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Age-dependent decrease in the affinity of muscarinic M1 receptors in neocortex of rhesus monkeys
M G Vannucchi1, P S Goldman-Rakic
1Section of Neurobiology, Yale University School of Medicine, New Haven, CT 06510.
Summary
Aging rhesus monkeys show reduced affinity of M1 muscarinic receptors in the cortex. This age-related decline in receptor affinity is reversible and suggests potential therapeutic targets for human memory disorders.
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Muscarinic acetylcholine receptors play crucial roles in cognitive functions.
- Age-related changes in neurotransmitter systems can impact memory and cognition.
Purpose of the Study:
- To investigate age-dependent alterations in muscarinic M1 receptor affinity in the primate cerebral cortex.
- To explore the reversibility and plasticity of these age-related receptor changes.
Main Methods:
- In vitro autoradiography on rhesus monkey cortical tissue sections.
- Receptor binding assays using carbachol competition experiments on cortical membrane homogenates.
- Assessment of M1 receptor affinity and density in young and aged monkeys.
Main Results:
- Aged rhesus monkeys exhibited a decrease in the affinity of high-affinity muscarinic M1 sites in cortical areas.
- Carbachol competition revealed a single low-affinity site class in aged monkeys versus two classes (low and high) in young adults.
- The observed decline in M1 site affinity was reversible and restored in the presence of Mg2+.
Conclusions:
- Functional changes in cerebral cortex muscarinic receptor activity occur with aging in primates.
- M1 muscarinic receptors retain plasticity in aged individuals, offering potential therapeutic avenues.
- These findings suggest M1 receptor modulation as a target for treating age-related memory impairments.