CHARACTERIZATION OF BETA-PHENYLETHYLAMINE-INDUCED MONOAMINE RELEASE IN RAT NUCLEUS-ACCUMBENS - A MICRODIALYSIS STUDY

In vivo microdialysis was used to investigate the effect of beta-pheny lethylamine on extracellular levels of monoamines and their metabolite s in the nucleus accumbens of conscious rats. At all doses tested (1, 10 and 100 mu M), infusion of beta-phenylethylamine through the microd ialysis probe significantly increased extracellular levels of dopamine in the nucleus accumbens. These increases were dose-related. The incr ease in dopamine levels induced by 100 mu M beta-phenylethylamine was not affected by co-perfusion of 4 mu M tetrodotoxin. The ability of 10 0 mu M beta-phenylethylamine to increase the extracellular level of do pamine was comparable to that of the same dose of methamphetamine. On the other hand, beta-phenylethylamine had a much less potent enhancing effect on 5-hydroxytryptamine (5-HT) than dopamine levels. Only the h ighest dose (100 mu M) caused a statistically significant effect on 5- HT levels. Over the dose range tested (1, 10 and 100 mu M), beta-pheny lethylamine had no effect on extracellular metabolite levels of dopami ne and 5-HT. The results suggest that beta-phenylethylamine increases the efflux of monoamines, preferentially dopamine, without affecting m onoamine metabolism, in the nucleus accumbens. (C) 1998 Elsevier Scien ce B.V. All rights reserved.