<prompt> Which is not a metabotrophic receptor?GABA receptorb receptor for NAAcetylcholine receptora receptor for NA  <response>: B b receptor for NA Glutamate receptors are of two types: metabotropic receptors and ionotropic receptors. The metabotropic receptors are serpentine G protein-coupled receptors that increase intracellular IP3 and DAG levels or decrease intracellular cAMP levels. Eleven different subtypes have been identified. They are both presynaptic and postsynaptic and both are widely distributed in the brain. They appear to be involved in the production of synaptic plasticity, particularly in the hippocampus and the cerebellum. Examples of metabotrophic receptors include Glutamate Receptors, Muscarinic Acetyl choline receptors, GABA 3 receptors and omst serotonin receptors, as well as receptors of norepinephric, epinephrine, histamine, Dopamine, neuropeptides and endocannabinoids. Knockout of the gene for one of these receptors, one of the forms of mGluRI, causes severe motor incoordination and deficits in spatial learning. The ionotropic receptors are ligand-gated ion channels that resemble the nicotinic cholinergic receptors and the GABA and glycine receptors. 