Indoleamines measurement

Both indoleamine (e.g., lysergic acid diethylamide, LSD psilocybin) and phenethylamine hallucinogens (e.g., mescaline) increased pupil diameter.26 There have been no systematic studies of the effects of these drugs on dynamic measures of the light reflex. Phencyclidine (PCP) does not cause marked changes in pupil size or light reflex. However, subjects intoxicated with PCP often show horizontal and vertical nystagmus.26... 

Indolealkylamines. GC-MS methods applied in studies of the biochemical pharmacology of indoleamines parallel work on the catecholamines. SIM assays for serotonin (5-hydroxytryptamine), 5-methoxytryptamine, JV-acetylserotonin and melatonin (5-methoxy-N-acetyltryptamine) in rat pineal and brain tissue have been described [453,469]. Pentafluoro-propionyl derivatives and structural homologue standardisation were employed with detection limits in the subpicomole range. Estimation of central indoleamine turnover in man currently depends upon metabolite determination in CSF. Ion monitoring determination of indole-3-acetic acid [454] a metabolite of tryptamine, and isotope dilution assays for 5-hydroxyindoleacetic acid (5-HIAA) [455,458] have been reported. Serotonin is converted by central monoamine oxidase to 5-HIAA and the measurement of this metabolite, formerly by fluorimetry, is of interest in patients with CNS disorders [470]. GC-MS has also contributed to the identification of N,N-dimethyltryptamine in vitro [471] and isotope dilution technique has been applied to the measurement of this metabolite in control subjects and in psychiatric patients [472]. 

Dialysis electrodes have been applied to the in vivo measurements of ascorbate [169], glutamate [170], neurotransmitters such as catecholamines and indoleamines [165] and the capability of measuring glycerol in hmnan serum samples in vitro [171] has been demonstrated. 

This chapter describes two microbore LC-based methods for measurement of monoamine neurotransmitters in rat brain dialysates a method for the determination of the catecholamines (CA) noradrenaline (NAD), adrenaline (AD), and dopamine (DA) and a method for the determination of the indoleamine serotonin (5HT) and its major metabolite 5-hydroxyindoleacetic acid (SHIAA) (3). For all compounds, a limit of detection of 1 pmol or less (in an injected volume of 10 pL) can be achieved. Basal serotonin can be measured in microdialysates without including a reuptake inhibitor in the microdialysis perfusion fluid. Both of these systems are routinely used in the authors laboratory for the analysis of dialysates from striatum, hippocampus, and substantia nigra. Both methods are selective, robust, and can be automated. 

Marsden, C. A., Bennett, G. W., Brazell, M., Sharp, T., and Stolz, J. F., 1981, Electrochemical monitoring of 5-hydroxytryptamine release in vitro and related in vivo measurements of indoleamines,/. Physiol. (Paris), 77 333-337. 

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