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PubMed1996

Neuroprotective effects of the dopamine D2/D3 agonist pramipexole against postischemic or methamphetamine-induced degeneration of nigrostriatal neurons.

We have examined the neuroprotective efficacy of the selective dopamine (DA) D2/D3 receptor agonist pramipexole in two models of nigrostriatal (NS) degeneration. The first involves the delayed (28-day) postischemic retrograde NS degeneration that takes place in gerbils following a 10-min episode of bilateral carotid arterial occlusion-induced forebrain ischemia. In vehicle (40% hydroxypropyl cyclodextrin)-treated male gerbils, there was a 40-45% loss of NS cell bodies in the pars compacta and pars reticulata (TH immunohistochemistry and Cresyl violet histochemistry) by 28 days after ischemia/reperfusion. Daily postischemic oral dosing (1 mg/kg p.o., b.i.d., beginning at 1 h after insult) decreased the 28-day postischemic loss of NS DA neurons by 36% (P < 0.01 vs. vehicle-treated). The effect was specific for dopamine neurons since no significant salvage of hippocampal CA1 neurons was observed. In a second model, pramipexole's effects were examined on methamphetamine-induced (10 mg/kg, i.p. X 4, each 2 h apart) NS degeneration in male Swiss-Webster mice. In vehicle-treated mice, there was a 40% loss of NS neurons by day 5. In contrast, pramipexole dosing (1 mg/kg, p.o., 1 h after the last methamphetamine dose, plus daily) attenuated the NS degeneration from 40% to only 8% (P < 0.00001 vs. vehicle). We postulated that pramipexole acts in both of these models to reduce the elevated DA turnover and the associated elevation in hydroxyl radical production secondary to increased MAO activity that could be responsible for oxidative damage to the NS neurons. Indeed, in the gerbil ischemia model, we documented by HPLC-ECD a 135% postreperfusion increase in DA turnover (DOPAC + HVA/DA) at 5 min after reperfusion. Pramipexole at the 1 mg/kg, p.o., dose level was able to significantly reduce the increased DA turnover, but by only 16%. Thus, it is conceivable that other mechanisms may also contribute to pramipexole's dopaminergic neuroprotection. Based on a preliminary examination of pramipexole's oxidation potential, it appears that the compound may possess significant intrinsic antioxidant properties that might contribute to its neuroprotective effects.

Animals↗
PubMed1999

Pramipexole--a new dopamine agonist for the treatment of Parkinson's disease.

Although L-DOPA is the current 'gold standard' for treatment of Parkinson's disease, its effectiveness fades rapidly and its use results in serious motor fluctuations (on-off, wearing off, freezing, involuntary movements) for most patients with Parkinson's disease. Pramipexole is an aminothiazole dopamine agonist with selective actions at dopamine receptors belonging to the D2 subfamily, where it possesses full activity similar to dopamine itself. Pramipexole's preferential affinity for the D3 receptor subtype could contribute to efficacy in the treatment of both the motor and psychiatric symptoms of Parkinson's disease. Both in vitro and in vivo studies in animals suggest that pramipexole possesses numerous neuroprotective properties, including dopamine autoreceptor agonist properties, antioxidant properties, ability to block the mitochondrial permeability transition pore and the ability to stimulate the release of trophic factors. Clinical studies have demonstrated that pramipexole has excellent pharmacokinetic properties and that it is an effective monotherapy in treating early Parkinson's disease and an effective adjunctive therapy with L-DOPA in treating late Parkinson's disease. In addition, pramipexole has demonstrated efficacy in a clinical trial for the treatment of major depression. In the early disease studies, pramipexole was able to retard the need for L-DOPA treatment for several years. Thus, a new 'L-DOPA-sparing' paradigm for treating Parkinson's disease may now be possible, whereby patients are initially treated with pramipexole and L-DOPA is added only as necessary.

Animals↗
PubMed1999

Neuroprotection by pramipexole against dopamine- and levodopa-induced cytotoxicity.

