ABSTRACT
Methodology is presented for constructing and using an electrode/microcannulae assembly that allows in vivo electrochemical measurements coupled with local application of dopamine (DA) and other chemicals in the unanesthetized freely-moving rat. Rats were implanted with a voltammetric electrode constructed of a carbon fiber sealed in fused silica tubing attached to a pair of stainless steel guide cannulae, into which fused silica injection cannulae were inserted for local application of DA and other chemicals. Precise delivery of nanoliter volumes was accomplished using a syringe drive combined with a fluid swivel to deliver the solutions to the injection cannulae. A newly-designed miniature potentiostat connected to a commutator via a modular telephone jack assembly allowed for high-speed chronoamperometric electrochemical recordings in freely-moving rats. Initial experiments characterized the in vitro electrochemical recording characteristics of the voltammetric electrode. In vivo studies were also carried out to study clearance of locally-applied DA and of potassium-evoked endogenous DA in the striatum and nucleus accumbens of freely-moving rats. In addition, the effects of chloral hydrate anesthesia on DA clearance signals in the nucleus accumbens were investigated. Moreover, the stability and reproducibility of this recording technique for measuring exogenous DA clearance was verified over a period of 5 days. Finally, the concurrent effects of systemic cocaine injection on DA uptake in nucleus accumbens and locomotor activity were examined. These studies support the conclusion that the methodology described herein allows for rapid chronoamperometric electrochemical recordings in freely-moving rats with precise microapplications of DA and other chemicals combined with concurrent measures of animal behavior.
Subject(s)
Brain Chemistry , Dopamine/administration & dosage , Electrochemistry/methods , Anesthesia , Animals , Behavior, Animal/drug effects , Calibration , Catheterization , Cocaine/administration & dosage , Cocaine/pharmacology , Dopamine/metabolism , Dopamine Uptake Inhibitors/administration & dosage , Dopamine Uptake Inhibitors/pharmacology , Electrodes, Implanted , Male , Microelectrodes , Potassium/administration & dosage , Potassium/pharmacology , Rats , Rats, Sprague-Dawley , Reproducibility of ResultsABSTRACT
Infrared spectroscopy combined with high pressure (pressure-tuning infrared spectroscopy) was applied to the study of paired sections of basal cell carcinomas (BCC) and normal skin from ten patients. Atmospheric pressure IR spectra from BCC were dramatically different from those from the corresponding normal skin. Compared to their normal controls, BCCs displayed increased hydrogen bonding of the phosphodiester group of nucleic acids, decreased hydrogen bonding of the C--OH groups of proteins, increased intensity of the band at 972 cm-1, a decreased intensity ratio between the CH3 stretching and CH2 stretching bands, and accumulation of unidentified carbohydrates. Some of these changes are shared by all human epithelial malignancies studied to date, while some others appear as yet unique to basal cell carcinoma. The diagnostic value of infrared spectroscopy in BCC remains to be determined.
