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40 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are the receptors for ACh in the CNS?
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Muscarinic (M1 and M2)
Nicotinic (N) |
M1 - G protein-coupled receptors. Slow excitation via decreasing membrane permeability to K+. Works through IP3 and DAG
M2 - G protein-coupled receptors. Inhibitory. Increases K+ conductance. Decreases cAMP Nicotinic receptors - inhibitory interneurons to provide negative feedback against alpha motor neurons |
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Where are ACh receptors located in the CNS?
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Muscarinic - located on cell bodies at all levels of CNS, and on short and long axons
Nicotinic - located on Renshaw cells in the spinal cord |
ACh receptors are found in ~5% of brain neurons
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What are some drugs that block the ACh pathways?
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Atropine (M1 and M2)
Pirenzepine (M1) |
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What are the receptors for Dopamine in the CNS?
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D1 and D2
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D1 - inhibitory. Increases cAMP
D2 (presynaptic) - Inhibitory. Inactivation of Ca2+ channels. D2 (postsynaptic) - G protein-coupled activation of K+ channels. Slow inhibition. Decreases cAMP |
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Where are DA receptors located in the CNS?
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Cell bodies at all levels, and on short, medium and long axons
D2 - basal ganglia Nigrostriatal, mesolimbic, tuberoinfundibular tracts |
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What are some drugs that block the DA pathways?
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Typical antipsychotics (Chlorpromazine, Haloperidol) - D2
Phenothiazines (D1, D2) |
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What drugs activate the DA pathways of the CNS?
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CNS stimulants (amphetamines, cocaine)
Anti-parkinsonian drugs (Levodopa) |
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What are the receptors for NE in the CNS?
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Alpha1, Alpha2 (presynaptic and postsynaptic), Beta1, Beta2
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Alpha1 - Excitatory. Decreases K+ conductance, increases IP3 and DAG
Beta 1 - Excitatory. Decreases K+ conductance. Increases cAMP Alpha2 (presynaptic) - inhibitory. Decreases Ca2+ conductance Alpha2 (postsynaptic) - Inhibitory. Increases K+ conductance, decreases cAMP Beta2 - Inhibitory. Mechanism unknown ?increase in electrogenic Na pump |
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Where are NE receptors located in the CNS?
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Cell bodies in the pons and brain stem
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What are some drugs that enhance the activity of noradreneregic pathways?
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CNS stimulants (amphetamines, cocaine)
MAOIs (phenelzine) TCAs (amitriptyline) |
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What are some drugs that inhibit the noradrenergic pathways?
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Prazosin (alpha1)
Clonidine (alpha2) Propranolol (beta1 and beta2) |
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What are the receptors for 5-HT in the CNS?
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5-HT1A, 5-HT2A, 5-HT3, 5-HT4
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5-HT1A - G protein-coupled receptor to K+ channel. Inhibitory. Increases K+ conductance (same K+ channel as GABAb)
5-HT2A - G protein-coupled receptor. Excitatory. Decreases K+ conductance. Increases IP3 and DAG 5-HT3 - Excitatory. Increases cation conductance 5-HT4 - G protein-coupled receptor. Excitatory. Decreases K+ conductance. Increases cAMP |
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Where are 5-HT receptors located in the CNS?
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Cell bodies in midbrain raphe and pons
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What drugs inhibit activity of 5-HT pathways?
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Buspirone (partial agonist of 5-HT1A)
Clozapine, Risperidone, Olanzapine (5-HT2A) Ondansetron "Zofran" (5-HT3) Reserpine (depletes vesicular stores of 5-HT and NE in CNS neurons) |
May induce Parkinsonian features
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What are the receptors for GABA in the CNS?
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GABAa
GABAb |
GABAa - Opens Cl- channels. Fast inhibition.
GABAb (presynaptic) - G protein-coupled receptor associated with Ca2+ channel. Slow inhibition. Decreases Ca2+ conductance GABAb (postsynaptic) - G protein-coupled receptor associated with K+ channel. Slow inhibition. Increases K+ conductance |
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Where are GABA receptors located in the CNS?
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Involved in Hierarchical systems
Supraspinal interneurons Spinal interneurons (involved in presynaptic inhibition) |
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What are some drugs that enhance the activity of the GABA pathways?
