The effects of 6-hydroxydopamine pretreatment on the accumulation of dopa and dopamine in brain and peripheral organs following l-dopa administration

Lytle, Loy D.; Hurko, Orest; Romero, Juan Antonio Martos; Cottman, K.; Leehey, David J.; Wurtman, Richard J.

doi:10.1007/bf01244728

Cited by 32 publications

(8 citation statements)

References 24 publications

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“…These results support previous data which show that either MPTP (Dluzen et al, 1993) or 6-OHDA- (Zetterstr6m et al, 1986) induced reduction of striatal DA concentrations also failed to alter L-DOPA evoked DA release when examined in vitro or in vivo. In addition, it has been shown that L-DOPA remains capable of increasing DA concentrations under conditions of reduced DA as achieved with 6-OHDA lesions (Lytle et al, 1972;Spencer and Women, 1984;Synder and Zigmond, 1990). Collating this information leads to the suggestion that most, if not all, of the DA released in response to L-DOPA represents that generated from the exogenous L-DOPA infusion, with endogenous vesicular DA stores and reduced storage capacity apparently exerting (Fig.…”

Section: Discussionmentioning

confidence: 92%

The effect of reserpine treatment in vivo upon L-dopa and amphetamine evoked dopamine and DOPAC efflux in vitro from the corpus striatum of male rats

Dluzen

Liu

1994

J. Neural Transmission

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In the present experiment we tested the effects of L-DOPA and amphetamine upon dopamine and DOPAC efflux in vitro from superfused corpus striatal tissue fragments of male rats who had been pretreated with reserpine. Male rats were treated with reserpine (5 mg/kg) or its vehicle at 24 hours prior to sacrifice and superfusion of the corpus striatum. Two different modes of L-DOPA (5 microM) and amphetamine (10 microM) stimulation, a brief 10-minute and a continuous 60-minute infusion, were tested for their ability to evoke striatal dopamine and DOPAC efflux. Depletion of monoamine storage capacity as achieved with reserpine significantly reduced the amount of basal dopamine and DOPAC released from superfused striatal tissue fragments of male rats. Although basal release rates were significantly reduced, the amount of dopamine and DOPAC released in response to in vitro L-DOPA infusions (10 or 60 minute infusions) was equivalent between reserpine and vehicle treated animals. In contrast, amphetamine stimulated DA release was significantly reduced in male rats treated with reserpine. For both L-DOPA and amphetamine, significantly greater amounts of dopamine were obtained with the 60- versus 10-minute infusion modes. These results demonstrate that the capacity for L-DOPA, but not amphetamine, to evoke dopamine efflux is unaltered under conditions when monoamine storage ability is diminished.

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Section: Discussionmentioning

confidence: 92%

The effect of reserpine treatment in vivo upon L-dopa and amphetamine evoked dopamine and DOPAC efflux in vitro from the corpus striatum of male rats

Dluzen

Liu

1994

J. Neural Transmission

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“…Another of our studies (12) indicates that the accumulation of brain dopamine after administration of L-dopa is not significantly decreased in rats whose central catecholamine-containing neurons have been largely destroyed by prior intracisternal administration of 6hydroxydopamine; hence dopamine probably is formed from exogenous Ldopa in all brain cells, even glia. It seems likely that, for the extensive polysome disaggregation to occur after the administration of L-dopa, the majority of brain cells, neurons and glia, must participate.…”

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confidence: 58%

“…The dewlap is secondarily reduced or lost in several unrelated species groups (12). Among the species of the monticola group Anolis christophei has a large dewlap and uniform squamation and lacks a bold body pattern, all characters suggesting that it is the most primitive species of the group (13); A. christophei again has the 2n = 36 karyotype.…”

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confidence: 99%

Dopamine: Mediator of Brain Polysome Disaggregation after L-Dopa

Weiss

Munro

Ordóñez

et al. 1972

Science

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The disaggregation of brain polysomes which is produced by giving large doses of (L)-dopa to rats is not reproduced by administering its metabolite, 3-O-methyldopa, by giving D-dopa, which also depletes the brain of S-adenosylmethionine but is not converted to catecholamines, or by giving the L-dopa after a decarboxylase inhibitor. Polysome disaggregation is potentiated by the prior administration of a monoamine oxidase inhibitor, indicating that formation of a catecholamine is an obligatory requirement. These observations suggest that the mechanism by which L-dopa disaggregates brain polysomes involves its conversion to dopamine within the majority of brain cells.

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“…Low molecular weight dextran (MW 33,000--40,000) was added in a final concentration of 4.0 ~ Overnight fixation of whole brains was followed by excision of small samples of cerebral cortex and thalamus that were postfixed in 2.0 ~ osmium tetroxide in cacodylate buffer at pH 7.4. More extensive sampling of brain regions was not undertaken in view of the conclusion (Lytle et al, 1972) that polyribosomal disaggregation observed in brain fractions a~er administration of L-dopa is great enough to indicate involvement of all, or nearly all, brain ceils. Dehydration in graded ethanols was followed by embedding in Epon 812.…”

Section: Methodsmentioning

confidence: 99%

Ultrastructural evidence against in vivo disaggregation of brain polyribosomes after administration of L-dopa or phenylalanine

Hartmann

Becker

1973

J. Neural Transmission

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SummaryL-dopa or phenylalanine was injected intraperitoneally into immature rats. Brain samples fixed and embedded by conventional methods were sectioned for electron microscopic study. In contrast to chemical evidence in the literature for disaggregation of brain polysomes in fractions of whole brain from animals so treated, we found no ultrastructural evidence of disaggregation in either neurons or glial cells. The fact that we and others have observed polysome disaggregation in electron micrographs of sections from other types of animal experiments suggests that our observation of stable polysomes in the present work is not the result of technical artifact, and that the disaggregation observed in brain fractions by others had probably not occurred in their intact animals. It is unlikely that the behavioral and physiological changes occurring in patients treated with L-dopa can be correlated with the state of aggregation of brain polyribosomes.

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The effects of 6-hydroxydopamine pretreatment on the accumulation of dopa and dopamine in brain and peripheral organs following l-dopa administration

Cited by 32 publications

References 24 publications

The effect of reserpine treatment in vivo upon L-dopa and amphetamine evoked dopamine and DOPAC efflux in vitro from the corpus striatum of male rats

The effect of reserpine treatment in vivo upon L-dopa and amphetamine evoked dopamine and DOPAC efflux in vitro from the corpus striatum of male rats

Dopamine: Mediator of Brain Polysome Disaggregation after L-Dopa

Ultrastructural evidence against in vivo disaggregation of brain polyribosomes after administration of L-dopa or phenylalanine

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