells expressing h5-HT1D beta receptors. [3H]Alniditan revealed very rapid association and dissociation binding kinetics and showed slightly higher affinity (Kd = 1-2 nM) than [3H]5-HT. We investigated 25 compounds for inhibition of [3H]alniditan and [3H]5-HT binding in the three membrane preparations; Ki values of the radioligands were largely similar, although some subtle differences appeared. Most compounds did not differentiate between 5-HT1D alpha and 5-HT1D beta receptors, except methysergide, ritanserin, ocaperidone, risperidone, and ketanserin, which showed 10-60-fold higher affinity for the 5-HT1D alpha receptor. The Ki values of the compounds obtained with 5-HT1D receptors in calf substantia nigra indicated that these receptors are of the 5-HT1D beta-type. We demonstrated that alniditan is a potent agonist at h5-HT1D alpha and h5-HT1D beta receptors; its properties probably underlie its cranial vasoconstrictive and antimigraine properties.

Animals↗

PubMed2004

Naratriptan for the treatment of acute migraine: meta-analysis of randomised controlled trials.

OBJECTIVE: To evaluate the comparative efficacy and tolerability of naratriptan in the treatment of acute attacks of migraine. DESIGN: Meta-analysis of randomised controlled trials using a random effects model. SUBJECTS: A total of 4499 patients suffering from moderate or severe attacks of acute migraine reported in ten trials. MAIN OUTCOME MEASURES: Response rate ratios for headache relief, pain-free response and sustained relief (4-24 hours). Adverse events were estimated with the rate ratio (RR), risk difference and number needed to harm. RESULTS: Pooled RRs relative to placebo for pain-free response at 2 and 4 hours for naratriptan 2.5 mg were 2.52 (95% CI: 1.78-3.57) and 2.58 (1.99-3.35). Naratriptan 2.5 mg was more effective than naratriptan 1 mg; the corresponding RRs for pain-free response at 2 and 4 hours were 1.54 (95% CI: 1.28-1.86) and 1.35 (1.20-1.51). In contrast, naratriptan 2.5 mg was less effective in pain-free response than either rizatriptan 10 mg at 4 hours (RR: 0.68; 95% CI: 0.55-0.85) or sumatriptan 100 mg at 4 hours (RR: 0.79; 95% CI: 0.67-0.93). However, significantly fewer patients experienced adverse effects with naratriptan 2.5 mg than with rizatriptan 10 mg (RR: 0.73; 95% CI: 0.56-0.97) or sumatriptan 100 mg (RR: 0.68; 95% CI: 0.55-0.86). CONCLUSIONS: Naratriptan is an effective and well-tolerated treatment for acute attacks of migraine. Head-to-head comparisons suggest that naratriptan 2.5 mg is significantly more effective than the 1 mg dose. Rizatriptan 10 mg and sumatriptan 100 mg were superior to naratriptan in terms of headache relief, while zolmitriptan 2.5 mg seemed to have comparable efficacy. Randomised controlled trials have shown that at licensed doses (1 and 2.5 mg), naratriptan is associated with a lower incidence of adverse effects than rizatriptan, sumatriptan and zolmitriptan. The incidence rates of adverse effects were similar to placebo.

Dose-Response Relationship, Drug↗

PubMed1998

Comparison of more and less lipophilic serotonin (5HT1B/1D) agonists in a model of trigeminovascular nociception in cat.

The trigeminovascular system consists of bipolar neurons innervating pain-producing intracranial structures, such as the superior sagittal sinus (SSS), and projecting to the medullary and upper cervical dorsal horn second order neurons. Zolmitriptan is a newly developed 5HT1B/1D receptor agonist with both peripheral and central sites of action in the trigeminovascular system due to greater lipophilicity relative to the more hydrophilic antimigraine compound sumatriptan. Given that we have seen electrophysiological and autoradiographic binding data to suggest that the compound may inhibit activity at second-order neurons this study was designed to examine whether such an effect could be demonstrated in a population of trigeminal neurons using Fos immunohistochemistry. Cats were anesthetised with alpha-chloralose (60 mg/kg intraperitoneal then 20 mg/kg intravenous maintenance) with all surgery being conducted using halothane (1-3%). The animals were prepared for physiological monitoring, including blood pressure, heart rate, rectal temperature, and end-expiratory CO2. They were intubated, ventilated, and paralyzed with gallamine triethiodide (6 mg/kg i.v.). A midline craniotomy was performed to expose the sinus for electrical stimulation using hook electrodes. Twenty-four hours after completion of the surgical procedures the animal was ready for treatment. Vehicle, sumatriptan (85 micrograms/kg), or zolmitriptan (30 micrograms/kg) was administered and the SSS was stimulated (250 microseconds, 100 V at 0.3 Hz) for 1 h. Following an additional 1 h the animal was perfused and immunohistochemistry was used to detect the protein product of the immediate early gene c-Fos. We compared the dorsal horns of the medulla (trigeminal nucleus caudalis) and the C1 and C2 cervical spinal cords in control animals with those receiving zolmitriptan or sumatriptan. We noted a significant reduction in Fos expression after treatment with zolmitriptan but no effect with sumatriptan. Given that zolmitriptan accesses central neurons and that the method of stimulation we have employed would bypass peripheral trigeminal mechanisms it is likely that the reduction in second-order trigeminal neuronal activity was due to a direct inhibitory effect of the compound on those cells. These neurons form a possible site for the treatment of acute attacks of migraine.