Pramipexole, a novel non-ergoline dopamine (DA) agonist, has been applied successfully for treatment of Parkinson's disease (PD). We report here that pramipexole can protect dopaminergic cell line Mes23.5 against dopamine- and levodopa-induced cytotoxicity possibly through a mechanism related to antioxidant activity. In the MES 23.5 cultures, DA and L-DOPA induce a dose- and time-dependent cytotoxicity, as determined by tetrazolium salt and trypan blue assays. Furthermore, an in situ terminal deoxynucleotidyl transferase assay demonstrates that DA-induced cell death is apoptotic. Pretreatment with pramipexole in a concentration range (4-100 microM) significantly attenuates DA- or L-DOPA-induced cytotoxicity and apoptosis, an action which is not blocked by D3 antagonist U-99194 A or D2 antagonist raclopride. Pramipexole also protects MES 23.5 cells from hydrogen peroxide-induced cytotoxicity in a dose-dependent manner. In cell-free system, pramipexole can effectively inhibit the formation of melanin, an end product resulting from DA or L-DOPA oxidation. These results indicate that pramipexole exerts its neuroprotective effect possibly through a mechanism, which is independent of DA receptors but related to antioxidation or scavenging of free radicals (e.g. hydrogen peroxide). As a direct DA agonist and potentially neuroprotective agent, pramipexole remains attractive in the treatment of PD.

Animals↗
PubMed2000

Pramipexole in the treatment of restless legs syndrome: a follow-up study.

The restless legs syndrome (RLS) is a condition characterized by unpleasant limb sensations occurring at rest and associated with an irresistible urge to move. Several treatments are used to treat RLS including benzodiazepines, opioids, dopaminergic agents, clonidine and anticonvulsant drugs such as carbamazepine and gabapentine. Dopaminergic agents are now considered the treatment of choice for RLS. Levodopa is effective in treating RLS; however, several patients treated with levodopa at bedtime developed morning or late afternoon restlessness. Recently, more attention has been paid to dopamine receptor agonists. Ergoline derivatives, bromocriptine and pergolide were found effective, but require concomitant administration of domperidone, a peripheral dopamine antagonist. In a recent study, we studied the efficacy and innocuity of pramipexole, a new dopamine agonist with a higher affinity for the D3 receptor subtype of the D2 family, in a double-blind, placebo-controlled, randomized trial. Pramipexole had major effects on RLS symptoms without severe side-effects. The present study aimed to assess the long-term efficacy of pramipexole. Seven patients were treated with the drug for a mean follow-up duration of 7.8 months. Treatment was started at a dosage of 0.25 mg, and progressively increased until the optimal therapeutic effect was obtained. Home questionnaires were completed for 7 consecutive days, after one month and after a mean of 7.8 months of treatment with pramipexole, assessing leg restlessness during the daytime, in the evening, at bedtime and during the night. There was no evidence of a decrease in the therapeutic effect of pramipexole in these patients, even 7.8 months after the initiation of treatment. The optimal dosage was 0.25 mg for one patient, 0.5 mg for five patients and 0.75 mg for one patient. While there was a progressive increase in severity of leg restlessness from daytime to nighttime before treatment, a suppression of leg restlessness was observed throughout the 24 h with a single dose of pramipexole at bedtime. The remarkable efficacy of pramipexole raises the possibility that the D3 receptors of the mesolimbic system may be more specifically involved in the physiopathology of RLS.

Adult↗
PubMed2003

Pramipexole in the management of restless legs syndrome: an extended study.

