Characterization of the head-twitch response induced by hallucinogens in mice: detection of the behavior based on the dynamics of head movement

RATIONALE

The head-twitch response (HTR) is a rapid side-to-side rotational head movement that occurs in rats and mice after administration of serotonergic hallucinogens and other 5-HT2A agonists. The HTR is widely used as a behavioral assay for 5-HT2A activation and to probe for interactions between the 5-HT2A receptor and other transmitter systems.

OBJECTIVE

High-speed video recordings were used to analyze the head movement that occurs during head twitches in C57BL/6J mice. Experiments were also conducted in C57BL/6J mice to determine whether a head-mounted magnet and a magnetometer coil could be used to detect the HTR induced by serotonergic hallucinations based on the dynamics of the response.

RESULTS

Head movement during the HTR was highly rhythmic and occurred within a specific frequency range (mean head movement frequency of 90.3 Hz). Head twitches produced wave-like oscillations of magnetometer coil voltage that matched the frequency of head movement during the response. The magnetometer coil detected the HTR induced by the serotonergic hallucinogens 2,5-dimethoxy-4-iodoamphetamine (DOI; 0.25, 0.5, and 1.0 mg/kg, i.p.) and lysergic acid diethylamide (LSD; 0.05, 0.1, 0.2, and 0.4 mg/kg, i.p.) with extremely high sensitivity and specificity. Magnetometer coil recordings demonstrated that the non-hallucinogenic compounds (+)-amphetamine (2.5 and 5.0 mg/kg, i.p.) and lisuride (0.8, 1.6, and 3.2 mg/kg, i.p.) did not induce the HTR.

CONCLUSIONS

These studies confirm that a magnetometer coil can be used to detect the HTR induced by hallucinogens. The use of magnetometer-based HTR detection provides a high-throughput, semi-automated assay for this behavior, and offers several advantages over traditional assessment methods.

Long-term serotonin effects in the rat are prevented by terguride

Long-term hyperserotoninemia induces heart valve disease in rats, and cases of cardiac valvulopathies have been reported in patients using ergolines, possibly through activation of the 5-hydroxytryptamine(2B) (5HT(2B)) receptor. The ergoline terguride (transdihydrolisuride) is a 5HT(2B/2C) receptor antagonist. Using a rat model, we have investigated whether terguride could prevent serotonin-induced changes in general and heart disease specifically. During 4 months, twelve Sprague-Dawley rats were given daily subcutaneous serotonin injections; twelve rats received a combination of serotonin injections and terguride by gavage, whereas ten rats were untreated controls. Using echocardiography, rats with aortic insufficiency were found in all 3 groups, while pulmonary insufficiency was only found in two rats injected with serotonin alone. Animals given serotonin alone had significantly higher heart weights compared to the controls (p=0.029) and rats given terguride (p=0.034). Rats injected with serotonin alone developed macroscopic skin changes at the injection sites, histologically identified as orthokeratosis and acanthosis. Terguride completely prevented these changes (p=0.0001, p=0.0003). Liver weights were higher in the animals given serotonin alone compared to controls (p=0.014) and terguride treated animals (p=0.009). Stomach weights were higher in animals given serotonin alone compared to rats given terguride (p=0.012). In the mesenchymal cell-line MC3T3-E1, terguride almost completely inhibited serotonin-induced proliferation (p<0.01). Serotonin increases heart, liver and stomach weights, possibly through enhanced proliferation. Terguride inhibits these effects. We propose that terguride may have beneficial effects in the treatment of diseases such as carcinoid syndrome, where serotonin plays an important pathogenic role.

Lisuride treatment of restless legs syndrome: first studies with monotherapy in de novo patients and in combination with levodopa in advanced disease

In two 4-week polysomnography pilot studies with 10 patients each, we investigated the efficacy of oral lisuride as monotherapy in de novo RLS patients as well as in combination with levodopa in advanced RLS. Daily doses at study end were 0.3 mg lisuride, plus 150 mg levodopa in the combination study. Marked improvements occurred in both studies in different PLM indexes and in the CGI. Levodopa dose could be decreased by 27%. Lisuride might be an efficacious treatment for RLS in general, and in combination with levodopa in advanced stage.

Dopamine Stimulation via Infusion in the Lateral Ventricle

Continuous dopamine (DA) stimulation is a therapeutic approach that applies to the treatment of motor fluctuations due to pulsatile DA stimulation in Parkinson's disease (PD), to cure the abuse of drugs, such as cocaine or amphetamine (which produce short-lasting peaks of extracellular DA), and as a safe therapeutic approach to avoid hedonistic homeostatic dysregulation (which sometime develops as an abuse pattern in PD patients receiving a pulsatile DA replacement therapy). However, systemic continuous delivery of DA agonists leads to a variety of side effects. In search for an alterative approach, in the present study we evaluated the possibility of delivering intracerebroventricularly (i.c.v.), a DA agonist: lisuride that was already shown to be effective when administered continuously subcutaneously (s.c.). In particular, we were interested in examining whether lisuride infused within the lateral ventricle was still able to stimulate DA receptor by inducing contralateral turning behavior in hemiparkinsonian rats. We found that lisuride, when infused in the lateral ventricle was effective in reducing the threshold for stimulating DA receptors. These results offer a more reliable and safe therapeutic approach to deliver continuous DA selectively in the brain.

Transdermal lisuride: short-term efficacy and tolerability study in patients with severe restless legs syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) patients suffer from symptoms not only at bedtime but also with variable circadian patterns. Transdermal application forms of dopamine agonists are expected to lead to a stable plasma concentration of the active drug which could ease treatment for RLS patients with daytime symptoms and avoid side effects of oral dopaminergic therapies.

PATIENTS AND METHODS

In this controlled pilot study, 10 patients (six females, four males, mean age 58 years) with severe and long-lasting idiopathic RLS were treated during an initial open-label phase for 2 weeks either with one (n=3 patients) or, if required, two patches of lisuride every other day (dose per patch: 3mg lisuride, nominal effective release rate 7.0 microg lisuride/h). Patients were then randomized to double-blind treatment with lisuride (n=5) or placebo (n=4) for 1 week.

