Anonymous asked in HealthDiseases & ConditionsOther - Diseases · 9 years ago

How does Parkinson's cause a slowing of movement when ACh is what is in excess, and it is an excitatory..?

if ACh is in excess in comparison to dopamine, why is it that there is a slowing of movement in Parkinson's if ACh propagates action potentials

2 Answers

  • Mags
    Lv 7
    9 years ago
    Favorite Answer

    VIsualize a balance scale with more acetylcholine on one side and considerably less dopamine on the other. Which side becomes dominant?

    In Parkinson's disease many symptoms may occur years before the diagnosis is made. At this time most diagnoses are made when the loss of dopamine neurons in the substantia nigra pars compacta of the basal ganglia is between 60-80%, That is a huge imbalance especially compared to the full-on presence of ACh.

    Dopamine, in this case, is acting as an inhibitory neurotransmitter as opposed to the excitatory roll of acetylcholine. Both DA and ACh initiate action potential. In PD they cannot be equalized.

    Tense your arms and legs - or rather try tensing one arm and the corresponding leg. Try to walk normally. Can't do it - sorry. In this example you have willed the ACh to continue to tense those left side or right side limbs. So you see what happens. Not only that, it hurts. In order to walk at a normal pace with a normal stride you need a balance betwen excitatory and inhibitory. In PD that balance is not present.

    Fewer dopamine neurons means fewer inhibitory messages. The acetylcholine just keeps transmitting.

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