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

Abstract

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.

Chronic metformin treatment improves post‐stroke angiogenesis and recovery after experimental stroke

“…One possible explanation is that metformin‐induced increases in angiogenesis may contribute to restoration of dopaminergic tone in the ischemic hemisphere (Potts & Lim, ; Sun et al ., ; Wang et al ., ). It is also possible that reduced rotation may be caused by non‐specific sedative effects of apomorphine (Muller et al ., ) or a drug interaction with metformin. We did not find any visual evidence of sedation at day 3 or day 30 while testing, and did not observe any differences in spontaneous locomotor activity between the metformin and vehicle groups when tested in open field following the apomorphine rotation test (data not shown).…”

Sprint starts and the minimum auditory reaction time

“…Reaction times are widely used to evaluate neuromuscular-physiological responses in such diverse areas as medicine (Muller et al, 2004) and impairment detection (Roehrs et al, 2003) through to environmental safety (Philipova, 1998, Haas andEdworthy, 2003) and sports (Guissard and Duchateau, 1990). Reaction time is dependent on several factors: arrival of the stimulus at the sensory organ, conversion by the sensory organ to a neural signal, neural transmissions and processing, muscular activation, soft tissue compliance, and the selection of an external measurement parameter.…”

Advances in clinical basic research: Performance, treatments, and mechanisms of Parkinson disease

“…The authors found the combined use of low‐dose l ‐Dopa and dopamine receptor agonists showed comparable efficacy to that of high‐dose l ‐Dopa alone, while the incidence of side effects was significantly reduced, indicating that sublingual film provided a useful, on‐demand treatment for off episodes 57 . Whereas it was also found by the authors that previous long‐term dopaminergic replacement may lead to tolerance to the binding of apomorphine to presynaptic autoreceptors, followed by sedation or suppression of motor activity 58 …”

“… 57 Whereas it was also found by the authors that previous long‐term dopaminergic replacement may lead to tolerance to the binding of apomorphine to presynaptic autoreceptors, followed by sedation or suppression of motor activity. 58 …”