Abstract
To measure dopamine (DA) in the brain in conscious rats, selective biosensor was developed with three layer membranes: iron-exchange membrane, enzyme-containing membrane and antioxidant-containing membrane. Electrochemical (500 mV between electrodes) detection of oxidative current of membrane permeable substances was carried out. DA selectivity was confirmed in vitro as follows. Oxidative current was not found in additions of Glu, Ach, GABA, 5-HT, Adr or NA but in DA treatment with three-layer biosensor, although it was detected in 5-HT, Adr, NA or DA treatment with no membranes. In addition, administration of tyrosine, l-dopa or DA metabolites (DOPAC, HVA, 3-MT) did not induced oxidative current with this biosensor, indicating the selective detection of permeable DA. We next investigated whether DA-selective probe detect the changes of DA content in vivo. Methamphetamine (3.0 mg/kg) was given to the adult rats and DA level in the striatum was monitored with this probe. Oxidative current was gradually increased from 10 min after the administration, exhibiting that real-time changes of DA level was monitored in vivo. Data suggest that real-time change of DA was measurable in vitro and in vivo with a biosensor that has relative high-sensitivity to DA. [J Physiol Sci. 2007;57 Suppl:S143]
