1. TRANSMITTERS a. Ionotropic (channel-linked) receptors: transmitter binds to binding site at ion channel (receptor coupled to channel) b. Metabotropic (G-protein linked) receptors: 1. Receptor activates G-protein » alpha subunit splits off » binds to ion channel. 2. Receptor activates G-protein » alpha subunit splits off » activates enzyme » enzyme produces 2nd messenger (e.g. cAMP) » 2nd messenger changes ion channel ( more common )

2. Metabotropic (G-protein linked):

3. TRANSMITTERS Acetylcholine (ACh): - nicotinic receptor (ionotropic) - muscarinic receptor (metabotropic) AChE= acetylcholine esterase Monoamines: - DA, NE, E » catecholamines - Serotonin (5-HT) » indolamine - Monoamine oxidase (MAO) - 5 DA receptors » all metabotropic - D1 » increases cAMP (2nd messenger) - D2 » decreases cAMP - 4 NE receptors » all metabotropic (cAMP) - œ1, œ2, ß1, ß2 - 7 5-HT receptors » 6 metabotropic cAMP= cyclic adenosine monophosphate

4. TRANSMITTERS Amino acids: Glutamate » NMDA, AMPA, Kainate -ionotropic Metabotropic 1 or 2 Glycine GABA a,b a=ionotropic, b=metabotropic. GABA a » 3 subtypes - affinity for GABA only - GABA + benzodiazepines - GABA + barbiturates +ETOH Neuropeptides » Enkephalins, Endorphins, etc. Nitric oxide (NO) - retrograde messenger

5. L-DOPA Physostigmine - AChE Amphet, Cocaine - DA Cocaine - DA Amphet-NE, Morph-End Prozac - 5HT PCPA-5HT; (tryptophan) Reserpine-5HT Botulinum toxin - ACh Atropine,curare » Ach Thorazine - DA (anti- psychotic) Apomorphine - DA from Pinel text