Mesenchymal stem cell-derived conditioned medium and Methysergide give rise to crosstalk inhibition of 5-HT2A and 5-HT7 receptors in neuroblastoma cells

OBJECTIVE

(s): We aimed to investigate the effects of mesenchymal stem cell secretome and methysergide combination on 5-hydroxytryptamine 2A, (5-HT2AR), 5-hydroxytryptamine 7 (5-HT7R), adenosine 2A (A2AR) receptors and CD73 on neuroblastoma cell line and how they affect biological characteristics. Methysergide was used as a serotonin antagonist on the neuroblastoma cells.

MATERIALS AND METHODS

Human dental pulp-derived stem cells (hDPSCs) used to obtain conditioned medium (CM). Methysergide drug was prepared in CM and applied to neuroblastoma cells. Analysis of 5-HT7R, 5-HT2AR, A2AR and CD73 expressions was performed by western blot and immunofluorescence staining. Total apoptosis, mitochondrial membrane depolarization, Ki-67 proliferation test, viability analysis, DNA damage and cell cycle analysis were performed in accordance with the product procedure by using biological activity test kits.

RESULTS

Our results showed that neuroblastoma cancer cells are normally on the Gs signaling axis via the serotonin 7 receptor and the adenosine 2A receptor. CM and Methysergide inhibited the 5-HT7 and A2A receptor levels in neuroblastoma cells. We found that CM and methysergide formed crosstalk inhibition between 5-HT2AR, 5-HT7R, A2AR and CD73. CM and Methysergide increased the total apoptosis in neuroblastoma cells and induced the mitochondrial membrane depolarization. CM and Methysergide induced the DNA damage and arrested in G0/G1 phase of cell cycle of the neuroblastoma cells.

CONCLUSION

These findings suggest that the combination of CM and methysergite may exert a therapeutic effect on neuroblastoma cancer cells, and future in vivo studies may be important in area of neuroblastoma research to support the findings.

Cluster headache

INTRODUCTION

The revised International Headache Society (IHS) criteria for cluster headache are: attacks of severe or very severe, strictly unilateral pain, which is orbital, supraorbital, or temporal pain, lasting 15 to 180 minutes and occurring from once every other day to eight times daily.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to abort cluster headache? What are the effects of interventions to prevent cluster headache? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations, such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 23 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: baclofen (oral); botulinum toxin (intramuscular); capsaicin (intranasal); chlorpromazine; civamide (intranasal); clonidine (transdermal); corticosteroids; ergotamine and dihydroergotamine (oral or intranasal); gabapentin (oral); greater occipital nerve injections (betamethasone plus xylocaine); high-dose and high-flow-rate oxygen; hyperbaric oxygen; leuprolide; lidocaine (intranasal); lithium (oral); melatonin; methysergide (oral); octreotide (subcutaneous); pizotifen (oral); sodium valproate (oral); sumatriptan (oral, subcutaneous, and intranasal); topiramate (oral); tricyclic antidepressants (TCAs); verapamil; and zolmitriptan (oral and intranasal).

Actions of derivatives of lysergic acid on the heart of Venus mercenaria

5-Hydroxytryptamine and a number of (+)-lysergic acid derivatives have been tested on the heart of Venus mercenaria. One group of derivatives was found to increase the amplitude and frequency of heart beat in a manner much like 5-hydroxytryptamine. It included the monoethylamide, diethylamide, propanolamide (ergometrine), butanolamide (methylergometrine) and certain peptide derivatives of lysergic acid without substituents in positions 1 or 2. Of these, lysergic acid diethylamide was the most active. Given sufficient time (up to 4 hr), as little as 10 ml. of 10(-16) M lysergic acid diethylamide produced a maximum increase in amplitude and frequency in about one-half of the 80 hearts on which it was tested. Its action was very slowly reversed by washing, as was true of all lysergic acid derivatives. A second group of lysergic acid derivatives, substituted in positions 1 or 2, had weak excitor action, if any, and specific 5-hydroxytryptamine blocking action. This group consisted of 1-methyl-, 1-acetyl-, and 2-bromo-lysergic acid diethylamide and 1-methyllysergic acid butanolamide (methysergide). Of these, the last showed least signs of excitor action, usually none up to 10(-4) M, and it blocked 5-hydroxytryptamine in a molar ratio of about one to one.

