Neurotransmitters in movement disorders Flashcards
What makes up the basal ganglia?
Basal ganglia: collection of nuclei in brain - striaita, globus pallidus, nucleus, substantia nigra
What makes up the striatum?
Caudate nucleus + putamen
Globus pallidus
- Single cluster of cell bodies - internal and external
- Cells are inhibitory
Why is it beneficial to have lots of neuromelanin in substantial nigra?
Protects against oxidative damage
Describe the direct pathway
Stimulation of cortex - excitatory output to striatum
Striatum inhibits GPI and SNR
Normally GPI and SNR inhibit the thalamus but because they themselves are inhibited, there is less of an inhibitory effect on the thalamus so it works
Describe the indirect pathway
Striatum is excited
Striatum inhibits external globes pallidus
EGP inhibits sub-thalamic nucleus
This excites SNR and GPI
This prevents thalamus from executing movement
Which dopamine receptors are found in the direct pathway?
D1 - excited neurones and makes them more likely to fire
Which dopamine receptors are found in the indirect pathway?
D2 receptors - dopamine inhibits and decreases indirect pathway
Pathophysiology of Parkinson’s
Dopamine cells in substantia nigra are destroyed
Dopamine can’t act on pathways - imbalance towards indirect pathway to motor activities inhibited
Pathophysiology of Huntington’s
Loss of cells in indirect pathway in striatum
Indirect pathway is less active -> direct pathway more active
How does tetrabenezene work?
blocks transporter protein so dopamine can’t be loaded into vesicles and released so can’t activate receptors - reduces dopamine effects by exciting direct pathway
Function of ACh on direct and indirect pathway
Inhibits direct and excites indirect
Huntington’s disease
Loss of ACh in striatum
Direct pathway is excited and indirect is inhibited
Causes tremor, increased muscle tone
