Blocking properties of terguride at the 5-HT2 receptor subtypes mediating cardiovascular responses in the rat.

In vitro studies have suggested that terguride blocks the contractile and relaxant responses produced by 5-hydroxytryptamine (5-HT) via 5-HT2A/2B receptors. This study has now investigated terguride's blocking properties on central/peripheral 5-HT2 receptors in anaesthetized or pithed rats. Male Wistar anaesthetized/pithed rats were cannulated for recording blood pressure and heart rate and for i.v. administration of several compounds. In both groups of rats, i.v. bolus injections of 5-HT or (±)-DOI (a 5-HT2 receptor agonist; 1-1000 µg/kg) produced dose-dependent increases in diastolic blood pressure and heart rate. These responses were dose-dependently antagonized by terguride (10-3000 µg/kg). In anaesthetized rats, i.v. bolus injections of BW723C86 (a 5-HT2B receptor agonist; 1-1000 µg/kg) produced dose-dependent increases in diastolic blood pressure and not dose-dependent increases in heart rate, while in pithed rats, these responses were attenuated. The vasopressor responses elicited by BW723C86 in anaesthetized rats were dose-dependently blocked by terguride (10-300 µg/kg), whereas its the tachycardic responses were dose-independently blocked. These results, taken together, suggest that terguride behaved as an antagonist at the 5-HT2 receptors located in the central nervous system and (or) the systemic vasculature. This is the first evidence demonstrating that terguride can block central/peripheral 5-HT2 receptors mediating cardiovascular responses in anaesthetized or pithed rats.

5-HT2 and 5-HT2B antagonists attenuate pro-fibrotic phenotype in human adult dermal fibroblasts by blocking TGF-ß1 induced non-canonical signaling pathways including STAT3 : implications for fibrotic diseases like scleroderma.

BACKGROUND: Release of 5-hydroxytryptamine (5-HT; serotonin) from activated platelets following microvascular injury leads to tissue fibrosis. 5-HT strongly induces extracellular matrix synthesis in dermal fibroblasts in a transforming growth factor beta 1 (TGF-ß1)-dependent manner. AIM: To evaluate anti-fibrotic properties of inhibitors of 5-HT2 and 5-HT2B (terguride, SB204741) respectively in human adult dermal fibroblasts (HADF) derived from a patient with scleroderma. METHODS: Anti-fibrotic efficacy of 5-HT2 and 5-HT2B inhibitors was evaluated as per two strategies: HADF were incubated with 5-HT (1 µM)/TGF-ß1 (10 ng/mL) for 1 hour followed by 5-HT (1 µM)/TGF-ß1 (10 ng/mL) and terguride or SB204741 (1 µM, each) for 24 hours (post-treatment strategy) and HADF were treated with terguride or SB204741 (1 µM, each) for 1 hour followed by 5-HT (1 µM)/TGF-ß1 (10 ng/mL) for 24 hours (pre-treatment strategy). Real time quantitative polymerase chain reaction for expression of pro-fibrotic (TGFΒ1, COL1A1, COL1A2, ACTA2, CTGF and FN1) and anti-fibrotic genes (MMP2/TIMP1) was performed. Expression of type I collagen, alpha smooth muscle actin (α-SMA), phosphorylation of Smad3, ERK1/2 and STAT3 was examined by immunoblotting. RESULTS: Stimulation of HADF cells with 5-HT/TGF-ß1 led to the increased expression of pro-fibrotic genes which was significantly reduced by both terguride and SB204741. Expression of anti-fibrotic genes was not affected upon incubation with the inhibitors. In 5-HT-stimulated HADF, treatment with terguride and SB204741 decreased type I collagen and α-SMA. In 5-HT/TGF-ß1 stimulated HADF, terguride and SB204741 treatment reduced ERK1/2 and STAT3 phosphorylation but did not influence Smad3 phosphorylation. CONCLUSION: Terguride and SB204741 reduce pro-fibrotic potential of HADF cells and suppress TGF-ß1-mediated non-canonical pathways, ERK1/2 and STAT3 which have been implicated in the regulation of pro-fibrotic genes and in the development of fibrosis. Taken together, our data suggest that 5-HT inhibitors might reduce fibrosis via suppression of TGF-beta1-mediated non-canonical signaling pathways. These observations have important therapeutic implications for fibrotic disorders like scleroderma.