Information processing in anxiety: a pilot study of the effect of manipulating 5-HT function

We gave the indirect 5-HT agonist, D-fenfluramine (30 mg), the 5 -HT antagonist methysergide (2 mg) and placebo to 11 patients with an anxiety disorder and 12 controls in a double-blind, balanced-order, cross-over design. Compared to controls, patients had significantly higher anxiety ratings, were slower in naming colours in computerized Stroop tests and showed greater interference for anxiety-related words. Patients tended to have a lower critical flicker fusion threshold (CFFT) than controls and in the subjects taken as a whole there was a significant inverse correlation between CFFT and Spielberger state (r=-0.54, p<0.01) and trait anxiety (r=-0.55, p<0.01). Neither drug had significant effects on anxiety ratings or on Stroop interference. D-Fenfluramine significantly increased CFFT (p < 0.02) and methysergide non-significantly reduced CFFT with no significant differences between patients and controls. 5-HT may be involved in lower-level visual information processing but we found no evidence for its direct involvement in the attentional bias for anxiety-related information in the emotional Stroop.

THE EFFECTS OF DRUGS ON THE UPTAKE OF AMINES BY MAST CELLS

Neoplastic mast cells, taken from an ascitic tumour in mice and incubated in vitro, took up (14)C-labelled 5-hydroxytryptamine and histamine from the medium. Uptake during the first hour gave an approximate measure of the initial rate. The amount of each amine taken up in this time was determined by bioassay and by radioactivity, the two methods giving similar results. The curves obtained by plotting initial rate of uptake against concentration in the medium suggested that the uptake of 5-hydroxytryptamine was by an active process and also by diffusion, whereas uptake of histamine was by diffusion only. The cells also took up (14)C-labelled (+/-)-noradrenaline and tryptamine, apparently by diffusion. The active uptake of 5-hydroxytryptamine was inhibited by lowering the temperature to 25 degrees C or by increasing the pH to 8.9, procedures which had little effect on histamine uptake. The effects of cocaine, imipramine, chlorpromazine, mepyramine, promethazine, phenoxybenzamine, lysergic acid diethylamide, bromolysergic acid diethylamide, methysergide, guanethidine, dichloroisoprenaline and pronethalol on the uptake of amines were examined. In general, any antagonist which inhibited uptake of 5-hydroxytryptamine had little effect on uptake of histamine, and vice versa. Possible ways in which these antagonists produce their effects on amine uptake are discussed. A high concentration of 5-hydroxytryptamine, of tryptamine or of noradrenaline inhibited uptake of histamine, but only tryptamine decreased uptake of 5-hydroxytryptamine. These results, together with those from experiments with antagonists, suggest that there are specific binding sites for 5-hydroxtryptamine in these cells.

A COMPARISON OF PLATELET AGGREGATION PRODUCED BY SEVEN COMPOUNDS AND A COMPARISON OF THEIR INHIBITORS

The aggregating effects of adenosine diphosphate, thrombin, 5-hydroxytryptamine, tryptamine, adrenaline and noradrenaline, and tri-ethyl tin have been carefully compared. The first three compounds in some circumstances produce remarkably similar effects although there are important differences. The kinetics of aggregation induced by adrenaline (and noradrenaline) are quite different and the tri-ethyl tin effects are different again. Anti-serotonins specifically inhibit 5-hydroxytryptamine and the anti-adrenaline drug phentolamine specifically inhibits the effects of the catecholamines. Experiments presented suggest but do not prove that aggregation produced by all these compounds is accompanied by the liberation of diphosphate from the platelets and that platelet triphosphate may be converted to diphosphate. How these different compounds all produce this effect is discussed. Either the presence of diphosphate or the action of a triphosphatase might be the immediate cause of aggregation if there is a single final common cause. The anti-adrenaline phentolamine prolongs the bleeding time, so adrenaline or noradrenaline may be involved in platelet phenomena in haemostasis.

