Scopolamine-induced learning and memory impairments in mice (Y-maze)

The Y-maze task was performed according to a slightly modified method described by (Moon et al., 2013). Donepezil HCl (0.3–10 mg/kg free drug dissolved in saline) was administered orally for four consecutive days to the corresponding treatment groups (14–16 animals per group). Scopolamine (1.0 mg/kg, subcutaneous [s.c.]) was administered 30 min after the fourth dose of donepezil HCl. After 30 minutes of scopolamine administration, the mice were placed in a Y-maze and observed. The Y-maze consisted of three identical acrylic arms (30 cm long ×8 cm wide ×15 cm high) resulting in pathways separated by 120° and extending from a central space (8×8 cm). Arm entry was monitored by placing a mouse in the center of the Y-maze and allowing it to move freely for 5 min. An arm entry was counted when all 4 paws of the mouse completely entered an arm. The sequence of arm entry was calculated as alternating behavior and % alternation. Alternation was defined as a sequential visit to three different arms. Percent spontaneous alternation (SA) as a measurement of shortterm spatial memory was calculated by the following equation: SA (%)=successive entries/(total arm entries −2)×100. Percent recovery of SAs was calculated by the following equation: recovery of SA (%)=(% SA of donepezil−% SA of control]/(% SA of normal−% SA of control)×100.