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At least 865 records · Page 48Linked to original sources
PubMed1997

Apical and basal uptake of L-dopa and L-5-HTP and their corresponding amines, dopamine and 5-HT, in OK cells.

The present study defined the kinetic characteristics of L-3,4-dihydroxyphenylalanine (L-dopa) and L-5-hydroxytryptophan (L-5-HTP) transport and their decarboxylation products, dopamine and 5-hydroxytryptamine (5-HT), respectively, in OK cells. The apical uptake of both L-dopa and 5-HTP was temperature dependent and stereoselective. Nonlinear analysis of the saturation curves revealed for L-dopa and L-5-HTP Michaelis constants of 13.8 and 29.1 microM, respectively, and maximal velocities of 21 and 29 nmol.mg protein-1.6 min-1, respectively, L-5-HTP inhibited the apical uptake of L-dopa with a half-maximal inhibitory constant of 29.1 microM. The accumulation of L-dopa and L-5-HTP from the basolateral cell border was dependent on the concentration used and saturable at nearly 50 microM. The accumulation of dopamine and 5-HT was found to be saturable only when the substrates were applied from the basolateral cell border. These results demonstrate that the L-dopa and L-5-HTP transporters in OK cells are located in both the apical and basolateral cell borders, whereas the uptake of dopamine and 5-HT is a saturable process only when the substrates are applied from the basolateral cell border.

5-Hydroxytryptophan↗
PubMed2003

Quercetin potentiates L-Dopa reversal of drug-induced catalepsy in rats: possible COMT/MAO inhibition.

L-Dopa plus carbidopa treatment remains the first-line therapy in Parkinson's disease. The use of catechol-O-methyltransferase (COMT) and/or monoamine oxidase (MAO) inhibitors as an adjunct to L-dopa therapy has yielded varying degrees of success. Quercetin, a flavonoid present in many plants, is reported to inhibit COMT and MAO activities, the key enzymes involved in the metabolism of dopamine. In the present study we have studied the effect of quercetin on the L-dopa plus carbidopa combination against perphenazine and reserpine-induced catalepsy in rats. Neuroleptic-induced catalepsy is a widely accepted animal model for testing the drugs used in parkinsonism. Catalepsy in rats was induced by administration of perphenazine (5 mg/kg i.p.) or reserpine (2.5 mg/kg i.p.) + alpha-methyl-P-tyrosine (200 mg/kg i.p.). Catalepsy in animals was assessed by using the bar test. The quercetin dose (25-100 mg/kg, p.o.) dependently reversed perphenazine- as well as reserpine-induced catalepsy. When quercetin was combined with a subthreshold dose of L-dopa plus carbidopa, the anticatatonic effect was potentiated. Pretreatment with a central COMT inhibitor, 3,5-dinitrocatechol (OR-486) (10 mg/kg p.o.), or a MAO-B inhibitor, selegiline (5 mg/kg i.p.), also potentiated the actions of threshold dose of quercetin against perphenazine- or reserpine-induced catalepsy. On the other hand adenosine (100 mg/kg i.p.), which is known to decrease the release of catecholamines through an action on presynaptic A(1) receptors, partly reversed the protective effect of quercetin against perphenazine-induced catalepsy. Quercetin through its COMT and MAO enzyme-inhibiting properties might potentiate the anticatatonic effect of L-dopa plus carbidopa treatment. The results of the present study strongly suggest that quercetin could serve as an effective adjunct to L-dopa therapy in Parkinson's disease.

Animals↗
PubMed2005

Increased dopamine content in lymphocytes from high-dose L-Dopa-treated Parkinson's disease patients.

OBJECTIVES: The intracellular (i.c.) content of dopamine and its metabolites was measured in the peripheral blood lymphocytes (PBLs) of Parkinson's disease (PD) patients and healthy controls. METHODS: Catecholamine levels of PBLs were measured using capillary electrophoresis in healthy controls and PD patients receiving different doses of L-dihydroxyphenylalanine (L-Dopa). RESULTS: Higher i.c. dopamine content was found in lymphocytes from PD patients receiving a high dose of L-Dopa (700 +/- 30 mg/day) as compared to lymphocytes from the healthy controls (p = 0.002) and from PD patients treated with a low dose of L-Dopa (400 +/- 30 mg/day) (p = 0.022). The dihydroxyphenylacetic acid to dopamine ratio was significantly lower in the high-dose L-Dopa-treated PD patients than in the controls (p = 0.013). CONCLUSIONS: These findings suggest that the dopamine content and metabolism in the peripheral lymphocytes of PD patients are influenced by L-Dopa administration. This is the first study in which a dose-related effect of L-Dopa treatment was found in lymphocytes from PD patients.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1975

Treatment of parkinsonism with l-dopa and a decarboxylase inhibitor. An electrophysiological and clinical study.