RESULTS

Severity of RLS clearly improved during open-label and double-blind treatment with lisuride but became worse under placebo according to the International Restless Legs Syndrome Study Group Rating Scale (IRLS), RLS-6, and Clinical Global Impressions (CGIs) scales, and actigraphy assessments (periodic leg movement index) in the 1-week double-blind period.

CONCLUSION

The explorative findings of this small controlled study suggest that lisuride patches might be an efficacious treatment for RLS patients without clinically relevant tolerability problems.

Transdermal lisuride delivery in the treatment of Parkinson's disease

Transdermal delivery of dopamine agonists (DA) is a promising therapeutic concept, which aims to ameliorate frequency and intensity of motor fluctuations in patients with Parkinson's disease (PD). We treated 8 PD patients with unpredictable on-off phenomena with lisuride patches (release: 2-5 microg lisuride base/cm2/hour in mice) in addition to their preexisting antiparkinsonian drug regime up to a period of 8 days. In order to quantify the intensity and frequency of motor fluctuations, we determined the motor changing rate (MCR), which corresponds to the patient's self rating of motor function, performed every thirty minutes, divided through the number of scored intervals minus 1. Additional lisuride patch application significantly (p = 0.023) improved the MCR compared to baseline. Relevant side effects were transient skin irritations in four patients. Our observational study demonstrates the safety, tolerability and efficacy of transdermal lisuride delivery in the treatment of motor complications.

Management of restless legs syndrome by the partial D2-agonist terguride

BACKGROUND

Terguride as a partial D2-receptors agonist seems suitable for treatment of restless legs syndrome (RLS).

METHODS

Nine RLS patients without previous dopaminergic therapy received a daily dose of terguride (0.25 mg) 29.9+/-16.9 (SD) days.

RESULTS

Two patients enrolled in the study failed to turn up for a successive check up. The seven subjects who were re-examined complied with the therapy. Their RLS symptoms improved (as measured on the International RLS intensity scale), decreasing from 24.3+/-5.3 to 14+/-4.7 (p=0.014). However, the terguride treatment did not significantly alter the daytime sleepiness or the subjective duration of nocturnal sleep. The daily dose was doubled in three patients who reported insufficient RLS improvement. One of the three patients later reported augmentation.

[Pharmacokinetic/pharmacodynamic analysis of anti-hyperprolactinemic effect of terguride based on dopamine D2 receptor occupancy]

Terguride has been widely used for the treatment of hyperprolactinemia via partial agonistic action on dopamine D2 receptors in the pituitary. The present study analyzed retrospectively the dopamine D2 receptor binding occupancy (phi) of terguride. The average phi value was estimated to be 14.1% after oral administration of the average/standard therapeutic dose of terguride. Taking the intrinsic activity (alpha) into consideration, the value of alpha. phi was 2.33%. These results suggest that the antihyperprolactinemic effect of terguride was elicited despite the low receptor occupancy. Furthermore, we developed a pharmacokinetic/pharmacodynamic model for ascertaining the serum prolactin-lowering effect of terguride, considering both the reversible binding to D2 receptors and the effect on the increase rate in the prolactin level. The developed model fit well with the actual data. Although this model could be improved, it could explain the long duration of the antihyperprolactinemic activity of terguride and might be useful for designing its rational dosage regimen.

[Arrest of lactation after 2nd trimester abortion with a single dose of cabergoline in comparison with 10-day administration of teguride]

OBJECTIVE

The objective of the work was to compare the effectiveness and tolerance of a single administration of 1 mg cabergoline and 10-day administration of 1.5 mg terguride divided into three doses after 8-hour intervals, in the indication of arrest of lactation after an abortion during the second trimester.

TYPE OF STUDY

Prospective clinical study. NAME AND PLACE OF DEPARTMENT: Gynaecological and Obstetric Clinic. First Medical Faculty Charles University and General Faculty Hospital Prague, Apolinárská 18, Prague 2.

METHOD

During the period between January and October 2000 to 41 patients after abortion induced during the 2nd trimester terguride, 0.5 mg after 8-hour intervals, was administered for a 10-day period. During the subsequent period from November 2000 to September 2001 to 43 patients cabergoline was administered in a single dose within 12 hours after the abortion. During hospitalization the patients were asked daily for their subjective evaluation of the effect of treatment (vertigo, palpitations, headache, nausea, vomiting, abdominal pain, sleepiness, secretion from the breast, tension in the breasts) and the doctor evaluated the success of treatment objectively. Within 21 days after the abortion the patients were addressed over the phone on subjective and objective effects of treatment. For statistical evaluation Fisher's exact bilateral test was used.

RESULTS

The "cabergoline" group displayed, as compared with the "terguride" group, significantly fewer undesirable effects (p < 0.01). No significant difference was found between groups (p = 0.1) as regards the necessity to repeat administration of the drug. None of the undesirable effects were so serious to call for interruption of treatment.

CONCLUSION

Arrest of lactation during the second trimester of gestation is an integral part of care of the patient. Symptoms associated with lactation are adversely accepted by the patient. The incidence of undesirable effects after a single dose of cabergoline is significantly lower as compared with 10-day administration of terguride. A single dose of cabergoline during hospitalization improves the patients' compliance and thus the effect of treatment. Cabergoline can be used as the drug of first choice for arrest of lactation after abortion during the second trimester of pregnancy.

Prospective randomized trial of lisuride infusion versus oral levodopa in patients with Parkinson's disease

Motor complications are a major source of disability for patients with advanced Parkinson's disease. Surgical therapies provide benefit to some, but these treatments are expensive and associated with adverse effects. Current research indicates that motor complications are associated with abnormal, intermittent, pulsatile stimulation of denervated dopamine receptors using short acting dopaminergic agents such as levodopa. Retrospective studies suggest that the use of longer-acting more continuous dopaminergic therapies can improve both motor fluctuations and dyskinesia. We performed a prospective, long-term (4-year) trial comparing patients randomized to receive subcutaneous infusion of the dopamine agonist lisuride versus conventional therapy with oral levodopa and dopamine agonists. We demonstrate that patients receiving lisuride infusions experienced a significant reduction in both motor fluctuations and dyskinesia compared with patients receiving standard dopaminergic therapies. Benefits persisted for the 4-year duration of the study. Mean Unified Parkinson's Disease Rating Scale scores in "ON" and "OFF" states did not significantly change between baseline and 4 years for patients in the lisuride group, but deteriorated in patients in the levodopa group. This study indicates that continuous lisuride infusion can be beneficial for patients with advanced Parkinson's disease and reverse established motor fluctuations and dyskinesia.

