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      Clarifying the involvement of the calcitonin gene-related peptide (CGRP) signalling mechanism in fear memory formation


      Science Impact, Ltd.

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          CGRP is a small peptide that seems to have a variety of roles, both in the peripheral and central nervous systems and potentially throughout the body. It has been implicated as a key factor in the nociceptor system of response to harmful stimuli. As such, it is involved in pain perception pathways. ‘’Notably, it has been heavily implicated in the pathophysiology of migraines,’ highlights Hashikawa-Hobara. ‘At the same time, it is also a strong vasodilator, capable of significantly reducing blood pressure in an individual administered with it.’ Receptors for CGRP appear to be expressed throughout the body, however, so many roles remain uncharacterised. Hashikawa-Hobara is researching the part that the peptide plays in fear memory formation and has been learning more about how CGRP is implicated in fear. ‘CGRP is distributed extensively in the brain, such as in the hypothalamus, preoptic area, amygdala, thalamus, hippocampus, and dentate gyrus granule cells,’ she clarifies. ‘CGRP is reported to be involved in various behaviours suggestive of anxiety as well as improved learning and memory processing. We do not clearly understand the role of CGRP in hippocampus-dependent fear memory, however. Some work has reported that a CGRP infusion will evoke a fear-like freezing, however, we believe the effect to be subtler.’ Hashikawa-Hobara’s results from her work suggest a nuanced role for CGRP in fear memory formation. She has shown that the peptide can have both PTSD-prevention and PTSD-stimulation properties. This is because they found that the administration of CGRP to fear-induced mice had different results depending on when the molecule was introduced. She showed that if administered immediately after fear induction, CGRP could help quickly erase the memory or perhaps eliminate its creation. However, if administered much later, it invokes fear in the studied mouse. ‘When CGRP is administrated just after the fear experience, it would erase the fear memory,’ she says. ‘When these early CGRP-administered mice were re-exposed to the context, no freezing time compared to saline treated controls. However, later administration of CGRP essentially caused greater fear and an immediate freezing response.’

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          Science Impact, Ltd.
          December 31 2018
          December 31 2018
          : 2018
          : 12
          : 102-104
          © 2018

          This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

          Earth & Environmental sciences, Medicine, Computer science, Agriculture, Engineering


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