Introduction to the Best Known Neurotransmitters
 (ACh for short)
Neurons which use ACh to send their messages are referred to as cholinergic neurons.
Key locations and functions:
1) ACh is the transmitter at all neuromuscular (nerve-to-skeletal muscle) junctions.
     It stimulates all muscle contractions and hence all behavior.
2) ACh is the transmitter of the parasympathetic half of the autonomic nervous system.
3) ACh is a transmitter in many brain areas (cortex, basal ganglia, hypothalamus to name a few) and is necessary for normal memory and cognition and motor control.
The action of ACh released at a synapse is ended via breakdown of ACh by the enzyme acetylcholinesterase.
(NE for short)
(aka noradrenaline)
Key locations and functions:
1) NE is the primary transmitter carrying messages from the sympathetic half of the autonomic nervous system to body organs and glands.
2) NE is a transmitter in many brain areas (reticular activating system, hypothalamus appetite areas, limbic system) and is involved in nervous system arousal, hunger, and mood control.
The action of NE at a synapse is brought to an end primarily via reuptake. NE may also be broken down by enzymes like MAO.
(think "NE and hams" for hunger,arousal, mood, sympathetic)
(DA for short)
DA is the precursor (chemical forerunner) that is turned into NE,  so is closely related to NE and often affected by the same drugs. DA and NE are members of the transmitter family known as the CATECHOLAMINES. In some neurons the synthesis of transmitter stops at the DA step and DA serves as the neurotransmitter.
Key Locations and Functions:
DA is an important transmitter in several brain systems:
1) Extrapyramidal motor system  (posture and movement control)
2) Mesolimbic/mesocortical system (midbrain connections to limbic system and cortex) (emotion and cognitive functions)
3) Hypothalamus-pituitary system (menstrual and other hormone regulation)
The action of DA at a synapse is brought to an end primarily via reuptake.
(think "DAMMM" for motor, mood/mesolimbic, menstrual/hormonal)
(aka 5-hydroxytryptamine)
(5HT for short)
Serotonin is a chemical cousin of the "catecholamines" discussed above. 5HT, NE and DA are sometimes grouped under the heading MONOAMINES or BIOGENIC AMINES, and because of their similarities they are influenced by some of the same drugs.
5HT is best known as a transmitter in several brain areas:
1) sleep regions
2) limbic system mood control regions
3) pain suppression system
The action of 5HT at a synapse is brought to an end primarily via reuptake. 5HT may also be broken down by the enzyme MAO.
(think "5HT and SLeeP" for sleep, limbic mood control and pain suppression)
Glutamate, an amino acid, is the single most widely distributed excitatory neurotransmitter in the CNS.
Gamma-aminobutyric acid (GABA for short)
GABA, another amino acid neurotransmitter widely distributed in the CNS, is the most important inhibitory transmitter.
Endorphins (& enkephalins)
A family of larger molecule transmitters involved in pain suppression, reward and positive mood states.