Soma-dendritic autoreceptors stimulation

The dopamine-containing nigro-neostriatal dopaminergic neurons possess receptors for dopamine. These dopamine receptors occur on both the nerve terminals within the neostriatum (pre-synaptic autoreceptors) as well as on the soma and dendrites (soma-dendritic autoreceptors). Stimulation of either category of autoreceptor can regulate the synthesis, turnover and release of dopamine in the neostriatum but by different mechanisms. 

Systemical or intranigral application of dopamine receptor agonists depresses the firing of nigrostriatal dopamine cells by stimulating soma-dendritic autoreceptors in the zona compacta, an effect again antagonized by neuroleptics (110, 111, 112). ... 

Autoreceptors (ARs) Interact with neurotransmitters produced by the same nerve, and consequently suppress or stimulate neurotransmitter release Into the synaptic cleft. They are located In the presynaptic nerve terminals or In the soma, dendrites, and axons of central nervous system neurons. 

Figure 17.4 The effect of neuroleptics on the activity of DA neurons. Although neuroleptics (DA antagonists) are used primarily to inhibit the postsynaptic effects of released DA they also increase the activity of the DA neuron itself since they (1) inhibit the effect of synaptic DA on nerve terminal autoreceptors and so increase DA release (2) block inhibitory DA autoreceptors on the soma of the DA neuron so that they cannot be stimulated by endogenous DA, possibly released from the neuron s own dendrites and (3) facilitate feedback excitation to the DA neuron from those neurons normally inhibited by distally released DA. All the DA receptors involved are D2 (or possibly D3). — Blocked by D2 antagonists (neuroleptics)...

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