Ghrelin administration enhances neurogenesis but impairs spatial learning and memory in adult mice

Central acylated ghrelin improves memory function and hippocampal AMPK activation and partly reverses the impairment of energy and glucose metabolism in rats infused with β-amyloid

“…Moon et al [15] demonstrated that intraperitoneal injection (80 µg/kg/day) of ghrelin ameliorates β-amyloid-induced cognitive impairment associated with neuroinflammation and neuronal loss in mice. However, hippocampal injection (8 ng/every other day) and intraperitoneal injection (80 ng/kg/day) of ghrelin blocks spatial memory formation in adult mice although it induces an increase in the number of newborn neurons in the adult hippocampus [16]. However, Kent et al [29] demonstrated that systemic administration of physiological levels of acyl-ghrelin for 8-10 days enhances hippocampal neurogenesis and spatial memory in rats.…”

“…In addition to energy and glucose metabolism, several studies have reported that higher circulating ghrelin levels and intraperitoneal injections of ghrelin improve cognitive function in experimental animals, but some studies have found that hippocampal injection of ghrelin does not enhance spatial memory and neurogenesis [15,16]. Traumatic brain injury patients with cognitive deterioration are reported to have significantly lower plasma ghrelin levels than those with without cognitive deterioration.…”

Evaluation of mTOR signaling pathway proteins in rat gastric mucosa exposed to sulfite and ghrelin

“…In addition, ghrelin was reported to stimulate cell proliferation and reduce apoptosis in prepubertal porcine ovarian granulosa and theca interna cells (31). Numerous studies indicated that ghrelin administration reduces caspase 3 levels and TUNEL positivity in spinal cord neurons and endothelial cells, enhances neurogenesis in the hippocampus, and stimulates proliferation, migration, and differentiation of neural progenitor's cells in the subventricular zone and rostral migratory system of interneurons in the olfactory bulb (32)(33)(34)(35). There are several studies about the effects of ghrelin on mTOR activity in literature.…”

Potential ghrelin-mediated benefits and risks of hydrogen water

“…These effects appear to be mediated, in part, by activation of PI3K and nitric oxide synthase, and by increased insertion of AMPA receptors into post-synaptic membranes [39][40][41]. Ghrelin also stimulates neurogenesis in the hippocampus [44,45]. At least one study has examined the impact of hydrogen water ingestion on hippocampus-dependent learning; although hydrogen water did not influence learning in nonstressed mice, it prevented the adverse impact of chronic restraint stress on learning and memory [46].…”