Twelve parkinsonian patients with an unsatisfactory therapeutic result on L-Dopa alone due to nausea, vomiting and involuntary movements were treated WITH L-Dopa and decarboxylase inhibitor. The daily dose reached 800mg L-Dopa and 200 mg decarboxylase inhibitor. Single doses of each of the components were also given. Electrophysiological examination of hypokinesia, tremor and rigidity, and clinical observation revealed clear evidence of rapid improvement on small doses of L-Dopa combined with decarboxylase inhibitor. Most of the improvement occurred during the 1st week before the maximal dose was reached. A single oral dose of decarboxylase inhibitor resulted in an improvement, suggesting the presence in the organism of a small AMOUNT OF L-Dopa. This work also shows the absence of liver toxicity of the drug used. Elimination of the extracerebral side effects nausea and vomiting in our opinion is a principle advantage of the compound compared to L-Dopa alone, wheras abnormal involuntary movements, which were found in all patients, remain the limiting adverse side effect.

Aged↗
PubMed1975

L-Dopa effects on serum LH and prolactin in old and young female rats.

Serum LH and prolactin changes in response to an acute systemic L-dopa injection were measured in young (4-6 months) proestrous, estrous and 2nd day diestrous rats, and in aged (23-30 months) constant estrous and pseudopregnant (long diestrous) Long-Evans rats. Serum LH and prolactin were measured by radioimmunoassays in serial blood samples taken before and 15, 60 and 120 min after i.p. injections of 0, 3 or 30 mg of L-dopa. Pretreatment serum prolactin levels were elevated in afternoon samples from young proestrous and estrous rats and in both aged groups. Both the 3- and 30-mg injections caused a reduction in serum prolactin in all groups. The reduction in serum prolactin following 3 mg of L-dopa was less in both the aged groups than in the young rats. The pretreatment serum LH concentration was markedly elevated only on the afternoon of proestrus. The pretreatment serum LH level of the aged constant estrous group was greater than that of either the young estrous or diestrous group. Pretreatment serum LH levels were lower in aged pseudopregnant rats than in young diestrous rats. After the 30-mg L-dopa injection serum LH increased in all groups except the aged pseudopregnant group. Although the increase in LH following L-dopa injection was similar in young estrous and aged constant estrous rats, the increase in serum LH occurred later and lasted longer in the latter group. These data indicate that the hypothalamic-anterior pituitary endocrine control mechanisms are less responsive to acute L-dopa treatment in the aging female rat.

Age Factors↗
PubMed1982

L-dopa restores amplitude of growth hormone pulses in old male rats to that observed in young male rats.

35 male Sprague-Dawley rats, 18 months old, were injected subcutaneously with the catecholamine precursor, L-dihydroxyphenylalanine (L-dopa) (100 mg/kg, twice daily), or vehicle alone, for 8 days in an attempt to increase the amplitude of growth hormone (GH) pulses in old male rats. 40% of young rats had at least one GH pulse greater than 600 ng/ml, over a 6.5 h sampling period, whereas only 22% of old vehicle-treated rats had pulses of similar amplitude. Treatment of old rats with L-dopa increased the number of animals showing elevated GH pulses to 53%. Young animals had mean GH concentrations of 136.5 +/- 14.0 ng/ml over the 6.5 h sampling period, whereas vehicle-treated old animals had mean GH levels of 95.2 +/- 7.7 ng/ml (p less than 0.05). Treatment of old animals with L-dopa increased mean plasma GH concentrations to 132.9 +/- 11.2 ng/ml (p less than 0.05) which was not significantly different from GH values in young rats. Pituitary GH concentration was less in old than in young rats (301 +/- 27.4 vs. 370 +/- 17.4 micrograms/mg protein, p less than 0.05). L-Dopa increased pituitary GH concentrations in old rats to 318 +/- 32.2 micrograms/mg protein, which was not significantly different from that in either young or old vehicle-treated animals. Hypothalamic somatostatin content in both rostral and caudal areas was lower in old than in young rats (p less than 0.01), and L-dopa had no significant effect on somatostatin content. These data indicate that L-dopa can increase the amplitude of GH pulses and elevate mean plasma GH in old male rats to levels present in young male rats, probably by increasing hypothalamic catecholamines.

