Repetitive Post-training Exposure to Enflurane Modifies Spatial Memory in Mice 

Abstract

Background Previously the authors found that a single post-training exposure to enflurane or isoflurane, but not halothane, enhanced memory storage in an active avoidance task, which is a behavior with underlying mechanisms that are poorly understood and still debated. In contrast, spatial tasks are known to depend on hippocampal functions. This study investigated the effects of repetitive post-training exposure to enflurane on spatial memory in mice. Methods Using an eight-arm radial maze, 80 mice were trained to eat a pellet placed on the end of each of the eight arms. Training occurred on four consecutive days with one trial per day. The number of errors in the first eight choices was recorded to determine performances for each day of training. Immediately after each training session, mice in the enflurane group received 1 h exposure to 0.5%, 1%, or 2% enflurane in air through a calibrated vaporizer. The performance ratios (the ratio of errors on each day compared with the first day of the 4 days) in the control and the enflurane groups were compared. Results The performance ratios (which equals the mean of the error in the fourth day/the error in the first day) in the control, and 0.5%, 1%, and 2% enflurane groups were 0.66, 0.65, and 0.32 (P < 0.01, vs. control), and 0.46 (P < 0.05, vs. control), respectively. Conclusions Repetitive post-training exposure to 1% and 2% enflurane significantly enhanced spatial memory in the eight-arm radial maze task. Enflurane enhances consolidation of spatial memory, possibly by affecting hippocampal activity.

Defective Brain Development in Mice Lacking the Hif-1α Gene in Neural Cells

“…The spatial memory function of mice was examined with the radial maze task test as described previously (20). Mice were subjected to a maze trial (once a day) for four consecutive days, and the number of errors in the maze task was measured on each day.…”

“…Spatial memory performance was estimated by the ratios of error rates on the day of experiments to the error rate on the first day. The spontaneous locomotor activity of mice was measured for 10 min in an activity box with an infrared beam (Animex; Muromachi, Tokyo, Japan) as described (20).…”

“…To evaluate the consequence of the morphological defects, adult nes-Cre;Hif-1␣ flox/⌬ mutant mice were examined for learning and memory functions by use of the radial maze task test (20). Examination of spontaneous locomotion before the radial maze task test exhibited no significant difference between the activity of nes-Cre;Hif-1␣ flox/⌬ mutant mice (933.8 Ϯ 60.5 counts/10 min, n ϭ 15) and nes-Cre;Hif-1␣ flox/ϩ control mice (774.8 Ϯ 102.45 counts/10 min, n ϭ 15) (Fig.…”

“…Spatial memory task was examined by measuring the day-by-day de- on May 7, 2018 by guest http://mcb.asm.org/ crease in the error rate of visiting wrong arms of the radial maze when a food pellet was placed behind each arm (20). It was previously shown that the initial storage of spatial memory is developed within 4 days in normal mice (20). We found that nes-Cre;Hif-1␣ flox/ϩ control mice (n ϭ 10) normally learned the maze well enough to find a food pellet within 4 days of the test (Fig.…”

Neurobehavioral effects of concurrent exposure to cesium-137 and paraquat during neonatal development in mice

“…The optimum strategy implies a minimum number of visits to empty arms. In each session, we measured the time spent in the arms, the number of incorrect arm choices (visit to the same arm more than once during a single test session), and the number of incorrect arm entries (animal visits an arm and did not eat the reward) (Komatsu et al, 1998).…”