GABAergic control of substantia nigra dopaminergic neurons

摘要: At least 70% of the afferents to substantia nigra dopaminergic neurons are GABAergic. The vast majority these arise from neostriatum, external globus pallidus and pars reticulata. Nigral express both GABA(A) GABA(B) receptors, inhibited by local application or agonists in vivo vitro. However, vivo, synaptic responses elicited stimulation neostriatal pallidal afferents, antidromic activation nigral reticulata GABAergic projection mediated predominantly exclusively receptors. clearest most consistent role for receptor is as an inhibitory autoreceptor that presynaptically modulates originate all three principal inputs. firing pattern also effectively modulated inputs vivo. Local blockade receptors causes shift a burst regardless original pattern. This accompanied modest increase spontaneous rate. axon collaterals seem be particularly important source tone neurons, inhibition which leads firing. exerts powerful control over input, through latter, disynaptically neurons. Inhibition output slight decrease due disinhibition whereas increased associated with rate significant extracellular levels dopamine neostriatum. disynaptic disinhibitory dominates monosynaptic influence because differential sensitivity GABA two neuron types. more sensitive GABA(A)-mediated than part hyperpolarized reversal potential. depolarized potential absence KCC2, chloride transporter responsible setting up hyperpolarizing Cl(-) gradient mature CNS data reviewed this chapter have made it increasingly clear addition effects on their target nuclei outside basal ganglia, interactions between crucially functioning