heteroreceptorer

Heteroreceptors are receptors located on a neuron that respond to neurotransmitters released by other neurons. They provide a mechanism for cross-talk between neural pathways, allowing one neuron to modulate the signaling of a neighboring neuron or circuit. By contrast, autoreceptors monitor the release of a neuron’s own transmitter and typically provide negative feedback to that same neuron.

Most heteroreceptors are presynaptic, situated on axon terminals or varicosities of a neuron and capable of modulating the release of its transmitter in response to inputs from neighboring neurons. Activation of these receptors can either inhibit or facilitate transmitter release, depending on the receptor type and the intracellular signaling it engages. Commonly, heteroreceptors are G protein–coupled receptors that influence calcium entry, cyclic adenosine monophosphate (cAMP) pathways, or potassium conductances, thereby shaping presynaptic release probability.

Examples include presynaptic dopamine receptors of the D2 family located on glutamatergic or GABAergic terminals, which can decrease release of the terminal’s transmitter; adenosine A1 receptors on glutamatergic terminals, which tend to reduce excitatory release; and GABA-B receptors on excitatory terminals, which can suppress glutamate release. Other transmitter systems, such as serotonin or acetylcholine, can also provide heteroreceptive control in specific brain regions.

Physiological and clinical relevance: heteroreceptors contribute to the dynamic regulation of neural circuits, influence synaptic plasticity, and affect processes such as pain perception, mood, attention, and reward. They are pharmacological targets for drugs intended to modulate neurotransmitter release in various disorders, including Parkinson’s disease, depression, and addiction.