Evaluation of pain related behaviors and disease related outcomes in an immunocompetent mouse model of prostate cancer induced bone pain.

Cancer-induced bone pain (CIBP) is the most common and devastating symptom of bone metastatic cancer that substantially disrupts patients' quality of life. Currently, there are few effective analgesic treatments for CIBP other than opioids which come with severe side effects. In order to better understand the factors and mechanisms responsible for CIBP it is essential to have clinically relevant animal models that mirror pain-related symptoms and disease progression observed in patients with bone metastatic cancer. In the current study, we characterize a syngeneic mouse model of prostate cancer induced bone pain. We transfected a prostate cancer cell line (RM1) with green fluorescent protein (GFP) and luciferase reporters in order to visualize tumor growth longitudinally in vivo and to assess the relationship between sensory neurons and tumor cells within the bone microenvironment. Following intra-femoral injection of the RM1 prostate cancer cell line into male C57BL/6 mice, we observed a progressive increase in spontaneous guarding of the inoculated limb between 12 and 21 days post inoculation in tumor bearing compared to sham operated mice. Daily running wheel performance was evaluated as a measure of functional impairment and potentially movement evoked pain. We observed a progressive reduction in the distance traveled and percentage of time at optimal velocity between 12 and 21 days post inoculation in tumor bearing compared to sham operated mice. We utilized histological, radiographic and µCT analysis to examine tumor induced bone remodeling and observed osteolytic lesions as well as extra-periosteal aberrant bone formation in the tumor bearing femur, similar to clinical findings in patients with bone metastatic prostate cancer. Within the tumor bearing femur, we observed reorganization of blood vessels, macrophage and nerve fibers within the intramedullary space and periosteum adjacent to tumor cells. Tumor bearing mice displayed significant increases in the injury marker ATF3 and upregulation of the neuropeptides SP and CGRP in the ipsilateral DRG as well as increased measures of central sensitization and glial activation in the ipsilateral spinal cord. This immunocompetent mouse model will be useful when combined with cell type selective transgenic mice to examine tumor, immune cell and sensory neuron interactions in the bone microenvironment and their role in pain and disease progression associated with bone metastatic prostate cancer.

Blockade of the colony-stimulating factor-1 receptor reverses bone loss in osteoporosis mouse models.

BACKGROUND: Mice lacking either colony-stimulating factor-1 (CSF-1) or its receptor, CSF-1R, display osteopetrosis. Accordingly, genetic deletion or pharmacological blockade of CSF-1 prevents the bone loss associated with estrogen deficiency. However, the role of CSF-1R in osteoporosis models of type-1 diabetes (T1D) and ovariectomy (OVX) has not been examined. Thus, we evaluated whether CSF-1R blockade would relieve the bone loss in a model of primary osteoporosis (female mice with OVX) and a model of secondary osteoporosis (female with T1D) using micro-computed tomography. METHODS: Female ICR mice at 10 weeks underwent OVX or received five daily administrations of streptozotocin (ip, 50 mg/kg) to induce T1D. Four weeks after OVX and 14 weeks after first injection of streptozotocin, mice received an anti-CSF-1R (2G2) antibody (10 mg/kg, ip; once/week for 6 weeks) or vehicle. At the last day of antibody administration, mice were sacrificed and femur and tibia were harvested for micro-computed tomography analysis. RESULTS: Mice with OVX had a significant loss of trabecular bone at the distal femoral and proximal tibial metaphysis. Chronic treatment with anti-CSF-1R significantly reversed the trabecular bone loss at these anatomical sites. Streptozotocin-induced T1D resulted in significant loss of trabecular bone at the femoral neck and cortical bone at the femoral mid-diaphysis. Chronic treatment with anti-CSF-1R antibody significantly reversed the bone loss observed in mice with T1D. CONCLUSION: Our results demonstrate that blockade of CSF-1R signaling reverses bone loss in two different mouse models of osteoporosis.

Chronic administration of Cl-amidine, a pan-peptidylarginine deiminase inhibitor, does not reverse bone loss in two different murine models of osteoporosis.

