TY - JOUR

T1 - Beyond appetite

T2 - Acylated ghrelin as a learning, memory and fear behavior-modulating hormone

AU - Reich, N.

AU - Hölscher, C.

PY - 2022/12/31

Y1 - 2022/12/31

N2 - Although often referred to as a hunger hormone, recent evidence highlights a neuroprotective function of acylated ghrelin (AG) and a substantial role in the regulation of declarative and aversive memories as well as fear behavior. As such, in this review, we i) evaluate what specific stages and forms of memory, as well as which respective brain areas are affected by acylated ghrelin, ii) illustrate the plasticity-associated signaling pathways of AG in the hippocampus, also involving memory resolution-enhancing neurogenesis, iii) elucidate how the peptide modulates neurotransmitter systems (glutamate, γ-aminobutyric acid, dopamine, serotonin), iV) clarify the role of AG in conditioned taste aversion, novelty learning and the formation of spatial, recognition, auditory fear, contextual fear and passive avoidance memories in the hippocampus and amygdala as well as V) solve the mystery behind AG, its impact on the 5-HT system, the recently established link to post-traumatic stress disorder and the either fear-suppressing or fear-potentiating effects under neutral and acutely stressed conditions or chronic stress, respectively.

AB - Although often referred to as a hunger hormone, recent evidence highlights a neuroprotective function of acylated ghrelin (AG) and a substantial role in the regulation of declarative and aversive memories as well as fear behavior. As such, in this review, we i) evaluate what specific stages and forms of memory, as well as which respective brain areas are affected by acylated ghrelin, ii) illustrate the plasticity-associated signaling pathways of AG in the hippocampus, also involving memory resolution-enhancing neurogenesis, iii) elucidate how the peptide modulates neurotransmitter systems (glutamate, γ-aminobutyric acid, dopamine, serotonin), iV) clarify the role of AG in conditioned taste aversion, novelty learning and the formation of spatial, recognition, auditory fear, contextual fear and passive avoidance memories in the hippocampus and amygdala as well as V) solve the mystery behind AG, its impact on the 5-HT system, the recently established link to post-traumatic stress disorder and the either fear-suppressing or fear-potentiating effects under neutral and acutely stressed conditions or chronic stress, respectively.

KW - Acylated ghrelin

KW - Alzheimer's disease

KW - Chronic stress

KW - Conditioned taste aversion

KW - Dopamine

KW - Fear memory

KW - Food reward response

KW - Neurogenesis

KW - Post-traumatic stress disorder

KW - Serotonin

KW - Synaptic plasticity

U2 - 10.1016/j.neubiorev.2022.104952

DO - 10.1016/j.neubiorev.2022.104952

M3 - Journal article

VL - 143

JO - Neuroscience and Biobehavioral Reviews

JF - Neuroscience and Biobehavioral Reviews

M1 - 104952

ER -