STUDY OBJECTIVES: To determine whether pramipexole used over an extended time for restless legs syndrome (RLS) remains effective; whether the dose of the drug needs to be increased; whether augmentation develops; and whether side effects, especially sleepiness, are prominent. DESIGN: Retrospective review of the records of consecutive patients treated with pramipexole for RLS. SETTING: Sleep disorders center in an academic hospital. PATIENTS: 60 consecutive patients treated with pramipexole for RLS. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Pramipexole was completely effective in controlling RLS in 67%, partially effective in 27%, and ineffective in 7% of patients. Eleven patients (18%) discontinued pramipexole after less than 4 months; the remainder were followed for a mean of 27.2 months, during which only 4 others stopped the drug. The median daily dose increased from 0.38 mg after stabilization to 0.63 mg at the end of the study. Forty percent experienced mild side effects, most commonly insomnia, nausea or dyspepsia, and dizziness. Only 5% experienced sleepiness, and none experienced sleep attacks while driving. Augmentation developed in 33%, most in the first year and all by 30 months. Augmentation was not predictable by prior augmentation with other dopaminergic agents. Only 1 patient discontinued pramipexole because of augmentation. CONCLUSIONS: Pramipexole was effective for RLS with continued response with time. Modest escalations in dose occurred, partly due to additional doses prescribed for augmentation. Side effects were common, but generally mild and tolerated. Sleepiness while driving was not a problem. Augmentation occurred in 33% of patients but was treatable with increased doses earlier in the day.

Adult↗
PubMed2006

Long-term treatment with pramipexole in restless legs syndrome.

The aim of the present study was to look at the long-term efficacy and side effects profiles of pramipexole in a large cohort of drug naïve patients with regard to dopaminergic medications. In all, 195 consecutive restless legs syndrome (RLS) patients who were prescribed pramipexole more than 1 year previously, agreed to undergo a telephone interview to assess both the efficacy and side effects of pramipexole. Forty-three patients had discontinued pramipexole: 20 because of side effects, six because of a lack of efficacy, six for both and 11 for other reasons. Patients who continued pramipexole for more than 1 year (n = 152) reported a mean decrease in RLS symptoms severity of 80.9% (SD = 19.6%). At the onset of treatment, the most common side effects were nausea (30%), tiredness (9%), dizziness (8%), headache (4%), insomnia (3%), dry mouth (2%), difficulty to concentrate (1.3%) and sleepiness (0.7%), At 30 months, most patients (n = 124/152; 81.6%) reported an absence of side effects of pramipexole. None of the adverse effects occurred in more than 5% of patients at follow-up. The present study confirms, in a large cohort of unselected patients, that pramipexole is effective and safe in the long-term treatment of RLS.

Adult↗
PubMed2004

Pramipexole protects against apoptotic cell death by non-dopaminergic mechanisms.

We have investigated the ability of pramipexole, a dopamine agonist used in the symptomatic treatment of Parkinson's disease (PD), to protect against cell death induced by 1-methyl-4-phenylpyridinium (MPP+) and rotenone in dopaminergic and non-dopaminergic cells. Pre-incubation with either the active (-)- or inactive (+)-enantiomer forms of pramipexole (10 microm) decreased cell death in response to MPP+ and rotenone in dopaminergic SHSY-5Y cells and in non-dopaminergic JK cells. The protective effect was not prevented by dopamine receptor blockade using sulpiride or clozapine. Protection occurred at concentrations at which pramipexole did not demonstrate antioxidant activity, as shown by the failure to maintain aconitase activity. However, pramipexole reduced caspase-3 activation, decreased the release of cytochrome c and prevented the fall in the mitochondrial membrane potential induced by MPP+ and rotenone. This suggests that pramipexole has anti-apoptotic actions. The results extend the evidence for the neuroprotective effects of pramipexole and indicate that this is not dependent on dopamine receptor occupation or antioxidant activity. Further evaluation is required to determine whether the neuroprotective action of pramipexole is translated to a disease-modifying effect in PD patients.

1-Methyl-4-phenylpyridinium↗
PubMed2006

Pramipexole protects against MPTP toxicity in non-human primates.

The neurotoxin MPTP induces nigral dopaminergic cell death in primates and produces a partial model of Parkinson's disease (PD). Pramipexole is a D2/D3 dopamine receptor agonist used in the symptomatic treatment of PD, and which also protects neuronal cells against dopaminergic toxins in vitro. We now demonstrate that pramipexole partially prevents MPTP toxicity in vivo in a primate species. Common marmosets were repeatedly treated with pramipexole either before, coincidentally with, or after low-dose MPTP treatment designed to induce a partial lesion of the substantia nigra. Animals pretreated with pramipexole had a significantly greater number of surviving tyrosine hydroxylase (TH) positive neurones in the pars compacta of the substantia nigra. Pramipexole pretreatment also prevented degeneration of striatal dopamine terminals. Treatment with pramipexole concurrently with MPTP or following MPTP did not prevent TH-positive cell loss. Pramipexole pretreatment appears to induce adaptive changes that protect against dopaminergic cell loss in primates.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2005

Transport of the dopamine D2 agonist pramipexole by rat organic cation transporters OCT1 and OCT2 in kidney.