The influence of personality on nicotine craving: a hierarchical multivariate statistical prediction model

The present study proposes a hierarchical multivariate statistical prediction model which enables to determine the most prominent variables (physiological, biochemical and personality factors) related to nicotine craving and dopaminergic activation. Based on animal studies reporting a reduction of the rewarding effects of psychotropic drugs after blockade or destruction of the mesolimbic dopamine (DA) system, changes in nicotine craving after pharmacological manipulation by means of a DA agonist (lisuride 0.2 mg) and a DA antagonist (fluphenazine 2 mg) were assessed in 36 healthy male heavy smokers. The major aim was the development of a multivariate prediction model which is applicable in samples lacking variance homogeneity or the prerequisite of a multivariate normal distribution. The model proposed is a combination of multivariate parametric and nonparametric methods taking advantage of their individual merits. Especially personality variables, such as sensation seeking, impulsivity, and neuroticism showed to be important predictors of craving in this responder approach.

Efficacy and tolerability of dopamine agonists in a parkinsonian population

A clinical retrospective study was carried out in a population of 366 Parkinson's disease (PD) outpatients, to analyse the efficacy and tolerability of nonergoline and ergoline dopamine agonist (DA), in monotherapy or in combination with L-dopa. Safety was comparable in both groups except for higher occurrence of gastrointestinal symptoms in ergoline group and somnolence in nonergoline group. No significant difference concerning efficacy and tolerability was found during DA monotherapy. Mean age at PD onset was slightly higher in patients withdrawing DA monotherapy for adverse events comparing to patients who needed the addition of L-dopa (60.36 +/- 7.53 versus 54.88 +/- 10.75; p<0.05), suggesting that older age at the onset of the disease increases the risk for adverse events during DA monotherapy. The follow-up of the remaining patients still in monotherapy with DA will allow a better evaluation of these aspects.

[Combined therapy of acromegaly with a combination of lanreotide and terguride]

BACKGROUND

The aim of the treatment of acromegaly is to normalise the hormonal activity. Besides the surgical and radiation treatment, medical therapy can be used. The project was set to determine the value of combined therapy with lanreotide and terguride in patients with active acromegaly.

METHODS AND RESULTS

Nine patients previously treated with lanreotide for at least one year without normalisation of hormonal activity were included in the study. Terguride was added to lanreotide for one month. The combined treatment brought about reduction of growth hormone (GH) levels, however, with marginal significance only. GH-BP, IGF-I and IGFBP-3 serum levels were not changed significantly. Considering the individual cases, the combined treatment resulted in normalisation of GH levels in one patient and that of IGF-I in another one. Substantial decrease of GH levels (> 50%) was found in three patients and that of IGF-I (> 20%) in another one patient.

CONCLUSIONS

The combined treatment of acromegaly appears to be more effective than monotherapy with lanreotide only in a subset of acromegalic patients.

Five-year follow-up of early lisuride and levodopa combination therapy versus levodopa monotherapy in de novo Parkinson's disease. The French Lisuride Study Group

The value of an early initial coadministration of levodopa (L-dopa) and lisuride in Parkinson's disease was the main goal of the present study. Eighty-two patients with recently diagnosed idiopathic Parkinson's disease were randomized into two groups for treatment with L-dopa alone or L-dopa + lisuride. The trial was double-blinded for the first year and open for the following 4 years. Selegiline (10 mg/day b.i.d.) was added in both groups at the end of the first year. Outcome measures were evolution of L-dopa dosage and Unified Parkinson's Disease Rating Scale scores and subscores, and incidence of motor complications. The dropout rate was higher in the L-dopa group (63.4%) than in the combination group. Motor improvement was better (p < 0.01) in the L-dopa + lisuride group. Expected motor complications were rare, moderate and equivalent in the two groups despite a difference in L-dopa dosage (446.7 vs. 387.5 mg/day). Long-term follow-up demonstrated the L-dopa-sparing effect of lisuride (average 1 mg/day), the beneficial effect of early combination therapy on motor status and the paucity of motor complications in both groups.

Antagonism of a PCP drug discrimination by hallucinogens and related drugs

Drugs such as PCP and MK-801 can cause psychotic reactions in humans by antagonizing NMDA receptors. This action is ultimately toxic to certain cortical neurons and may be one mechanism underlying neurodegenerative diseases, including schizophrenia. It has been reported that hallucinogens such as LSD, DOM, and DOI can block the neurotoxic effects of NMDA antagonists, possibly by activating inhibitory 5-HT2A receptors on GABAergic interneurons that normally inhibit glutamatergic projections to the retrosplenial and cingulate cortexes. The purpose of this experiment was to determine the extent to which similar drugs might also alter the behavioral effects of one NMDA antagonist, PCP. Rats were trained to discriminate this compound (2.5 mg/kg) from saline and were then given a series of antagonist tests. It was found that LSD (0.32 mg/kg) and DOM (4.0 mg/kg) blocked the PCP cue completely; DMT (8.0 mg/kg) and a structural congener of LSD, lisuride (LHM; 0.4 mg/kg), blocked the effects of PCP partially. The 5-HT/DA antagonists spiperone and ritanserin had no effect on the PCP cue. These data suggest that LSD, DOM, and, less effectively, DMT and LHM can block the behavioral as well as the neurotoxic effects of NMDA antagonists most likely through agonist actions at 5-HT2 receptors.

