Apomorphine doses impair the reaction time of fast reacting but not slow reacting rats

Wilcox, Richard E.; Spirduso, Waneen W.

doi:10.1007/bf00174524

Cited by 10 publications

(5 citation statements)

References 22 publications

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“…The impaired SRT execution after rest confirms previous outcomes on reactivity in PD patients with exact timing of both LD intake and test performance 10. An animal study also showed an impaired RT after cued dopaminergic stimulation in a particular species of fast-reacting rats 11. Sedative effects of LD may play a role, and release of fatigue-counteracting brain norepinephrine is lower during rest than during exercise 12.…”

Section: Discussionsupporting

confidence: 80%

Effect of exercise on reactivity and motor behaviour in patients with Parkinson's disease

Müller

Muhlack

2010

Journal of Neurology, Neurosurgery & Psychiatry

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Background Following cued levodopa (LD) intake, endurance exercise showed a beneficial effect on scored motor performance in patients with Parkinson's disease (PD) in comparison with rest. This may result from an exercise induced increase in endogenous dopamine synthesis. As a result, beneficial effects on movement and reactivity may occur. Objectives To measure reactivity and motor performance in a repeated fashion with instrumental tasks after cued administration of soluble 200 mg of LD/50 mg of benserazide. Design PD patients consecutively performed paradigms, which assess reactivity and movement performance, after a standardised period of rest or of age-related, heart rate adapted endurance exercise on two consecutive days in a random order. Results Reactivity and execution of simple and complex motion series were significantly better following exercise than after rest. Discussion Endurance exercise has a beneficial effect on reactivity and movement behaviour in PD patients following cued application of LD probably due to an augmented synthesis and release of dopamine and other catecholamines and release in the prefrontal cortex, the nucleus accumbens and the basal ganglia. Small changes in catecholamine modulation of prefrontal cortex cells can have profound effects on the ability of the prefrontal cortex to guide behaviour. Previous exercise may also improve pedunculopontine nucleus function, which is involved in motor-related attention processes.

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Section: Discussionsupporting

confidence: 80%

Effect of exercise on reactivity and motor behaviour in patients with Parkinson's disease

Müller

Muhlack

2010

Journal of Neurology, Neurosurgery & Psychiatry

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“…None have reported the detrimental effect on saccadic latency we describe here, but there is evidence to suggest that in some circumstances dopamine might have an adverse effect on manual and saccadic reaction times. It has recently been reported that a simple manual reaction time task is delayed in PD patients as a result of subcutaneous apomorphine injection, a D1 and D2 receptor agonist (Muller et al 2002), and similarly apomorphine has been reported to impair the reaction time in certain strains of rats (Wilcox and Spirduso 1988). Amphetamine causes dopamine release and reuptake inhibition, and has been found to prolong saccadic latencies in humans (Dursun et al 1999), whereas haloperidol, a dopamine antagonist with mild anticholinergic action, has been found not to affect saccades (Lynch et al 1997).…”

Section: The Effect Of L-dopa On Latency Distributionsmentioning

confidence: 99%

Saccadic latency distributions in Parkinson’s disease and the effects of l-dopa

Michell

Fritz

et al. 2006

Exp Brain Res

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Parkinson's disease (PD) is associated with a loss of central dopaminergic pathways in the brain leading to an abnormality of movement, including saccades. In PD, analysis of saccadic latency distributions, rather than mean latencies, can provide much more information about how the neural decision process that precedes movement is affected by disease or medication. Subject to the constraints of intersubject variation and reproducibility, latency distribution may represent an attractive potential biomarker of PD. Here we report two studies that provide information about these parameters, and demonstrate a novel effect of dopamine on saccadic latency, implying that it influences the neural decision process itself. We performed a detailed cross-sectional study of saccadic latency distributions during a simple step task in 22 medicated patients and 27 agematched controls. This revealed high intersubject variability and an overlap of PD and control distributions. A second study was undertaken on a different population specifically to investigate the effects of dopamine on saccadic latency distributions in 15 PD patients. L-dopa was found to prolong latency, although the magnitude of the effect varied between subjects. The implications of these observations for the use of saccadic latency distributions as a potential biomarker of PD are discussed, as are the effects of L-dopa on neural decision making, where it is postulated to increase the criterion level of evidence required before the decision to move is made.

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“…To date, an impaired performance of a CRT-like paradigm after apomorphine application was only shown in a certain species of fast reacting rats (32). CRT significantly increased in our previously untreated PD patients.…”

Section: Discussionmentioning

confidence: 67%

“…We assume, that apomorphine at least partially binded to presynaptic autoreceptors and thus inhibited locomotor activity, as presynaptic dopaminergic receptors are at least six to 10 times more sensitive to dopamine agonists compared with postsynaptic dopaminergic receptors (17,32,47,48). We assume, that apomorphine at least partially binded to presynaptic autoreceptors and thus inhibited locomotor activity, as presynaptic dopaminergic receptors are at least six to 10 times more sensitive to dopamine agonists compared with postsynaptic dopaminergic receptors (17,32,47,48).…”

Section: Discussionmentioning

confidence: 99%

“…A further interesting result is the missing significant impact of apomorphine on MT in treated PD patients and the significant delay of MT after 30 min in previously untreated parkinsonian subjects. We assume, that apomorphine at least partially binded to presynaptic autoreceptors and thus inhibited locomotor activity, as presynaptic dopaminergic receptors are at least six to 10 times more sensitive to dopamine agonists compared with postsynaptic dopaminergic receptors (17,32,47,48).…”

Section: Discussionmentioning

confidence: 99%

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Differential response in choice reaction time following apomorphine based on prior dopaminergic treatment

et al. 2004

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Choice reaction time (CRT) paradigms demonstrated deficits in the preparation and execution of movements in patients with Parkinson's Disease (PD). Predominantly these trials did not consider an influence of acute and long-term dopaminergic substitution. Objective was to determine the acute effect of apomorphine on the response to a repeatedly performed CRT task. We repeatedly executed the CRT paradigm before and after subcutaneous apomorphine injection in previously treated, untreated and long-term dopamine substituted PD patients, who took placebo. No significant change of CRT and movement time (MT) appeared in PD patients with chronic dopaminergic drug intake after apomorphine injection. CRT and MT both significantly worsened in untreated PD patients. Placebo application induced no significant alteration. Binding of apomorphine to presynaptic autoreceptors with subsequent sedation or inhibition of locomotor activity hypothetically explain our results in before untreated PD patients. Previous long-term dopaminergic substitution may cause a certain tolerance to this phenomenon.

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Apomorphine doses impair the reaction time of fast reacting but not slow reacting rats

Cited by 10 publications

References 22 publications

Effect of exercise on reactivity and motor behaviour in patients with Parkinson's disease

Effect of exercise on reactivity and motor behaviour in patients with Parkinson's disease

Saccadic latency distributions in Parkinson’s disease and the effects of l-dopa

Differential response in choice reaction time following apomorphine based on prior dopaminergic treatment

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