Effects of different serotonin receptor subtype antagonists on the development of cardiac allograft vasculopathy in murine aortic allografts.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the main obstacle for long-term survival after heart transplantation. Alloimmune mediated chronic vascular rejection results in several mechanisms like platelet activation, immigration of inflammatory cells through the endothelial layer and proliferation and migration of smooth muscle cells (SMCs). Serotonin (5-HT) promotes these processes via activation of 5-HT2 receptors. We hypothesized that inhibiting 5-HT2 receptors ameliorates the development of CAV. METHODS: CBA/JRj mice recieved aortic grafts from C57BL/6 mice. After transplantation until recovery of organs, recipients were treated with serotonin receptor antagonists: sarpogrelate (5-HT2A), SB 204741 (5-HT2B) or terguride (5-HT2A+B). Mice were sacrificed after 14 days for qRT-PCR analysis or after 30 days for histological evaluation. Serum serotonin ELISA was done at both time points. RESULTS: Elevated serum serotonin levels were significantly reduced after 5-HT2A antagonist treatment as was 5-HT2A receptor expression. This went along with reduced inflammation characterized by significantly fewer infiltrating macrophages and pro-inflammatory intragraft cytokines and with reduced tissue remodeling evident as significantly less neointima formation. CONCLUSION: Inhibition of the 5HT/5-HT2A receptor axis leads to significantly reduced neointima proliferation after aortic transplantation associated with reduced transendothelial migration of macrophages and decreased expression of inflammatory cytokines. These findings have translational implications as inhibitors of 5HT2A like sarpogrelate are already approved for clinical use.

Effects of 2-bromoterguride, a dopamine D2 receptor partial agonist, on cognitive dysfunction and social aversion in rats.

RATIONALE: 2-Bromoterguride, a dopamine D2 receptor partial agonist with antagonist properties at serotonin 5-HT2A receptors and α2C-adrenoceptors, meets the prerequisites of a putative atypical antipsychotic drug (APD). We recently showed that 2-bromoterguride is effective in tests of positive symptoms of schizophrenia in rats without inducing extrapyramidal side effects or metabolic changes. OBJECTIVE: In continuation of our recent work, we now investigated the effect of 2-bromoterguride on apomorphine and phencyclidine (PCP)-induced disruptions of prepulse inhibition (PPI) of the acoustic startle response, a measure of sensory gating. In addition, we used subchronic PCP treatment to produce cognitive deficits and social aversion, and assessed the effect of 2-bromoterguride on the performance in the novel object recognition (NOR) task (model for studying cognitive deficit symptoms of schizophrenia) and the social interaction test (model for studying negative symptoms of schizophrenia). Finally, we extended the side effect profile of 2-bromoterguride by measuring the prolactin response to systemic administration of the drug in rats. RESULTS: Treatment with 2-bromoterguride (0.1 and 0.3 mg/kg) reversed PPI deficits induced by apomorphine and PCP, respectively. Subchronic PCP induced impairments in object memory and social interaction behavior which were ameliorated by 2-bromoterguride but not by clozapine and aripiprazole, respectively. Prolactin concentration in blood serum was not elevated at 1, 2, or 4 h post-2-bromoterguride treatment, which further supports the safe and effective use of this drug. CONCLUSIONS: Our data support 2-bromoterguride as a promising APD candidate due to its beneficial effect on cognitive impairments and negative symptoms of schizophrenia.

5-HT7 receptor antagonism (SB-269970) attenuates bleomycin-induced pulmonary fibrosis in rats via downregulating oxidative burden and inflammatory cascades and ameliorating collagen deposition: Comparison to terguride.

