Neuroreceptors, or simply receptors, are specialized proteins found on the surface of neurons and other cells in the nervous system.
They play a crucial role in the communication between neurons by detecting and responding to signaling molecules, such as neurotransmitters, hormones, or other chemical messengers.
Types of Neuroreceptors:
1. Ionotropic receptors:
These receptors are also known as ligand-gated ion channels. When a neurotransmitter binds to an ionotropic receptor, it directly causes the opening of an ion channel within the receptor complex, allowing specific ions to flow across the cell membrane.
This flow of ions creates an electrical current that can either depolarize (excite) or hyperpolarize (inhibit) the postsynaptic neuron, influencing the probability of generating an action potential.
Examples
NMDA, AMPA, and kainate receptors for glutamate.
GABA-A receptors for gamma-aminobutyric acid (GABA).
Nicotinic acetylcholine receptors for acetylcholine.
2. Metabotropic receptors:
These receptors, also called G protein-coupled receptors (GPCRs), do not have ion channels within their structure.
Instead, they indirectly influence ion channels and other cellular processes through a series of intracellular signaling pathways involving G proteins and second messengers.
Metabotropic receptors can modulate neuronal excitability, synaptic transmission, or gene expression over a longer time scale compared to ionotropic receptors.
Examples
Muscarinic acetylcholine receptors.
GABA-B receptors.
Most serotonin, dopamine, and adrenergic receptors..