Table 1: Localization of common receptor subtypes in the brain (adapted from [19]).

SubtypeFrequencyLocalization

α 1β 2γ 2Major (60%) synapticCerebral cortex (layer I–VI), hippocampus, striatum, cerebellum, amygdala, brainstem.
α 2β nγ 2Minor (15–20%) synapticCerebral cortex (layers I–IV), hippocampus, striatum, hypothalamus, amygdala.
α 3β nγ 2Minor (10–15%) synapticCerebral cortex (layers V-VI), hippocampus, cerebellum, amygdala, brainstem (including raphe nuclei and locus coeruleus), spinal cord.
α 4β nδ/γMinor (<10%) extrasynapticHippocampus (dentate gyrus), thalamus, cortex.
α 5β nγ 2Minor (<5%) extrasynapticCerebral cortex, hippocampus, amygdala, hypothalamus, spinal cord.
α 6β nγ2/δMinor (<5%)(extra) synapticCerebellum.