Exogenous Ligands and Receptor Signaling

agonist

mimics endogenous ligand, binds at same site, and activates receptor when binded (e.g. nicotine, cannabis)

antagonist

binds to receptor, prevents endogenous molecules from activation receptor

inverse agonist

induce opposite effects of endogenous ligand

allosteric modulator

binds to different site from endogenous ligand, can increase/decrease impact that endogenous ligand has 

Uptake Inhibitor/Transport Blocker

blocks uptake of endogenous ligand, increases action at synapse 

Ionotropic Receptor

fast neurotransmitter binding where the receptor opens its ion channels (e.g. GABA-A, AMPA); produces rapid excitation/inhibition

Metabotropic Receptor

slower neurotransmitter binding (activating g-protein) where intracellular signaling cascades are activated or inactivated, changing the excitability of a neuron

AMPA Receptors

ionotropic receptors that are ligand-gated 

NMDA Receptor

ionotropic receptors that are ligand and voltage gated at the same time

intracellular signaling cascades

the change in permeability of ion channels

Exogenous

body doesn’t produce it (natural or synthetic)

Endogenous

body produces it

Nicotine

agonist ligand that binds to nicotinic acetylcholine receptors

Cannabis

agonist ligand that binds to CB1/CB2 receptors

Antipsychotic Medication

antagonist ligand that blocks dopamine receptors

First Generation Antipsychotics (Typical)

D2 Receptor antagonists (reduce positive symptoms)

Second Generation Antipsychotics (Atypical) 

D2 + serotonin receptor antagonist (reduce positive and negative symptoms)

SR141716A

inverse agonist of CB1 receptors

Alcohol

allosteric modular binding to GABA-A receptors at benzodiazepine binding site + increasing amount of chloride influx when GABA binds at GABA site

Cocaine 

uptake inhibitor blocking dopamine uptake 

Dopamine

neurotransmitter for ionotropic receptors in the midbrain

Acetylcholine

neurotransmitter made by colinergic neurons binded to ionotropic and metabotropic receptors in basal forebrain

Norepinephrine

neurotransmitter that binds to metabotropic receptors in locus coeruleus or adrenal cortex (PNS)

Serotonin

neurotransmitter made by serotonergic neurons that binds to metabotropic receptors (and one ionotropic) in Raphe Nuclei