Arterial diameter during central volume depletion in humans

The luminal diameter of the radial artery was followed by high frequency ultrasound during 50 degrees head-up tilt-induced central volume depletion in ten healthy subjects of whom six were tilted twice and pretreated with the serotonin receptor antagonist methysergide or placebo following a double-blind randomized design. Eight subjects without active treatment experienced presyncopal symptoms after 16-45 (mean 32 min). Central volume depletion was indicated by an increase in mean thoracic electrical impedance [from 31.5 (SEM 1.6) to 33.4 (SEM 1.7) omega; P < 0.05]. Cardiac output decreased [from 4.1 (SEM 0.3) to 2.2 (SEM 0.3) 1.min-1] and heart rate [HR, from 64 (SEM 3) to 100 (SEM 7) beats.min-1], mean arterial pressure (MAP, from 77 (SEM 4) to 89 (SEM 2) mmHg [10.3 (SEM 0.53 to 11.9 (SEM 0.27) kPa]) and total peripheral resistance (TPR, from 19 (SEM 2) to 34 (SEM 4) mmHg.min.1-1 [2.5 (SEM 0.27) to 4.5 (SEM 0.53) kPa.min.1-1]) increased; but with the appearance of presyncopal symptoms, HR, MAP and TPR were reduced to 65 (SEM 8) beats.min-1, 46 (SEM 4) mmHg [6.1 (SEM 0.53) kPa] and 18 (SEM 3) mmHg.min.1-1 [2.4 (SEM 0.4) kPa.min-1.1-1], respectively (P < 0.05). Vascular resistance was reflected in the arterial diameter which decreased from 2.42 (SEM 0.17) to 2.27 (SEM 0.14) mm during head-up tilt and increased to 2.71 (SEM 0.14) mm with the appearance of presyncopal symptoms (P < 0.05). Methysergide reduced the resting radial (15 +/- 2%) and temporal artery diameters (10 +/- 3%) (P < 0.05); however, it affected neither tilt-tolerance nor the central cardiovascular response to tilt. The results suggested a serotonergic influence on arterial tone at rest, and demonstrated that vessels as large as the radial artery participated in vascular control during central volume depletion independent of such a serotonergic influence.

Effects of enhancement and antagonism of 5-hydroxytryptamine activity on the influence of metoclopramide on gastric emptying

This study examines the influence of the serotonergic system on the effect of metoclopramide on gastric emptying. Six subjects received the following pretreatments before metoclopramide and paracetamol: fluoxetine (5-HT uptake inhibitor); meterogoline (5-HT1 antagonist); pizotifen (5-HT2 antagonist) or methysergide (5-HT1 and 5-HT2 antagonist). One regimen consisted of metoclopramide (5-HT3 antagonist and 5-HT4 agonist) alone. Gastric emptying was measured by the mean cumulative fraction absorbed-time profiles of paracetamol. Methysergide/metoclopramide significantly delayed gastric emptying from 30 min onwards. Metoclopramide with either metergoline or pizotifen did not retard gastric emptying to the same extent, suggesting a greater influence with simultaneous 5-HT1 and 5HT2 blockade. Metoclopramide/fluoxetine caused a significant decrease in the fractional absorption of paracetamol at 5 min when compared to the metoclopramide regimen. It was assumed that the influence of metoclopramide was not optimal at this stage, therefore possibly indicating domination of 5-HT3 over 5-HT4 effects, resulting in gastric delay. It therefore seems as if all the 5-HT receptors present in the gut have a role to play in the control of gastric emptying.

Effect of electrical field stimulation on muscle strips from chicken crop

The effect of electrical field stimulation (EFS) on smooth muscle strips from the chicken crop was investigated. The EFS (5 Hz, 2 ms, 400 mA; 10 Hz, 2 ms, 400 mA; 5 Hz, 2 ms, 500 mA; 10 Hz, 2 ms, 500 mA) produced contractions in all preparations. Atropine (10(-5) mol l-1) diminished muscle contraction in response to EFS. Tetrodotoxin (5 X 10(-6) mol l-1) fully suppressed the contractile responses to EFS. A serotonin antagonist (methysergide, 10(-4) mol l-1) did not alter contractions elicited by EFS. Propranolol (10(-5) mol l-1) led to an increase of contractions induced by EFS. Noradrenaline (10(-6)-10(-4) mol l-1) reduced acetylcholine-induced (1.1 X 10(-6) mol l-1) contraction of the crop smooth muscle strips. Propranolol (10(-5) mol l-1) abolished noradrenaline-induced relaxation almost fully. Tetrodotoxin (5 X 10(-6) mol l-1) did not change the relaxing effect of noradrenaline. These results suggested that the responses of crop smooth muscle to EFS involve excitatory cholinergic and non-cholinergic (probably peptidergic) as well as inhibitory adrenergic nerves.

