Hey guys, so in the pathway for the basal ganglia, First Aid states that dopamine activate D1 receptors to stimulate movement and it activates D2 receptors to inhibit movement. However, some of the drugs that are used to treat Parkinsons (ropinirole) are D2 receptor agonists, so wouldn't that worsen Parkinsons disease symptoms since you are stimulating a receptor that decreases movement in a patient who already suffers from bradykinesia?
BOTH Parkinsons disease Question
- Thread starter ChaoWow
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I’m pretty sure that dopamine is essentially “pro-movement” in both recetors. D1 stimulation activates the direct pathway, ultimately relaxing inhibition on the thalamus-cortical system and allowing movement.
In the indirect pathway, movement is restricted. However, you can relax this pathway via stimulation of the D2 receptor, attenuating the indirect pathway and allowing more movement.
In PD, the problem is both too-little direct pathway activity, and too much indirect pathway activity. So an agonist for either D1 or D2 will be helpful.
In the indirect pathway, movement is restricted. However, you can relax this pathway via stimulation of the D2 receptor, attenuating the indirect pathway and allowing more movement.
In PD, the problem is both too-little direct pathway activity, and too much indirect pathway activity. So an agonist for either D1 or D2 will be helpful.
D2 receptors are inhibitory. In the normal basal ganglia indirect pathway, the striatum will inhibit the GPe, which releases the STN from inhibition. Remember that the STN is the only excitatory nucleus in the basal ganglia so that will excite the GPi, which will inhibit the thalamus resulting in net motor ******ation. Since the D2 receptors exert an inhibitory effect on this pathway, this means that this entire pathway is inhibited, i.e. inhibition of the indirect pathway = inhibiting the inhibitor = net activating.
