Lecture 6 Peptides, Lipid, Nucleosides, gas Flashcards
(28 cards)
What are the four main types of ‘non-traditional’ neurotransmitters?
Peptides, Lipids, Nucleosides, and Gases
Criteria of Non-traditional neurotransmitters
- DO NOT satisfy ALL criteria for a Neurotransmitter
I. Present in presynaptic terminals 存在于突触前末端
II. Released from presynaptic terminals after neuron fires
神经元激发后从突触前末端释放
III. Existence of receptors on postsynaptic neurons 突触后神经元上存在受体
What major class of peptides is involved in pain relief?
Opioids
What is the primary function of opiate drugs?
Pain relief (analgesia) and euphoria
What is a key downside of opiate drugs?
They are highly addictive
What is the mechanism of action of buprenorphine?
Partial agonist at opioid receptors; used to treat heroin dependence
What is naloxone used for?
Full antagonist at opioid receptors; rapidly blocks heroin effects and prevents overdose
Why is methadone used in treatment for heroin dependence?
Agonist like heroin but with a much slower time course
Where are most cannabinoid receptors (CB1) found?
CB1 is found in the brain and is believed to be responsible for the main psychological effects (CB2 is found in peripheral tissue).
What do CB1 receptors do when activated?
shortens the duration of action potentials in the presynaptic neuron –> decreasing amount of neurotransmitter released
What is the active compound in cannabis?
THC (tetrahydrocannabinol)
What are some therapeutic uses of cannabis?
- Reduces nausea,
- relieves asthma attacks,
- decreases intraocular pressure in glaucoma
What condition led to the first legal access to medicinal cannabis in Victoria (2017)?
Severe intractable epilepsy in children
What are nucleosides and what is a key example?
Subunits of nucleic acids like DNA/RNA; Adenosine is a key example
What effect does adenosine have in the brain?
Promotes sleepiness and suppresses arousal
How does caffeine work in relation to adenosine?
Because adenosine increases firing rate in brain areas that promote sleepiness, caffeine increases alertness by reducing the firing/activation of these neurons.
What are some natural sources of caffeine?
Coffee beans, cocoa beans, tea
How is nitric oxide (NO) different from traditional neurotransmitters?
- NO is not synthesized and stored in vesicles like other neurotransmitters.
- NO is produced throughout the cell including dendrites and defuses out of the cell as soon as it is produced.
- NO **does not activate receptors ** but simply enters the neighboring cell
- NO is **very short lived **and is degraded or reacted within a few seconds of being produced
What functions does nitric oxide (NO) serve in the brain?
Involved in synaptic plasticity, learning, memory, and vasodilation
Why is nitric oxide’s action limited in the brain?
It has a very short half-life and degrades within seconds
What are the three criteria for a ‘true’ neurotransmitter?
- Present in presynaptic terminals, 2. Released after neuron fires, 3. Receptors on postsynaptic neurons
Do peptides, lipids, nucleosides, and gases satisfy all neurotransmitter criteria?
No, they do not satisfy all three criteria
What is the main role of lipids like endocannabinoids in neurotransmission?
Modulate the modulators by regulating neurotransmitter release
What distinguishes neuromodulators from neurotransmitters?
Neuromodulators have slower, more global effects and influence sensitivity/function of neurons
