The Neurocognitive Effects of Ghrelin-induced Signaling on the Hippocampus: A Promising Approach to Alzheimer's Disease.

The communication between the gastrointestinal tract and the central nervous system (CNS) allows for certain peptide hormones to influence neurocognitive function. Ghrelin, also known as the 'hunger hormone,' has the unique ability to enter the CNS and interact with the growth hormone secretagogue receptor (GHS-R) within the hippocampus. Upon interaction with ghrelin, a conformational change in the receptor causes an increase in transcription factors to foster a wide array of physiologic changes in response to caloric deprivation. With the GHS-R in a relatively high concentration within the hippocampus, ghrelin can promote memory, spatial, learning, and behavioral effects. In fact, ghrelin appears to also have a neuroprotective and neuromodulatory response once active within the hippocampal dentate gyrus. Through the GHS-R, higher levels of ghrelin may alter cognitive circuitry and offer a possible link to the treatment of some pathologies implicated in neurological dysfunction. Alzheimer's disease (AD) is already becoming a significant target for ghrelin neuroreceptor therapy. In such experimental models, ghrelin has been shown to combat this degenerative process by eliciting an ameliorative and regenerative response. Although trials and research are still ongoing, further studies are indicated as early research into this adjuvant therapy is promising. The research team explored the effects of ghrelin by reviewing the downstream signaling modifications of ghrelin's interaction with a specific CNS receptor, the GHS-R. Although the GHS-R is found in multiple locations within the CNS, the team investigated the role of the GHS-R within the hippocampus to focus solely on the neurocognitive implications of ghrelin. The team noted which signaling pathways in particular that ghrelin initiated and used this approach to determine whether ghrelin may have any therapeutic benefits. The team explored the possible therapeutic indications of ghrelin by looking at studies conducted with a specific neurodegenerative disease known to target the hippocampus.