Differential effects of clozapine on ethanol-induced ascorbic acid release in mouse and rat striatum

Effect of morphine on brain uracil release in mouse striatum detected by microdialysis

Effect of acute treatment of morphine is associated with neurotransmitter and neuromodulator changes in the brain. A possible relationship between pyrimidines and morphine has also been discussed. Uracil, a common and naturally occurring pyrimidine derivative which found in RNA, has been suggested to modulate many neurotransmitters or neuromodulators, especially in the mature central nervous system. The present study was performed to determine the effect of acutely intraperitoneal morphine treatment on the release of uracil in mouse striatum. The results showed that morphine significantly decreased the release of uracil at the dose of 10 and 20mg/kg in a dose dependent manner. Naloxone could reverse the morphine-induced reduction of uracil levels in mouse striatum, at the dose of 4 mg/kg, without affecting basal uracil release. The results suggest that the extracellular level of uracil in mouse striatum could be specifically regulated by the centrally acting drugs, such as morphine. However, the pharmacological implications of such regulation should be further evaluated.

Continuous On-Line Monitoring of Extracellular Ascorbate Depletion in the Rat Striatum Induced by Global Ischemia with Carbon Nanotube-Modified Glassy Carbon Electrode Integrated into a Thin-Layer Radial Flow Cell

This study describes a novel analytical system integrating in vivo microdialysis sampling with a radial thin-layer flow cell with a single-walled carbon nanotube (SWNT)-modified glassy carbon electrode as working electrode for continuous and on-line monitoring of ascorbate depletion in the rat striatum induced by global ischemia. The SWNTs, especially those after vacuum heat treatment at 500 degrees C, are found to be able to enhance the electron-transfer kinetics of ascorbate oxidation at a low potential (ca. -50 mV) and possess a strong ability against electrode fouling. These properties essentially make it possible to determine ascorbate with a good stability and high selectivity against catecholamines and their metabolites and other electroactive species of physiological levels. While being integrated with in vivo microdialysis to assemble an on-line analytical system, the electrode is proved useful for continuous and sensitive monitoring of the basal dialysate level of ascorbate and its depletion in the rat striatum induced by global ischemia. The basal dialysate level of ascorbate is determined to be 5.0 +/- 0.5 microM (n = 5) and a 50 +/- 10% (n = 3) depletion is recorded for the basal ascorbate after 4 h of global ischemia.