In substantia nigra, the major neurotransmitter is:

Ans. A. Dopaminergica. There is a system of dopaminergic neurons in nigrostriatal dopaminergic system with cell bodies in substantia nigra and axon endings in caudate nucleus.b. In Parkinson's disease there is loss of dopaminergic cells in the substantia nigrawhich leads to striatal dopamine depletion.c. As DOPAMINE activates excitatory D1 receptors in the direct pathway and represses inhibitory D2 receptors in the indirect pathway, this depletion leads to decreased activity of the direct pathway and increased activity of the indirect pathway