The neurotransmitter 5-hydroxytryptamine (5-HT) is involved in regulation of local tissue inflammation and repair through a set of receptors (5-HT1-7 receptors), which are expressed in the lung. Considering the protective importance of 5-HT receptor antagonists against development of pulmonary fibrosis, we evaluated whether 5-HT7 receptor antagonist (SB-269970) modulates lung inflammatory and fibrogenic processes in comparison with 5-HT2A/B receptor antagonist (terguride), in bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF) model. IPF model induced by a single dose of intra-tracheal BLM instillation (5mg/kg), and rats were treated with intraperitoneal injection of SB-269970 (1mg/kg day) or terguride (1.2mg/kg/d). The experiment was carried out on two separate sets of rats that were killed at day 7th and day 21st to evaluate the endpoint of the IPF inflammatory and fibrogenic phases, respectively. During the inflammatory phase 5-HT2A/B and 5-HT7 receptor antagonists attenuated the BLM-induced increase in the lung fluid content, the inflammatory cytokines levels and oxidative stress burden. In the fibrogenic phase, both SB-269970 and terguride reduced the serotonin concentrations in lung homogenates and significantly protected against IPF fibrogenic phase by attenuating collagen deposition and mRNA expression of both transforming growth factor-ß1 (TGF- ß1), and procollagen type Ӏ (PINP). 5-hydroxytryptamine 5-HT7 receptor antagonist showed more benefits than 5-HT2A/B receptor antagonist on the deleterious effects accompanied BLM instillation. The present study showed involvement of 5-HT7 receptor in the pathophysiology of BLM-induced IPF in rats and identified it as a potential therapeutic target in lung fibrotic disorders.

Use of biologics and other novel therapies for the treatment of systemic sclerosis.

INTRODUCTION: Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by vasculopathy, inflammation and fibrosis. These three main disease-determining pathways are the target of the currently available treatments used to possibly modify the progression of disease-related manifestations, although this synergy has not been fully applied on SSc joint, skin or lung involvement yet. Areas covered: we describe the current status of SSc treatment/therapy performing a literature search in MEDLINE/Pubmed and Thomson Reuter's Web of Science for articles published until March 2016. Moreover, ongoing registered clinical trials (RCTs) on SSc were searched through clinicaltrials.gov website. Expert commentary: presently, promising drugs are under evaluation to target the different pathogenic pathways of systemic sclerosis: Tocilizumab and Abatacept for skin and lung fibrosis; Riociguat and Selexipag are approved for pulmonary arterial hypertension but promising anti-fibrotic effects are now being studied. Finally, several anti-fibrotic molecules are currently involved in RCTs, such as Nintedanib, IVA-337, Terguride.

2-Bromoterguride-a potential atypical antipsychotic drug without metabolic effects in rats.

RATIONALE: Recently, we showed that 2-bromoterguride acted as a dopamine D2 receptor partial agonist, a serotonin 5-HT2A and α2C-adrenergic receptor antagonist, and exhibited antidopaminergic efficacy in amphetamine-induced locomotion (AIL) in rats without inducing catalepsy. OBJECTIVE: To extend our knowledge on the antipsychotic effects of 2-bromoterguride, we used convergent preclinical animal models and tests; i.e., conditioned avoidance response (CAR), predictive of antipsychotic-like effects; Fos protein expression, a molecular marker for (atypical) antipsychotic activity; wet dog shake behavior, a test for the in vivo effects of drugs acting on central 5-HT2A receptors; and investigated metabolic changes as a common side effect of atypical antipsychotic drugs (APDs). RESULTS: Acute treatment with 2-bromoterguride (0.1 and 0.3 mg/kg) decreased the CAR at 30, 90, and 270 min post-injection in rats without inducing escape failures at any time. Fos protein expression, as shown by Western blotting, was enhanced by 2-bromoterguride in the nucleus accumbens (NAc), the dorsolateral striatum (dStr), and the medial prefrontal cortex (mPFC). (±)-2,5-Dimethoxy-4-iodoamphetamine (DOI)-induced wet dog shakes in rats were reduced by 2-bromoterguride. Chronic treatment with 2-bromoterguride did not affect metabolic parameters such as body weight development and body fat composition as well as behavioral parameters such as food intake and locomotor activity. CONCLUSIONS: Our data suggest that 2-bromoterguride is a promising candidate in the treatment of schizophrenia due to its atypical antipsychotic-like activity and its inability to induce weight gain.

Why drugs fail in clinical trials in pulmonary arterial hypertension, and strategies to succeed in the future.

The past three decades have witnessed a welcome expansion of the therapeutic armamentarium for the management of pulmonary arterial hypertension (PAH). However, against this backdrop, there have been some notable disappointments in drug development. Here we use these as case studies to emphasize the importance of informed drug target selection, the early evaluation of dose-response relationships in human studies, and the value of the deep phenotyping of patients in clinical studies to better understand inter-individual variation in patient response. The integration of "omics" technologies and advanced clinical imaging offer the potential to reduce the risk, and so cost, of drug development in PAH and bring much needed new medicines to those patients most likely to benefit with greater efficiency.

