Memory deficits in rats after scopolamine injection. Male rats had intraperitoneal injections of scopolamine (2 mg/kg body weight/day) at 30 min after daily feeding of casein (MD-control), porcine brain enzyme hydrolysates (PBEH; 7 mg total nitrogen/mL) at 0.053 mL (Low-PBEH), 0.159 mL (Medium-PBEH), 0.478 mL (High-PBEH), or 10 mg donepezil (Positive-control) per kilogram body weight per day for six weeks. (A) Latency time to enter the dark box (s) during the first, second, and third trials; (B) novel object recognition index during novel objective recognition test and the number of the right turns among the total turns in the Y-maze test; (C) latency time to the first visit, frequencies to visit zone 5, and duration in zone 5. The bars and error bars represent the means ± standard deviations (n = 10). a–c Different superscript letters on the bars indicate a significant difference among the groups according to a Tukey test at p < 0.05.