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Gastrointestinal mucositis is a major side effect of chemotherapy, leading to life quality reduction in patients and interrupting the therapy of cancer. Chimonanthus nitens var. salicifolius (CS) is a traditional Chinese herb for enteral disease. Considering the protective effect of CS on intestine, we hypothesize that the aqueous extract of CS could be benefcial to gastrointestinal mucositis. To verify this, a mouse mucositis model was induced by 5-Fluorouracil (5-Fu). Male Balb/C mice were treated with CS aqueous extract (5, 10, and 20 g/kg) or loperamide (0.2 mg/kg) intragastrically for 11 days, and the severity of mucositis was evaluated. Furthermore, the chemical compounds of CS aqueous extract were also analysed by high-performance liquid chromatography (HPLC). Our results demonstrated that CS aqueous extract improved mice body weight, diarrhoea, and faecal blood, maintained the liver function and intestinal length, alleviated villus shortening, and suppressed the apoptosis and inflammation in small intestine. We concluded that CS could protect mice against 5-Fu induced mucositis by inhibiting apoptosis and inflammation, and this protective effect might be associated with the 3 flavonoids (rutin, quercetin, and kaempferol) identified in CS aqueous extract.

Opioid receptors are widely distributed in central nervous system and peripheral tissues. Endogenous opioid receptor ligands are involved in many physiological processes.Exogenous peptides, derived from food proteins with gastrointestinal proteases, also exert opioid-like activities, and they include gluten exorphins (wheat), casomorphins (milk), rubiscolins (spinach), and soymorphins (soybean). Milk-derived opioid peptides play both agonistic and antagonistic roles, and most of the opioid peptides exert regulatory functions in the central nervous system, related to nociception, emotion and memory after oral, intracerebroventricular, or intraperitoneal administration. This indicates that the peptides may have crossed the blood-brain barrier or acted peripherally.Furthermore, some food-derived opioid peptides influence gastrointestinal functions such as gut motility, hormone release, appetite, mucus production, and local immunity. In healthy states, food-derived opioid peptides could benefit both the nervous and digestive systems, whereas in pathological conditions, the gastrointestinal permeability change and opioid excess may contribute to pathogenesis of some disorders. Practical applicationsOpioid receptors are important biological targets for the treatment of multiple diseases. Traditional opiate compounds, such as alkaloids, are demonstrated to exert numerous side effects, thereby limiting their clinical effectiveness. It is thought that food-derived opioid peptides may be safer than the alkaloids, and therefore can be applied in functional food development. In this review, we summarized the already discovered food opioid peptides from different sources, and elaborated their physiological functions on the central nervous and gastrointestinal systems. These effects support further exploration of the opioid peptides as therapeutic agents or as functional food ingredient for human health promotion. K E Y W O R D Scasomorphins, central nervous system, exorphins, food peptides, gastrointestinal tract, opioid peptides, rubiscolins, soymorphins

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g-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system. The termination of GABA transmission is through the action of a family of membrane proteins, called GABA transporters (GAT1 -4). It is well established that GABA system is involved in the modulation of memory. Our previous study showed that homozygous GAT1 2/2 mice exhibited impaired hippocampus-dependent learning and memory. To evaluate the impact of endogenous reduced GABA reuptake on mice cognitive behaviors, the ability of learning and memory of heterozygous GAT1 1/2 mice was detected by the passive avoidance paradigm and Morris water maze. The hole board paradigm was also used to measure changes in anxiety-related behavior or exploratory behavior in such mice. As one form of synaptic plasticity, longterm potentiation was recorded in the mouse hippocampal CA1 area. We found that GAT1 1/2 mice displayed increased learning and memory, decreased anxiety-like behaviors, and highest synaptic plasticity compared with wild-type and homozygous GAT1 2/2 mice. Our results suggest that a moderate reduction in GAT1 activity causes the enhancement of learning and memory in mice.