We investigated the mechanism of renal tubular secretion of the dopamine D2 receptor agonist pramipexole in rats, focusing on organic cation transporters 1 and 2. The uptake of [14C]pramipexole by Xenopus oocytes injected with complementary RNA of either rat organic cation transporter (rOCT) 1 or rOCT2 was significantly higher than that by water-injected oocytes: the kinetic parameters, K(m) and V(max), of pramipexole uptake were 49.5 muM and 234 pmol/60 min/oocyte for rOCT1, and 16.9 microM and 12.8 pmol/60 min/oocyte for rOCT2. Pramipexole was taken up into kidney slices in a time- and concentration-dependent manner, and Eadie-Hofstee plots revealed the involvement of two saturable components. The kinetic parameters, K(m1) and V(max1), of the high-affinity component were 12.9 microM and 10.7 nmol/15 min/g kidney, respectively. The uptake of [14C]pramipexole by rOCT1, rOCT2, and kidney slices was inhibited by procainamide and corticosterone, which are selective inhibitors of rOCT1 and rOCT2, respectively. The IC50 values of procainamide and corticosterone for the uptake of [14C]pramipexole by rOCT1, rOCT2, and kidney slices were 7.7, 167.0, and 47.0 microM and 163.7, 10.7, and 47.7 microM, respectively. These results demonstrate that both rOCT1 and rOCT2 are involved in the renal uptake of pramipexole across the basolateral membrane of the proximal tubular epithelial cells.

Amantadine↗
PubMed1999

Efficacy, safety, and tolerance of the non-ergoline dopamine agonist pramipexole in the treatment of advanced Parkinson's disease: a double blind, placebo controlled, randomised, multicentre study.

OBJECTIVES: Pramipexole, a non-ergot dopamine D2/D3 receptor agonist, was investigated as an add on drug in advanced parkinsonian patients with motor fluctuations to assess efficacy, safety, and tolerance. METHODS: Seventy eight patients of either sex with advanced Parkinson's disease and treatment complications such as motor fluctuations were enrolled into a double blind, placebo controlled, randomised, multicentre study (phase II) and assigned to add on treatment with pramipexole (n=34) versus placebo (n=44) to a previously stabilised antiparkinsonian medication (7 week dose titration interval, 4 week maintenance period). The primary end point of efficacy was the change from baseline in the total score of the unified Parkinson's disease rating scale (UPDRS) in the on "period" (2 hours after intake of study medication). Safety and tolerability were assessed on the basis of adverse events, vital signs, laboratory measurements, and ECG recordings. RESULTS: There was a significant improvement of the pramipexole group in UPDRS total scores, subscores part II, III (activities of daily living and motor examination), and IV (complications of therapy). Mean UPDRS total score decreased by 37.3% under pramipexole compared with 12.2% under placebo (p<0.001). Patients under pramipexole reported an overall reduction in "off" periods of 12%--resulting in 1.7 more hours "on" time a day--compared with an increase in "off" periods of 2% under placebo. There were no unexpected safety results. The adverse event profile disclosed a high tolerability. The most important adverse events under pramipexole were fatigue, dyskinesia, and vivid dreams. CONCLUSION: Pramipexole administration is an efficacious and well tolerated add on therapy in patients with advanced Parkinson's disease with an improvement in activities of daily living, motor function, and treatment associated complications.

Adult↗
PubMed2004

Low-dose pramipexole in the management of restless legs syndrome. An open label trial.

