Effects of Hydrolysates from Silkworms Fed Cudrania tricuspidata Leaves on Improvement of Memory in Rats with Impaired Memory Induced by Scopolamine

This study investigated the memory-improving effects and mechanisms of action of hydrolysate from silkworm fed Cudrania tricuspidata leaves (HSCT) in rats with scopolamine-induced memory impairment. Thirty-two rats were categorized into 4 groups and the experiment was conducted for 6 weeks. The experimental diet groups are as follows: control, control diet; scopolamine, control diet + scopolamine (0.7 mg/kg); HSCT, HSCT diet + scopolamine (0.7 mg/kg); and donepezil, control diet + scopolamine (0.7 mg/kg) + donepezil (1.0 mg/kg). Except for the control group, the experimental groups received scopolamine 0.7 mg/kg intraperitoneally to induce decline in memory. Animal behavioral tests such as the Barnes maze, novel object recognition test, and Y-maze were performed to investigate the effects of HSCT on memory improvement. In addition, brain acetylcholine (ACh) concentration and acetylcholinesterase (AChE) activity were assessed to investigate the mechanism of memory improvement. Results of the animal behavior test suggested that the rats administered HSCT displayed improved memory behavior compared to those administered scopolamine (p < 0.05). The concentration of Ach was increased in the HSCT group compared to the scopolamine group (p < 0.05), and the activity of AChE was significantly reduced (p < 0.05). These results suggest that HSCT effectively improves memory by reducing AChE activity and increasing ACh content in the brains of rats with scopolamine-induced memory impairment. As a natural compound, HSCT has the potential to be used as a material to improve memory.