Previous study has demonstrated that the lack of μ-opioid receptor decreased LTP in the dentate gyrus of the hippocampus, suggesting the possibility that the lack of μ-opioid receptor may accompany a change in learning and memory. However, no behavioral study has been undertaken to correlate LTP deficits with spatial memory impairment in μ-opioid receptor knockout mice. Therefore, the present study investigated the hypothesis that μ-opioid receptors contribute to learning and memory by using the Morris water maze, and comparing responses in wild type and μ-opioid receptor gene knockout mice. Our results indicated that μ-opioid receptor knockout mice showed a significant spatial memory impairment compared to wild type in the Morris water maze. This result suggests that the expression of μ-opioid receptor plays an important role in spatial learning and memory examined by Morris water maze.
Bibliographical noteFunding Information:
This study was supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (02-PJ1-PG3-21301-0017).
- Learning and memory
- Morris water maze
- μ-Opioid receptor knockout mice