Dopaminergic agents are considered the treatment of choice for restless legs syndrome (RLS); levodopa is the only substance licensed for this disorder in some European countries. However, in a substantial proportion of patients symptoms are not adequately controlled for a whole night due to the short half-life of levodopa or because symptom augmentation may develop. To further investigate the impact of pramipexole on the management of RLS we performed a short-term open label trial with pramipexole in 17 patients who were being insufficiently treated with levodopa or for whom pramipexole was primarily being considered because of the severity of the RLS symptoms. A single dose of 0.125-0.75 mg pramipexole (mean 0.3 +/- 0.2 mg) in the evening resulted in a significant improvement of subjective RLS symptoms as rated by the International RLS Study Group Severity Scale (IRLS scores: 29.8 +/- 4.7 baseline vs. 7.3 +/- 5.9 endpoint; p = 0.0001). Polysomnographic recordings showed a significant improvement of the periodic leg movements (PLM) index, PLM sleep arousal index, sleep-onset latency, total sleep time and sleep efficiency. All patients who had developed a worsening of RLS symptoms under levodopa recovered from daytime symptoms after their medication was switched to pramipexole. Since pramipexole was well tolerated, an ideal dosage to control RLS symptoms could be reached rapidly. Pramipexole has proven a suitable alternative in patients with moderate to severe RLS, particularly when their therapy has to be switched to a dopamine agonist.

Administration, Oral↗
PubMed2004

[Pharmacological profiles and clinical effects of antiparkinsonian agent, pramipexole].

Pramipexole hydrochloride (pramipexole) is a nonergot dopamine D(2) agonist, and the S(-)enantiomer is used for the treatment of Parkinson's disease (PD). Pramipexole possessed the highest affinity with the D(3) subtype among the D(2) receptor subfamily members (D(2), D(3), D(4)), lacking affinity with the D(1) and D(5) subtype. Pramipexole ameliorated the motor disturbances in PD animal models, induced contralateral rotational behavior reflecting post-synaptic D(2) receptor stimulation in the striatum, and showed a variety of neuroprotective effects in vitro and in vivo experimental systems. The neuroprotective effects of pramipexole seemed to be derived from several mechanisms: stimulation of D(2) autoreceptor, stimulation of D(3) receptor, inhibition of oxidative reaction and following radical production, increase of Bcl-2 protein and inhibition of apoptotic cell death, and production of neurotrophic factor. Clinical efficacy of pramipexole both in monotherapy and combined use with L-DOPA were confirmed evaluating by UPDRS (Unified Parkinson's Disease Rating Scale) II (Activities of daily living) and III (Motor), in the results of clinical studies mainly performed in USA and European countries and partly in Japan. In addition, patients initially treated with pramipexole demonstrated reduction in problematic symptoms and in loss of striatal [(123)I]2beta-carboxymethoxy-3beta-(4-idodophenyl)tropan uptake, a marker of dopamine neuron degeneration, compared with those initially treated with L-DOPA.

Animals↗
PubMed1997

Safety and efficacy of pramipexole in early Parkinson disease. A randomized dose-ranging study. Parkinson Study Group.

CONTEXT: Monotherapy with dopamine agonists may be useful in early Parkinson disease. OBJECTIVE: To evaluate dose-response relationships for tolerability, safety, and efficacy of the synthetic dopamine agonist pramipexole. DESIGN: Multicenter, multidosage, parallel-group, double-blind, placebo-controlled, randomized clinical trial. SETTING: University or academically based movement disorder clinics. PATIENTS: A total of 264 patients with early Parkinson disease (PD) who were not requiring or receiving levodopa or other dopamine agonists were enrolled. INTERVENTION: Subjects were randomized to 1 of 5 treatment groups: pramipexole doses of 1.5 mg/d, 3.0 mg/d, 4.5 mg/d, and 6.0 mg/d, or matching placebo. A 6-week dosage escalation period was followed by a 4-week maintenance period and a 1-week period during which active treatment was withdrawn. MAIN OUTCOME MEASURES: The primary measure of tolerability was the proportion of subjects completing the study on the assigned treatment. The primary measure of efficacy was the change from baseline to 10 weeks in the total score on the Unified Parkinson's Disease Rating Scale (UPDRS). RESULTS: Pramipexole was generally safe and well tolerated in this 10-week study. The proportion of subjects completing the study on the originally assigned dosage was 98% for placebo and 81% for the 1.5-mg/d, 92% for the 3.0-mg/d, 78% for the 4.5-mg/d, and 67% for the 6.0-mg/d treatment groups. There was a trend toward increased frequency of adverse experiences, particularly somnolence, in the 6.0-mg/d group. After 10 weeks of treatment, pramipexole-treated subjects showed a 20% improvement in total UPDRS scores, with mean improvements in scores ranging from 5.9 to 7.0 units among active treatment groups, compared with 0.9 units for the placebo group (P<.005 for each comparison with placebo). There was also evidence that the treatment effects were more pronounced in subjects with worse UPDRS scores at baseline. CONCLUSIONS: Pramipexole is safe and effective as short-term monotherapy in patients with early PD who are not receiving levodopa. Further study is warranted to determine the long-term impact of pramipexole on the progression of disability in PD and its value in comparison with levodopa therapy and other dopamine agonists.