5-Hydroxytryptamine affects rat migrating myoelectric complexes through different receptor subtypes: evidence from 5-hydroxytryptophan administration

The effect of the serotonin precursor 5-hydroxytryptophan (5-HTP) on jejunal migrating myoelectric complexes (MMCs) was investigated in conscious rats. Subcutaneous administration of low doses of 5-HTP (1-2 mg/kg) shortened the period between migrating complexes, whereas high doses of the compound (4-8 mg/kg) disrupted the MMC pattern. The serotonin (5-HT2) antagonist methysergide (8 mg/kg s.c.) did not alter basal MMC, neither did it prevent the effect of a low dose of 5-HTP; conversely, it antagonized the disruption due to the high dose. The 5-HT3 antagonist ICS 205-930 (30 micrograms/kg s.c.) decreased MMC frequency; administration of 2 mg/kg 5-HTP following ICS 205-930 brought the frequency of myoelectric complexes back to basal values. Both effects of 5-HTP were prevented by the decarboxylase inhibitor benserazide (85 mg/kg i.p.), which per se caused a transient inhibition of spiking activity. The results suggest that rat MMCs can be influenced in a composite fashion by progressively increasing concentrations of 5-HT, which in turn activate different receptor subtypes. A peripheral neuronal receptor, probably belonging to the 5-HT3 subclass, mediates the increase in MMC frequency observed after low doses of 5-HTP; higher levels of serotonin activate 5-HT2 receptors, causing disruption of cycling activity. Additionally, 5-HT3 receptors, but not 5-HT2, appear to be relevant for the regulation of the MMC pattern by the endogenous amine.

An electrophysiological study of habenular influence on hippocampus

The action of lateral habenula (LH) stimulation on focal epileptiform activity in the hippocampus was studied. Local microinjection of sodium penicillin induced a steady interictal activity in the dorsal hippocampus. Low frequency electrical stimulation of the habenula caused a marked enhancement of spike activity in both frequency and amplitude. The effect was blocked by intraperitoneally injected methysergide. The facilitatory influence of the habenula on hippocampal activity might be due to a disinhibitory mechanism. The results are regarded as suggesting that the habenula may be a relay station between the basal ganglia and the hippocampal formation. LH as well as basal ganglia might modulate hippocampal excitability, exerting a control on the genesis and diffusion of abnormal activities.

Alterations in nociception following lesions of the A5 catecholamine nucleus

Neurons located in the nucleus raphe magnus (NRM), a region important in the control of nociception, appear to be tonically inhibited by noradrenergic (NA) neurons. Anatomical studies have suggested that the A5 catecholamine nucleus may be the primary source of noradrenergic neurons whose terminals are located in the NRM. The purpose of the present study was to examine the role of A5 neurons in the modulation of nociception. Bilateral electrolytic lesions of the A5 nuclei produced a marked and long lasting antinociception as assessed by both the tail-flick and hot-plate tests. Unilateral A5 lesions also produced a long-lasting elevation in hot-plate latency, but the elevation of tail-flick latency was smaller in magnitude and was only observed one day following the lesion. This finding is consistent with previous studies which have shown that blockade of the NA input to the NRM by the microinjection of NA antagonists also produces antinociception. These data indicate that neurons located in the A5 nucleus may be the origin of this NA projection to the NRM. The elevation in tail-flick latency observed following A5 lesions was significantly attenuated by the intrathecal injection of either the NA antagonist phentolamine or the serotonergic antagonist methysergide. However, the elevation in hot-plate latency was not significantly altered by these monoaminergic antagonists. Similarly, previous studies have shown that the elevation in tail-flick, but not hot-plate latency, produced by the microinjection of NA antagonists in the NRM is attenuated by the intrathecal injection of either phentolamine or methysergide.(ABSTRACT TRUNCATED AT 250 WORDS)

