Alpha-synuclein promoter haplotypes and dementia in Parkinson's disease

Dementia is a common complication of Parkinson's disease (PD). It correlates significantly with the presence of cortical, limbic or nigral Lewy bodies, mainly constituted of alpha-synuclein. Mutations of the alpha-synuclein gene (SNCA) have been linked to rare familial forms of PD, while association studies on the promoter polymorphisms have given conflicting results in sporadic patients. We have performed a case control study to investigate whether genetic variability in the promoter of the alpha-synuclein gene could predispose to dementia in PD. A total of 114 demented patients and 114 non-demented patients with sporadic PD were included in the study. Six polymorphic loci (including the Rep1 microsatellite) in the promoter of the SNCA gene were examined. Each marker, taken individually, did not show association to dementia and no significant differences were observed in the inferred haplotype frequencies of demented and non-demented patients. Our data suggest the lack of involvement of the SNCA promoter in the pathogenesis of dementia in PD. Further studies in other populations are needed to confirm these results.

[Total laparoscopic hysterectomy versus vaginal hysterectomy: a prospective randomized trial]

AIM

The aim of the study was to compare the effects of total laparoscopic hysterectomy with those of vaginal hysterectomy.

METHODS

We conducted a prospective randomised trial on 400 patients who agreed to be randomized to either laparoscopic total hysterectomy or vaginal hysterectomy. They were monitored for one year to evaluate the rate of major complications and the results on quality of life.

RESULTS

Total laparoscopic hysterectomy was associated with a higher rate of major haemorrhages and ureteric injuries than vaginal hysterectomy (7% vs 2.5% and 2.5% vs 0%; P<0.05) only during the first year of study according to a normal learning-curve. It took longer to perform (85.9 min vs 46.6 min), but was less painful (visual analogue scale 5.3 vs 6.0; P<0.01) and there was a shorter stay in hospital after the operation (2.9 vs 3.3 days). Six weeks after the operation, total laparoscopic hysterectomy was associated with less pain and better quality of life than vaginal hysterectomy (SF-12).

CONCLUSION

Total laparoscopic hysterectomy was associated with a significantly higher rate of major haemorrhages and ureteric injuries than vaginal hysterectomy only during the first year of study according to a normal learning-curve. It took longer to perform but was associated with less pain, quicker recovery, and better short term quality of life.

[Laparoscopic lymphadenectomy as treatment of endometrial cancer]

AIM

This study compares the effects of laparoscopic lymphadenectomy versus those of abdominal lymphadenectomy in patients with endometrial cancer.

METHODS

A prospective randomized study was performed among 80 patients randomly assigned to laparoscopic lymphadenectomy and to abdominal lymphadenectomy in the treatment of endometrial cancer. Clinical outcomes and complications were compared for 1 year of follow-up.

RESULTS

Forty patients were assigned to laparoscopic lymphadenectomy and 40 patients to abdominal lymphadenectomy. The laparoscopic approach was associated with a longer operative time (234.1 min vs 137.3 min) but was less painful (VAS 5.3 vs 7.9; P<0.000) and resulted in a shorter hospital stay (4.4+/-1 vs 7.9+/-1.2 days; P<0.000). At 6 weeks the quality of life was better in patients who had laparoscopic lymphadenectomy (SF-12).

CONCLUSION

Laparoscopic lymphadenectomy was associated with a significantly lower rate of major and minor postoperative complications and a better short term quality of life.

[Laparoscopic supracervical hysterectomy versus laparoscopic total hysterectomy: a prospective randomized study]

AIM

The aim of this study was to compare surgical complications and clinical outcomes after supracervical versus total laparoscopic hysterectomy for the control of abnormal uterine bleeding or symptomatic uterine leiomyomata.

METHODS

We conducted a prospective randomized trial on 141 patients who had laparoscopic hysterectomy for symptomatic uterine leiomyomata, abnormal bleeding refractory to hormonal treatment, or both. Patients were randomly assigned to receive a supracervical or total laparoscopic hysterectomy. We compared surgical complications and clinical outcomes for 2 years after randomization.

RESULTS

Seventy-one participants were assigned to supracervical laparoscopic hysterectomy (SLH) and 70 to total laparoscopic hysterectomy (TLH). Hysterectomy by either techniques led to statistically significant reductions in most symptoms, including pelvic pain or pressure, back pain and urinary incontinence. Patients assigned to SLH tended to have more hospital readmissions than those randomized to TLH. There were no statistically significant differences in the rate of complications, degree of symptoms improvement, or activity limitation. Participants weighing more than 100 kg at study entry were more than twice as likely to be readmitted to the hospital during the 2-year of follow-up (OR 2.48, 95% CI 0.11; 1.91, P=0.04).

