Question

Benzodiazepines are positive allosteric modulators at the GABA-A receptor.

a) Describe how positive allosteric modulators affect receptor function.

b) Discuss the mechanism of action of benzodiazepines and their effect on central nervous system (CNS) activity.

c) GABA is also an agonist at GABA-B receptors, which are G protein coupled receptors that couple to Gi. Explain the signalling pathways that will be activated when GABA binds to the GABA-B receptor.

Answer 1

a) Allosteric modulators are group of substance that bind to the receptors to change the receptor response to the stimuli.Benzodiazepines like diazepam are positive allosteric modulators at GABA-A,they increases the affinity of agonist and or efficacy.

b)GABA receptor is a chloride ion channel receptor it consists of subunits such as 2 alpha ,2 beta,1 gamma subunits.Benzodiazepines bind between alpha and gamma subunit thus increases the opening of chloride channels this results in more entry of chloride ions into the lumen results in neural relaxation which leads to sedation and hypnosis.

c)GABA is an inhibitory neurotransmitter that binds at the GABA-B receptor which are G protein coupled receptor that couple the Gi the alpha subunit closes the chloride channel in the receptor the binding of GABA at the junction of Alpha and beta causes openiy of chloride channels by pushing the alpha subunit back which leads to entry of chloride ions into the lumen this causes the neural relaxation which leads to sedation and hypnosis.