Metergoline

Metergoline inhibits the neuronal Nav1.2 voltage-dependent Na(+) channels expressed in Xenopus oocytes.[Pubmed:24909513]

Acta Pharmacol Sin. 2014 Jul;35(7):862-8.

AIM: Metergoline is an ergot-derived psychoactive drug that acts as a ligand for serotonin and dopamine receptors. The aim of this study was to investigate the regulatory effects of Metergoline on the neuronal Nav1.2 voltage-dependent Na(+) channels in vitro. METHODS: Xenopus oocytes were injected with cRNAs encoding rat brain Nav1.2 alpha and beta1 subunits. Voltage-activated Na(+) currents were recorded using two-electrode voltage clamp technique. Drugs were applied though perfusion. RESULTS: Both Metergoline and lidocaine reversibly and concentration-dependently inhibited the peak of Na(+) currents with IC50 values of 3.6 +/- 4.2 and 916.9 +/- 98.8 mumol/L, respectively. Metergoline (3 mumol/L) caused a 6.8 +/- 1.2 mV depolarizing shift of the steady-state activation curve of the Na(+) currents, and did not alter the inactivation curve. In contrast, lidocaine (3 mumol/L) caused a 12.7 +/- 1.2 mV hyperpolarizing shift of the inactivation curve of the Na(+) currents without changing the steady-state activation curve. Both Metergoline and lidocaine produced tonic and use-dependent inhibition on the peak of Na(+) currents. CONCLUSION: Metergoline exerts potent inhibition on the activity of neuronal Nav1.2 channels, which may contribute to its actions on the central nervous system.

Development of suspension polymerized molecularly imprinted beads with metergoline as template and application in a solid-phase extraction procedure toward ergot alkaloids.[Pubmed:23130751]

Anal Chem. 2012 Dec 4;84(23):10411-8.

The first successfully developed molecularly imprinted polymer toward six ergot alkaloids and their respective epimers is described. A new imprinting molecule, Metergoline, was used as template analogue in the production of suspension polymerized beads. These spherical particles functioned as selective sorbent in a solid-phase extraction column. The application of this column in the cleanup of barley samples prior to liquid chromatography coupled with tandem mass spectrometry allowed simple and cost-efficient sample preparation. The performance of the imprinted polymer and a non-imprinted control polymer was evaluated. This includes determination of the recovery values and the matrix effect of each of the 12 tested ergot alkaloids as well as a cross-reactivity study with 25 common mycotoxins. The binding isotherms were obtained for Metergoline, thus allowing comparison with other (imprinted) sorbents. A comparison between bulk and suspension polymerization is provided to determine the appropriate production technique.

Regulation of Human Kv1.4 Channel Activity by the Antidepressant Metergoline.[Pubmed:27251511]

Biol Pharm Bull. 2016;39(6):1069-72.

Metergoline is an ergot-derived psychoactive drug that is a ligand for various serotonin and dopamine receptors. Little is known about the effect of Metergoline on different types of receptors and ion channels. Potassium channels are the most diverse group of ion channels. Kv1.4, a shaker family K channel alpha subunit, is one of a family of voltage gated K channels that mediates transient and rapid inactivating A-type currents and N-type inactivation. We demonstrated previously that Metergoline inhibited the activity of neuronal voltage-dependent Na(+) channels in Xenopus laevis oocytes (Acta Pharmacol. Sin., 35, 2014, Lee et al.). In this study, we sought to elucidate the regulatory effects underlying Metergoline-induced human Kv1.4 channel inhibition. We used the two electrode voltage-clamp (TEVC) technique to investigate the effect of Metergoline on human Kv1.4 channel currents in Xenopus laevis oocytes expressing human Kv1.4 alpha subunits. Interestingly, Metergoline treatment also induced inhibition of peak currents in human Kv1.4 channels in a concentration-dependent manner. The IC50 of peak currents of hKv1.4 currents was 3.6+/-0.6 microM. These results indicate that Metergoline might regulate the human Kv1.4 channel activity that is expressed in X. laevis oocytes. Further, this regulation of potassium currents by Metergoline might be one of the pharmacological actions of Metergoline-mediated psychoactivity.

Aptamer-based molecular recognition of lysergamine, metergoline and small ergot alkaloids.[Pubmed:23242153]

Int J Mol Sci. 2012 Dec 14;13(12):17138-59.

Ergot alkaloids are mycotoxins produced by fungi of the genus Claviceps, which infect cereal crops and grasses. The uptake of ergot alkaloid contaminated cereal products can be lethal to humans and animals. For food safety assessment, analytical techniques are currently used to determine the presence of ergot alkaloids in food and feed samples. However, the number of samples which can be analyzed is limited, due to the cost of the equipment and the need for skilled personnel. In order to compensate for the lack of rapid tests for the detection of ergot alkaloids, the aim of this study was to develop a specific recognition element for ergot alkaloids, which could be further applied to produce a colorimetric reaction in the presence of these toxins. As recognition elements, single-stranded DNA ligands were selected by using an iterative selection procedure named SELEX, i.e., Systematic Evolution of Ligands by EXponential enrichment. After several selection cycles, the resulting aptamers were cloned and sequenced. A surface plasmon resonance analysis enabled determination of the dissociation constants of the complexes of aptamers and lysergamine. Dissociation constants in the nanomolar range were obtained with three selected aptamers. One of the selected aptamers, having a dissociation constant of 44 nM, was linked to gold nanoparticles and it was possible to produce a colorimetric reaction in the presence of lysergamine. This system could also be applied to small ergot alkaloids in an ergot contaminated flour sample.