CONCLUSIONS

We did not observe statistically significant differences between SLH and TLH in surgical complications and clinical outcomes during the 2-years of follow-up.

Olive mill wastewater biological treatment by fungi biomass

Olive oil extraction is one of the most important traditional food industries in the Mediterranean region, especially in Italy. In addition to olive oil, this industry produces by-products, in particular olive mill wastewaters (OMWs) and olive husks, which represent a serious environmental problem. OMWs can be rarely treated in a municipal WWTP, using conventional wastewater treatments. A novel biological process has to be considered in order to treat OMWs. Literature data show that yeasts and different kinds of fungi are able to reduce both the organic and the phenolic content of the OMW. The present work is aimed at investigating the growth of a biomass rich in fungi in a batch reactor filled with OMW and its capacity to degrade the organic and phenolic load. The aerobic OMW degradation obtained using this biomass reached a COD and TP removal efficiency of 86 and 70%, respectively. Respirometric tests have been carried out in order to measure the biomass activity on different substrates: OMW and phenolic compounds (gallic and p-coumaric acids). The polyphenolic biodegradation efficiency of fungi biomass was higher than the one of a non-acclimated activated sludge biomass. Fungi biomass was able to completely degrade pure phenolic compounds.

Behaviour and chemical signature of pre-hibernating females of Polistes dominulus infected by the strepsipteran Xenos vesparum

Polistes dominulus are social wasps which are the host of the strepsipteran endoparasite Xenos vesparum. In the hibernating phase, unparasitized and parasitized wasps leave natal nests and aggregate together in sheltered quarters. In aggregations, wasps are socially active, and some individuals perform helping behaviour. Here we investigated if castrated parasitized wasps perform worker tasks in mixed aggregations. Moreover, by gas chromatography and mass spectrometry, we examined the cuticular hydrocarbons of unparasitized and parasitized wasps to evaluate if the infection alters the composition of cuticular waxes that are recognition cues in social insects. In clusters, infected females do not perform helping behaviour and they are less active than unparasitized wasps. Cuticular hydrocarbons are slightly differentiated between unparasitized and parasitized wasps but, generally, unparasitized wasps are more similar to wasps infected by Xenos females compared to wasps infected by Xenos males. Wasps infected by Xenos males do not usually survive the winter. This chemical similarity is probably a consequence of the similar physiological condition of unparasitized and female-affected Polistes wasps. At this stage, it is difficult to affirm whether these modifications are a true parasite manipulation or a consequence of infection.

Subchronic-intermittent caffeine amplifies the motor effects of amphetamine in rats

Caffeine, the most widely consumed psychostimulant drug, acutely stimulates motor behaviour and enhances dopamine agonists actions whilst chronically it induces tolerance to either caffeine- or dopamine agonist-induced motor activating effects. The present study examined whether subchronic caffeine administration (15 mg/kg, on alternate days for 14 days) induces enduring modifications in caffeine- and amphetamine-mediated motor activity. To this end, motor activation and rotational behaviour stimulated by either caffeine or D-amphetamine (0.5, 2 mg/kg), given 3 days after the last caffeine administration, were evaluated in neurologically intact and unilaterally 6-hydroxydopamine-lesioned rats respectively. Subchronic caffeine resulted in an increase in caffeine-induced motor and turning behaviour. Furthermore, caffeine pretreatment potentiated the motor effects of amphetamine in both intact and 6-hydroxydopamine-lesioned rats. These results suggest that subchronic caffeine treatment results in an enhancement of its motor stimulant effects, rather than in tolerance, and induces neuroadaptive facilitatory changes in dopamine transmission.

Olive mill wastewater treatment: an experimental study

Olive oil production, one of the main agro-industries in Mediterranean countries, generates significant amounts of olive mill wastewaters (OMWs), which represent a serious environmental problem, because of their high organic load, the acidic pH and the presence of recalcitrant and toxic substances such as phenolic and lipidic compounds (up to several grams per litre). In Italy, traditional disposal on the soil is the most common way to discharge OMWs. This work is aimed at investigating the efficiency and feasibility of AOPs and biological processes for OMW treatment. Trials have been carried out on wastewaters taken from one of the largest three-phase mills of Italy, located in Quarrata (Tuscany), as well as on synthetic solutions. Ozone and Fenton's reagents applied both on OMWs and on phenolic synthetic solutions guaranteed polyphenol removal efficiency up to 95%. Aerobic biological treatment was performed in a batch reactor filled with raw OMWs (pH = 4.5, T = 30 degrees C) without biomass inoculum. A biomass rich of fungi, developed after about 30 days, was able to biodegrade phenolic compounds reaching a removal efficiency of 70%. Pretreatment of OMWs by means of oxidation increased their biological treatability.

