Intro To CNS Flashcards
Describe the small molecules neurotransmitters.
They are:
- “classical” low-molecular weight neurotransmitter substances
- there are many biochemical similarities including biosynthetic and degradation pathways.
- all of these are amines and six derived from amino acids (ACh is the exception)
What are two major classes of neurotransmitters?
1) small molecules
2) peptides
What are the small molecule neurotransmitters?
1) acetylcholine (ACh)
2) dopamine (DA)
3) norepinephrine (NE)
4) epinephrine
5) serotonin (5HT)
6) glutamate
7) GABA
Describe peptide neurotransmitters.
- These are also “small” molecules, these are typically larger than the ‘small molecules’.
- There is an incredible diversity of peptide neurotransmitters in the brain.
What classes are included in the peptide neurotransmitters?
1) opioid-type peptides (like endorphins and enkephalins)
2) gut-brain peptides (like substance P)
3) hypothalamic-releasing hormones
4) the pituitary hormones
What is ACETYLCHOLINE?
- ACh is an excitatory neurotransmitter used in the CNS and PNS.
- In the PNS, ACh is used by motor neurons to trigger muscle contractions.
- In the CNS, it maintains the electro-encephalographic (EEG) signals of the cortex and plays a role in memory by maintaining neuronal excitability.
How is Alzheimer’s disease related to ACh?
Alzheimer’s disease is related to the death of cholinergic (ACh-containing) neurons in the cortex.
What are the two types of ACh receptors?
- 2 types of ACh receptors are : 1) muscarinic and 2) nicotinic.
- Muscarinic ACh receptors are G-protein coupled receptors
- nicotinic ACh receptors are ion channels
What is ACh made of?
- ACh is made from acetyl-CoA and choline by the enzyme cholineacetyltransferase (ChAT).
- acetyl-CoA is derived from the Krebs cycle in mitochondria
- choline is only obtained from the diet and transported into neurons.
How is ACh eliminated?
ACh is eliminated by the enzyme acetylcholinesterase (AChE) that breaks down the neurotransmitter into choline and acetate.
ACh: What is an organophosphate-containing insecticides drug?
Malathion
ACh: What drug are nerve gases that are irreversible AChE inhibitors?
Sarin
What are used for Alzheimer’s symptoms?
Reversible AChE inhibitors
What is ACh receptor agonist?
Nicotine
What is a ACh receptor antagonist?
scopolamine
What are CATECHOLAMINES?
Catecholamines are a family of neurotransmitters that contain a “catechol” nucleus.
What neurotransmitters are CATECHOLAMINES?
1) DOPAMINE
2) NOREPINEPHRINE
3) EPINEPHRINE
What are the uses Dopamine?
- Dopamine is involved in regulation of motor activity, motivation and reward, mood, sleep, learning, attention, etc.
- Parkinson’s disease is related to the death of dopaminergic neurons in the substancia nigra (part of the subthalamus).
- Reduced levels of dopamine may be related to attention deficit hyperactivity disorder (ADHD).
- Too much dopamine may be related to schizophrenia.
What are the uses of Norepinephrine?
Norepinephrine is involved in alertness, focus, positive feelings of reward.
What are the uses of epinephrine ?
Epinephrine (also referred to as adrenalin) is involved in alertness and, together with NE, is part of the “fight-or-flight” stress response.
How are catecholamines made?
-catecholamines are derived from the amino acid tyrosine by a series of enzymatic steps that convert tyrosine into dopamine, then into norepinephrine, then into epinephrine.
How are catecholamines eliminated?
eliminated from the synaptic cleft by either
1) reuptake transporters or
2) by degradation enzymes (like monoamine oxidase [MAO] or catechol-O-metyltransferase [COMT]).
What drugs disrupt reuptake transporters in catecholamines ?
1) cocaine
2) amphetamines
What are used as antidepressants?
MAO inhibitors
