D-Allulose cooperates with glucagon-like peptide-1 and activates proopiomelanocortin neurons in the arcuate nucleus and central injection inhibits feeding in mice.

A rare sugar D-Allulose has sweetness without calorie. Previous studies have shown that D-Allulose improves glucose and energy metabolism and ameliorates obesity. However, underlying mechanisms remain elusive. This study explored the effect of central injection of D-Allulose on feeding behavior in mice. We also examined direct effects of D-Allulose on the neurons in the hypothalamic arcuate nucleus (ARC) that regulate feeding, including the anorexigenic glucagon-like peptide-1 (GLP-1)-responsive neurons and proopiomelanocortin (POMC) neurons. Single neurons were isolated from ARC and cytosolic Ca2+ concentration ([Ca2+]i) was measured by fura-2 microfluorometry. Administration of D-Allulose at 5.6, 16.7 and 56 mM concentration-dependently increased [Ca2+]i in ARC neurons. The [Ca2+]i increases took place similarly when the osmolarity of superfusion solution was kept constant. The majority (40%) of the D-Allulose-responsive neurons also responded to GLP-1 with [Ca2+]i increases. D-Allulose increased [Ca2+]i in 33% of POMC neurons in ARC. D-Allulose potentiated the GLP-1 action to increase [Ca2+]i in ARC neurons including POMC neurons. Intracerebroventricular injection of D-Allulose significantly decreased food intake at 1 and 2 h after injection. These results demonstrate that D-Allulose cooperates with glucagon-like peptide-1 and activates the ARC neurons including POMC neurons. Furthermore, central injection of D-Allulose inhibits feeding. These central actions of D-Allulose may underlie the ability of D-Allulose to counteract obesity and diabetes.

Onion component, isoalliin, stimulates feeding and activates the arcuate nucleus neuropeptide Y, ghrelin- and Ninjin'yoeito-responsive neurons.

Appetite loss or anorexia substantially decreases the quality of life in patients with cancer, depression and gastrointestinal disorders, and can lead to sarcopenia and frailty. Foods that restore appetite have been sought-for but are not currently available. Historically, onion intake was adopted to treat a variety of diseases with reduced appetite including cancer and gastrointestinal disturbances. While isoalliin is a core component of onion, the effects of isoalliin on feeding behavior and feeding centers remain unknown. Neuropeptide Y (NPY) and ghrelin are the most potent central and peripheral inducers of appetite. A Japanese kampo medicine Ninjin'yoeito activates ghrelin-responsive NPY neurons in the hypothalamic arcuate nucleus (ARC) and counteracts anorexia induced by an anti-cancer drug cisplatin. This study explored the effects of isoalliin on feeding behavior and activities of ARC neurons in mice. Isoalliin, injected intraperitoneally, dose-dependently increased food intake during dark phase (DP) and daily without altering light phase (LP) food intake. We measured cytosolic Ca2+ concentration ([Ca2+]i) in single ARC neurons including NPY neurons identified by GFP fluorescence. Isoalliin increased [Ca2+]i in 10 of 18 (55.6%) NPY neurons, a majority of which also responded to ghrelin with [Ca2+]i increases, indicating that the ARC ghrelin-responsive NPY neuron is the major target of isoalliin. Isoalliin also increased [Ca2+]i in the ARC neurons that responded to Ninjin'yoeito. These results indicate that isoalliin enhances feeding at the active period and activates ARC ghrelin-responsive NPY neurons and Ninjin'yoeito-responsive neurons. These abilities of isoalliin to stimulate DP feeding and activate ARC orexigenic neurons provide scientific evidence for the health beneficial effects of onion experienced historically and globally.