Vitamin A deficiency induces motor impairments and striatal cholinergic dysfunction in rats

Vitamin A and its derivatives, retinoids, are involved in the regulation of gene expression by binding two nuclear receptor families, retinoic acid receptors and retinoid X receptors. Retinoid receptors are highly expressed in the striatum, revealing an involvement of this system in the control of movement as demonstrated by previous observations in knockout mice. To further assess the role of retinoids in adult striatal function, the present study investigated the effect of vitamin A deprivation on rat motor activity and coordination, the rate of synthesis and release of dopamine, the functioning of D1 and D2 receptors and their expression in the striatum. Moreover, the content of acetylcholine in the striatum was measured. Results show that 24 weeks of postnatal vitamin A deprivation induced severe locomotor deficits and impaired motor coordination. Vitamin A deprivation rats showed a significant hyperactivity following D1 receptor stimulation by R(+)-6-chloro-7,8-dihydroxy-1-phenyil-2,3,4,5-tetrahydro-1H-3-benzazepine or amphetamine and reduced catalepsy in response to haloperidol treatment. This different response to the above drugs is not due to a change in striatal DA release or synthesis between vitamin A deprivation and control animals. In situ hybridization experiments showed identical level of expression for the D1 and D2 receptor transcripts. On the other hand, the striatal tissue content of acetylcholine was reduced significantly by about 30% starting from the initial manifestation of motor deficits. We suggest that the locomotor impairment could be imputable to the dysfunction in striatal cholinergic interneurons. Our results stress the basic role of vitamin A in the maintenance of basal ganglia motor function in the adult rat brain.

Caffeine and the dopaminergic system

Caffeine is the most widely consumed psychostimulant substance, being self-administered throughout a wide range of conditions and present in numerous dietary products. Due to its widespread use and low abuse potential, caffeine is considered an atypical drug of abuse. The main mechanism of action of caffeine occurs via the blockade of adenosine A1 and A2A receptors. Adenosine is a modulator of CNS neurotransmission and its modulation of dopamine transmission through A2A receptors has been implicated in the effects of caffeine. This review provides an updated summary of the results reported in the literature concerning the behavioural pharmacology of caffeine and the neurochemical mechanisms underlying the psychostimulant effects elicited by caffeine. The review focuses on the effects of caffeine mediated by adenosine A2A receptors and on the influence that pre-exposure to caffeine may exert on the effects of classical drugs of abuse.

Different responsiveness of striatonigral and striatopallidal neurons to L-DOPA after a subchronic intermittent L-DOPA treatment

Early gene induction by L-DOPA in the striatum of dopamine denervated rats represents a useful way to study long-term modifications produced by this drug. The effects of acute and subchronic L-DOPA administration on zif-268 mRNA expression were compared in 6-hydroxydopamine-lesioned rats. Rats received a subchronic intermittent L-DOPA (6 mg/kg) treatment, which produces behavioural sensitization, a correlate of dyskinetic movements. Three days after interruption of subchronic treatment, zif-268 mRNA was evaluated after an L-DOPA challenge. Zif-268 mRNA levels increased in the lesioned dorsolateral striatum after either acute or subchronic L-DOPA administration. Double labelling of striatal cells with zif-268 and enkephalin or dynorphin mRNA probes was performed to assess neuronal activation in the indirect and direct output pathway. Single acute L-DOPA significantly increased zif-268 in all striatal neurons reflecting a hyperresponsiveness of dopamine-depleted striatum. After subchronic L-DOPA, zif-268 mRNA labelling was still increased in the striatonigral pathway, limited to dynorphin(+) neurons, whereas in all other neurons it was similar to the control value. Results suggest that striatal neurons responding to acute L-DOPA differ from those responding to subchronic L-DOPA. L-DOPA-induced behavioural sensitization was associated to a down-regulation in the responsiveness of striatopallidal and striatonigral dynorphin(-) neurons, whereas in striatonigral neurons containing dynorphin a hyperresponsiveness to L-DOPA was observed. High levels of zif-268, together with a persistent hyperresponsiveness of striatonigral dymorphinergic neurons and hyporesponsiveness of striatopallidal neurons, by creating an unbalanced state of striatal efferent neurons, may be implicated in dyskinetic movements observed in Parkinson's disease (PD).

