6 Questions
Where do benzodiazepines bind on the GABA extsubscript{A} receptor?
At a specific, high-affinity site at the interface of the $ extalpha$ subunit and the $ extgamma$ subunit
What is one mechanism through which benzodiazepines produce anxiolytic effects at low doses?
By enhancing GABAergic transmission in neurons having the $ extalpha_2$ subunit in their GABA extsubscript{A} receptors
What is the main action of benzodiazepines on chloride ion channels?
Increasing the frequency of channel openings produced by GABA
What designations are given to common BZ receptor subtypes in the CNS?
BZ extsubscript{1} and BZ extsubscript{2}
How do benzodiazepines affect the affinity of GABA for its binding site?
They increase the affinity of GABA for the binding site
Which part of the brain is most involved in the anxiolytic effects of benzodiazepines?
Limbic system
Study Notes
Anxiolytic and Hypnotic Drugs
- Benzodiazepines modulate GABA effects by binding to a specific, high-affinity site on the GABA(_A) receptor, located at the interface of the α subunit and the γ subunit.
Mechanism of Action
- Benzodiazepines increase the frequency of channel openings produced by GABA.
- Binding of a benzodiazepine to its receptor site increases the affinity of GABA for the GABA-binding site (and vice versa).
BZD Receptor Subtypes
- BZ(_1) subtype: includes an α(_1) subunit.
- BZ(_2) subtype: includes an α(_2) subunit.
Clinical Effects
- The clinical effects of benzodiazepines correlate well with the binding affinity of each drug for the GABA receptor–chloride ion channel complex.
Actions of Benzodiazepines
- Reduction of anxiety: anxiolytic effects at low doses.
- Mechanism of anxiolytic action: selectively enhancing GABAergic transmission in neurons having the α(_2) subunit in their GABA(_A) receptors, thereby inhibiting neuronal circuits in the limbic system of the brain.
This quiz covers the effects and mechanisms of benzodiazepines on GABA receptors in the CNS, including receptor subtypes and binding sites.
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