Animals↗

PubMed1991

Rationale for the use of 5-HT1-like agonists in the treatment of migraine.

Migraine headache is thought to be associated with a dilatation of cranial blood vessels, particularly those in the dura mater, and an accompanying localized sterile inflammatory response. Sumatriptan is a highly selective 5-HT1-like receptor agonist which selectively constricts cranial blood vessels (including those in the dura mater). It also inhibits neurogenically-mediated plasma protein extravasation in the dura mater. Haemodynamic studies in anaesthetized animals have shown that sumatriptan selectively constricts the carotid arterial circulation and this effect appears to be restricted to an effect on carotid arteriovenous anastomoses. Sumatriptan has a much more selective pharmacological profile than ergot preparations which are also used in the acute treatment of migraine. The development of sumatriptan has been based on a vascular theory of migraine and its high degree of efficacy in the treatment of migraine strengthens the argument that dilatation of cranial blood vessels is the cause of vascular headache.

Animals↗

PubMed1997

Effects of avitriptan, a new 5-HT 1B/1D receptor agonist, in experimental models predictive of antimigraine activity and coronary side-effect potential.

Several acutely acting antimigraine drugs, including ergotamine and sumatriptan, have the ability to constrict porcine arteriovenous anastomoses as well as the human isolated coronary artery. These two experimental models seem to serve as indicators, respectively, for the therapeutic and coronary side-effect potential of the compounds. Using these two models, we have now investigated the effects of avitriptan (BMS-180048; 3-[3-[4-(5-methoxy-4-pyrimidinyl)-l-piperazinyl[propyl]-N-methyl-l H-indole-5-methane-sulfonamide monofumarate), a new 5-HT 1B/1D receptor agonist. In anaesthetized pigs, avitriptan (10, 30, 100 and 300 micrograms.kg-1) decreased the total carotid blood flow by exclusively decreasing arteriovenous anastomotic blood flow; capillary blood flow was increased. The mean +/- SEM i.v. dose of avitriptan eliciting a 50% decrease (ED50) in the porcine carotid arteriovenous anastomotic blood flow was calculated to be 76 +/- 23 micrograms.kg-1 (132 +/- 40 nmol.kg-1) and the highest dose (300 micrograms.kg-1) produced a 72 +/- 4% reduction. In recent comparative experiments (DeVries et al. 1996), the mean +/- SEM ED50 (i.v.) of sumatriptan in decreasing carotid arteriovenous anastomotic blood flow was 63 +/- 17 micrograms.kg-1 (158 +/- 43 nmol.kg-1), with a reduction of 76 +/- 4% by 300 micrograms.kg-1, i.v. Both avitriptan (pD2; 7.39 +/- 0.09; Emax: 13.0 +/- 4.5% of the contraction to 100 mM K+) and sumatriptan (pD2: 6.33 +/- 0.09; Emax: 15.5 +/- 2.3% of the contraction to 100 mM K+) contracted the human isolated coronary artery. The above results suggest that avitriptan should be able to abort migraine headaches in patients, but may exhibit sumatriptan-like effects on coronary arteries. Initial clinical studies have demonstrated the therapeutic action of the drug in acute migraine.

Animals↗

PubMed2001

Unravelling the pharmacological profile of the canine external carotid vasodilator '5-HT1-like' receptors: coexistence of sympatho-inhibitory 5-HT1B and postjunctional 5-HT7 receptors.

