Bche, also known as butyrylcholinesterase, is an enzyme typically associated with hydrolyzing the neurotransmitter acetylcholine. It has been long considered an "orphan enzyme" with no clear physiological role, other than metabolizing exogenous bioactive esters in diet or medicines [1]. However, recent studies suggest it is involved in multiple biological processes, such as lipid metabolism, weight gain, fat metabolism, and emotional behaviors [1,2].

In gene knockout mouse models, BChE-knockout mice showed faster weight gain on high-fat diets [1]. Viral gene transfer studies in mice revealed that BChE hydrolyzes ghrelin, the "hunger hormone", affecting its circulating levels, which in turn impacts weight gain, fat metabolism, and emotional behaviors like aggression [1]. Overexpression of BChE led to low ghrelin levels, reducing aggression and social stress in mice, and in some cases, increasing lifespan in group-housed animals [1].

In conclusion, Bche plays important roles in lipid metabolism, weight and fat regulation, and emotional behaviors as revealed through mouse model-based research. Its function in hydrolyzing ghrelin has implications for understanding weight-related and emotional-behavioral disorders. Moreover, Bche has been associated with diseases such as endometrial cancer, Alzheimer's disease, and is related to the prolonged effect of muscle relaxants, indicating its significance in multiple disease areas [1,3,4,5].