Aged↗
PubMed2000

Pramipexole versus bromocriptine for levodopa-induced complications in Parkinson's disease.

OBJECTIVES: To compare the efficacy and safety of adjuvant pramipexole versus bromocriptine therapy in patients with Parkinson's disease, already established on levodopa and suffering from motor complications. SEARCH STRATEGY: Electronic searches of MEDLINE, EMBASE and the Cochrane Controlled Trials Register. Handsearching of the neurology literature as part of the Cochrane Movement Disorders Group's strategy. Examination of the reference lists of identified studies and other reviews. Contact with Pharmacia Upjohn and Boehringer Ingelheim. SELECTION CRITERIA: Randomised controlled trials of pramipexole versus bromocriptine in patients with a clinical diagnosis of idiopathic Parkinson's disease and long-term complications of levodopa therapy. DATA COLLECTION AND ANALYSIS: Data was abstracted independently by the authors and differences settled by discussion. The outcome measures used included Parkinson's disease rating scales, levodopa dosage, 'off' time measurements and the frequency of drop outs and adverse events. MAIN RESULTS: One randomised controlled trial has compared pramipexole with bromocriptine using a double-blind, parallel group, multicentre design. It was not powered to examine differences between active treatment arms. There was a larger reduction in off time with pramipexole therapy compared with bromocriptine (weighted mean difference 1.4 hours; 0, 2.8, 95% CI). No differences occurred in dyskinesia rating scale, dyskinesia as an adverse event or UPDRS complication score. The UPDRS ADL and motor scores showed similar improvements compared to placebo with both agonists. Levodopa dose reduction was similar with both agonists. Subscales of the Functional Status Questionnaire showed significant improvements compared to placebo with both agonists. The finding that the EuroQol improved significantly compared with placebo with pramipexole but not bromocriptine should be treated with caution. Dopaminergic adverse events were similar with each agonist, as was the all cause withdrawal rate. REVIEWER'S CONCLUSIONS: Although pramipexole and bromocriptine improved off time and reduced parkinsonian motor impairments and disability compared with placebo, no conclusions regarding their comparative effectiveness and safety can be drawn as this single trial did not have adequate power to assess such differences. Further larger trials are required to examine this issue in the future.

Antiparkinson Agents↗
PubMed1997

Attenuation of levodopa-induced toxicity in mesencephalic cultures by pramipexole.

The direct-acting dopamine (DA) agonist pramipexole (2 amino-4,5,6,7-tetrahydro-6-propyl-amino-benzthiazole-dihydrochlori de) was evaluated for its ability to attenuate levodopa-induced loss of tyrosine hydroxylase immunoreactive (THir, a marker for dopamine neurons) cells in mesencephalic cultures. Pramipexole reduced levodopa-induced THir cell loss in a dose-dependent and saturable fashion (ED50 = 500 pM), its inactive stereoisomer was significantly less potent in this regard and pergolide and bromocriptine had negligible cytoprotective effects. Culture media from mesencephalic cultures incubated with pramipexole for 6 days increased THir cell counts in freshly harvested recipient cultures. The magnitude of this effect was directly proportional to the amount of pramipexole in the donor cultures and heat-inactivation of the media abolished the growth promoting effect. The results from this exploratory set of experiments suggest that pramipexole may be cytoprotective to dopamine neurons in tissue culture. Pramipexole's affinity for DA receptors, its antioxidant action or its ability to enhance mesencephalic trophic activity could be responsible for this effect.