Selective modifications in GAD67 mRNA levels in striatonigral and striatopallidal pathways correlate to dopamine agonist priming in 6-hydroxydopamine-lesioned rats

The present study investigated long-term alterations in striatal gene expression after single exposure of unilaterally 6-hydroxydopamine-lesioned rats to different dopamine agonists (priming). Rats were primed with the D1 agonist SKF38393 (10 mg/kg), the D2/D3 agonist quinpirole (0.2 mg/kg), the dopamine precursor L-DOPA (50 mg/kg) or with vehicle (drug-naive), and GAD67, dynorphin and enkephalin mRNAs were evaluated in the striatum by in situ hybridization, 3 days after priming. To evaluate GAD67 mRNA in striatonigral and striatopallidal neurons, identified as enkephalin (-) and (+) neurons, double-labelling in situ hybridization was used. Drug-naive lesioned rats showed an increase in GAD67 mRNA in enkephalin (-) and (+) neurons, an increase in enkephalin and a decrease in dynorphin mRNAs. Priming with either SKF38393 or quinpirole further increased GAD67 mRNA in enkephalin (-) and (+) neurons, however, while SKF38393 produced a high and unbalanced activation toward enkephalin (-) neurons, after quinpirole the increase was of low intensity and similar in the two pathways. Dynorphin mRNA was increased by SKF38393 but not by quinpirole, whereas enkephalin mRNA was not changed by either priming. L-DOPA produced a high and similar increase in GAD67 mRNA in enkephalin (-) and (+) neurons. Priming differentially affected peptides and GAD67 mRNA in striatopallidal and striatonigral neurons depending on the dopamine agonist used. The degree of enduring overactivity of the striatopallidal and striatonigral pathways may be related to the ability of L-DOPA and D1 or D2/D3 receptor agonists to prime motor behavioural responses and to produce dyskinetic side-effects.

Memory distortion during acute and chronic pain recalling

AIM

The aim of this study was to evaluate the presence of pain memory distorsion using different quantitative pain scales.

METHODS

A retrospective study on 2333 patients treated in a Pain Therapy Centre from 1994 to 2000 was carried out. VAS and NRS scores have been evaluated, as referred by patients, at the beginning and at the end of treatment. Moreover pain relief has been evaluated by means of correlation between initial and final pain.

RESULTS

Patients do not remember initial pain correctly, using both VAS and NRS.

CONCLUSION

Pain memory distorsion is related to pain intensity variation during treatment rather than present pain, and it is inversely related to the initial pain intensity. For this reason, it is not correct to evaluate pain relief at the end of treatment since this procedure can under- or over-estimate the initial pain.

Comparison between two laparoscopic retropubic urethropexy

BACKGROUND

To compare two different transperitoneal laparoscopic urethropexy procedures.

METHODS

In this prospective randomized open trial, 60 women affected by genuine stress incontinence were enrolled and randomized in two groups of surgical technique. Group A was treated with transperitoneal laparoscopic retropubic urethropexy using non absorbable sutures, and group B with prolene meshes fixed with tackers or staplers. The failure rate was defined subjectively and objectively. The subjective evaluation was performed asking the patients if they had urine loss and expressing the symptomatology using a visual analog scale before surgery and after each follow-up visit. The objective evaluation was performed with clinical evaluation and/or with the use of multichannel urodynamic studies.

RESULTS

No significant differences in intra- operative and postoperative complications between the two groups were observed. The subjective failure rate was not significantly different between the two groups at 3, 6, and 12 months from surgery. At 3 and 6 months follow-up, the objective failure rate was not significantly different between the two groups. Moreover, at 12 months from surgical procedure the objective failure rate was significantly lower in group A than in group B.

CONCLUSIONS

Transperitoneal laparoscopic retropubic urethropexy performed using sutures is more effective than the mesh technique.

