Neurotransmission

Action potential - a rapid electrical signal that travels along the axon of a neuron

Neurotransmitter - a chemical messenger between neurons e.g. serotonin, dopamine, glutamate etc.

 

Neurotransmitters

• often endogenous chemicals
• naturally occurring in the brain
• They can also be exogenous, meaning they can be introduced into the brain from the outside in the form of drugs such as THC, MDMA, alcohol.

Endogenous neurochemicals

• Vast majority of these are neurotransmitters
• Neurotransmitters bind to 'receptors' on a neuron to influence its firing
• Neurotransmitters are released by neurons
• e.g. Dopamine is released by dopamine neurons

Neurotransmitters bind to receptors

• Neurotransmitter = key; Receptors = lock
• When a receptor is bound by a neurotransmitter, it becomes activated
• This can either cause or inhibit action potentials (cell firing)

 

Types of Receptors

• Dopamine receptors: D1, D2, D3, D4
• 17 Serotonin (5-HT) Receptor: 5-HTIA, 1B, 1C, 2A, 2B, etc.
• 3 Glutamate Receptors: mGlur, AMPA, Kainate
• GABA receptors
• Norephinephrine (adrenaline) receptors
• Acetylcholine (ACh) receptors

Serotonin (5-HT) 1A is inhibitory, while 5-HT2A is excitatory

ex. Nicotine

Releases dopamine into the brain. Dopamine is a monoamine neurotransmitter that signals for reward. When smoked, nicotine enters the blood stream, and makes its way into the brain in 7 seconds. Nicotine-Induced Dopamine Release occurs when dopamine are on neurons. When nicotine binds to the nicotinic receptors (nAChRs) on the dopamine neurons on the VTA/Ventral Tegmental Area, these neurons release dopamine into the NAcc/Nucleus Accumbens.

This dopamine release gives the smoke the feeling of reward, which reinforces positive feelings associated with repeated smoking.