Behavioral effects of dopamine receptor inactivation in the caudate-putamen of preweanling rats: role of the D2 receptor.

RATIONALE: Inactivating dopamine (DA) receptors in the caudate-putamen (CPu) attenuates basal and DA agonist-induced behaviors of adult rats while paradoxically increasing the locomotor activity of preweanling rats. OBJECTIVE: The purpose of this study was to determine (a) whether D1 or D2 receptor inactivation is responsible for the elevated locomotion shown by preweanling rats and (b) whether DA receptor inactivation produces a general state in which any locomotor-activating drug will cause a potentiated behavioral response. METHODS: Dimethyl sulfoxide (DMSO) or N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) was bilaterally infused into the CPu on postnatal day (PD) 17. In experiment 1, DA receptors were selectively protected from EEDQ-induced alkylation by pretreating rats with D1 and/or D2 antagonists. On PD 18, rats received bilateral microinjections of the DA agonist R(-)-propylnorapomorphine into the dorsal CPu, and locomotor activity was measured for 40 min. In subsequent experiments, the locomotion of DMSO- and EEDQ-pretreated rats was assessed after intraCPu infusions of the selective DA agonists SKF82958 and quinpirole, the partial agonist terguride, or after systemic administration of nonDAergic compounds. RESULTS: Experiment 1 showed that EEDQ's ability to enhance the locomotor activity of preweanling rats was primarily due to the inactivation of D2 receptors. Consistent with this finding, only drugs that directly or indirectly stimulated D2 receptors produced a potentiated locomotor response in EEDQ-treated rats. CONCLUSIONS: These results show that DA receptor inactivation causes dramatically different behavioral effects in preweanling and adult rats, thus providing additional evidence that the D2 receptor system is not functionally mature by the end of the preweanling period.

Relationships between serotoninergic system and skin fibrotic.

Cutaneous fibrosis seen in systemic sclerosis (SSc) is a generalized connective tissue disorder, characterized by a wide spectrum of microvascular and immunological abnormalities. Serotonin (5-hydroxytryptamine; 5-HT) is a neurotransmitter and immune modulator, is also an important mediator of bidirectional interactions between the vasoactive amines and the skin.5-HT, a commonly secreted amine, is a known inducer of fibrosis, although the mechanistic basis for it and growth factors regulating fibrosis and proliferation in the microenvironment are unclear. We review that as serotonin has powerful vasodilator, immunomodulator, and growth factor actions, this pathway could be involved in skin fibrotic. Since serotoninergic system play a role in skin fibrotic, and 5-HTs drugs, an usual treatment for this type of patients. These provides a future perspective for research and drug development.

Pharmacological profile of 2-bromoterguride at human dopamine D2, porcine serotonin 5-hydroxytryptamine 2A, and α2C-adrenergic receptors, and its antipsychotic-like effects in rats.

Dopaminergic, serotonergic, and adrenergic receptors are targets for therapeutic actions in schizophrenia. Dopamine D2 receptor partial agonists such as aripiprazole represent a treatment option for patients with this severe disorder. The ineffectiveness of terguride, another D2 receptor partial agonist, in treating schizophrenia was recently attributed to its considerably high intrinsic activity at D2 receptors. In this study, we used functional assays for recombinant D2 receptors and native 5-hydroxytryptamine 2A (5-HT2A), α2C-adrenergic, and histamine H1 receptors to compare the pharmacological properties of terguride and three of its halogenated derivatives (2-chloro-, 2-bromo-, 2-iodoterguride) with those of aripiprazole. Subsequently, we studied the antidopaminergic effects of 2-bromoterguride using amphetamine-induced locomotion (AIL). Its influence on spontaneous behavior was tested in the open field. Extrapyramidal side effect (EPS) liability was evaluated by catalepsy test. In a guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding assay, 2-chloro-, 2-bromo-, and 2-iodoterguride produced intrinsic activities at human D2short (hD2S) receptors that were half as high as the intrinsic activity for terguride; aripiprazole lacked agonist activity. 2-Bromoterguride and aripiprazole activated D2S receptor-mediated inhibition of cAMP accumulation to the same extent; intrinsic activity was half as high as that of terguride. All compounds tested behaved as antagonists at human D2long/Gαo (hD2L/Gαo) receptors. Compared with aripiprazole, terguride and its derivatives displayed higher affinity at porcine 5-HT2A receptors and α2C-adrenoceptors and lower affinity at H1 receptors. 2-Bromoterguride inhibited AIL and did not induce catalepsy in rats. Because of its in vitro and in vivo properties, 2-bromoterguride may be a strong candidate for the treatment of schizophrenia with a lower risk to induce EPS.

