Chap 6 lec 2 Flashcards
What are the three catecholamines, and what amino acid are they derived from?
Dopamine, Norepinephrine, and Epinephrine; all derived from Tyrosine.
What are the key brain regions where dopamine is produced?
Substantia nigra and ventral tegmental area (VTA).
What is the primary function of dopamine?
Coordination of Movement (nigrostriatal pathway), reward/motivation pathway, (mesolimbic),
cognition/attention (mesocortical).
Which receptors does dopamine act on, and how are they classified?
Metabotropic receptors:
D1 and D5 receptors: (Gs-coupled) - Stimulatory
D2, D3, and D4 receptors: (Gi-coupled) - Inhibitory
What transporter is responsible for dopamine reuptake, and what drug inhibits it?
Dopamine Transporter (DAT); Cocaine inhibits DAT, increasing dopamine in the synapse.
How is norepinephrine synthesized from dopamine?
Dopamine β-hydroxylase (DBH) converts dopamine to norepinephrine inside vesicles.
What are the primary functions of norepinephrine?
Regulates arousal, attention, stress response
Autonomic (sympathetic) functions: heart rate, blood pressure
What enzyme converts norepinephrine to epinephrine?
Phenylethanolamine-N-Methyltransferase (PNMT).
What are the primary receptors for norepinephrine and epinephrine?
α1 & β adrenergic receptors = Stimulatory
α2 adrenergic receptors = Inhibitory (negative feedback on NE release)
How are catecholamines degraded?
By Monoamine Oxidase (MAO) and Catechol-O-Methyltransferase (COMT).
What neurotransmitter is synthesized from tryptophan?
Serotonin (5-HT).
What enzyme converts tryptophan to serotonin?
Tryptophan-5-hydroxylase.
What are the key functions of serotonin?
Mood regulation, sleep, appetite, and cognition.
What transporter is responsible for serotonin reuptake, and what class of drugs inhibits it?
Serotonin Transporter (SERT); Selective Serotonin Reuptake Inhibitors (SSRIs) inhibit it (e.g., fluoxetine).
What is the major difference between serotonin receptors?
Most serotonin receptors (5-HT1, 5-HT2, 5-HT4-7) are metabotropic (GPCRs).
5-HT3 is ionotropic (fast-acting, excitatory).
What neurotransmitter is synthesized from histidine?
Histamine.
What are the key functions of histamine in the brain?
Wakefulness (H1), attention, and immune responses.
What are the major histamine receptors?
H1 → Wakefulness, arousal
H2 → Gastric acid secretion
H3 → Negative feedback inhibition (autoreceptor)
H4 → Immune function
What are the two types of ATP receptors, and how do they function?
P2X (Ionotropic) → Excitatory, Na⁺ & Ca²⁺ influx
P2Y (Metabotropic) → Inhibitory, G-protein-coupled
What is the role of adenosine in neurotransmission?
Inhibitory neuromodulator that promotes sedation and inhibits neurotransmitter release.
How does caffeine affect neurotransmission?
Caffeine is an adenosine receptor antagonist (A1, A2A), blocking sedative effects and increasing alertness.
Which three neurotransmitters use vesicular monoamine transporter-2 (VMAT-2) for storage?
Dopamine, Norepinephrine, and Serotonin.
Which reuptake transporters correspond to dopamine, norepinephrine, and serotonin?
DAT for Dopamine
NET for Norepinephrine
SERT for Serotonin
What is the key difference between ionotropic and metabotropic receptors?
Ionotropic receptors = Fast-acting, ion channels (e.g., P2X, NMDA).
Metabotropic receptors = Slow, G-protein-coupled (e.g., Dopamine D1/D2, Histamine H1-H4).
Where are neuropeptides synthesized, and how do they differ from small-molecule neurotransmitters?
Synthesized in the soma, packaged in large dense-core vesicles, and have long-lasting effects.
Give an example of a neuropeptide involved in pain modulation.
Substance P.
What neuropeptide acts as a natural opioid?
Endorphins.
How is nitric oxide (NO) different from traditional neurotransmitters?
Not stored in vesicles
Synthesized on demand from Arginine via NO synthase
Diffuses freely and activates guanylate cyclase → cGMP
What is the primary role of NO in the nervous system?
Modulates synaptic plasticity and regulates vascular tone (vasodilation).
What are the five major types of neurotransmitters covered?
Biogenic Amines (Dopamine, Norepinephrine, Epinephrine, Serotonin, Histamine)
Amino Acid NTs (Glutamate, GABA, Glycine)
ATP & Purines (P2X, P2Y, Adenosine)
Neuropeptides (Substance P, Endorphins)
Nitric Oxide (NO)
Which neurotransmitters are primarily involved in mood regulation?
Serotonin, Dopamine, and Norepinephrine.
Which neurotransmitter is mainly responsible for wakefulness and arousal?
Histamine (H1 receptor activation).
What enzyme degrades dopamine, norepinephrine, and serotonin?
Monoamine Oxidase (MAO).
What are two unconventional neurotransmitters covered?
ATP and Nitric Oxide (NO).
Which neurotransmitter is synthesized on demand rather than stored in vesicles?
Nitric Oxide (NO).
How do SSRIs (Selective Serotonin Reuptake Inhibitors) work?
Block serotonin reuptake via SERT, increasing serotonin levels in the synaptic cleft.