Neural control of the sphincter of Oddi. A physiological role of 5-hydroxytryptamine in the regulation of basal sphincter of Oddi motor activity in the cat

The effect of 5-hydroxytryptamine (5-HT) on the sphincter of Oddi (SO) was studied in the cat. The SO had two motor responses to 5-HT: the most common was an initial contraction followed by a more prolonged relaxation, and the other was an exclusive relaxation. Tetrodotoxin did not impair the magnitude of the net contraction induced by 5-HT, but it completely blocked the relaxation. Methysergide partially inhibited the SO contraction in response to submaximal doses of 5-HT (5-20 micrograms/kg). Atropine decreased the SO excitatory response to all doses of 5-HT. The combination of atropine and methysergide completely antagonized the 5-HT excitatory effect, which changed the SO biphasic response to an exclusive relaxation. After tetrodotoxin, the effect of 5-HT was almost completely antagonized by methysergide alone. The SO contraction and relaxation caused by 5-HT were almost completely blocked by 5-HT tachyphylaxis. In contrast, a 5-HT depletion with reserpine enhanced the sensitivity of the SO to 5-HT, responding to doses a thousand times smaller than in control animals. Hexamethonium, phentolamine, propranolol, and 5-methoxy-N,N-dimethyltryptamine did not antagonize the 5-HT-induced contraction or relaxation. These findings indicate that 5-HT caused SO contraction by stimulating postganglionic cholinergic neurons and the smooth muscle directly and caused relaxation by stimulating postganglionic, noncholinergic, nonadrenergic inhibitory neurons. 5-HT blockade or depletion resulted in a significant reduction in basal tonic pressures and in the amplitude of phasic contractions, which suggested that serotonergic neurons may play a physiologic role in the regulation of basal SO motor activity.

Serotonergic mediation of descending inhibition from midbrain periaqueductal gray, but not reticular formation, or spinal nociceptive transmission in the cat

Electrical stimulation in the midbrain periaqueductal gray (PAG) and lateral midbrain reticular formation (LRF) strongly suppresses the responses of spinal dorsal horn neurons to noxious heating of the skin. The possible role of serotonin (5-hydroxytryptamine, 5-HT) was investigated by quantitatively comparing certain parameters of descending inhibition from PAG and LRF in normal cats [14,15] and cats whose central 5-HT levels had been reduced by pretreatment with p-chlorophenylalanine (PCPA, 300 or 500 mg/kg i.p., 72 h prior to acute experiment). Single lumbar dorsal horn neuronal responses to noxious radiant heating of glabrous footpad skin(50 degrees C, 10 sec, 1/3 min) were recorded in normal and PCPA-pretreated cats anesthetized with sodium pentobarbital and N2O. Inhibition of neuronal heat-evoked responses during midbrain stimulation (mean frequency 30 Hz, up to 800 microA current intensity) was expressed as percent of the unit's control response in the absence of midbrain stimulation. Inhibition by PAG stimulation of units from cats pretreated with 300 mg/kg PCPA (mean inhibition at 450 microA to 60% of control in 12 units) was not detectably different from that in control (non-pretreated) cats. However, inhibition by PAG stimulation was significantly weaker in units from cats pretreated with 500 mg/kg PCPA (mean to 83.4% of control in 9 units). In the latter group, mean current threshold for inhibition was higher, and slope of current-intensity plots lower, than in the control and 300 mg/kg PCPA pretreatment groups. In contrast, mean inhibition by LRF stimulation was enhanced in the 300 and 500 mg/kg PCPA treatment groups in a dose-related manner. In normal (non-pretreated) cats, systemic administration of the putative 5-HT antagonist methysergide (0.07--1 mg/kg) reduced or abolished inhibition by PAG stimulation in each of 8 units. Low doses of methysergide had little or no effect on inhibition produced by LRF stimulation in 6 units. The results suggest pharmacologically distinct mechanisms of inhibition produced by stimulation in PAG and LRF.

