The Use of Mao Inhibitors in Lesion Studies: An Assessment of ‘Flooding’ in Trace Amine Measurements
Recent studies have demonstrated that selective lesions of mammalian CNS may result in decreases in trace amine concentrations in selected areas of the brain (see review, Juorio, 1987). In the case of tyramines this has been demonstrated in the absence of MAO inhibitor (Juorio and Jones, 1981). With other trace amines, MAO inhibition has been used to elevate the normally low endogenous levels so that relative decreases in accumulation may be used as an index of lesion effects (PE and T studies: Greenshaw et al., 1986; Juorio et al., 1987). The reason for the latter strategy is to circumvent ‘floor effects’ that occur when attempting to measure decreases in quantities that are already close to the limits of sensitivity of the available assay systems. Concentrations of trace amines increase greatly after administration of MAO inhibitors (Philips and Boulton, 1979). While the rationale for the use of MAO inhibitors in lesion studies is clear, there is the problem of lipophilicity to be considered with respect to substrate localisation in CNS. The present study was conducted to assess the relative dependence of some reported lesion effects on the type of MAO inhibitor used in this context.
KeywordsLesion Side Lesion Effect Selective Lesion Trace Amine Measured Amino Acid
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