“No day is so bad it can't be fixed with a nap.” Carrie Snow

2) Neurotransmitter pathways (NTs are projected across the brain through pathways)

The neurotransmitters are projected through pathways to different regions around the brain.

A basic example of the Norepinephrine neurotransmitter’s pathway in the human brain.

1) The neurotransmitters are produced by the nuclei around the body (the blue blobs).

2) The neurotransmitters are then projected along the pathways (the blue lines) to the area of the brain they are designed for.

This is a basic example of the Serotonin (5HT) neurotransmitter’s pathway projection.

Serotonin in different areas of the brain can affect a person’s:

• ·         Feeding
• ·         Sleep
• ·         Anxiety
• ·         Aggression
• ·        Depression

However when the Transmitter gets to where it needs to go it then matches up with the correct receptor. There are loads of different types of receptors which all do different things, for example serotonin (5HT)….

(5HT goes up to 5HT 7)

5HT 1a, (high concentrations in hippocampus and hypothalamus

5HT 1b,

etc …,

5HT 2a

5HT 2b

5HT 2c

etc …,

5HT 3a

etc …,

5HT 4a

etc …

5HT 7a

etc …,        This really shows that the brain is a very complex thing, whereas drugs are very simple.

This leads to drugs having side effects, Uh oh!

• Prozac (SSRI) increases the serotonin (5HT) in all 5HT pathways and at nearly every 5HT receptor, oh dear me, there are side effects.
• Stimulation of 5HT 2a projected from the raphe nuclei to the limbic cortex effecting the agitation and anxiety behaviours.
• There is also a change in the motor movements in the Basal ganglia.
• 5HT 2a in the brainstem effects the movement made in sleep and disrupts the slow-wave sleep.
• 5HT 2a in the spinal cord also inhibits orgasms and general sexual functioning.
• 5HT 2a in the dopamine pleasure centers effects the apathy and decreases the libido.
• 5HT 3 in the hypothalamus effects nausea and appetite
• 5HT 3&4 in the intestine can cause cramps, and bowel motility.

To summarize:

• ·         Neurotransmitter pathways modulate behaviour.

• ·         Actions of drugs can be understood by considering their action at the synapse AND on the pathway.

• ·         Neurotransmitter pathways interact so unexpected drugs can be therapeutic (and problematic).

Next Post

3) Drug use (Tolerance and withdrawal)