Tryptamine-Induced Changes in Endogenous 5-Hydroxytryptamine and [ ³H] -5HT Release from Mouse Hypothalamic Slices

Abstract

Tryptamine (T) is present in low amounts in rodent brain (Saavedra and Axelrod, 1973; Marsden and Curzon, 1974; Philips et al., 1974) and when it is administered peripherally to rats or mice pretreated with a MAO inhibitor it results in behavioural effects similar to those produced by indirect and direct acting 5HT agonists (Marsden and Curzon, 1978; Marsden, 1980; Luscombe, et al.,1982; Jones, 1982). Furthermore, interventions that disrupt 5HT functional integrity such as 5HT depletion and administration of 5HT antagonists, reduce both 5HT mediated and T-induced syndromes (Marsden and Curzon, 1978; Luscombe et al., 1982). This suggests that T acts as a 5HT agonist to induce behavioural responses, probably by releasing neuronal 5HT. Fuxe and Ungerstedt (1968) demonstrated that T increased release of extragranular 5HT using fluorescence histochemistry while Baker et al (1980) showed that T caused release of [ ³H]-5HT from rat striatal slices. However, more recent work by Cox and Ennis (1982) and Mounsey et al (1982) has shown that T inhibits the potassium evoked release of [ ³H]-5HT from superfused rat hypothalamic and cortical slices.