Neurotransmitters

Common Neurotransmitters

Dopamine
Norepinephrine & Epi
Endorphins
Serotonin
Oxytocin
Acetylcholine

Catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine.

END: Epi, NE, DA

GOES GA: GABA, Oxytocin, Endorphins, Serotonin; Glycine, Acetylcholine.

Neurotransmitters, Functions, and Related Diseases

Neurotransmitter	Function in the brain	Diseases Related to these NT
Acetylcholine (ACh)	Involved in Thought, Learning, and Memory.	Alzheimer’s disease’ muscle movement in the PNS; Myasthenia Gravis
Dopamine (DA) (The Pleasure NT)	Involved in reward circuits. Feelings of pleasure, and also addiction, movement, and motivation. People repeat behaviors that lead to dopamine release.	Parkinson’s disease; Schizophrenia
Norepinephrine (NE)	Arousal	Depression
Serotonin		Depression; Aggression; Schizophrenia
Glutamate (Glu)	Learning; Major excitatory NT in the brain
GABA		Anxiety disorders; Epilepsy; Major inhibitory NT in the brain
Endogenous Opioids (Endorphins, Enkephalins)		Pain; Analgesia; Reward

NT = Neurotransmitter.

In the brain, acetylcholine is involved in learning and memory. In the rest of the body, it stimulates muscle contractions. Medications with strong anticholinergic effects can have side effects like memory problems and confusion. These effects are more pronounced in older people. As such, medications with strong anticholinergic effects should be avoided in elderly patients.

Some SSRIs have stronger anticholinergic side effects than others, but in general they have a relatively low anticholinergic effect. Other newer antidepressants, including SNRIs such as venlafaxine and atypical antidepressants such as bupropion, have a very low anticholinergic effect.

Benzodiazepines bind to benzodiazepine receptors; enhances GABA effects.
Alcohol’s effects of ethanol in the CNS are mediated through GABA receptors.
Sedative-hypnotics (Zolpidem, Eszopiclone, Zaleplon) all interact with GABA-Benzodiazepine receptor complexes.

Drugs, Mechanism of Action, and Use

Drug	Mechanism of Action	Use	Agonist / Antagonist
L-dopa	Increases synthesis of DA	Parkinson’s disease	Agonist for DA
Mixed amphetamine salts (Adderall)	Increase release of DA, NE	ADHD	Agonist for DA, NE
Ritalin (methylphenidate)	Blocks removal of DA, NE and lesser (5HT) from synapse	ADHD	Agonist for DA, NE mostly
Donepezil (Aricept)	Blocks removal of ACh from synapse	Alzheimer’s disease	Agonist for ACh
SSRI’s eg. Fluoxetine	Blocks removal of 5HT from synapse	Depression, OCD	Agonist 5HT
SNRIs e.g. duloxetine and venlafaxine	Block the reuptake of both serotonin and NE.	Depression, neuropathic pain.
NDRIs e.g. Bupropion	Block reuptake of NE and DA from synapse	Tobacco cessation; Depression
Quetiapine (Seroquel)	Blocks DA and 5HT receptors	Schizophrenia, Bipolar disorder	Antagonist for DA, 5HT
Naltrexone	Blocks opioid post-synaptic receptors	Alcoholism, opioid addiction	Antagonist for opioids

Selective serotonin reuptake inhibitors (SSRIs)
Serotonin and norepinephrine reuptake inhibitors (SNRIs)
Norepinephrine and dopamine reuptake inhibitors (NDRIs)

Neurotransmitter Receptors That Are Ligand-Gated Ion Channels

Some Neurotransmitter and Neuropeptide Receptors That Are Coupled to G Proteins

G-Protein Coupled Receptors.

CLASSIC NEUROTRANSMITTERS
Acetylcholine* (muscarinic receptors)
GABA* (B-class receptors)
Adenosine
ATP
Dopamine
Epinephrine, norepinephrine
GABA* (B-class receptors)
Glutamate*
Histamine
Serotonin* (5HT1, 5HT2, 5HT4 receptors)

NEUROPEPTIDES
Adrenocorticotropic hormone (ACTH)
Bradykinin
Cholecystokinin (CCK)
Endothelin
Gastrin
Luteinizing hormone-releasing hormone (LHRH)
Opioids (e.g., β-endorphin)
Oxytocin
Tachykinins (e.g., substance P)
Thyrotropin-releasing hormone (TRH)
Vasoactive intestinal peptide (VIP)
Vasopressin