Beyond appetite: Acylated ghrelin as a learning, memory and fear behavior-modulating hormone

Area of Science:

• Neuroscience
• Endocrinology
• Behavioral Science

Background:

• Acylated ghrelin (AG) is traditionally known as a hunger hormone.
• Emerging research reveals AG's significant neuroprotective functions.
• AG is implicated in regulating memory and fear-related behaviors.

Purpose of the Study:

• To review the specific effects of AG on different memory types and brain regions.
• To illustrate AG's role in hippocampal plasticity and neurogenesis.
• To elucidate AG's modulation of key neurotransmitter systems and its implications in stress and memory.

Main Methods:

• Literature review of studies investigating acylated ghrelin.
• Analysis of signaling pathways related to AG in the hippocampus.
• Examination of AG's influence on neurotransmitter systems (glutamate, GABA, dopamine, serotonin).

Main Results:

• AG affects specific stages and forms of memory, impacting brain areas like the hippocampus and amygdala.
• AG influences plasticity-associated signaling pathways and neurogenesis.
• AG modulates neurotransmitter systems, affecting conditioned taste aversion, novelty learning, and various fear memories.

Conclusions:

• Acylated ghrelin has diverse roles beyond appetite regulation, including significant impacts on memory and fear behavior.
• AG's interaction with the 5-HT system and its link to PTSD warrant further investigation.
• The context-dependent effects of AG on fear (suppressing or potentiating) highlight its complex role in stress responses.