Recent in vitro studies have shown a role for the peptidyl-arginine deiminases (PADs) in bone resorption. However, it is unknown whether these enzymes are involved in bone loss in vivo. Thus, we evaluated the antiresorptive effect of a pan-PAD inhibitor in two murine models of osteoporosis: (a) primary osteoporosis induced by ovariectomy (OVX); and (b) secondary osteoporosis associated to Type-1 diabetes induced by streptozotocin (STZ, 50 mg/kg, i.p., five daily administrations). Five weeks after OVX and 15 weeks after injections of STZ, mice received daily administrations of Cl-amidine (3 or 10 mg/kg, i.p.) or vehicle for 30 consecutive days. At the end of the treatment, femur and vertebra were harvested for microCT analysis. Blood samples were collected for determination of antibodies against cyclic citrullinated peptides (anti-CCP) by enzyme-linked immunosorbent assay. Serum levels of anti-CCP antibodies from diabetic mice were not significantly different compared to control mice. However, a significant loss of both trabecular bone at the femoral neck and cortical bone at the femoral diaphysis was found in diabetic mice, and Cl-amidine did not reverse the diabetes-induced bone loss. Mice with OVX had significantly lower serum levels of anti-CCP compared to mice with sham surgery. OVX resulted in significant loss of both trabecular bone at the L5 vertebra and distal femoral metaphysis. Cl-amidine did not block the OVX-induced bone loss. Our results suggest that chronic treatment with Cl-amidine at the doses and period of time administered is not long enough to inhibit bone loss in two different murine models of osteoporosis.

Potential vascular α1-adrenoceptor blocking properties of metformin in rat aorta and tail artery.

Metformin is a widely used drug for the treatment of type 2 Diabetes Mellitus. Several studies have also suggested that metformin decreases blood pressure; although an interaction with α-adrenoceptors has been proposed, this mechanism needs to be further investigated. Since α1-adrenoceptors play a significant role to regulate vascular tone, this study has analysed the potential ability of metformin to block α1-adrenoceptors in rat aorta and tail artery. For this purpose, the contractile responses induced by noradrenaline, methoxamine, and phenylephrine were determined in the absence or presence of metformin in rat aorta and tail artery rings. In both arteries, noradrenaline, methoxamine, and phenylephrine produced concentration-dependent contractile responses. Interestingly, the contractile responses to noradrenaline, methoxamine, and phenylephrine were significantly and differentially blocked by metformin (1, 3.1 and/or 10 mM) but not by vehicle. These results suggest that metformin is capable to block α1-adrenoceptors and may explain, at least in part, the anti-hypertensive effect observed in several clinical trials.

Trigeminovascular calcitonin gene-related peptide function in Cacna1a R192Q-mutated knock-in mice.

Familial hemiplegic migraine type 1 (FHM1) is a rare migraine subtype. Whereas transgenic knock-in mice with the human pathogenic FHM1 R192Q missense mutation in the Cacna1a gene reveal overall neuronal hyperexcitability, the effects on the trigeminovascular system and calcitonin gene-related peptide (CGRP) receptor are largely unknown. This gains relevance as blockade of CGRP and its receptor are therapeutic targets under development. Hence, we set out to test these effects in FHM1 mice. We characterized the trigeminovascular system of wild-type and FHM1 mice through: (i) in vivo capsaicin- and CGRP-induced dural vasodilation in a closed-cranial window; (ii) ex vivo KCl-induced CGRP release from isolated dura mater, trigeminal ganglion and trigeminal nucleus caudalis; and (iii) peripheral vascular function in vitro . In mutant mice, dural vasodilatory responses were significantly decreased compared to controls. The ex vivo release of CGRP was not different in the components of the trigeminovascular system between genotypes; however, sumatriptan diminished the release in the trigeminal ganglion, trigeminal nucleus caudalis and dura mater but only in wild-type mice. Peripheral vascular function was similar between genotypes. These data suggest that the R192Q mutation might be associated with trigeminovascular CGRP receptor desensitization. Novel antimigraine drugs should be able to revert this complex phenomenon.

High-fat diet exacerbates pain-like behaviors and periarticular bone loss in mice with CFA-induced knee arthritis.