[Dermal application of lisuride on parkinsonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the common marmoset and on cases with Parkinson's disease]

Dermal administration is a nonoral drug delivery system that can keep the concentration of a drug in the body at a proper level for a long time. This is suitable especially in patients in the advanced stages of Parkinson's disease with a wearing-off phenomenon (short duration of effects on antiparkinsonian drugs), or in postoperative patients who cannot be treated with oral administration. We studied the effects of lisuride, a dopamine receptor agonist, in the dermal application on MPTP-treated common marmosets and on 5 patients with Parkinson's disease. Lisuride was applied to 4 x 5 cm of skin of the abdomen of monkeys. In patients with Parkinson's disease, lisuride was applied to the skin of the chest. The agent reversed akinesia of MPTP-treated animals within 30 min following the application and relieved the animal of parkinsonism for 5 days at a dose of 2 mg/kg. In patients, the dermal application of lisuride increased the duration of the ON period at doses of 1 to 2 mg/kg. These results suggest that the dermal application of lisuride is a useful treatment in parkinsonism.

Efficacy of a low-dose subcutaneous lisuride infusion in Parkinson's disease

Five parkinsonian patients with motor fluctuations and dyskinesia after long-term treatment with levodopa were treated with subcutaneous lisuride infusion (0.24-0.42 mg/day) together with oral levodopa for a mean period of 27 (range 13-36) months. All 5 patients showed marked initial improvement in mobility. Mild psychiatric side effects were observed in three patients; however, these side effects disappeared with reduction in the dosage of lisuride to 0.06 mg per day without a significant increase in motor fluctuations. A low dose of subcutaneous lisuride infusion with oral levodopa is an effective treatment for fluctuations of motor performance in parkinsonian patients without adverse psychiatric effects.

Ropinirole: new preparation. Wait for more convincing data

In previously untreated parkinsonian patients at an early stage of the disease, three comparative trials have shown that, during the first six months of treatment, the effect of ropinirole on motor symptoms almost equates to that of levodopa and is a little better than that of bromocriptine monotherapy. Until these trials have been completed (they are planned to last for 3 to 5 years), it will be impossible to know whether the postponement of dopatherapy with ropinirole administration influences the long-term outcome of Parkinson's disease. In patients already on levodopa who have mobility fluctuations, the only demonstrated effect in one trial was that the addition of ropinirole allowed the daily dose of levodopa to be reduced. However, this is a surrogate end point with no clinical relevance. A single comparative trial, versus another dopamine agonist, bromocriptine, is available, but its complex methodology makes it impossible to draw firm conclusions. The adverse effects of ropinirole are the same as those of other dopamine agonists. Again, this means that the assessment of ropinirole must continue to determine whether the drug carries an increased risk of dyskinesias or psychological effects.

Clinical implications of sustained dopaminergic stimulation

Fluctuations in motor performance are the major problems in chronic management of Parkinson's disease. Most of these fluctuations reflect the decline of levodopa availability. As a consequence, levodopa dosage might be increased and the interdose interval progressively shortened. The postsynaptic dopamine receptors at this point are exposed to a nonphysiologic shift in dopamine level, which may induce changes at the receptor site and contribute to the appearance of "on-off" phenomena and dyskinesias. We compared a group of 18 patients treated for 60 consecutive months with continuous subcutaneous lisuride infusion with a group of 20 patients treated with conventional oral levodopa treatment. The clinical evaluations performed during the study showed in the lisuride group only a worsening of dyskinesias, whereas the other symptoms remained unchanged. In the other group the evaluation scores showed a significant worsening of all long-term treatment complications. The slow-release preparations of levodopa may ensure a more continuous dopaminergic stimulation than standard formulations. However, the use of these compounds is difficult in severely fluctuating patients because the lack of a plasma peak level usually leads to a very long delay before patients turn "on." We studied the pharmacokinetic and clinical effects of the two slow-release preparations of levodopa [Madopar HBS and Sinemet controlled-release (CR)] and a combination of Sinemet CR plus standard Sinemet in 13 fluctuating parkinsonian patients. The results of this study show that the combination of standard Sinemet and Sinemet CR ensures a more prolonged clinical effect with a very short latency to the "on" phase.

Lisuride prevents learning and memory impairment and attenuates the increase in extracellular dopamine induced by transient global cerebral ischemia in rats

In this experiment, we tested the efficacy of neuroprotection with lisuride, a dopamine agonist, using the 4-vessel occlusion rat model. Functional improvement was evaluated with two behavior tests exploring learning and memorization capacity in the rat, the Morris water maze and the 14-unit T-maze, 18 days after ischemia. Extracellular dopamine levels during ischemia were determined in search of a possible neuroprotection mechanism. Dopamine and its metabolites, DOPAC and HVA, as well as the serotonin metabolite, 5-HIAA, were assayed with HPLC-EC, in striatal extracellular fluid obtained by in vivo microdialysis in the awake rat. Lisuride was administered at a total dose of 10 ng by continuous intrastriatal infusion or at the dose of 0.5 mg/kg by i.p. infusion, 160 minutes before onset of ischemia for the neurochemical study and at the dose of 0.5 mg/kg via i.p. infusion, 1 hour before occlusion of the carotid arteries, for the behavior tests. Behavioral testing showed significantly better recovery in both sets of behavioral tests, with more pronounced positive results with the 14-unit T-maze, in comparison with the saline-treated animals. Microdialysis confirmed a significant attenuation of the ischemia-induced dopamine surge, whatever the mode of administration, compared with saline-treated animals. These results show that lisuride offers significant neuroprotection from the effect of experimental transient global forebrain cerebral ischemia in the rat; the mechanism would imply, at least in part, reduced levels of extracellular dopamine.

[Parkinson disease--problems in long-term treatment. Dopamine agonists optimize L-dopa therapy]

In a 59-year-old male with a 10 year history of Parkinson's disease, progressive movement disorders occurred under medical treatment (end-of-dose akinesia and peak-dose dyskinesia). Thereupon his treatment was changed to a combination of L-dopa/ decarboxylase inhibitor administered during the day in 5 fractions, and additionally a slow-release dopa preparation given on retiring for the night. At the same time, the patient received the dopamine agonist lisuride. While the patient was hospitalized for surgery, his anti-parkinsonism regimen was initially stopped and then continued in changed form. In the following weeks he experienced a drastic impairment of mobility and, in particular, suffered pronounced nocturnal hypokinetic events. A second period of hospitalization became necessary, a complex medical therapeutic regimen similar to the previously successful combination was established. This resulted in satisfactory mobility, and the patient was able to go back to work.