Age Factors↗
PubMed1992

Dopa accumulates in the hypothalamic-hypophysial portal vessels and is taken into the anterior pituitary of NSD-1015-treated rodents.

DOPA was measured in the anterior pituitary and hypothalamic-hypophysial portal blood after treatment with NSD-1015, a DOPA decarboxylase inhibitor. NSD-1015 caused DOPA to accumulate in the anterior pituitary of mice and rats, and increased DOPA in the hypothalamic-hypophysial portal blood of rat. Serum prolactin was also increased. Interruption of the anterior pituitary blood supply from the hypothalamic-hypophysial system by cannulation of the entire pituitary stalk eliminated the NSD-1015-induced DOPA accumulation in the rat pituitary. We conclude that DOPA can be taken into the anterior pituitary from the portal blood of NSD-1015-treated rodents and that the anterior pituitary lacks tyrosine hydroxylase activity in both mice and rats.

Animals↗
PubMed1978

On the mechanism of hyperglycemia and stimulation of growth hormone secretion by L-dopa.

The mechanism of hyperglycemia produced by L-dopa was studied in normal trained dogs with 3-3H-glucose infusion to measure rates of hepatic glucose output (production) and overall glucose uptake (utilization). Infusion of L-dopa (20 mg/kg/h) increased glucose production causing hyperglycemia. Despite the hyperglycemia plasma insulin did not increase nor did glucose uptake, indicating a relative inhibition of glucose utilization. These effects resemble those produced by epinephrine infusion. Pretreatment with a decarboxylase inhibitor, carbidopa, prevented the L-dopa effect to increase glucose production and no hyperglycemia occurred. Hyperglycemia was not prevented by pimozide, a dopamine receptor blocker, nor by propranolol but was prevented by phentolamine. L-Dopa also increased plasma growth hormone levels without affecting plasma cortisol. The effect on growth hormone was prevented by carbidopa and by phentolamine but not by pimozide; propranolol potentiated the rise in growth hormone. The data suggest that the L-dopa-induced hyperglycemia is due to a peripheral action, whereas stimulation of growth hormone secretion may be due to a central action of a L-dopa metabolite.

Animals↗
PubMed1994

Different effects of harmine on plasma concentrations of L-dopa and on cerebral dopamine metabolism in rabbits and rats.

The effects of short-term intravenous administration of harmine, a monoamine oxidase inhibitor, on the plasma concentrations of L-Dopa and on dopamine levels in the brain striata of rats and rabbits after L-Dopa administration were studied. Harmine affects the L-Dopa plasma concentrations in rabbits but not in rats: in fact in the former species the area under the concentration-time curve observed after administration of L-Dopa alone increased significantly when animals were pretreated with harmine. Dopamine striatal levels increased in concert with plasma L-Dopa concentrations after administration of L-Dopa in rats and rabbits. However pretreatment with harmine resulted in a significant increase of dopamine levels in the brain striata of rabbits only. These results suggest that harmine or one of its metabolites affect the brain dopamine system not merely as a type A monoamine oxidase inhibitor but with a modulatory effect, without a precise indication of site or mode of action of harmine.

Animals↗
PubMed1986

Role of dopamine in the inhibition of vasopressin secretion by L-dopa in carbidopa-treated dogs.

