Receptors (Neuroreceptor) - Ionotropic & Metabotropic

Receptors (Neuroreceptor) are specialized proteins located on the surface of neurons and other cells in the nervous system.
They play a crucial role in communication between neurons by detecting and responding to signaling molecules such as neurotransmitters, hormones, and other chemical messengers.

Types of Receptors:

Also known as ligand-gated ion channels.
When a neurotransmitter binds to an ionotropic receptor, it directly opens an ion channel within the receptor complex, allowing specific ions to flow across the cell membrane.
This ion flow generates an electrical current that can either depolarize (excite) or hyperpolarize (inhibit) the postsynaptic neuron, influencing the likelihood 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.

Also called G protein-coupled receptors (GPCRs).
These receptors do not have ion channels within their structure.
They influence ion channels and other cellular processes indirectly through intracellular signaling pathways involving G proteins and second messengers.
Metabotropic receptors modulate neuronal excitability, synaptic transmission, and gene expression over a longer time scale compared to ionotropic receptors.
Examples:
- Muscarinic acetylcholine receptors.
- GABA-B receptors.
- Most serotonin, dopamine, and adrenergic receptors.