Effects of various serotonin receptor subtype-selective antagonists alone and on m-chlorophenylpiperazine-induced neuroendocrine changes in rats.[Pubmed:1432690]

J Pharmacol Exp Ther. 1992 Nov;263(2):588-95.

Administration of m-chlorophenylpiperazine [m-CPP, a serotonin (5-HT) agonist] to rats increases plasma concentrations of prolactin and corticosterone. Pretreatment with various doses of ritanserin (5-HT1C/5-HT2 antagonist), ICS 205-930 and MDL-72222 (5-HT3 antagonists), iodocyanopindolol or CG361A (beta adrenoceptor antagonists) and spiperone (5-HT1A/5-HT2 antagonist) did not attenuate m-CPP-induced increases in plasma concentrations of prolactin. In contrast, pretreatment with various doses of Metergoline (5-HT1/5-HT2 antagonist), propranolol (beta adrenoceptor antagonist that also has binding affinity for 5-HT1A, 5-HT1B and 5-HT1C sites), mesulergine and mianserin (5-HT1C/5-HT2 antagonists) attenuated m-CPP-induced increases in plasma prolactin. On the other hand, m-CPP-induced increases in corticosterone concentrations were attenuated only by pretreatment with a low dose of mianserin and a high dose of spiperone. When administered without m-CPP, Metergoline, mesulergine, ritanserin, ICS 205-930 and high doses of mianserin, spiperone and propranolol increased plasma corticosterone secretion. On the other hand, none of the antagonists used in the present study, except spiperone, had any significant effect on plasma prolactin secretion. These findings suggest that m-CPP-induced prolactin secretion is mediated by stimulation of 5-HT1C receptors while corticosterone secretion may be mediated either by an antagonistic effect at 5-HT3 receptor subtype or by nonserotonergic mechanisms. Alternatively, enhancement of corticosterone secretion by the 5-HT antagonists when administered alone may be responsible for their failure to block m-CPP-induced corticosterone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological characterization of serotonin receptor subtypes involved in vasopressin and plasma renin activity responses to serotonin agonists.[Pubmed:1535317]

Eur J Pharmacol. 1992 Jan 21;210(3):285-9.

Serotonergic drugs with 5-HT2 receptor agonist properties have been suggested to increase plasma vasopressin concentration, blood pressure (BP) and plasma renin activity (PRA). To study whether these actions are mediated by the same or different receptors, we used three potent 5-HT agonists with different structures and receptor binding profiles. All drugs were administered i.v. to conscious, unrestrained rats. The selective agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), which has high affinity for 5-HT2 receptors, caused marked increases in BP and PRA but no change in plasma vasopressin concentrations. The 5-HT1C agonist, m-chlorophenylpiperazine (m-CPP), which also binds to other 5-HT receptors, caused moderate increases in BP and PRA and significantly elevated plasma vasopressin concentrations. The 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), did not increase any of these parameters. BP and PRA elevations paralleled each other after all drugs, while vasopressin responses were clearly different. Vasopressin responses to m-CPP were entirely antagonised by the 5-HT1/5-HT2 antagonist Metergoline, partially by the 5-HT2/5-HT1C antagonists ritanserin and LY 53857, but not by the 5-HT2 antagonist ketanserin. Ritanserin, LY53857 and ketanserin all very effectively blocked BP responses to m-CPP. These findings suggest that BP and PRA but not vasopressin responses are mediated by 5-HT2 receptors. Vasopressin secretion is mediated by 5-HT1 receptors, most likely by 5-HT1C receptors.

Agonist activity of sumatriptan and metergoline at the human 5-HT1D beta receptor: further evidence for a role of the 5-HT1D receptor in the action of sumatriptan.[Pubmed:1330643]

Eur J Pharmacol. 1992 Sep 1;227(1):99-102.

We have recently cloned a novel human 5-HT1D receptor subtype termed 5-HT1D beta. CHO K1 cells expressing the human serotonin 5-HT1D beta receptor were assayed to determine the second messenger system of this receptor. Cyclic AMP radioimmunoassays revealed that the 5-HT1D beta receptor is negatively coupled to adenylate cyclase in this cell system. A maximum of 50% inhibition of forskolin stimulated cAMP production was obtained with 5-HT1 receptor agonists which was blocked by the non-selective 5-HT receptor antagonist methiothepin (pKB = 100 nM). The novel anti-migraine drug sumatriptan, a putative 5-HT1D selective compound, acted as an agonist at the 5-HT1D beta receptor. Most notably Metergoline, a putative 5-HT1 receptor antagonist, did not block the effects of 5-HT and was found to be acting as a full agonist at the 5-HT1D beta receptor. The ability of Metergoline to act as an agonist at the 5-HT1D beta receptor may explain why it does not inhibit 5-HT and sumatriptan induced contraction of dog saphenous vein and other large conducting arteries. These results suggest that the 5-HT1D beta receptor may be the site of action of sumatriptan in preventing migraine, and that Metergoline's actions on the dog saphenous vein are not contradictory to that hypothesis, as previously reported.

Metergoline is a psychoactive drug of the ergoline chemical class which acts as a ligand for various serotonin and dopamine receptors.

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