Pathways in pulmonary arterial hypertension: the future is here.

It is well established that the endothelin, nitric oxide and prostacyclin pathways play an important role in the development of pulmonary arterial hypertension (PAH). Indeed, the therapeutic options currently available for the management of PAH all act on one of these mechanistic pathways. However, this is an exciting time for both clinicians and scientists, as increased understanding of the mechanisms involved in the pathogenesis and progression of PAH has resulted in the development of a number of novel therapeutic options. This article highlights how the introduction of new compounds such as macitentan, riociguat and selexipag, which act on the endothelin, nitric oxide and prostacyclin pathways, respectively, have the potential to further improve the prognosis for patients with PAH.

Antiserotonergic properties of terguride in blood vessels, platelets, and valvular interstitial cells.

Serotonin (5-hydroxytryptamine; 5-HT) is involved in heart valve tissue fibrosis, pulmonary arterial fibrosis, and pulmonary hypertension. We aimed at characterizing the antiserotonergic properties of the ergot alkaloid derivative terguride [1,1-diethyl-3-(6-methyl-8α-ergolinyl)urea] by using functional receptor assays and valvular interstitial cell culture. Terguride showed no vasoconstrictor effect in porcine coronary arteries (5-HT(2A) receptor bioassay) and no relaxant effect in porcine pulmonary arteries (5-HT(2B) receptor bioassay). Terguride behaved as a potent antagonist at 5-HT(2A) receptors (noncompetitive antagonist parameter pD'2 9.43) and 5-HT(2B) receptors (apparent pA2 8.87). Metabolites of terguride (N″-monodeethylterguride and 6-norterguride) lacked agonism at both sites. N″-monodeethylterguride and 6-norterguride were surmountable antagonists at 5-HT(2A) receptors (pA2 7.82 and 7.85, respectively) and 5-HT(2B) receptors (pA2 7.30 and 7.11, respectively). Kinetic studies on the effects of terguride in pulmonary arteries showed that the rate to reach drug-receptor equilibrium for terguride was fast. Washout experiments showed that terguride easily disappeared from the receptor biophase. Pretreatment with terguride inhibited 5-HT-induced amplification of ADP-stimulated human platelet aggregation (IC50 16 nM). In porcine valvular interstitial cells, 5-HT-induced activation of extracellular signal-regulated kinase (ERK) 1/2, an initiator of cellular proliferation and activity, was blocked by terguride as shown by Western blotting. In these cells, the stimulatory effect of 5-HT on [³H]proline incorporation (index of extracellular matrix collagen) was blocked by terguride. Because of the inhibition of both 5-HT(2A) and 5-HT(2B) receptors, platelet aggregation, and cellular proliferation and activity (ERK1/2 phosphorylation and collagen production) terguride may have therapeutic potential in the treatment of fibrotic disorders.

Terguride ameliorates monocrotaline-induced pulmonary hypertension in rats.

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterised by vasoconstriction and remodelling of the pulmonary vasculature. The serotonin (5-hydroxytryptamine (5-HT)) pathway has been shown to play a major role in the pathogenesis of PAH, but pharmacological modulation of this pathway for treatment of PAH is, to date, at a pre-clinical level. Terguride is a 5-HT receptor (5-HTR) antagonist that is well tolerated and clinically approved for ovulation disorders. Immunohistochemistry against 5-HTR(2A/B) on human lungs revealed their localisation to the vascular smooth muscle layer and quantitative RT-PCR showed 5-HTR(2B) upregulation in pulmonary artery smooth muscle cells (PASMC) isolated from PAH patients. Proliferation and migration of cultured primary human PASMC were dose-dependently blocked by terguride. Therapeutic 5-HT signalling inhibition was 1) demonstrated in isolated, ventilated and perfused rat lungs and 2) by chronic terguride treatment of rats with monocrotaline (MCT)-induced pulmonary hypertension in a preventive or curative approach. Terguride inhibited proliferation of PASMCs and abolished 5-HT-induced pulmonary vasoconstriction. Chronic terguride treatment prevented dose-dependently the development and progression of MCT-induced PAH in rats. Thus, terguride represents a valuable novel therapeutic approach in PAH.

