Motor control impairment 91-92

The nigrostriatal system is predominantly involved in motor control, which is particularly evident in Parkinson s disease (PD), where a progressive loss of these neurons results in loss of motor function. In the early stages of the disorder, the motor impairment can be reversed by the administration of the dopamine precursor l-DOPA (L-3,4-dihydroxyphenylalanine), which bypasses the need for TH in dopamine... 

Huntington s disease, an autosomal dominant disorder, has a mean age-of-onset of 43-48 years. Symptoms appear gradually and worsen over a period of about 15 years until death occurs. Mood disturbance, impaired memory, and hyperrefiexia are often the first signs, followed by abnormal gait, chorea (loss of motor control), dystonia, dementia, and dysphagia. Cases of juvenile onset (<10 years old) are more severe and most frequently occur when the defective allele is inherited paternaily. About 25% of cases have late onset, slower progression, and milder symptoms. 

Sudden infant death syndrome (SIDS) is strongly linked to smoking in pregnant women and new mothers. Children of smoking mothers are more likely to have motor control problems, perception impairments, symptoms of hyperactivity, and conduct disorder in childhood. These children have a higher risk for cancer later in life. 

In addition to the mental effects described above, nitrous oxide impairs motor control and causes a partial insensitivity to pain. Users may lose consciousness at high doses. The intoxication from nitrous is typically short-lived—sometimes lasting under a minute. 

Benzodiazepine drugs can cause a range of side effects, including dizziness, confusion, and impaired motor control. Long-term benzodiazepine use can lead to physical dependence. Despite these problems, benzodiazepines have remained the standard antianxiety drugs for approximately 50 years. 

Rotation provides a very simple measure of the asymmetry in motor activation associated with dopamine lesions. However, PD patients have a more complex range of motor deficits, not just in akinesia and rigidity, but in the initiation of voluntary and purposive movement, and in fine motor control. To develop the validity of the animal models, we need to determine the extent to which dopamine denervation in experimental animals produces comparable impairments in simple motor behaviors not dependent on pharmacological activation, and in more complex behaviors whilst controlling for confounding effects of simple performance deficits. 

Despite the plethora of causal insults and molecular mechanisms that underlie neurodegeneration in CNS proteopathies, the resultant symptoms are commonly manifested (with different severity depending on each disease) as disturbances in motor control, dementia, cognitive impairment, depression, and sleep disturbances. This last section briefly summarizes the data that support a therapeutically beneficial role for HD AC inhibition on these different disease domains. ... 

The euphoric feelings associated with Cannabis use are thus ascribable to the interaction of A -THC with CBj receptors on presynaptic nerve terminals. However, CB receptors are also present in other areas of CNS, and thus, the same cannabinoids also cause impairment of cognition and memory (hippocampus) [43], involuntary movements and partial loss of motor control (basal ganglia and cerebellum) [44], and a beneficial and potential therapeutically useful inhibition of emesis [45], especially of the chemotherapy-induced emesis. It is still unclear whether the CB receptors are responsible for all of the centrally mediated actions of the cannabinoids. 

As mentioned in the chapter opening, Parkinson s disease is a neurodegenerative disorder marked by a decreased production of dopamine in the brain. Since dopamine regulates motor function, the decrease in dopamine leads to impaired motor control. Although there is no cure for Parkinson s disease, the symptoms can be treated by a variety of methods. The most effective course of treatment is to administer a drug called L-dopa, which is converted into dopamine in the brain ... 

The primary system of cannabimimetic activity is the nervous system. The CB1 receptor is omnipresent in the brain, especially in areas that control functions affected by cannabimimetics. One of the functions most pronouncedly influenced by cannabimimetics is motor behavior. Catalepsy, immobility, ataxia, and impairment of complex behavioral acts after acute administration of high doses of cannabimimetics are manifestations of such motor effects (Pertwee, 1997). In lower doses cannabimimetics produce the opposite effects. The very dense presence of CB1 in the cerebellum and the basal ganglia, areas responsible for motor activity, is... 

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