OBJECTIVE: Our aim was to quantify nociceptive spontaneous behaviors, knee edema, proinflammatory cytokines, bone density, and microarchitecture in high-fat diet (HFD)-fed mice with unilateral knee arthritis. METHODS: ICR male mice were fed either standard diet (SD) or HFD starting at 3 weeks old. At 17 weeks, HFD and SD mice received intra-articular injections either with Complete Freund's Adjuvant (CFA) or saline into the right knee joint every 7 days for 4 weeks. Spontaneous pain-like behaviors and knee edema were assessed for 26 days. At day 26 post-first CFA injection, serum levels of IL-1ß, IL-6, and RANKL were measured by ELISA, and microcomputed tomography analysis of knee joints was performed. RESULTS: HFD-fed mice injected with CFA showed greater spontaneous pain-like behaviors of the affected extremity as well as a decrease in the weight-bearing index compared to SD-fed mice injected with CFA. Knee edema was not significantly different between diets. HFD significantly exacerbated arthritis-induced bone loss at the distal femoral metaphysis but had no effect on femoral diaphyseal cortical bone. HFD did not modify serum levels of proinflammatory cytokines. CONCLUSIONS: HFD exacerbates pain-like behaviors and significantly increases the magnitude of periarticular trabecular bone loss in a murine model of unilateral arthritis.

Heteroreceptors Modulating CGRP Release at Neurovascular Junction: Potential Therapeutic Implications on Some Vascular-Related Diseases.

Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide belonging to the calcitonin gene peptide superfamily. CGRP is a potent vasodilator with potential therapeutic usefulness for treating vascular-related disease. This peptide is primarily located on C- and Aδ-fibers, which have extensive perivascular presence and a dual sensory-efferent function. Although CGRP has two major isoforms (α-CGRP and ß-CGRP), the α-CGRP is the isoform related to vascular actions. Release of CGRP from afferent perivascular nerve terminals has been shown to result in vasodilatation, an effect mediated by at least one receptor (the CGRP receptor). This receptor is an atypical G-protein coupled receptor (GPCR) composed of three functional proteins: (i) the calcitonin receptor-like receptor (CRLR; a seven-transmembrane protein), (ii) the activity-modifying protein type 1 (RAMP1), and (iii) a receptor component protein (RCP). Although under physiological conditions, CGRP seems not to play an important role in vascular tone regulation, this peptide has been strongly related as a key player in migraine and other vascular-related disorders (e.g., hypertension and preeclampsia). The present review aims at providing an overview on the role of sensory fibers and CGRP release on the modulation of vascular tone.

Pharmacological characterization of the mechanisms involved in the vasorelaxation induced by progesterone and 17ß-estradiol on isolated canine basilar and internal carotid arteries.

Progesterone and 17ß-estradiol induce vasorelaxation through non-genomic mechanisms in several isolated blood vessels; however, no study has systematically evaluated the mechanisms involved in the relaxation induced by 17ß-estradiol and progesterone in the canine basilar and internal carotid arteries that play a key role in cerebral circulation. Thus, relaxant effects of progesterone and 17ß-estradiol on KCl- and/or PGF2α-pre-contracted arterial rings were investigated in absence or presence of several antagonists/inhibitors/blockers; the effect on the contractile responses to CaCl2 was also determined. In both arteries progesterone (5.6-180 µM) and 17ß-estradiol (1.8-180 µM): (1) produced concentration-dependent relaxations of KCl- or PGF2α-pre-contracted arterial rings; (2) the relaxations were unaffected by actinomycin D (10 µM), cycloheximide (10 µM), SQ 22,536 (100 µM) or ODQ (30 µM), potassium channel blockers and ICI 182,780 (only for 17ß-estradiol). In the basilar artery the vasorelaxation induced by 17ß-estradiol was slightly blocked by tetraethylammonium (10mM) and glibenclamide (KATP; 10 µM). In both arteries, progesterone (10-100 µM), 17ß-estradiol (3.1-31 µM) and nifedipine (0.01-1 µM) produced a concentration-dependent blockade of the contraction to CaCl2 (10 µM-10mM). These results suggest that progesterone and 17ß-estradiol produced relaxation in the basilar and internal carotid arteries by blockade of L-type voltage dependent Ca(2+) channel but not by genomic mechanisms or production of cAMP/cGMP. Potassium channels did not play a role in the relaxation to progesterone in both arteries or in the effect of 17ß-estradiol in the internal carotid artery; meanwhile KATP channels play a minor role on the effect of 17ß-estradiol in the basilar artery.

Cranioselectivity of sumatriptan revisited: pronounced contractions to sumatriptan in small human isolated coronary artery.

