Effects of aging on rat cortical presynaptic cholinergic processes

Area of Science:

• Neuroscience
• Aging Research
• Neurochemistry

Background:

• Acetylcholine (ACh) is a critical neurotransmitter for cognitive functions.
• Aging is associated with cognitive decline, potentially linked to altered neurotransmission.
• Presynaptic muscarinic receptors modulate ACh release.

Purpose of the Study:

• To investigate the impact of aging on acetylcholine metabolism and release in rat cortical synaptosomes.
• To examine the role of presynaptic muscarinic receptors in modulating ACh release in aged rats.

Main Methods:

• Preparation of cortical synaptosomes from Fischer 344 male rats of different ages (6 and 24 months).
• Measurement of [3H]-choline uptake and acetylation.
• Assessment of K+-depolarization-induced [3H]-ACh release.
• Evaluation of muscarinic receptor modulation using oxotremorine and atropine.

Main Results:

• Aging did not affect [3H]-choline uptake or acetylation.
• Older rats exhibited significantly reduced K+-evoked [3H]-ACh release compared to younger rats.
• Presynaptic muscarinic receptor inhibitory activity remained functional in aged rats, with no significant difference in sensitivity to oxotremorine.

Conclusions:

• Acetylcholine release is impaired in aged rats, independent of uptake and acetylation processes.
• Presynaptic muscarinic receptor-mediated regulation of ACh release is preserved in aging.
• Muscarinic receptor-mediated modulation presents a viable pharmacological target for addressing age-related decreases in ACh release.