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Sedative-hypnotics (Benzodiazepines, Barbiturates, Zolpidem "Ambien") - GABAa
Anticonvulsants (gabapentin, tiagabine, vigabatrin) - GABAa Baclofen - GABAb |
GABAa - fast IPSPs
GABAb - slow IPSPs |
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What are the receptors for Glutamate in the DNS?
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NMDA
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NMDA - Excitatory. Increases Ca2+ or cation conductance
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Where are Glu receptors located in the CNS?
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Involved in Hierarchical systems
Relay neurons at all levels |
Involved in arousal, synaptic plasticity related to learning and memory
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What are some drugs taht inhibit the activity of the Glu pathways?
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PCP
Ketamine Memantine |
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What are the receptors for Glycine in the CNS?
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Single subtype
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Inhibitory. Increase Cl- conductance
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Where are receptors for Glycine located in the CNS?
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Interneurons in spinal cord and brain stem
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What drugs inhibit the activity of Glycine pathways?
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Strychnine
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Spinal convulsant
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What are receptors for opioid peptides in the CNS?
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3 major subtypes (mu, delta, kappa)
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Presynaptic - inhibitory. Decrease Ca2+ conductance. Decrease cAMP
Postsynaptic - Inhibitory. Increase K+ conductance. Decrease cAMP |
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Whare are the opioid peptide receptors located in the CNS?
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Located in cell bodies at all levels of the CNS
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What are some opioid peptides?
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Beta-endorphin
Met-enkephalin Leu-enkephalin Dynorphin |
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What is the activity of endocannabinoids?
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They are released from the postsynaptic neuron but act presynaptically (retrograde) to decrease transmitter release
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What characteristics of drug molecules afford access to the CNS?
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Lipid solubility allows for molecules to cross the BBB
Only low molecular weight polar molecules can cross the BBB (ethanol, lithium) |
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What concerns are there regarding CNS drug use in the pregnant patient?
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CNS drugs readily cross the placental barrier. Concerns include possible effects on fetal development or use near the time of delivery
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How are CNS drugs eliminated from the body?
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Almost all CNS drugs require metabolism to more polar metabolites to allow for elimination (exception is Lithium).
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What neurotransmitters are solely inhibitory?
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Dopamine
GABA Glycine Opioid peptides |
No neurotransmitters are solely excitatory
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What receptors are solely inhibitory?
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M2 (ACh)
D1, D2 (DA) Alpha2, Beta2 (NE) 5-HT1A (5-HT) GABAa, GABAb (GABA) Presynaptic Glu receptors Glycine receptor Opoid receptors (mu, delta, kappa) |
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What receptors produce slow EPSPs?
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ACh (M1)
NE (alpha1, beta1) 5-HT (5-HT2A, 5-HT4) Postsynaptic Glu receptors |
Work through decreasing K+ conductance, slowly depolarizing cells
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What receptors produce slow IPSPs?
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ACH (M2)
DA (D2 postsynaptic) NE (alpha 2 postsynaptic) 5-HT (5-HT1A) GABA (GABAb postsynaptic) Opioid (mu/delta/kappa postsynaptic) |
Work through increases K+ conductance, slowly hyperpolarizing cells
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What receptors are present on the presynaptic neuron?
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DA (D2)
NE (alpha2) GABA (GABAb) Glu Opioids |
Provide feedback to inhibit release of NTs (all presynaptic are inhibitory - involve decreasing Ca2+ conductance)
Glu is the sole NT that works as excitatory on the postsynaptic while inhibitory on the presynaptic |
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What receptors work via a Cl- channel?
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GABA, Glycine
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What receptors involve decreasing cAMP levels?
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M2 (ACh)
D1 (DA) Alpha2 (NE) presynaptic Glu receptors pre- and post-synaptic opioid receptors |
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What receptors involve increasing cAMP levels?
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Beta1 (NE)
5-HT4 |
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What receptors involve increasing IP3 and DAG levels?
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M1 (ACh)
Alpha1 (NE) 5-HT2A postsynaptic Glu receptor |
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What receptors involve decreasing IP3 and DAG levels?
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None
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