BACKGROUND: Initial concerns about the coronary side-effect potential of the anti-migraine drug sumatriptan and second-generation triptans initiated cranioselectivity studies using proximal human coronary arteries. However, myocardial ischaemia may originate from both large and small human coronary arteries. METHODS: We investigated the contractions to sumatriptan in proximal (internal diameter 2-3 mm), distal (internal diameter 1,000-1,500 µm) and small (internal diameter 500-1,000 µm) human epicardial coronary arteries and compared these with contractions in the human middle meningeal artery. Concentration response curves to sumatriptan in human coronary arteries were constructed in the absence or presence of the 5-hydroxytryptamine1B (5-HT1B) receptor antagonist SB224289 and the 5-HT1D receptor antagonist BRL15572. The effect of sumatriptan on increased cyclic adenosine monophosphate (cAMP) levels induced by forskolin in proximal and distal coronary artery segments was investigated using a biochemical assay. Western blotting was used to analyse the 5-HT1B receptor density in the human arteries. RESULTS: Contractions in the proximal human coronary artery were significantly smaller than those in the human meningeal artery, as we showed previously. In contrast, contractions to sumatriptan in distal and small human coronary arteries were not different from those in the human meningeal artery. The 5-HT1B receptor antagonist SB224289, but not the 5-HT1D receptor antagonist BRL15572, inhibited the contraction induced by sumatriptan in the coronary arteries. Moreover, in distal, but not in proximal, coronary arteries, sumatriptan inhibited the increase in cAMP levels induced by forskolin. Contrary to our expectations, the 5-HT1B receptor expression was more pronounced in the proximal human coronary artery than in the distal and small human coronary artery. CONCLUSIONS: Based on functional experiments in distal and small human coronary arteries, contractions to sumatriptan are not as cranioselective as previously assumed. However, the vast clinical experience with sumatriptan and other triptans has proven that these drugs are cardiovascularly safe when contraindications are taken into account.

Activation of 5-hydroxytryptamine1B/1D/1F receptors as a mechanism of action of antimigraine drugs.

INTRODUCTION: The introduction of the triptans (5-hydroxytryptamine (5-HT)1B/1D receptor agonists) was a great improvement in the acute treatment of migraine. However, shortcomings of the triptans have prompted research on novel serotonergic targets for the treatment of migraine. AREAS COVERED: In this review the different types of antimigraine drugs acting at 5-HT receptors, their discovery and development are discussed. The first specific antimigraine drugs were the ergot alkaloids, consisting of ergotamine, dihydroergotamine and methysergide, which are agonists at 5-HT receptors, but can also bind α-adrenoceptors and dopamine receptors. In the 1990s, the triptans became available on the market. They are 5-HT1B/1D receptor agonists, showing fewer side effects due to their receptor specificity. In the last years, compounds that bind specifically to 5-HT1D, 5-HT1F and 5-HT7 receptors have been explored for their antimigraine potential. Furthermore, the serotonergic system seems to act in tight connection with the glutamatergic as well as the CGRP-ergic systems, which may open novel therapeutic avenues. EXPERT OPINION: Although the triptans are very effective in treating migraine attacks, their shortcomings have stimulated the search for novel drugs. Currently, the focus is on 5-HT1F receptor agonists, which seem devoid of vascular side effects. Moreover, novel compounds that affect multiple transmitter and/or neuropeptide systems that are involved in migraine could be of therapeutic relevance.

Pharmacological evidence that Ca²+ channels and, to a lesser extent, K+ channels mediate the relaxation of testosterone in the canine basilar artery.