Elevation of brain catecholamine levels by systemic administration of L-dopa in dogs pretreated with the dopa decarboxylase inhibitor carbidopa inhibits the secretion of vasopressin and adrenocorticotropic hormone (ACTH) and decreases arterial blood pressure. The aim of the present study was to determine whether the inhibition of vasopressin secretion is mediated by dopamine or norepinephrine, both of which have been implicated in the control of vasopressin secretion, and whether the decrease in vasopressin secretion contributes to the suppression of ACTH secretion and fall in blood pressure produced by L-dopa. This was accomplished by comparing the effects of dopamine and alpha-adrenergic receptor antagonists on vasopressin, ACTH, and blood pressure responses to L-dopa. The effect of a specific antagonist of the vasoconstrictor action of vasopressin also was studied. Injection of L-dopa (20 mg/kg i.v.) in dogs pretreated with carbidopa (20 mg/kg i.v.) caused reductions in plasma vasopressin concentration (from 16.0 +/- 4.8 to 3.8 +/- 0.9 pg/ml; p less than 0.05), plasma ACTH concentration (from 96.0 +/- 20.4 to 49.2 +/- 10.0 pg/ml; p less than 0.05), and mean arterial pressure (from 121 +/- 6 to 78 +/- 5 mm Hg; p less than 0.05). Pretreatment with pimozide (1 mg/kg i.p.) completely blocked the inhibition of vasopressin secretion by L-dopa but failed to block the suppression of ACTH secretion (57.6 +/- 11.8 to 34.0 +/- 5.1 pg/ml; p less than 0.05) or the decrease in mean arterial pressure (126 +/- 5 to 93 +/- 7 mm Hg; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1977

L-Dopa inhibits prolactin secretion in proestrous rats.

Female rats received an ip injection of L-dopa on the afternoon of proestrus. L-Dopa reduced serum prolactin concentrations within 1 h, whether administered just prior to, or during, the normal surge in serum hormone level. This inhibition lasted for 2-3 h, after which serum prolactin concentrations rose substantially. Pretreatment of proestrous rats with MK-486, a peripheral inhibitor of aromatic-L-amino acid decarboxylase, did not block the effect of L-dopa on serum prolactin levels. In fact, MK-486 pretreatment appeared to prolong the effectiveness of L-dopa. Pretreatment with RO4-4602 at a dose sufficient to block central decarboxylase activity, however, did prevent dopa from inhibiting the proestrous surge in serum prolactin. These data are consistent with a role for dopamine in the control of prolactin secretion and suggest that the mechanism of action of L-dopa apparently does not require peripheral decarboxylation.

Animals↗
PubMed1986

Dopamine and L-dopa: inhibition of thyrotropin-stimulated thyroidal thyroxine release.

Previous studies had suggested that norepinephrine (NE) and its precursors dopamine (DA) and L-DOPA acted similarly on iodine metabolism of isolated thyroid cells. Present studies indicate that this similarity extends to the inhibition by catecholamines of TSH-stimulated T4 release by mouse thyroids incubated in vitro. DA (5 X 10(-4) M), like NE, shown previously, inhibits TSH-stimulated T4 release. This inhibition was reversed by the alpha-blockers phentolamine, prazosin, and yohimbine, but not by the beta-blocker L-propranolol. DU-18288 and diethyldithiocarbamate, inhibitors of DA beta-hydroxylase, did not reduce DA inhibition, suggesting that prior conversion to NE was not a condition for DA activity. Apomorphine, a dopaminergic agonist but not a NE precursor, acted like DA, and its inhibition was also reversed by alpha-blockers. Furthermore, sulpiride, a dopaminergic blocker, reversed DA and apomorphine inhibition of TSH stimulation. These results suggest that DA inhibits TSH-stimulated T4 release through both adrenergic and dopaminergic receptors. On the other hand, L-DOPA, exerting an inhibition like that of DA, was also reversed by alpha-blockers, but its activity was greatly diminished by carbidopa, an inhibitor of aromatic L-amino acid decarboxylase, the enzyme converting L-DOPA to DA. This indicated that L-DOPA had to be converted to DA for activity. Both DA and L-DOPA inhibited stimulation of T4 release induced by (Bu)2cAMP, suggesting that their effect was exerted at a locus distal to cAMP generation. Indirect confirmation of a cAMP-independent pathway was obtained when DA inhibited TSH-stimulated cAMP formation, but, contrary to T4 release, this inhibition was not reversed by dopaminergic or adrenergic blockers. Presumably, therefore, DA inhibition of TSH-stimulated cAMP production was not related to T4 release. We conclude that 1) DA inhibits TSH-stimulated T4 release in mouse thyroids via alpha-adrenergic and dopaminergic receptors; 2) L-DOPA has to be converted to DA to produce inhibition; and 3) cAMP is unlikely to be an intermediary in DA inhibition.

Adrenergic alpha-Antagonists↗
PubMed1976

Potentiation of the ACTH response to metyrapone by L-dopa in the monkey.