Animals↗
PubMed1997

Antidepressant effects of pramipexole, a novel dopamine receptor agonist.

Pramipexole (2-amino-4,5,6,7-tetrahydro-6-propyl-amino-benzthiazole-dihydrochl oride), a new dopamine receptor agonist with preference for D3 compared to D2 and D4 receptors, was tested in rats in respect of its potential antidepressant activity. In the forced swimming test the drug under study, given three times in rats, reduced the immobility time. In the forced swimming test, joint treatment with antidepressants (imipramine, amitriptyline) and pramipexole evoked a more potent effect than any of the drugs given alone; however, the locomotor hyperactivity was weaker after joint administration. Citalopram and fluoxetine, inactive per se in the forced swimming tests, visibly enhanced the antidepressant-like effect of pramipexole but, on the other hand, they attenuated the locomotor hyperactivity evoked by the drug. Repeated treatment with pramipexole (0.3 or 1 mg/kg, twice daily for 14 days) increased the locomotor activity measured at 1 h after the last dose. Repeated administration of pramipexole (as above) potentiated the D-amphetamine- or quinpirole-induced locomotor hyperactivity. The obtained results indicate that, in the tests used, pramipexole evokes effects similar to those of typical antidepressants and, at the same time, enhances their activity (the forced swimming test in rats); therefore it may be regarded as a potential antidepressant drug.

Animals↗
PubMed2002

Potential antidepressant properties of pramipexole detected in locomotor and operant behavioral investigations in mice.

RATIONALE: Pramipexole is a dopamine agonist which binds selectively to dopamine D(3) and D(2) receptors. There is evidence that, in addition to its beneficial effects in parkinsonism, this compound may also be of value in addressing symptomatology associated with depressive diseases. OBJECTIVES: The present study was aimed at investigating behavioral effects of pramipexole that may indicate possible antidepressant properties. METHODS: We measured how different doses of pramipexole influence nocturnal locomotion and operant responding after prolonged conditioning of a schedule of FI 2 min (FI2) in female NMRI mice. RESULTS: The present data indicate that active doses of pramipexole inhibit nocturnal locomotion during the first hour after administration and later elevate activity in mice. After prolonged FI conditioning some of the mice changed to a pattern of lowered responding prior to reinforcement ("low temporal control") whereas others maintained the typical high increase of responding prior to reinforcement ("high temporal control"). Additionally, low oral doses of pramipexole increase operant behavior in "low temporal control" mice prior to reinforcement leaving the pattern of operant responding of "high temporal control" mice unchanged. CONCLUSIONS: Based on other preclinical data and initial clinical results, we speculate that these effects may reflect anti-anhedonic/antidepressive properties of pramipexole.

Animals↗
PubMed2000

Pramipexole attenuates the dopaminergic cell loss induced by intraventricular 6-hydroxydopamine.

The D3 preferring dopamine agonist pramipexole has been shown to attenuate the cell loss induced by levodopa in vitro. Pramipexole was herein evaluated in the 6-hydroxydopamine lesion model to determine its in vivo effect. Rats were treated with pramipexole or saline before and after an intracerebroventricular 6-hydroxydopamine injection. In the preliminary study, 6-hydroxydopamine produced a 68% reduction in striatal dopamine and a 62% loss in tyrosine hydroxylase immunoreactive (THir) cell counts in the substantia nigra. Pramipexole treated animals exhibited a 29% and a 27% reduction in striatal dopamine and THir cell counts, respectively. THir cell counts and striatal dopamine were significantly correlated. In the stereological study, 6-hydroxydopamine reduced THir cell counts by 47% in saline treated animals and 26% in pramipexole treated animals. These data demonstrate that pramipexole attenuates the biochemical and THir cell changes normally produced by 6-hydroxydopamine consistent with its neuroprotective actions in vitro.

Animals↗