Neurotransmitters - Chapter 15

Question 1

What are the three types of neurotransmitters? Give examples of each:

Answer 1

Monoamines: serotonin, dopamine, norepinephrine, melatonin, histamine.
Peptides: oxytocin, vasopressin, insulin, angiotensin, endogenous opioids
Gaseous: Nitric Oxide, Carbon Monoxide, Hydrogen Sulfide

Question 2

Describe Acetylcholine degradation at the neuromuscular junction:

Answer 2

Acetylcholine that enters the folds of the neuromuscular junction is broken down into choline and acetate by acetylcholine esterase. Choline is taken back up into the presynaptic cell by cotransport with Na+. Acetylcholine Acetyl-Transferase converts the choline back into acetylcholine. Acetylcholine Vesicular Acetylcholine transferase pumps ACh back into vesicles.

Question 3

Describe Glutamate re-uptake at the synapse:

Answer 3

GLT, a glutamate transport protein cotransports glutamate with Na+ back into the presynaptic cell. Glutamate also taken up into the astrocyte by Na+ cotransport and converted into glutamine. Glutamine is removed from the cell by antiport exchanging Gln for H+. Gln is taken back up into the presynaptic cell and converted back into glutamate. VGlut pumps glutamate into vesicles using H+ as a cotransport molecule.

Question 4

Describe retrograde signalling of endogenous cannabinoids:

Answer 4

Calcium release due to NMDA activity in the post-synaptic cell results in synthesis and release of ananadamine (2-AG). 2-AG activates CB1 receptors (G-protein coupled) on GABAergic pre-synaptic cells. Activation of the CB1 receptor decreases the probability of release.