The intravenous injection of L-Dopa (15 mg/kg) to monkeys (Macaca mulatta) failed to alter plasma concentrations of ACTH and of 11-deoxy-cortisol. When cortisol synthesis was blocked with iv metyrapone, potentiation of ACTH secretion by L-Dopa became apparent. Simultaneous injection of L-Dopa and metyrapone resulted in a marked increase in plasma ACTH from 93 +/- 18 pg/ml to 432 +/- 80 pg/ml, whereas plasma 11-deoxycortisol increased from 1.5 +/- 0.2 mug/100 ml to 14.6 +/- 1.0 mug/100 ml 90 min after treatment. Throughout the experiment the rise in ACTH and in 11-deoxycortisol following coadministration of L-Dopa and metyrapone was significantly (P less than 0.01) higher than that produced by metyrapone administration alone. The results suggest that acute administration of L-Dopa in monkeys enhances the response of ACTH to metyrapone. L-Dopa (or one of its metabolites) probably acts upon a noradrenergic or a dopaminergic system located in the hypothalamus to alter the release of hypothalamic corticotropin regulatory factor(s) and thereby enhance the release of ACTH.

Adrenocorticotropic Hormone↗
PubMed1992

Effects of long-term infusions of dopa and carbidopa on renin and steroid secretion in the rat.

Plasma, kidney, and adrenal catecholamine concentrations were varied by infusing rats with L-dopa and/or carbidopa for 2 weeks. L-Dopa infusion (300 micrograms/day) increased dopamine concentrations in plasma, adrenal zona glomerulosa, and kidney by 140%, 74%, and 224%, respectively: the dopamine content of the adrenal inner cortex plus medulla was not increased. Infusion of carbidopa alone had no detectable effect upon endogenous dopamine concentrations. Concomitant infusion (300 micrograms/day) of carbidopa with L-dopa blocked the rise in plasma and adrenocortical dopamine caused by L-dopa alone. Plasma aldosterone and plasma and kidney active renin concentrations were unaffected by L-dopa administration but plasma corticosterone and deoxycorticosterone (DOC) were significantly elevated (P < 0.05); increases in DOC appeared greater than those of corticosterone. These data cast doubt on the theory that dopamine is a physiological tonic inhibitor of aldosterone synthesis in rats. However, in the rat, stimulatory effects of L-dopa on plasma concentrations of precursors of aldosterone might be of physiological significance since DOC is a potent mineralocorticoid.

Adrenal Cortex↗
PubMed1980

Effects of L-dopa and bromocriptine on calcitonin secretion in medullary thyroid carcinoma.

The secretion of calcitonin (CT) by thyroid C cells has been reported to be reduced by dopamine in vitro and by L-dopa in patients with medullary thyroid carcinoma (MTC). These results have suggested that dopa uptake ad decarboxylation to dopamine may play an inhibitory role in the control of CT secretion. We studied the effects of either L-dopa or bromocriptine, a dopamine agonist, on CT secretion in 11 patients with MTC. Seven patients had multiple endocrine adenomatosis type II (MEA II), 1 had MEA III, and 3 had sporadic MTC. Metastatic disease was confirmed in 8, was probable in 2, and was absent in 1. L-Dopa (500 mg orally) was given to 10 patients in 12 trials. Serum obtained serially for CT measurement RIA over a 4-h period showed a fall in 4 instances in 3 patients; there was no decrease in 7 patients. Absorption of L-dopa was confirmed by the finding of the expected rise in serum GH concentration in all nonresponders except 1. Bromocriptine administered in increasing doses (7.5-50 mg/day) for periods from 4-18 weeks in 5 patients with metastatic disease failed to lower the serum CT concentration in any patient. In 2 of 4 cases, pentagastrin-induced CT release was augmented during bromocriptine administration. These results show L-dopa suppression of CT secretion only in a minority of patients with MTC; the lack of response to bromocriptine suggessts that dopamine receptor stimulation by dopaminergic ergots does not inhibit CT secretion in this same group of patients.

Adolescent↗
PubMed1994

[11C]raclopride and positron emission tomography in previously untreated patients with Parkinson's disease: Influence of L-dopa and lisuride therapy on striatal dopamine D2-receptors.