Adenosine A(2a) receptor antagonists: potential therapeutic and neuroprotective effects in Parkinson's disease

The most effective treatment of Parkinson's disease (PD) is, at present, the dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA), however a number of disadvantages such as a loss of drug efficacy and severe side-effects (psychoses, dyskinesias and on-off phenomena) limit long-term effective utilisation of this drug. Recent experimental studies in which selective antagonists of adenosine A(2A) receptors were used, have shown an improvement in motor disabilities in animal models of PD. The A(2A) antagonist [7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-(4,3-e)-1,2,4-triazolo(1,5-c) pyrimidine] (SCH 58261) potentiated the contralateral turning behavior induced by a threshold dose of L-DOPA or direct dopamine receptor agonists in unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats, an effect accompanied by an increase in Fos-like-immunoreactivity in neurons of the lesioned striatum. Likewise, other A(2A) receptor antagonists such as (3,7-dimethyl-1-propargylxanthine) (DMPX), [E-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine] (KF 17837) and [E-1,3-diethyl-8(3,4-dimethoxystyryl-7-methyl-3,7-dihydro-1H-purine-2,6-dione] (KW 6002) antagonized catalepsy induced by haloperidol or reserpine in the rat, whereas in non-human primate models of PD, KW 6002 reduced the rigidity and improved the disability score of MPTP-treated marmosets and cynomolgus monkeys. Moreover, in contrast to L-DOPA, selective A(2A) receptor antagonists administered chronically did not produce dyskinesias and did not evoke tolerance in 6-OHDA and MPTP models of PD. An additional therapeutic potential of adenosine A(2A) antagonists emerged from studies showing neuroprotective properties of these compounds in animal models of cerebral ischemia and excitotoxicity, as well as in the MPTP model of PD. Adenosine A(2A) receptor antagonists by reversing motor impairments in animal models of PD and by contrasting cell degeneration are some of the most promising compounds for the treatment of PD.

Laparoscopic Burch colposuspension: a randomized controlled trial comparing two transperitoneal surgical techniques

OBJECTIVE

To compare the effectiveness of two transperitoneal laparoscopic Burch procedures.

METHODS

The sample size required was 30 subjects per group to detect a statistically significant estimated difference of 15% between two surgical procedures with an alpha = 0.05 and a power of 0.7. Sixty women affected by genuine stress incontinence (GSI) were enrolled and randomly assigned to two groups of 30 women each. All women were treated with the transperitoneal laparoscopic Burch procedure using nonabsorbable sutures (group A) or Prolene mesh (Ethicon, Somerville, NJ) fixed with tacks or staples (group B). The failure rate was defined subjectively and objectively. The subjective evaluation was performed by asking the women to rate their urine loss on a visual analog scale. The objective evaluation was a clinical evaluation using multichannel urodynamic studies.

RESULTS

The subjective failure rate was not significantly different between the two groups at 3 months (0% for both groups), 6 months (3.7% versus 3.8% for groups A and B, respectively), and 12 months (7.4% versus 15.4% for groups A and B, respectively) after surgery. At 3 months (3.7% versus 3.8% for groups A and B, respectively) and 6 months (7.4% versus 15.4% for groups A and B, respectively) follow-up, the objective failure rate was not significantly different between the two groups. However, at 12 months after the surgical procedure, the objective failure rate was significantly lower in group A than in group B (11.1% versus 26.9%, respectively; P <.05).

CONCLUSION

Transperitoneal laparoscopic Burch colposuspension performed using sutures was more effective than the mesh technique.

[Prenatal diagnosis of beta-thalassemia. A study based in Calabria]

BACKGROUND

The aim of this study was to underline, given the well-known incidence of beta thalassemia in Calabria, the possibility of establishing a prevention programme based on an increased awareness among the population using information and health education, genetic consultancy to identify high-risk subjects and prenatal diagnosis.

METHODS

Between January 1992 and December 1999, we analysed 181 high-risk couples for beta thalassemia using chorionic villi sampling (CVS) performed with an echoguided transcervical or transabdominal route. A steady rise was observed over the years in the number of couples asking for prenatal diagnosis, thus demonstrating that patients and doctors are increasingly aware of the importance of a correct prenatal diagnosis. The variability of molecular defects found and the number of complications linked to the technique used are underlined.

RESULTS

Prenatal diagnosis revealed 46 fetuses with the disease (24.8%), 97 heterozygotes (53.2%) and 41 healthy fetuses (22%). Only one malformation was observed in the 41 healthy fetuses. The authors also report the incidence of complications linked to CVS. In overall terms, 2.2% of pregnancies ended in spontaneous abortions (4 cases) and 2.75% with preterm births (5 cases). These complications could not be correlated with gestational age at the time of biopsy or the number of attempts made to obtain an appropriate sample.

