There are over 100 known neurotransmitters that transmit signals between neurons in the nervous system. The major excitatory neurotransmitters are glutamate, acetylcholine, and dopamine. Glutamate, glycine, and GABA are the primary inhibitory neurotransmitters. Acetylcholine is involved in muscle movement and is both excitatory and inhibitory depending on the receptor. Serotonin and dopamine play important roles in behaviors and mood, while GABA decreases excitatory activity in the nervous system.

1. Neurotransmitters

2. Neurotransmitters
• More than 100 neurotransmitters are now recognized, and more will surely be
discovered.
• Acetylcholine is important and one of the first ones discovered because its
involvement in muscle movement.
• Dopamine and serotonin hugely important for many behaviors.
• The workhorses of the brain are glutamate, glycine, and γ-aminobutyric acid
(GABA).

3. Acetylcholine
• Acetylcholine is for motor neuron arising in the spinal cord and it
function at all the nerve to skeletal muscles
• Stimulates muscles
• Also found throughout nervous system
• Usually excitatory, but can be inhibitory depending on the receptor
• Synthesis from acetyl CoA and choline in presence of enzyme choline
acetylase.

5. Acetylcholine

6. Dopamine
 Excitatory (but sometimes inhibitory) depending on the location in the nervous
system
 It is immediate precursor of norepineprine and plays motor function in CNS
 Requires a transport protein to inactivate

7. Serotonin
 Excitatory or inhibitory depending on area of CNS
 Involved in sleep, appetite, mood
 Drugs like prozac (SSRIs – selective serotonin reuptake inhibitor)
slows down transport protein
 Transporter also binds cocaine and amphetamines.

9. Dopamine

10. GABA
It is an amino acid called ſ- aminobutyric acid.
It is present only in CNS and synthesized from glutamic acid by
enzymes decarboxylase.
Present in higher con. in diencephalon and occipital lobe, lower conc.
In pons, medulla and cerebral cortex. It stabilized membrane potential.
It decrease the excitory activity. GABA enhance the uptake of CI- ions.

11. Epinephrine
Position and secretion
It is an tyrosine derivative.
In adrenal medula the epinephrine stored in the granules bounded by
ATP and protein.
Its secretion is initiated by acetylcholine, released from preganglionic
neurons.
Cyclic AMP help in action.
Its nature of action on tissue are stimulation or depression ,
constriction or relaxation.

13. Norepinephrine
It is an immediate precursor of epinephine.
The main function of Norepinephrine is release of free fatty acids from adipose tissue.
1) Heart rate- decreases
2) Cardiac output – Variable
3) Blood pressure- Greater rise
4) Total peripheral resistance- Increase
5) Respiration- Stimulation
6) Skin vessels- Constriction
7) Muscle Vessels- Constriction
8) Uterus - Stimulation