Turnover Rate Assessments of Cerebral Neutrotransmitter Amines and Acetylcholine

The aim of the present review is to summarize the methods used to estimate the turnover of various neurotransmitters of low molecular weight in the intact animal brain First, some introductory remarks and definitions are given. The following description of the terms used is derived mainly from (1969 ), (1957 ) and some references therein. The chemical compound whose quantitative behavior will be studied is called a substance and the behavior of the substance is studied in a system Thus, the turnover of the substance acetylcholine (ACh) may be studied in a system, such as the rat striatum or the whole mouse brain In vivo studies of the central nervous system are usually considered to be an open system, meaning that a precursor enters the system and metabolites leave the system. The behavior of a substance is not necessarily uniform in the system, and, therefore, a system may contain several pools or compartments of that substance. A compartment is defined as a quantity of a substance that has distinguishable and uniform kinetics of transformation The boundaries of a compartment may, but do not necessarily, conform to anatomical boundaries, and conversely, anatomical boundaries are not necessarily divisions of the compartments.