Testosterone induces vasorelaxation through non-genomic mechanisms in several isolated blood vessels, but no study has reported its effects on the canine basilar artery, an important artery implicated in cerebral vasospasm. Hence, this study has investigated the mechanisms involved in testosterone-induced relaxation of the canine basilar artery. For this purpose, the vasorelaxant effects of testosterone were evaluated in KCl- and/or PGF(2α)-precontracted arterial rings in vitro in the absence or presence of several antagonists/inhibitors/blockers; the effect of testosterone on the contractile responses to CaCl2 was also determined. Testosterone (10-180 µM) produced concentration-dependent relaxations of KCl- or PGF(2α)-precontracted arterial rings which were: (i) unaffected by flutamide (10 µM), DL-aminoglutethimide (10 µM), actinomycin D (10 µM), cycloheximide (10 µM), SQ 22,536 (100 µM) or ODQ (30 µM); and (ii) significantly attenuated by the blockers 4-aminopyridine (K(V); 1 mM), BaCl2 (K(IR); 30 µM), iberiotoxin (BK(Ca²+); 20 nM), but not by glybenclamide (K(ATP); 10 µM). In addition, testosterone (31, 56 and 180 µM) and nifedipine (0.01-1 µM) produced a concentration-dependent blockade of the contraction to CaCl2 (10 µM to 10 mM) in arterial rings depolarized by 60mM KCl. These results, taken together, show that testosterone relaxes the canine basilar artery mainly by blockade of voltage-dependent Ca²+ channels and, to a lesser extent, by activation of K+ channels (K(IR), K(V) and BK(Ca²+)). This effect does not involve genomic mechanisms, production of cAMP/cGMP or the conversion of testosterone to 17ß-estradiol.

Activation of 5-HT1B receptors inhibits the vasodepressor sensory CGRPergic outflow in pithed rats.

The importance of calcitonin gene-related peptide (CGRP) in the regulation of vascular tone has been widely documented. Indeed, stimulation of the perivascular sensory outflow in pithed rats results in vasodepressor responses, which are mediated by CGRP release. These vasodepressor responses are inhibited by clonidine via prejunctional alpha(2A/2C)-adrenoceptors, but no study has yet reported the role of prejunctional 5-hydroxytryptamine (5-HT) receptors in this experimental model. Since activation of prejunctional 5-HT(1) receptors results in inhibition of neurotransmitter release, this study sets out to investigate as an initial approach the role of 5-HT(1B) receptors in the inhibition of the vasodepressor sensory outflow in pithed rats. Male Wistar pithed rats were pretreated with hexamethonium (2mg/kg.min) followed by i.v. continuous infusions of methoxamine (20 microg/kg min), and then by saline (0.02 ml/min) or CP-93,129 (a rodent 5-HT(1B) receptor agonist; 0.1, 1 and 10 microg/kg min). Under these conditions, electrical stimulation (0.56-5.6 Hz; 50 V and 2 ms) of the spinal cord (T(9)-T(12)) resulted in frequency-dependent decreases in diastolic blood pressure. The infusions of CP-93,129, as compared to those of saline, inhibited the vasodepressor responses induced by electrical stimulation without affecting those to i.v. bolus injections of exogenous alpha-CGRP (0.1, 0.18, 0.31, 0.56 and 1 microg/kg). This inhibition by CP-93,129 was abolished by the antagonists GR127935 (5-HT(1B/1D)) or SB224289 (5-HT(1B)), but not by BRL15572 (5-HT(1D)). The above results suggest that CP-93,129-induced inhibition of the vasodepressor (perivascular) sensory outflow in pithed rats is mainly mediated by activation of prejunctional 5-HT(1B) receptors.

Pharmacological characterization of the inhibition by moxonidine and agmatine on the cardioaccelerator sympathetic outflow in pithed rats.

This study analysed the inhibition produced by the agonists moxonidine (imidazoline I(1) receptors>alpha(2)-adrenoceptors) and agmatine (endogenous ligand of imidazoline I(1)/I(2) receptors), using B-HT 933 (6-ethyl-5,6,7,8-tetrahydro-4H-oxazolo[4,5-d]azepin-2-amine dihydrochloride; alpha(2)-adrenoceptors) for comparison, on the rat cardioaccelerator sympathetic outflow. Male Wistar rats were pithed and prepared to stimulate the cardiac sympathetic outflow or to receive i.v. bolus of exogenous noradrenaline. Sympathetic stimulation or noradrenaline produced, respectively, frequency-dependent and dose-dependent tachycardic responses. I.v. continuous infusions of moxonidine (3 and 10 microg/kg min), agmatine (1000 and 3000 microg/kg min) and B-HT 933 (30 and 100 microg/kg min) inhibited the tachycardic responses to sympathetic stimulation, but not those to noradrenaline. The cardiac sympatho-inhibition by either moxonidine (3 microg/kg min) or B-HT 933 (30 microg/kg min) was not modified by i.v. injections of saline or the antagonists AGN192403 [(+/-)-2-endo-Amino-3-exo-isopropylbicyclo[2.2.1]heptane hydrochloride; 3000microg/kg; imidazoline I(1) receptors] or BU224 (2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride; 300 microg/kg; imidazoline I(2) receptors) and abolished by rauwolscine (300 microg/kg; alpha(2)-adrenoceptors). At the same doses of these compounds, the sympatho-inhibition to moxonidine (10 microg/kg min) and agmatine (1000 microg/kg min) was: (1) not modified by saline, AGN192403 or BU224; (2) partially blocked by rauwolscine or the combination of rauwolscine plus BU224; and (3) abolished by the combination of rauwolscine plus AGN192403. These results demonstrate that the cardiac sympatho-inhibition to: (1) 3 microg/kg min moxonidine or 30 microg/kg min B-HT 933 involves alpha(2)-adrenoceptors; and (2) 10 microg/kg min moxonidine or 1000 microg/kg min agmatine involves alpha(2)-adrenoceptors and imidazoline I(1) receptors.

