New approaches to clinical and postmortem investigations of cholinergic mechanisms

This chapter discusses some new clinical and post-mortem techniques and shows the use in the study of cholinergic mechanisms in man in normal and pathological states. Clinical research on cholinergic mechanisms in the CNS of man is hampered by the lack of appropriate methods and markers. The different tissues and techniques used for cholinergic research in man are discussed in the chapter. Data for the cholinergic system in the human brain is mainly obtained from neurochemical studies in autopsy brains however occasionally also from biopsied brains. The analysis is restricted to the measurement of enzyme activities and cholinergic receptor densities. Acetylcholine (ACh) is a labile compound that is difficult to measure because it is easily hydrolysed post-mortem. New techniques using labeled isotopes enables to measure in autopsy brain tissue dynamic, functional mechanisms, such as regulations of transmitter activity and second messenger response. Positron emission tomography (PET) is a new technique for in vivo studies of the central cholinergic activity in the human brain.