Mild stress facilitates learning and exercise improves retention in aged mice

Area of Science:

• Neuroscience
• Gerontology
• Behavioral Biology

Background:

• Chronic stress negatively impacts the brain, but moderate stress can enhance learning in young animals.
• The effects of mild stress on learning and memory in aged animals remain largely unknown.
• Exercise is known to counteract stress and facilitate cognitive functions.

Purpose of the Study:

• To investigate the impact of mild stress on learning and memory retention in young versus aged mice.
• To determine if voluntary exercise can improve task retention in these age groups.
• To examine the regulation of specific learning/memory genes (BDNF exon VI, synapsin, MAPK, CRFR1) in the hippocampus.

Main Methods:

• Assessment of learning and 1-week retention tasks in young and aged mice.
• Administration of mild stress 24 hours before the initial learning test.
• Implementation of a 1-week voluntary exercise intervention between learning and retention tests.
• Real-time PCR analysis of gene expression (BDNF exon VI, synapsin, MAPK, CRFR1) in the hippocampus.

Main Results:

• Mild stress significantly improved learning performance in aged mice, but not in young mice.
• Voluntary exercise enhanced task retention performance in both young and aged mice.
• In aged mice, exercise led to significant increases in all four examined learning/memory related genes.

Conclusions:

• Mild stress facilitates learning in aged animals.
• Voluntary exercise improves the retention of learned tasks in both young and aged mice.
• Exercise positively influences the expression of key learning and memory genes in the hippocampus of aged mice.