Spinal sumatriptan inhibits capsaicin-induced canine external carotid vasodilatation via 5-HT1B rather than 5-HT1D receptors.

Migraine is a neurovascular disorder associated with trigeminal activation, vasodilatation and trigeminal release of calcitonin gene-related peptide (CGRP). The antimigraine properties of triptans may be due to: i) vasoconstriction of the carotid arterial bed via 5-HT(1B) receptors; and ii) inhibition of CGRP release from trigeminal nerves, via 5-HT(1B/1D) receptors. This study investigated the effects of intrathecally administered sumatriptan (a 5-HT(1B/1D) receptor agonist) and PNU-142633 (a 5-HT(1D) receptor agonist) on the canine external carotid vasodilator responses to capsaicin, alpha-CGRP and acetylcholine. For this purpose, 42 mongrel dogs were anaesthetised with sodium pentobarbitone and, subsequently, vagosympathectomized. The animals were prepared to measure arterial blood pressure, heart rate and external carotid blood flow; the thyroid artery was cannulated for infusion of agonists. 1-min intracarotid (i.c.) continuous infusions of capsaicin, alpha-CGRP and acetylcholine produced dose-dependent increases in external carotid blood flow without affecting arterial blood pressure or heart rate. These vasodilator responses remained unaffected after intrathecal (i.t.) administration of physiological saline (0.5 ml) or PNU-142633 (300-1000 microg); in contrast, i.t. sumatriptan (300-1000 microg) significantly inhibited the vasodilator responses to capsaicin, but not those to alpha-CGRP or acetylcholine. Furthermore, i.t. administration of SB224289 (a 5-HT(1B) receptor antagonist), but not of BRL15572 (a 5-HT(1D) receptor antagonist), abolished the above inhibition by sumatriptan. These results suggest that sumatriptan-induced inhibition of the external carotid vasodilatation to capsaicin involves a central mechanism mainly mediated by 5-HT(1B) receptors.

Pharmacological characterization of ergotamine-induced inhibition of the cardioaccelerator sympathetic outflow in pithed rats.

Ergotamine inhibits the sympathetically-induced tachycardia in pithed rats. The present study identified the pharmacological profile of this response. Male Wistar rats were pithed and prepared to stimulate the preganglionic (C(7)-T(1)) cardiac sympathetic outflow. Intravenous continuous infusions of ergotamine dose-dependently inhibited the tachycardic responses to sympathetic stimulation, but not those to exogenous noradrenaline. Using several antagonists, the sympatho-inhibition to ergotamine was: (1) partially blocked by rauwolscine (alpha(2)), haloperidol (D(1/2)-like) or rauwolscine plus GR127935 (5-HT(1B/1D)); (2) abolished by rauwolscine plus haloperidol; and (3) unaffected by either saline or GR127935. In animals systematically pretreated with haloperidol, this sympatho-inhibition was: (1) unaffected by BRL44408 (alpha(2A)), partially antagonized by MK912 (alpha(2C)); and (3) abolished by BRL44408 plus MK912. These antagonists failed to modify the sympathetically induced tachycardic responses per se. Thus, the cardiac sympatho-inhibition by ergotamine may be mainly mediated by alpha(2A)/alpha(2C)-adrenoceptors, D(2)-like receptors and, to a lesser extent, by 5-HT(1B/1D) receptors.