[Clinical aspects and follow-up of dopamine-induced psychoses in continuous dopaminergic therapy and their implications for the dopamine hypothesis of schizophrenic symptoms]

We present the case reports of 11 Parkinsonian patients who developed acute psychosis under continuous dopaminergic stimulation. Psychopathologically, two of the patients mainly suffered from organic hallucinosis, while nine patients showed the clinical symptoms of delirium. The clinical course and psychopathological findings in these patients did not differ from other acute organic psychoses. However, the symptoms of these dopaminergically induced psychoses varied significantly from the psychopathological findings of paranoid schizophrenic patients who were regularly treated and evaluated in our clinic. These differences in symptoms and clinical course of dopamine-induced and schizophrenic psychosis do not support the hypothesis that the pathogenesis of schizophrenic symptoms can be explained only by a hyperfunction of dopaminergic transmission. Instead, the involvement of other neurotransmitter system must be considered in order to explain the pathogenesis of schizophrenic symptoms on a neurobiological level.

Terguride in stable Parkinson's disease

Terguride (TER) (2 mg/day) was compared with a placebo in 41 stable Parkinson's disease (PD) patients, so as to test its efficacy as an add-on treatment to spare levodopa (LD). After the 4th week of add-on treatment, LD was reduced by about 25%. The number of "stable" patients (--those with an increase of no more than 20% of the basal Columbia University Rating Scale (CURS) score--remaining after LD reduction was used to compare the two add-on treatments. Most patients, remained "stable" in spite of LD reduction, and no significant differences between the therapies were discovered; the CURS score decreased over time only in the TER group. Hence, TER was shown to be a drug that has DA-ergic properties but with minimal antiparkinsonian efficacy.

Combination treatment of the partial D2 agonist terguride with the D1 agonist SKF 82958 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned parkinsonian cynomolgus monkeys

The optimal combination of a dopamine D2 agonist and a D1 agonist was evaluated for symptomatic treatment of Parkinson's disease. Behavioral effects of combination treatment of the full D2 agonist quinpirole or the partial D2 agonist terguride with the full D1 agonist SKF 82958 [(I) 6-Chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2, 3, 4, 5-tetra-hydro-1H-3-benzazepine] were investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys with attention to the induction of hyperactivity such as irritability, excitability and aggressiveness and of dyskinesias such as licking of paws, chewing and biting. Both quinpirole and SKF 82958 alone improved the parkinsonism with a slight induction of the hyperactivity and dyskinesias. Terguride also improved the parkinsonism but did not induce the hyperactivity and dyskinesias. Combination treatment of quinpirole with SKF 82958 not only showed a tendency to augment the antiparkinsonian effects but also induced the marked hyperactivity and dyskinesias. On the other hand, combination treatment of terguride with SKF 82958 also augmented the antiparkinsonian effects but did not induce any hyperactivity and dyskinesias. These findings suggest that combination therapy with a partial D2 agonist and a full D1 agonist or monotherapy with a dopamine agonist that has both partial D2 and full D1 agonist properties might be beneficial for treating motor dysfunction in Parkinson's disease without inducing dopaminergic side effects.

Circadian plasma level profile of lisuride in rats and mice after continuous administration via the diet

Lisuride (Dopergin, CAS 18016-80-3), a dopamine D2 agonist, was administered to male and female rats and mice continuously via the diet for 14 days. The doses were 0.2 mg/kg/d in mice and 1 mg/kg/d in mice and rats. Plasma level profiles (0-22 or 24 h) were determined by measuring lisuride concentrations by radioimmunoassay. At all doses a plateau-like plasma level of lisuride was observed. A clear circadian rhythm of lisuride concentrations (highs during night, low levels during day) was found for male rats (1 mg/kg/d) and for male mice (0.2 mg/kg/d). Female animals did not show this phenomenon as pronounced. At the same dose of 1 mg/kg/d rats showed higher plasma levels than mice. For males the ratio of total AUCs was 1.9 and for female animals 8.6.

Is alpha-methyldopa-type autoimmune hemolytic anemia mediated by interferon-gamma?

Drug-related autoimmune hemolytic anemia appearing with warm-reacting antibodies can be classified according to the offending substances. One of the subtypes can be induced by alpha-methyldopa. However, the pathophysiology of the underlying mechanism is not yet known. In parallel, patients with Parkinson's disease and other extrapyramidal disorders, who are under administration of dopaminergic drugs, often present with abnormal findings with respect to immune parameters. In order to reveal further mechanisms within the immune response, the capability of patients under dopaminergic medication to release cytokines after a stimulatory signal was examined. Therefore, 18 patients who were treated with the dopamine analogue lisuride were compared with an aged-matched control group of 21 healthy volunteers. After stimulation with phytohemagglutinin (PHA), mitogen-induced concentrations of interferon-gamma were significantly higher in the patients treated with lisuride than in the control group. Interferon-gamma leads to an upregulation of MHC class-I and especially class-II molecules on antigen-presenting cells and to an induction of antibody production in B cells. This condition can result in the induction of an autoimmune process. It might be supposed that alpha-methyldopa-type autoimmune hemolytic anemia is mediated by elevated levels of interferon-gamma produced in T cells after a stimulatory signal.