Effect of three serotonin antagonists on plasma prolactin response to suckling in puerperal women

The effect of the acute administration of three serotonin antagonists on plasma PRL levels and on the PRL response to suckling was investigated in a group of puerperal women. A single oral dose of metergoline or methysergide induced a significant decrease of plasma PRL levels and abolished the PRL response to suckling. Cyproheptadine administration did not modify either the plasma PRL levels or the PRL response to suckling. These results are discussed in light of the known pharmacological properties of the three antiserotonergic drugs.

The effect of methysergide, pimozide, and sodium valproate on the diazepam-stimulated growth hormone secretion in man

Diazepam-induced GH secretion was tested on 28 male volunteers before and after a 3-day treatment with methysergide, pimozide, or sodium valproate. Serum GH, diazepam, and blood glucose levels were determined. Without prior medication, the mean serum GH level increased 336% 1 h after diazepam administration. Treatment with the serotonin antagonist, methysergide, had no effect on the diazepam-stimulated GH secretion, whereas pimozide, the selective dopamine receptor-blocking agent, reduced the GH response to diazepam by 50% (P less than 0.05). Sodium valproate, a gamma-aminobutyric acid transaminase inhibitor, also inhibited diazepam-induced GH secretion; stimulated GH levels were 51% at 30 min (P less than 0.025), 39% at 60 min (P less than 0.025), and 46% at 90 min (P less than 0.025) relative to the stimulated levels without medication. No difference was found in blood glucose or serum diazepam levels after the drug treatments relative to the values obtained under basal conditions. It is suggested that diazepam-induced GH secretion is at least partly mediated via dopaminergic mechanisms. Serotonin does not seem to be involved. It is further proposed that gamma-aminobutyric acid plays an inhibitory role in GH secretion.

Failure of nocturnal prolactin suppression by methysergide to entrain changes in testosterone in normal men

In order to investigate further the postulated relationship between the secretion of PRL and testosterone, 10 normal young men were studied during polygraphically recorded sleep. Concentrations of LH and testosterone were measured in plasma every 20 min, and the results were analyzed in relation to sleep parameters and previously reported (J Clin Invest 56: 690, 1975) concentrations of PRL. All subjects were studied on a control night after placebo administration and on an experimental night after ingestion of the serotonin receptor blocker, methysergide. Analysis of variance revealed that concentrations of testosterone rose gradually during sleep on both nights, as has been noted in previous studies. Highest LH values occurred during stage 1 sleep, but were only 25% higher than the lowest values, which were seen in stage 4. As shown previously, PRL concentrations were markedly suppressed by methysergide treatment. However, no significant change in testosterone values were observed on the methysergide nights as compared to the control nights. When the data were analyzed by a correlational approach, again, no significant relation between concentrations of PRL and testosterone was found. Although these data do not support the concept that PRL-stimulated testosterone secretion occurs during the night in normal men, this study does not rule out the possibility that such a mechanism may be operative during daytime hours, or under conditions of PRL stimulation rather than PRL suppression.

Increase in sialic acids removable by neuraminidase during the shape change of platelets

Human or rabbit platelets were activated by ADP or 5-hydroxytrypatamine and rapidly fixed with glutaraldehyde. The shape change associated with activation gave rise to an increase in sialic acids removable by neuraminidase. This increase, like the shape change, was prevented by adenosine or methysergide added before ADP or 5-hydroxytryptamine respectively. The results indicate the exposure of additional glycoprotein(s) on the platelet surface.

[Charge-transfer complexes of indolalkylamine and ergoline derivatives]

Charge-transfer complexes of 1,3,5-trinitrobenzene and pyromellitic dianhydride with indolalkylamines (5-hydroxytryptamine, dimethyltryptamine, etryptamine) and with ergoline derivatives having antiserotonin activity (methysergide, methylergometrine, metergoline, nicotergoline) were studied. The value of the association constant of indole derivatives with trinitrobenzene is influenced by variations on the chain; on the contrary, with pyromellitic dianhydride - only etryptamine and dimethyltryptamine form CT-complexes - the different behaviour can not be correlated with any particular structural characteristics. The association constant values of ergoline derivatives with trinitrobenzene are of the same order of magnitude as that of serotonin; with pyromellitic dianhydride only metergoline and nicotergoline form CT-complexes.