We studied cerebral dopamine D2-receptor binding using [11C]raclopride and PET in 18 previously untreated patients with Parkinson's disease (PD) and 14 healthy volunteer subjects. Sixteen patients were scanned before and after 3 to 4 months of stable oral therapy with either L-dopa (300 mg/d) (n = 7) or lisuride (0.8 to 1.2 mg/d) (n = 9). Two additional patients were investigated before and after a continuous IV infusion of L-dopa. In addition, we studied the effect of acute IV L-dopa and lisuride administration on [11C]raclopride binding in a healthy rhesus monkey. At baseline, PD patients showed higher uptake values in the putamen than did healthy subjects (p < 0.0001). Oral lisuride treatment lowered [11C]raclopride uptake in the putamen (-19%) and in the caudate nucleus (-15%) compared with baseline, but the difference did not reach significance upon Bonferroni correction for multiple comparisons. However, putamen tracer uptake returned to baseline in two patients when we repeated [11C]raclopride scans 4 days after lisuride withdrawal. Oral L-dopa treatment did not induce changes in the putamen or caudate nucleus indices. Acute lisuride (25 micrograms) administration in a healthy monkey reduced striatal uptake values, but acute injection of L-dopa (300 mg) did not. The results suggest that lisuride blocks [11C]raclopride binding at dopamine D2-receptor sites and demonstrate that 3 to 4 months' oral therapy with L-dopa or lisuride does not change striatal dopamine D2-receptor density in PD patients.

Adult↗
PubMed1999

D1 receptor blockade improves L-dopa-induced dyskinesia but worsens parkinsonism in MPTP monkeys.

OBJECTIVE: To determine whether dopamine (DA) D1 or DA D2 receptors are associated predominantly with the antiparkinsonian versus the dyskinetic effect of levodopa. METHODS: The authors used four L-dopa-primed, dyskinetic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-exposed monkeys to test whether acute and selective blockade of the DA D1 receptor subtype, using SCH 23390 and NNC 01-112, could reduce L-dopa-induced dyskinesias without altering the relief of symptoms. Blockade of DA receptors using sulpiride (D2) and clozapine (D1-D2-like) was studied for comparison. RESULTS: With the notable exception of the lowest dose of clozapine tested, coadministration of DA D1 or D2 antidopaminergic agents with L-dopa reduced the L-dopa-induced dyskinesias but also caused a return of parkinsonian disability. Prolonged latencies from intake of a single oral dose of L-dopa to turning "on," decreased duration of the "on" state, and a complete failure to induce benefit was also observed. CONCLUSION: Low-dose clozapine could be an effective adjunct to reduce L-dopa-induced dyskinesias without altering the relief of parkinsonian symptoms. Interactions with many neurotransmitter systems may explain the better pharmacologic profile of clozapine, including DA D4 (rather than D1), serotonin, acetylcholine, and noradrenaline. Neither dyskinesias nor antiparkinsonian effects can be ascribed solely to the D2 or D1 receptor. Thus, some cooperation between the two receptors appears necessary for these behavioral effects.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1999

Striatal dopaminergic function in restless legs syndrome: 18F-dopa and 11C-raclopride PET studies.

OBJECTIVE: To use PET to study striatal dopaminergic function in restless legs syndrome (RLS). BACKGROUND: RLS is a common disorder experienced by as much as 5% of the population. It has been suggested that this condition is associated with a disturbance of dopaminergic transmission. METHODS: The authors measured nigrostriatal terminal dopamine storage with 18F-dopa and striatal D2 receptor binding with 11C-raclopride PET in 13 RLS patients, five of whom were receiving treatment with L-dopa at the time of scanning. RLS results were compared with those of age-matched control subjects. RESULTS: Mean caudate and putamen 18F-dopa uptake were mildly reduced in the RLS patients compared with control subjects, and this reached significance (p = 0.04) in the putamen. Mean D2 binding was reduced in the caudate (p = 0.01) and the putamen (p = 0.008) in RLS patients compared with control subjects. Six of the 13 RLS patients had caudate and putamen D2 binding reduced below the control range. Three other RLS patients showed only reduced putamen D2 binding. There were no significant differences in striatal 18F-dopa uptake or D2 binding between L-dopa-naive and L-dopa-treated RLS patients. CONCLUSIONS: These PET findings support the hypothesis of central dopaminergic dysfunction in RLS.

Aged↗