A longitudinal, multi-parametric functional MRI study to determine age-related changes in the rodent brain

Area of Science:

• Neuroscience
• Aging Research
• Medical Imaging

Background:

• Cognitive decline and neurological diseases increase with age.
• Rodent models are crucial for understanding age-related brain changes.
• Investigating neuronal activity in aging is vital for mechanistic insights.

Purpose of the Study:

• To assess a novel anesthesia and functional MRI (fMRI) protocol for studying age-related neuronal activity changes in rodents.
• To examine alterations in neurotransmitter activity and neurovascular coupling during physiological aging.

Main Methods:

• 11 Wistar Han female rats aged 7-18 months were studied.
• A minimally invasive propofol anesthesia protocol combined with fMRI and functional magnetic resonance spectroscopy (fMRS).
• Forepaw stimulation was used to quantify glutamate changes (ΔGlu), and arterial spin labelling (ASL) measured cerebral blood flow (CBF).

Main Results:

• A significant age-related decrease in the BOLD (blood oxygen level dependent) active region size (P < 0.05).
• Significant reduction in stimulated glutamate change (ΔGlu) with age (P < 0.05), becoming negative from 12 months.
• Global cerebral blood flow (CBF) remained stable throughout the study.

Conclusions:

• Age-related changes in the BOLD response observed in rodents mirror those in humans.
• Reduced synaptic glutamate turnover may explain the diminished BOLD response in aging.
• Cerebral blood flow is preserved in aging rodents despite altered neuronal activity.