Neurotransmitters are chemical messengers that play a crucial role in transmitting signals between neurons in the nervous system.
They are released by the presynaptic neuron at a synapse, diffuse across the synaptic cleft, and bind to specific receptors on the postsynaptic neuron.
This binding can either excite or inhibit the postsynaptic neuron, influencing the likelihood of generating an action potential.
1. Amino acids:
These are the most common neurotransmitters in the central nervous system (CNS). Examples include:
Glutamate: The primary excitatory neurotransmitter in the CNS, involved in learning and memory.
Gamma-aminobutyric acid (GABA): The primary inhibitory neurotransmitter in the CNS, involved in reducing neuronal excitability.
Glycine: An inhibitory neurotransmitter found mainly in the spinal cord and brainstem.
2. Monoamines:
Derived from single amino acids, these neurotransmitters include:
Dopamine: Involved in the regulation of movement, reward, motivation, and cognition.
Norepinephrine (noradrenaline): Involved in the regulation of attention, alertness, and the fight-or-flight response.
Serotonin: Involved in mood regulation, appetite, sleep, and cognitive functions such as learning and memory.
Histamine: Involved in the regulation of arousal, wakefulness, and inflammatory responses.
3. Neuropeptides:
These are short chains of amino acids that act as neurotransmitters or neuromodulators, regulating neuronal activity. Examples include:
Endorphins: Involved in pain relief and the regulation of emotions.
Substance P: Involved in pain transmission and inflammation.
Oxytocin: Involved in social bonding, childbirth, and lactation.
4. Acetylcholine:
Found in both the central and peripheral nervous systems.
Functions: Involved in muscle movement, memory, and the regulation of autonomic functions such as heart rate and digestion.
5. Purines:
Involved in energy metabolism and cellular signaling.
Examples:
A. Adenosine: Involved in energy metabolism.
B. ATP (Adenosine Triphosphate): Involved in cellular signaling..
6. Gasotransmitters:
Small gaseous molecules that can act as neurotransmitters.
Example:
Nitric Oxide (NO): Plays a role in vasodilation and synaptic plasticity.