Abstract
Chronic treatment (2 weeks) with either scopolamine (4 mg/kg, once daily p.o.) or choline (200 mg/kg, once daily p.o.) resulted in a pronounced muscarinic cholinergic receptor up- or down-regulation in the frontal cortex of young (4 weeks) but not of aged (18 months) female mice. It is speculated that a similar age-related decline of muscarinic receptor plasticity might contribute to the profound dysfunction of cholinergic neurotransmission in Alzheimer's disease.