Brain Neurotransmitters Overview

Question 1

Glutamate

Answer 1

Generally a stimulatory motor NT

Postsynaptically stimulatory NT that acts on three main types of receptors: AMPA (Na and K), NMDA (Ca, Na, and K) –> needs depolarized membrane to work, long term potentiation, and Kainic acid (Na and K)

Presynaptically can inhibit neutransmission via metabotropic receptors.

Question 2

GABA

Answer 2

Inhibitory Motor Neurotransmitter with two main receptors:

GABAa is a Cl- channel that hyperpolarizes

GABAb is a metabotropic channel that inhibits adenylyl cyclase to augment K or inhibit Ca channels

*Benzodiazapenes activate GABA receptors to cause sedation. Baclofen is a GABA receptor agonist used as a muscle relaxant.

Question 3

Glycine

Answer 3

Inhibitor Motor NT of spinal cord and brainstem whose receptor is permeable to Cl-.

Strychnine is an antagonist of glycine receptors. Poison that causes intense muscle spasms.

Question 4

Acetylcholine

Answer 4

Two classes of receptors:

Nicotinic - sodium channel causing depolarization

Muscarinic - inhibitory metabotropic receptor reducing cAMP or increasing Ca++. Also icreases K+ permeability. Involved in cognitive functions and memory (anticholinesterases sometimes given to fight AD)

Question 5

Dopamine

Answer 5

Acts on two main receptors:

Motor stiumulatory (inhibition of inhibiton) NT with two main receptors:

D1: couples Gs protein to stimulate cAMP production. Associated with Tourrette’s Syndrome

D2: Couples Gi protein to suppress cAMP production. Acts to suppress GABA release (inhibition of inhibition)

Particularly important in substantia nigra to neostriatum projections where dopamine depletion is linked to Parkinson’s disease.

Antipsychotics frequently antagonize these receptors. Some antidepressants prevent dopamine uptake into neuron increasing receptor stimulation.

Functions: Reward, pleasure, motor function, compulsion, perserveration

Question 6

Norepinepherine

Answer 6

Motor inhibitory NT that acts via alpha 2 receptors to increase potassium conductance hyper-polarizing and inhibiting cells.

Alpha - 2 agonists can be used as muscle spasmolytics

Alpha 1 and Beta are involved with attention and arousal.

Question 7

Serotonin (5-HydroxyTryptamine)

Answer 7

5HT3 - Ionotropic and excitatory (conducts cations)

5HT2a - metabotropic –> agents blocking this improve schizophrenia and bipolar. SSRIs increase the amount of serotonin interacting with this receptor producing an anti-depressant effect (be careful for causing bi-polars from going manic)

Question 8

Opiods

Answer 8

Suppress pain by interacting with a u receptro which decreases calcium and cAMP in spinal cord.