[Is dopaminergic therapy immunologically rejuvinating? Increased interferon-gamma production with the dopaminergic agent lisuride]

Eighteen patients with advanced Parkinson's disease (n = 13) or dopamine-sensitive dystonia (n = 5) were treated with the dopaminergic agent, lisuride, applied as a long-term subcutaneous infusion. The results were compared with those obtained in a group of younger, and a group of older, healthy volunteers. The liberation of gamma-interferon (gamma-IFN) following mitogenic stimulation of whole blood with phytohemagglutinin (PHA) was highly significantly elevated in comparison with the group of older healthy volunteers, and clearly, but not significantly, elevated in comparison with the younger group. There was no difference between patients with dystonia and those with Parkinson's disease. The effect observed is thus probably due to lisuride. This effect might explain the longer life expectancy and reduced proclivity for infection shown by patients with Parkinson's disease. It needs to be determined whether, on the basis of these initial data, a therapeutic principle for the treatment of diseases that can be directly influenced by gamma-IFN can be derived.

Lisuride reduces intravenous cocaine self-administration in rats

The maintenance of intravenous (i.v.) cocaine self-administration appears to depend upon activation of dopamine terminals within mesocorticolimbic areas. Since the nonaddictive ergot derivative lisuride is a direct dopamine receptor agonist, the present study was designed to investigate whether administration of lisuride to rats trained to lever-press for IV self-administration of cocaine could affect the intake of cocaine. IP administration of several doses of lisuride reduced, in a dose-dependent manner, cocaine self-administration. In a control experiment, lisuride did not increase the psychomotor-activating properties of cocaine as measured by locomotor activity, suggesting that lisuride did not simply potentiate the activating effects of cocaine. The present results show that lisuride reduced IV cocaine self-administration in rats; the possibility of a new therapeutic approach to the treatment of cocaine abuse in humans using lisuride may therefore deserve clinical attention.

Terguride as a new anti-hyperprolactinemic agent: characterization in rats and dogs in comparison with bromocriptine

Terguride, a derivative of the ergot alkaloid, was characterized as a new anti-hyperprolactinemic agent in rats and dogs in comparison with bromocriptine. Terguride was found to bind selectively to the pituitary dopamine D2-receptors with a high affinity (Kd = 0.39 nM). In reserpinized rats, terguride at 0.03 mg/kg, p.o. significantly reduced the serum prolactin (PRL) level. The PRL lowering effect and the effective dose were longer lasting and about 30 times lower than those of bromocriptine, respectively. In rats bearing estrogen-induced pituitary prolactinoma, chronic terguride induced shrinkage of the prolactinoma as well as reduction of the high serum PRL level. In lactating rats, terguride (1.0 mg/kg, s.c.) reduced milk production in the mammary gland, whereas bromocriptine showed no significant effect up to 10 mg/kg, s.c. Terguride (10 mg/kg, p.o.) did not induce any stereotypy and hypermotility in reserpinized rats, while bromocriptine induced both stereotypy and hypermotility significantly at 10 mg/kg, p.o. In dogs, terguride, like bromocriptine, reduced the serum PRL level, but did not affect the serum levels of growth hormone and luteinizing hormone. In dogs, bromocriptine induced both emesis and PRL-lowering at almost the same dose, whereas emesis-inducing doses of terguride were about 100 times higher than the PRL-lowering dose. These results suggest that terguride as a dopamine D2-agonist is a potent inhibitor of PRL secretion with less neurotropic side effects compared to bromocriptine, and thus a useful drug for the treatment of galactorrhea and hyperprolactinemia including prolactinoma.

Terguride in fluctuating parkinsonian patients: a double-blind study versus placebo

Terguride (TER), a semisynthetic derivative of lisuride, has been found to display dopamine (DA) agonist and DA antagonist effects in animals, depending on the experimental model used. TER (2 mg/day) was compared to placebo in 41 fluctuating Parkinson's disease patients to test its effect on akinesia and dyskinesia. Mean hours "off" decreased at weeks 6 and 12 (p < 0.05) in the TER group but the overall difference from the placebo group was not significant. Only the TER group displayed a decrease over time in mean Columbia University Rating Scale total score "on" and "off" (p = 0.001 and p = 0.03, respectively). Duration of involuntary movements and resulting disability were not significantly different between patients on TER and those on placebo administration. In the overall evaluation, patients preferred TER (p = 0.01). Tolerance of TER was very good in all but one patient whose wearing-off increased; no one dropped out because of side effects. This 3-month double-blind study showed that TER, added to stable doses of L-dopa, may have slight antiparkinsonian efficacy.

Malignant growth of a recurrent macroprolactinoma after radiation therapy

The authors report a case of a 60-year-old woman with a macroprolactinoma. After radiation therapy of the subtotally excised recurrent tumor, it developed a rapid malignant-destructive growth with invasion into adjacent structures. The causal factors are discussed and the literature is briefly reviewed.

Effects of several partial dopamine D2 receptor agonists in Cebus apella monkeys previously treated with haloperidol

Eight Cebus apella monkeys were treated with haloperidol for 2 years. Five monkeys had developed mild oral tardive dyskinesia and all were primed for neuroleptic induced dystonia, thus serving as a model for both chronic and acute extrapyramidal side effects. In this model, the partial dopamine D2 receptor agonists SDZ HDC-912, SDZ HAC-911, terguride, (-)-3-(3-hydroxyphenyl)-N-propylpiperidine) ((-)-3-PPP) and SND 919 were tested for extrapyramidal side-effect liability. Their antipsychotic potential was also tested, using a dose of dextroamphetamine producing mild stereotypy and moderate motoric unrest. For comparison, the dopamine D2 receptor agonist, LY 171555 and antagonist, raclopride were used. In contrast to the other drugs tested, SDZ HAC-911 consistently reduced oral activity, P < 0.05 (at doses from 0.005 to 0.025 mg/kg). The relative dystonic potencies were raclopride > SDZ HDC-912 > SDZ HAC-911 = terguride. Neither (-)-3-PPP nor SND 919 produced dystonia, but had observable dopamine D2 receptor agonistic effects, (-)-3-PPP producing emesis at 1-4 mg/kg and SND 919 producing motoric unrest and stereotypy at 0.05-0.25 mg/kg. Comparing the antiamphetamine effects of the more antagonist-like drugs with raclopride, the relative potencies were terguride = SDZ HAC-911 > SDZ HDC-912 > raclopride. Comparing the antiamphetamine effects of the more agonist-like drugs with LY 171555, the relative potencies were SND 919 > (-)-3-PPP > LY 171555 in relation to motoric unrest, while neither (-)-3-PPP nor LY 171555 produced inhibition of stereotypy.

