An enriched environment ameliorates memory impairments in PACAP-deficient mice

Area of Science:

• Neuroscience
• Behavioral Science
• Molecular Biology

Background:

• Pituitary adenylate cyclase-activating polypeptide (PACAP) plays a role in neural function.
• PACAP-knockout (PACAP(-/-)) mice exhibit behavioral and cognitive deficits.
• Previous studies showed enriched environments (EE) ameliorate some behavioral issues in juvenile PACAP(-/-) mice.

Purpose of the Study:

• To investigate the impact of EE on memory function in PACAP(-/-) mice.
• To examine the effects of EE on memory-related protein levels in the hippocampus.
• To determine the long-lasting effects of EE on memory and protein expression.

Main Methods:

• Assessment of fear memory using contextual fear conditioning.
• Evaluation of cognitive function with a novel object recognition test.
• Quantification of hippocampal protein levels (NR2B, phospho-ERK, phospho-CaMKII, BDNF, neurotrophin-3) via Western blotting.

Main Results:

• PACAP(-/-) mice showed memory deficits, which were improved by EE.
• EE-induced memory improvements were sustained for at least two weeks after returning to standard environment (SE).
• EE increased hippocampal levels of NR2B, phospho-ERK, phospho-CaMKII, and BDNF, but decreased neurotrophin-3.

Conclusions:

• EE effectively ameliorates long-lasting memory impairments in PACAP(-/-) mice.
• Increased hippocampal memory-related proteins and BDNF contribute to the beneficial effects of EE.
• The maintenance of EE's effects is not solely dependent on sustained elevated protein levels.