The dopamine D(2) partial agonist and antagonist terguride decreases heroin self-administration on fixed- and progressive-ratio schedules.

Dopamine partial agonists have been suggested to be potential therapeutic candidates for pharmacological intervention in drug addiction. These drugs bind to dopamine receptors with high affinity and low intrinsic activity and are hypothesized to behave as functional antagonists in conditions of high dopaminergic tone. The aim of the present study was to characterize the effects of terguride, a partial dopamine agonist at the dopamine D(2) receptor, on intravenous heroin self-administration on fixed- and progressive-ratio schedules of reinforcement. The effects of terguride on oral sweet solution (4% sucrose) self-administration on a fixed-ratio schedule were also tested. Terguride dose-dependently decreased heroin self-administration on the fixed-ratio schedule and decreased the maximum number of responses for heroin self-administration on a progressive-ratio schedule. In contrast, terguride did not significantly affect oral sucrose self-administration. These data suggest that terguride may represent a novel pharmacological strategy for the treatment of opiate addiction.

Increased expression of 5-hydroxytryptamine2A/B receptors in idiopathic pulmonary fibrosis: a rationale for therapeutic intervention.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) has a poor prognosis and limited responsiveness to available treatments. It is characterised by epithelial cell injury, fibroblast activation and proliferation and extracellular matrix deposition. Serotonin (5-hydroxytryptamine; 5-HT) induces fibroblast proliferation via the 5-HTR(2A) and 5-HTR(2B) receptors, but its pathophysiological role in IPF remains unclear. A study was undertaken to determine the expression of 5-HT receptors in IPF and experimental lung fibrosis and to investigate the effects of therapeutic inhibition of 5-HTR(2A/B) signalling on lung fibrosis in vivo and in vitro. METHODS AND RESULTS: Quantitative RT-PCR showed that the expression of 5-HTR(1A/B) and 5-HTR(2B) was significantly increased in the lungs of patients with IPF (n=12) and in those with non-specific interstitial pneumonia (NSIP, n=6) compared with transplant donors (n=12). The expression of 5-HTR(2A) was increased specifically in IPF lungs but not in NSIP lungs. While 5-HTR(2A) protein largely localised to fibroblasts, 5-HTR(2B) localised to the epithelium. To assess the effects of 5HTR(2A/B) inhibition on fibrogenesis in vivo, mice were subjected to bleomycin-induced lung fibrosis and treated with the 5-HTR(2A/B) antagonist terguride (or vehicle) in a therapeutic approach (days 14-28 after bleomycin). Terguride-treated mice had significantly improved lung function and histology and decreased collagen content compared with vehicle-treated mice. Functional in vitro studies showed that terguride is a potent inhibitor of transforming growth factor ß(1)- or WNT3a-induced collagen production. CONCLUSION: The studies revealed an increased expression of 5-HTR(2A) specifically in IPF. Blockade of 5-HTR(2A/B) signalling by terguride reversed lung fibrosis and is thus a promising therapeutic approach for IPF.

Evaluation of the efficacy and safety of terguride in patients with fibromyalgia syndrome: results of a twelve-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study.

