There are two different types of adrenoreceptor – the α and β receptors. The α receptors are further classified into α1 and α2 subtypes and the β receptors are further classified into β1, β2 and β3 subtypes. The α2 receptors are widely distributed throughout the body and are found in adrenergic neurons, blood vessels, the pancreas and in smooth muscle. Coupled to inhibitory G-proteins, α2 adrenoreceptors have an inhibitory effect on neurotransmission when bound by an agonist through negative feedback on the presynaptic neuron.1
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