Should severe monolateral asymptomatic carotid artery stenosis be treated at the time of coronary artery bypass operation?

OBJECTIVE

The optimal treatment of severe monolateral asymptomatic carotid artery stenosis (SMACS) in patients undergoing coronary artery bypass grafting (CABG) is still controversial.

MATERIALS AND METHODS

This study is based on the in-hospital and mid-term (>5 years) clinical results of a cohort of 139 consecutive CABG patients with SMACS operated at our Institution between January 1989 and December 1995. In the first 73 patients (no carotid surgery group), the SMACS was left untouched at the time of coronary surgery, whereas in the remaining 66 (carotid endoarterectomy group), the carotid stenosis was treated either immediately before or concomitantly with the CABG procedure (depending on the severity of the anginal symptoms).

RESULTS

The overall preoperative characteristics of the patients were comparable. The in-hospital results were similar between the two groups with regard to mortality, stroke and major postoperative complications. However, at mid-term follow-up, significantly more patients of the no carotid surgery group suffered cerebral events (transient or permanent) ipsilateral to the SMACS or the lesion had to be operated on.

CONCLUSIONS

The concomitant treatment (either staged or simultaneous) of SMACS at the time of CABG does not influence the in-hospital results, but confers significant neurological protection during the years after the operation.

Immunohistochemical TRF1 expression in human primary intracranial tumors

BACKGROUND

The telomeric-repeat binding factor (TRF1) participates in a physiological homeostatic mechanism controlling telomere shortening by inhibiting telomerase activity: down-regulation of TRF1 expression results in telomere elongation and may be involved in cell immortalization.

PATIENTS AND METHODS

To determine the TRF1 expression by immunohistochemistry (IHC) in human brain tumors, a cohort of 20 consecutive flash-frozen surgical specimens (14 meningiomas and 6 anaplastic astrocytomas (AA)) were collected.

RESULTS

Variable levels of TRF1 expression in 12 out of the 14 (87.5%) meningioma samples were observed. By contrast, no expression of TRF1 in tissue samples from AA (p = 0.008) was detected. Positive TRF1 cells were usually more differentiated (less atypical features) and Ki67 negative (inverse statistical association, chi2 = p < 0.001).

CONCLUSION

We demonstrated, for the first time, that routine IHC techniques are capable of identifying TRF1 expression in intracranial tumors, which is heterogeneously expressed in meningiomas, but absent in AA. Although these preliminary observations need confirmation from larger studies, the TRF1 status in intracranial tumors might become of prognostic value.

Motor stimulant effects of the adenosine A2A receptor antagonist SCH 58261 do not develop tolerance after repeated treatments in 6-hydroxydopamine-lesioned rats

Several evidences indicate that the selective blockade of adenosine A2A receptors counteracts the motor activity impairment in experimental models of Parkinson's disease. In the present study, the effects of the adenosine A2A receptor antagonist, SCH 58261 (5-amino-7-beta-phenylethyl)-2-(8-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine, were assessed following a repeated treatment schedule in the contralateral turning behavior rat model of Parkinson's disease. Unilateral lesions of the nigrostriatal pathway were induced by injecting 6-hydroxydopamine (6-OHDA in medial forebrain bundle. Repeated administration of SCH 58261 was performed either alone (7 and 14 days repeated SCH 58261) or together with L-dopa (19 days repeated SCH 58261 plus L-dopa or L-dopa alone). After a 7- and 14-day repeated administration schedule, SCH 58261 (5 mg/kg) maintained its ability to potentiate the contralateral turning behavior induced by a subthreshold dose of L-dopa (2 mg/kg i.p.), showing no tolerance to its stimulant effects. SCH 58261 (5 mg/kg) plus L-dopa (3 mg/kg) or L-dopa (6 mg/kg) alone induced, at these dosages, the same number of contralateral turnings after the first administration. While chronic intermittent SCH 58261 plus L-dopa did not lead to a modified turning behavior during treatment, L-dopa alone produced a progressive increase in turning behavior intensity and duration. These results provide evidence that SCH 58261 retains its ability to potentiate L-dopa effects in a validated rat model of Parkinson's disease even after repeated treatments. Moreover, these results suggest that adenosine A2A blockade prevents the appearance of motor response alterations in L-dopa-treated rats, supporting the concept that A2A receptor antagonists have a therapeutic potential for the treatment of Parkinson's disease