It has been suggested that the external carotid vasodilatation produced by serotonin (5-hydroxytryptamine; 5-HT) in anaesthetised dogs with intact vagosympathetic trunks is mediated by sympatho-inhibitory '5-HT1D' receptors and musculotropic '5-HT1-like' receptors. The present study has re-analysed this suggestion with regard to the classification schemes recently proposed by the NC-IUPHAR subcommittee on 5-HT receptors. In pentobarbital-anaesthetised dogs with intact vagosympathetic trunks, 1-min intracarotid (i.c.) infusions of 5-carboxamidotryptamine (5-CT; 0.01-0.3 microg/min), 5-HT (0.3-30 microg/ min), 5-methoxytryptamine (5-MeO-T; 1-100 microg/min) or sumatriptan (1-100 microg/min) dose-dependently increased the external carotid blood flow without affecting blood pressure or heart rate. The selective 5-HT1D receptor agonist, PNU-142633 (1-1000 microg/min), was essentially inactive. After mesulergine (300 microg/kg, i.v.), an antagonist at cardiovascular 5-HT7 receptors, the above responses to 5-HT, 5-CT and 5-MeO-T were blocked, whilst those to sumatriptan remained unaffected. In contrast, after the 5-HT1B/1D receptor antagonist, GR127935 (10 microg/kg, i.v.), the responses to 5-HT, 5-CT and 5-MeO-T were not affected, but those to sumatriptan were abolished. Furthermore, after the selective 5-HT1B receptor antagonist, SB224289 (300 microg/kg, i.v.), the responses to 5-HT, 5-CT and 5-MeO-T were significantly enhanced, whereas those to sumatriptan were abolished. Interestingly, the responses to all these agonists remained unmodified after the selective 5-HT1D receptor antagonist, BRL15572 (300 microg/kg, i.v.). The above results suggest that the '5-HT1-like' receptors, which mediate canine external carotid vasodilatation, display the pharmacological profile of sympatho-inhibitory 5-HT1B receptors and musculotropic 5-HT7 receptors, and confirm the existence of vasoconstrictor 5-HT1B receptors.

5-Methoxytryptamine↗

PubMed1991

Cortical and striatal variations in drug competition studies with putative 5-hydroxytryptamine1D binding sites.

The ability of 5-hydroxytryptamine (5-HT), 5-carboxytryptamine (5-CT) and sumatriptan to compete for [3H]5-HT binding sites in various brain tissues was analyzed in bovine, guinea pig, pig and human cortex and caudate. Radioligand binding conditions were designed to allow for the selective labeling of putative 5-HT1D binding sites. 5-HT competed monophasically with putative 5-HT1D binding sites in each of the 8 tissues studied. By contrast, both 5-CT and sumatriptan competed with markedly shallow displacement curves in each of the 8 tissues. In the case of sumatriptan, complete displacement of [3H]5-HT could not be achieved even at concentrations as high as 2000 times its IC50 value. These data indicate that 10(-5) M 5-HT should not be used to define specific binding to 5-HT1D receptors in radioligand binding assays. Instead, 5-HT1D receptor binding sites should be redefined as [3H]5-HT-labeled binding sites displaced by 10(-5) M sumatriptan.

Animals↗

PubMed1995

Differences in the effects of ketanserin and GR127935 on 5-HT-receptor mediated responses in rabbit saphenous vein and guinea-pig jugular vein.

Ketanserin has higher affinity for 5-HT1D alpha receptors compared to 5-HT1D beta receptors, whereas, GR127935 (N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2(methyl-4(-(5-methyl- 1,2,4-oxadiazol-3-yl)[1,1-biphenyl]-4-carboxamide), a novel and selective 5-HT1D receptor antagonist, has higher affinity for 5-HT1D beta receptors compared to 5-HT1D alpha receptors. In the present study, we compared the effects of ketanserin and GR127935 on sumatriptan-induced responses of rabbit saphenous vein and guinea-pig jugular vein. In rabbit saphenous vein, contractile responses elicited by sumatriptan were antagonised by ketanserin (pA2 = 6.76) and GR127935 (apparent pA2 = 9.4). In guinea-pig jugular vein, concentration-dependent relaxations evoked by sumatriptan were antagonised by ketanserin and GR127935 (apparent pA2 = 5.9 and 10, respectively). Ketanserin but not GR127935, inhibited Ca(2+)-induced contraction of depolarised strips of guinea-pig ileum longitudinal muscle/myenteric plexus, however, in rabbit saphenous vein and guinea-pig jugular vein, 5-HT receptor mediated responses were insensitive to nifedipine (Ca2+ channel blocker), eliminating the possibility that the inhibitory effects of ketanserin and GR127935 were due to the blockade of voltage-operated Ca2+ channels. Thus, antagonism by ketanserin and GR127935 confirms the presence of 5-HT1D receptors in rabbit saphenous vein and guinea-pig jugular vein. The differential effects of ketanserin and GR127935 on responses elicited by sumatriptan in rabbit saphenous vein and guinea-pig jugular vein may reflect either species differences in 5-HT1D receptors or the involvement of 5-HT1D alpha and 5-HT1D beta receptor subtypes.

Animals↗