In vivo simultaneous monitoring by Pt-disk microelectrodes of intracerebral hydrogen peroxide and dopamine in rats

A technique was developed for simultaneous monitoring of temporal changes in hydrogen peroxide (H₂O₂) and dopamine (DA) levels by using Pt-disk microelectrodes ( φ 30 μ m). H₂O₂ and DA were determined by differential double-pulse amperometry (for H₂O₂; 1st step, 750 mV, 1000 ms; 2nd step, 1100 mV, 1000 ms: for DA; 1st step, 150 mV, 600 ms; 2nd step, 250 mV, 50 ms). The electrode for H₂O₂ or DA is capable of determining each target substance and these substances do not interfere with each other. For an in vivo application, the electrodes were implanted into the striatum of rats and used successfully to monitor intrastriatal changes in H₂O₂ and DA simultaneously after intraperitoneal injection of methamphetamine while the animals were moving freely.