Slowing of information processing in Parkinson's disease

In this study, we criticize the notion of bradyphrenia and argue that "slowness of thought" in Parkinson's disease (PD) must be analyzed as slowness of different information-processing stages and that unselected patients should not be used in experimental studies. We selected 32 patients with a long history of PD and 50 control subjects. Sixteen patients had mild cognitive deterioration (not dementia) and 16 patients had preserved cognitive capacities; otherwise the groups were matched. By using computerized tests, we investigated three separate stages: automatic and controlled processing and motor programming. The results indicate that patients with mild cognitive deterioration are slower than patients with preserved cognitive capacities or controls in automatic visual and in controlled processing but not in motor programming. We conclude that the slowing of controlled processing reflects the disruption of central neural networks, that a long history of PD does not necessitate cognitive slowing, and that PD is not a neuropsychologically serviceable category.

Natriuretic effects of dopamine agonist drugs in models of reduced renal mass

In addition to recognized neurotransmitter properties in the central nervous system, dopamine (DA) plays a role in the physiological activity of the kidney through its hemodynamic and natriuretic effects. On the basis of these data, some pharmacological interventions have focused their attention on the use of DA-related drugs to improve renal sodium handling. We summarize the data obtained from two studies using two DA agonist drugs, lisuride (LIS) and fenoldopam (FEN), in two situations of reduced renal mass. During an intravenous sodium load performed on 10 uninephrectomized dogs, LIS induced a significant blockade of the concomitant pressor response, estimated by lower blood pressure and norepinephrine levels. Under these same conditions, FEN significantly decreased blood pressure and elevated the natriuretic response. In a second study, when FEN was administered at nonhypotensive doses to chronic renal failure patients, it evoked an enhancement of diuresis, natriuresis, and creatinine clearance. These data seem to confirm the involvement of DA in the regulation of cardiovascular homeostasis and its role in renal sodium handling. Furthermore, these beneficial effects support the use of DA-related drugs in the field of hypertension.

Extrapyramidal syndrome responsive to dopaminergic treatment following recovery from central pontine myelinolysis

A 52-year-old woman developed severe hyponatremia following treatment for hypertension with chlorthalidone. Rapid correction of hyponatremia resulted in coma, quadriplegia and hypopnea compatible with central pontine myelinolysis. She recovered with residual facial hypomimia, bradykinesia, cogwheel rigidity and coarse resting tremor, responding to dopaminergic treatment. Her symptoms and signs, which are quite similar to idiopathic Parkinson's disease, are still responsive to treatment 7 years after onset.

Long-term observation of chronic subcutaneous administration of lisuride in the treatment of motor fluctuations in Parkinson's disease

Twenty-nine patients with advanced Parkinson's disease were treated with subcutaneous lisuride infusion in addition to a basic therapy consisting of levodopa + PDI in all, and deprenyl in some patients. At the time of the report, 13 patients are still receiving lisuride infusion after 5-36 months, while 16 have dropped out after 0.5-30 months: one because of psychosis, three because of insufficient efficacy, three due to death unrelated to treatment, three because of difficulties in handling the pump as outpatients, and six for other reasons. "Off"-periods and Parkinsonian disability in "off" and in "on" were reduced significantly. These improvements remained constant throughout the observation period. Once the optimal dose regimen is established, only minor adjustments of the doses of lisuride and levodopa are required in the individual case.

Improvement of parkinsonian features correlate with high plasma levodopa values after broad bean (Vicia faba) consumption

Five healthy volunteers and six patients with Parkinson's disease (PD) ate 250 g cooked broad beans after 12 hours without treatment. During the next four hours a substantial clinical improvement was noted, three patients showed severe dyskinesias, and plasma levodopa concentrations rose.

Continuous subcutaneous lisuride infusion in OPCA

Four patients with sporadic olivopontocerebellar atrophy (OPCA) and severe signs of Parkinsonism received continuous subcutaneous lisuride infusion via a small external pump. All 4 patients benefitted from this treatment: 3 showed an overall improvement in motor performance, in 1 patient mainly dysphagia and dysarthria improved. Therapeutic benefit lasted for at least 6 months of follow up. With a daily dose of 1.0 mg subcutaneous lisuride, treatment limitations were reached in the form of dysphagia, probably due to oropharyngeal dystonia. Subcutaneous lisuride infusion should be taken into consideration in OPCA patients with signs of Parkinsonism if oral dopaminergic treatment has failed earlier on.

Tolerance to hypoactivity and sensitization to hyperactivity after chronic treatment with a presynaptic dose of lisuride in rats

We studied the adaptive changes of the locomotor effects of lisuride, a selective agonist for dopamine (DA) D2 receptors, and the functional state of D1 and D2 receptors after repeated administration of lisuride at a dose supposed to act preferentially on DA autoreceptors. Rats were treated daily with saline or lisuride, at a dose that causes a significant reduction in locomotor activity when given to naive rats (25 micrograms/kg i.p.), for 33 days and the effect of different challenging doses of the drug on locomotor activity was measured at different times during and after the treatment. The functional state of D1 and D2 DA receptors was evaluated by measuring SKF 82526-stimulated and LY 171555-inhibited adenylate cyclase (AC) activity in the caudatus/putamen, nucleus accumbens and substantia nigra and naive and chronically treated rats. There was a progressive decline in the ability of lisuride to decrease locomotor activity in rats given daily injections of lisuride, and there was a marked reduction in the threshold dose of lisuride for causing hypermotility. The functional state of DA receptors, positively or negatively linked to AC activity, was not modified by the treatment. The most suitable explanation of the reported adaptive behavioral changes is a down-regulation of DA autoreceptors after chronic treatment with presynaptic doses of lisuride.

