Background:
Cerebral amyloid angiopathy (CAA) is the most common cause of lobar intracerebral hemorrhage in the aging population. It is mostly a consequence of amyloid beta40 (Aβ40) deposition within the cerebral blood vessels. A recent study has shown that this amyloid plaque deposition is more prevalent in the brain of elderly women compared to men. The increase in amyloid plaque deposition is linked to increased cerebral microbleeds (CMBs) and reduced cognition. The major objective of this study to discern if a sexual dichotomy existed in CMBs and cognition using mouse model of CAA.
Methods:
We used the Tg-SwDI mouse (“CAA mouse”, harboring Swedish, Dutch, and Iowa mutations of human amyloid precursor protein) model that develops Aβ deposits and cognitive deficits at 3-4 months. Cognitive deficits were analyzed using Fear Conditioning (FC) in pre-symptomatic (3 month) and (12 month) old male and female mice. Briefly, mice were acclimated to the FC chamber for a 2 minute training trial to record baseline. After 1 hour rest, mice were placed back in the chamber for 2 minutes, where they received a 2 millisecond shock (1,000 u/amp). Day 2, activity was recorded for 3 minutes and this measure was compared to baseline to determine Mean Inactive State (MIS-seconds). Mice were euthanized following FC, and brains scanned
ex vivo
using a MRI T2 Star sequence to assess for CMBs.
Results:
FC showed a significant difference in MIS (p<0.05) between male (3 and 12 months old) and female (3 months only) mice, n=6/group, suggesting that aged females had significantly lower MIS (Figure 1). MRI showed that aged female mice had more CMBs compared to aged male mice (females, 15.3±7 vs. males 0.25 ±0.2, n= 3/group, p=0.05.
Conclusion:
In a mouse model of CAA, our results demonstrate that aged females have increased CMBs as compared to males, which may be contributing to decreased cognition as seen on FC. Ongoing studies are designed to further understand the etiology of this sex difference.
Age-Dependent Neurovascular Dysfunction and Damage in a Mouse Model of Cerebral Amyloid Angiopathy