Related Experiment Video
Updated: May 24, 2026
Morris Water Maze Test for Learning and Memory Deficits in Alzheimer's Disease Model Mice
Published on: July 20, 2011
Isoflurane induces cognitive deficits in the Morris water maze task in rats
Jennifer K Callaway1, Nigel C Jones, Colin F Royse
1Department of Pharmacology, University of Melbourne and Melbourne Brain Centre, Carlton, Victoria, Australia. callaway@unimelb.edu.au
Background:
Postoperative cognitive dysfunction has been reported in young, middle-aged and elderly patients with greater incidence with increasing age. Neurocognitive deficits are associated with anaesthetic exposure in aged rodents but in younger adult animals the findings are inconsistent and in middle-aged animals they are unknown. We aimed to compare the effects of moderate duration isoflurane anaesthesia in 100% oxygen on Morris water maze performance in young adult and middle-aged rats. We hypothesised that isoflurane would have greater effects on learning and memory in middle-aged compared with young rats.
Materials And Methods:
Young adult (3 months, n = 25) and middle-aged (12 months, n = 20) male Sprague Dawley rats were assigned randomly to isoflurane exposure (1 minimum alveolar concentration, 4 h) or control conditions. Spatial learning (acquisition phase) and memory (probe trial) were tested in the Morris water maze 1 week after exposure. Middle-aged rats were retested in the probe trial 4 weeks after exposure for long-term memory retention. Latency to locate the hidden platform and time spent in the platform quadrant were compared between ages and treatments.
Results:
Isoflurane did not affect acquisition of the water maze task in either age group. Isoflurane exposure induced a significant deficit in memory retention in young rats, but not middle-aged rats, in the probe trial 24 h after acquisition. Irrespective of treatment, middle-aged rats took longer to acquire the task than young rats. Four weeks after exposure, isoflurane-treated middle-aged rats showed no preference for target location, compared with sham-exposed rats which retained memory for previous platform location.
Conclusion:
Isoflurane exposure impaired retention memory for platform location 1 week after exposure in young adult rats and resulted in a delayed although weak impairment at 4 weeks in middle-aged rats. The great variation in reported effects of isoflurane suggests a complex effect of this agent on memory which warrants further investigation.
Insights
Isoflurane anesthesia impaired memory retention in young rats but not middle-aged rats. Middle-aged rats showed delayed memory deficits after isoflurane exposure, indicating complex effects on cognition.
Area of Science:
- Anesthesiology
- Neuroscience
- Gerontology
Background:
- Postoperative cognitive dysfunction (POCD) incidence increases with age.
- Anesthetic effects on cognition are known in aged rodents but unclear in younger and middle-aged animals.
- This study investigates isoflurane's impact on cognitive function in young adult and middle-aged rats.
Purpose of the Study:
- To compare the effects of isoflurane anesthesia on spatial learning and memory in young adult and middle-aged rats.
- To determine if isoflurane has a greater impact on cognitive function in middle-aged rats compared to young rats.
- To assess short-term and long-term memory retention after anesthesia exposure.
Main Methods:
- Young adult (3 months) and middle-aged (12 months) male Sprague Dawley rats were exposed to isoflurane (1 MAC, 4h) or control conditions.
- Spatial learning and memory were assessed using the Morris water maze 1 week post-exposure.
- Long-term memory retention in middle-aged rats was evaluated 4 weeks after exposure.
Main Results:
- Isoflurane did not affect the acquisition of the Morris water maze task in either age group.
- A significant deficit in memory retention was observed in young rats 24 hours after isoflurane exposure.
- Middle-aged rats exhibited longer acquisition times than young rats, irrespective of treatment, and showed delayed memory impairment at 4 weeks post-exposure.
Conclusions:
- Isoflurane exposure impaired short-term memory retention in young rats and caused a delayed, weak impairment in middle-aged rats.
- The findings suggest a complex, age-dependent effect of isoflurane on memory.
- Further research is warranted to elucidate the intricate mechanisms underlying isoflurane's impact on cognitive function.
