Endogenous acetylcholine modulates synaptic plasticity in the hippocampus in vivo

Abstract

Long-term potentiation (LTP) provides a model for the synaptic mechanisms underlying learning and memory. Acetylcholine (ACh) is an important excitatory transmitter in the hippocampus, and cholinergic activity is essential for learning in a range of behavioral tasks. Thus, the search for the physiological actions of ACh may be of major importance for understanding the role of ACh in cognitive functions. The role of ACh in synaptic plasticity was assessed in anaesthetised and freely behaving adult rats. Electrodes were implanted into the CAl area of the hippocampus, and field excitatory postsynaptic potential (EPSP) slope was measured. Drugs were injected via a cannula into the lateral cerebral ventricle. The effects of M2 muscarinic ACh receptor (mAChR) antagonists on glutamatergic synaptic transmission and possible mechanisms were investigated.