OBJECTIVE: To assess the efficacy and safety of terguride, a partial dopamine agonist, in patients with fibromyalgia syndrome (FMS). METHODS: In a 12-week, multicenter, double-blind, placebo-controlled, parallel-group study, 99 patients were randomized at a ratio of 2 to 1 to receive terguride or placebo. Over 21 days, the dosage was titrated to a maximum daily dose of 3 mg of terguride or placebo, and this fixed dosage was continued over 9 weeks. The primary efficacy variable was the intensity of pain (100-mm visual analog scale). Secondary efficacy variables included the Fibromyalgia Impact Questionnaire (FIQ) score, the tender point score (TPS), and the Hamilton Depression Scale (HDS) score. During the study, patients were evaluated for the presence of cervical spine stenosis by magnetic resonance imaging (MRI). RESULTS: No significant differences in the change in pain intensity, FIQ score, TPS, or HDS score between baseline and 12 weeks were observed in the terguride group as compared with the placebo group. Cervical spine stenosis was detected in 22% of the patients. Only patients with cervical spine stenosis responded to terguride treatment. FIQ scores improved significantly (per-protocol analysis), and pain intensity, the TPS score, and the HDS score showed a trend toward improvement in the terguride group as compared with the placebo group. Terguride treatment was safe. Only those adverse events already known to be side effects of terguride were observed. Premature termination of the study in patients receiving terguride (26%) occurred predominantly during up-titration and in the absence of comedication for treatment of nausea. CONCLUSION: Terguride treatment did not improve pain, the FIQ score, the TPS, or the HDS score in the total study population. However, a subgroup of patients with cervical spine stenosis seemed to benefit from terguride treatment.

Co-administration of the partial dopamine D2 agonist terguride with L-dopa attenuates L-dopa-induced locomotor sensitization in hemiparkinsonian mice.

While dopamine replacement remains the standard pharmacotherapy for Parkinson's disease, chronic L-dopa treatment is associated with development of debilitating motor fluctuations such as L-dopa-induced dyskinesia (LID). In this study we evaluated the effects of the partial dopamine D(2) agonist terguride on the development of LID in hemiparkinsonian mice (unilaterally lesioned with 6-hydroxydopamine). First, consistent with the partial agonist property, terguride had 1000-fold higher potency than dopamine, yet producing one-third level of maximal activation of dopamine, as assayed by [(35)S]GTPgammaS binding. Furthermore, in the absence and presence of dopamine in vitro, terguride increased and decreased striatal [(35)S]GTPgammaS binding, respectively. Next, we found that co-administration of terguride (at 0.1 and 0.5mg/kg, i.p.) with L-dopa (1.8 mg/kg) daily for 14 days, significantly attenuated the development and expression of L-dopa-induced rotational sensitization. Furthermore, the cross-challenge paradigm revealed that chronic L-dopa treatment (but not terguride) sensitized locomotor response to the dopamine D(1) agonist SKF 81297 while chronic treatment with terguride (but not L-dopa) produced sensitized locomotor responses to the adenosine A(2A) antagonist 8-(3-chlorostyryl)caffeine (CSC). Importantly, the co-administration of terguride with L-dopa did not show locomotor sensitization to either SFK 81297 or CSC upon challenge. Together, these results suggest that co-administration of partial dopamine D(2) agonists with L-dopa may prophylactically attenuate L-dopa-induced abnormal behavioral responses such as LID.

The effect of terguride in carbon tetrachloride-induced liver fibrosis in rat.

BACKGROUND: Hepatic stellate cells (HSCs) are considered to be of vital importance in the pathogenesis of liver fibrosis. In vitro studies have demonstrated antiproliferative effects of 5-hydroxytryptamine(2) (5-HT(2), serotonin) receptor antagonists upon HSCs. Terguride, recognized as a partial dopamine agonist, also has potent 5-HT(2) receptor antagonist qualities and has been shown to prevent serotonin-induced organ changes and fibrosis in rats. AIM: In the current study, the carbon tetrachloride (CCL(4)) hepatic fibrosis rat model was used in combination with daily administration of terguride to evaluate potential preventive effects of a 5-HT(2) receptor antagonist upon liver fibrosis. MATERIALS AND METHODS: Forty rats (Sprague-Dawley) were included in the study. Twelve animals received terguride in combination with CCL(4) and 12 animals were given only CCL(4). The remaining 16 animals served as model controls. The extent of fibrosis was evaluated by liver weight, histologic analysis, biochemical analysis, and alpha-smooth muscle actin (alpha-SMA) immunohistochemistry. RESULTS: There were no significant differences in liver weight, hydroxyproline content, serum alanine and aspartate transaminases, serum hyaluronic acid, or alpha-SMA immunostaining between rats treated with terguride in combination with CCL(4) and rats given only CCL(4). All parameters, however, were significantly lower (P < 0.01) in the model controls. CONCLUSION: Terguride, a potent 5-HT(2) antagonist, did not prevent the development of liver fibrosis in rats given CCL(4).