Effects of the dopamine D2 agonists lisuride and CQ 32-084 on rat feeding behaviour

The influence on rat-feeding behaviour of lisuride and CQ 32-084, agonists at dopamine D2 receptors, was examined using two procedures. In a first series of experiments, the apparatus was an X-maze baited with food pellets where individual fasted rats were observed for 5 min. A number of parameters were recorded: latency to tasting and feeding, interval between tasting and feeding, total feeding time, and total grooming time. Lisuride (0.05 and 0.1 mg/kg) and CQ 32-084 (0.05 and 0.5 mg/kg) behaved as stimulants of eating; lisuride (0.4 mg/kg) inhibited the phenomenon. Both drugs always antagonized grooming. Subsequently, when food intake was determined in the home cages of fasted animals lisuride reduced feeding at all doses during the first hour after treatment, while CQ 32-084 had no effect. The data show that the two compounds display different activity on ingestive behaviour according to the dose and experimental model used. Discussion centres on the possible dependence of feeding enhancement in the X-maze on the anxiolytic activity exerted by low D2 autoreceptorial doses.

Effect of aging and dopaminomimetic therapy on mitochondrial respiratory function in Parkinson's disease

Oxygen consumption and enzyme activity were evaluated in platelet mitochondria from 17 patients with Parkinson's disease. In comparison with age-matched controls, no consistent abnormality could be discerned in complex I, complex II-III, or complex IV oxygen consumption, or in the enzyme activity of these respiratory chain complexes. Neither chronic therapy with levodopa/carbidopa alone nor in combination with deprenyl significantly affected any measure of mitochondrial respiratory function. There was no discernible relationship between patient age or disease severity and any parameter of mitochondrial respiration. Moreover, blood lactate levels following glucose loading were not different in patients and controls. These results fail to support the occurrence of a generalized defect in any mitochondrial respiratory function in Parkinson's disease.

[Chronic administration of lisuride hydrogen maleate increases muscarinic acetylcholine receptor binding in aged rat brain]

Changes in the distribution and densities of muscarinic acetylcholine receptors (mACh-R) in young adult and aged rat brain, and the effects of chronic administration of lisuride hydrogen maleate (lisuride) on these changes were studied by in vitro quantitative autoradiography of [3H] quinuclidinyl benzilate binding. mACh-R was relatively higher in the striatum, hippocampus and cerebral cortex in the young adult rats. In contrast, mACh-R binding was markedly reduced in the striatum, accumbens nucleus, amygdaloid nucleus and frontal cerebral cortex of aged rats compared to young adult rats. However, chronic administration of lisuride significantly increased mACh-R binding in the parietal cerebral cortex as well as in the above-mentioned regions in aged rats. This lisuride-induced increase in mACh-R of aged rat brain is considered to have important implications concerning the mechanism of therapeutic efficacy of lisuride.

TRH test and the continuous dopaminergic stimulation in complicated Parkinson's disease

Marked, disabling fluctuations in motor performance (on-off phenomena) appear after chronic L-Dopa therapy in Parkinson's disease (PD). Intravenous infusion of L-Dopa greatly reduces these motor fluctuations, but it is not reliable as a chronic treatment. Therefore, infusion of the potent, water-soluble dopaminergic agonist lisuride has been tested. However, many patients did not respond to infusion of lisuride alone, and no clinical parameter is known to correlate with the lacking response. In order to study this problem, we performed the TRH test (200 micrograms i.v.) in 8 PD patients with severe motor fluctuations; before and during lisuride subcutaneous infusion, we measured PRL and TSH responses to TRH. Both PRL and TSH receive an inhibitory control from dopaminergic receptors on pituitary cells, whereas they are stimulated by TRH. The TRH test, given during lisuride infusion, allows an indirect evaluation of the 'brake function' of the dopaminergic system on anterior pituitary, i.e. of dopaminergic receptor sensitivity in vivo. In our study, TRH induced a significant TSH rise in all PD patients, before and during lisuride infusion. Moreover, the lisuride responders (i.e. patients showing constant 'on' period during lisuride infusion, 4 patients) showed a significant lower TSH response as compared to nonresponders. PRL levels followed the same trend without reaching statistical significance. These data are compatible with the presence, in the two groups, of a different pituitary dopaminergic sensitivity which would suggest the presence of pharmacodynamic factors associated with the lacking response to intravenous lisuride infusion.

Antagonist effect of terguride in Parkinson's disease

The effects of the partial dopamine agonist terguride (9,10 transdihydrolisuride; THDL) on striatal dopamine receptors were studied by its i.v. administration to 13 patients with Parkinson's disease. Patients were maintained in a steadily mobile state with abnormal involuntary movements by a constant i.v. infusion of levodopa. Terguride showed dopamine antagonist properties in nine patients. In two of these nine patients, a decrease in dyskinesia score was observed without a concomitant worsening of parkinsonian symptoms, whereas in the remaining seven, full parkinsonian akinesia followed THDL administration. The subsequent i.v. injection of the dopamine agonist lisuride reversed THDL-induced akinesia in these seven patients. In the remaining four patients, no clinically significant motor effects were observed. These results show dopamine antagonist activity of terguride in patients with Parkinson's disease treated with Levodopa. Further studies using a wider dose titration are required to evaluate the possible role of dopamine partial agonists in the therapy of levodopa-induced dyskinesias.

Treating organic abulia with bromocriptine and lisuride: four case studies

Abulia refers to an impairment of will, or the inability to initiate behaviour and action. There are reports of successful treatment of akinetic mutism, the most severe form of abulia, with bromocriptine. Four case studies are presented describing the successful treatment of abulia at a lesser severity than akinetic mutism with bromocriptine. Abulia was caused by brain damage due to alcohol in two cases, Wilson's disease and basal ganglia infarct in one each. Maximum bromocriptine dose varied from 25-70 mg. All improved considerably. Withdrawal or reduction of medication in three produced deterioration. The prescription of a neuroleptic drug had a similar effect in the fourth. One patient with a previous history developed a depressive relapse and so the drug was withdrawn and lisuride introduced. This produced a similar improvement. These cases highlight the value of identifying the syndrome of organic abulia and suggest that dopamine agonists may have a place in its treatment, though controlled studies are needed.