Question

Background information: Prolonged exposure of nicotinic acetylcholine receptors to acetylcholine results in a change in the receptors that decreases their subsequent sensitivity to acetylcholine (i.e. higher acetylcholine concentrations are then needed to activate the receptor). This modification is known as desensitization. Some nerve terminals that release acetylcholine also contain the peptide neurotransmitter, calcitonin gene related peptide (CGRP). Following high frequency stimulation of these terminals, the post-synaptic nicotinic acetylcholine receptors become phosphorylated. Once phosphorylated, the receptors desensitize much more rapidly. The phosphorylation of the nicotinic acetylcholine receptor requires release of CGRP from the presynaptic terminals and a subsequent post-synaptic increase in cyclic AMP.

Q. Briefly discuss why a neurotransmitter peptide such as CGRP provides a suitable means to signal to the post-synaptic neuron that there has been high frequency stimulation of the nerve terminals

Answer 1

Calcitonin gene related peptide or CGRP is a type of peptide neurotransmitter helps in signaling the post synaptic neuron of high frequency stimulation of nerve terminals. The CGRP is required for the nerve terminal high frequency stimulation as they are majorly concentrated and localized across the non-neuronal tissues. It helps in mediating the sympathetic outflow of the information from the brain and hence it helps in passing the signal and the message which helps in phosphorylating the terminal ends and hence helps in the process of activation. The CGRP helps in higher and quicker activation of the terminal receptors and provides a suitable means as it receives the signal immediately and helps in sending across the multiple nerve terminals.