Testing the calcium hypothesis of aging in the rat hippocampus in vivo using manganese-enhanced MRI

Area of Science:

• Neuroscience
• Biomedical Imaging

Background:

• Aging is associated with cognitive decline, potentially linked to altered calcium (Ca2+) signaling.
• The calcium hypothesis of aging posits that dysregulated Ca2+ homeostasis contributes to age-related neuronal dysfunction.

Purpose of the Study:

• To noninvasively investigate age-related changes in Ca2+ influx in the hippocampal CA1 region using Mn(2+)-enhanced magnetic resonance imaging (MEMRI).
• To test the sensitivity of MEMRI to age-related alterations in Ca2+ dynamics.

Main Methods:

• Longitudinal MEMRI studies were conducted on two groups of male Long-Evans rats at different age points (2.5, 7, and 19 months).
• Manganese (Mn2+), a surrogate for Ca2+ with low cellular efflux, was used as an MRI contrast agent to measure uptake in the hippocampal CA1.
• Statistical analysis was performed on separate and combined datasets to assess age-related changes in Mn2+ accumulation.

Main Results:

• A significant age-dependent increase in Mn2+ accumulation within the hippocampal CA1 region was observed (p < 0.05).
• These findings demonstrate that MEMRI can detect age-related changes in Ca2+ influx in vivo.

Conclusions:

• This study provides the first in vivo confirmation of the calcium hypothesis of aging.
• The results support the use of MEMRI in future longitudinal studies to explore the mechanisms underlying age-related cognitive decline and its relationship with Ca2+ signaling.