OBJECTIVE To investigate dopamine level changes in the Nucleus Accumbens (NAc) of the limbic system by salicylate and the role of dopamine in the mechanisms of tinnitus.METHODS We recorded the change of dopamine before and after sodium salicylate injection in rats by microdialysis combined with electrochemical methodologies in the nucleus accumbens (NAc).RESULTS Salicylate produced significant increase in dopamine level in the NAc, to a maximum of (321±97)% of baseline and then remain stable. In contrast, saline only produced slight increase.CONCLUSION The increase of dopamine in the NAc may be related to the generation of tinnitus. The data in vivo provide direct evidence of the important role that the dopaminergic system plays in the generation of tinnitus.

A new embedded telemetry system for potentiometric sensors was developed. The system consisted of a transmitter unit, a receiver unit and a personal computer ( PC) . The transmitter unit included a current amplifier, a∑-Δanalog-to-digital converter ( ADC) , a microcontroller unit ( MCU) and a radio module. The receiver unit was composed of a radio module, a microcontroller unit and a serial-to-USB converter module. The receiver unit was connected to an upper computer via a universal serial bus ( USB ) . The embedded software written in C language controlled the signal acquisition and transmission. The computer software written in LabVIEW language was used for data storage and display. The range of the acquisition voltages was from-1. 17 V to +1. 17 V. In order to verify the accuracy and reliability of this system, a control experiment had been done with this system and a digital multimeter. Moreover, a response test of acidity changes had been done with the self-made H+ selective electrode. The results showed that the accuracy of this system could be up to 0. 1 mV and it had strong anti-noise ability. The square of the linear correlation coefficient of the response of the changes in pH values was 0 . 998 . The curve of the results measured by this system was consistent with that measured by the commercial electrochemical analyzer. The system was built with standard hardware components and the size of the transmitter unit was only 29 mm×14 mm×11 mm. It can be easily used for remote and real-time detection for the potentiometric sensor.

A new micro embedded telemetry system was developed for the amperometric sensing detection. Its output voltage range was ±0. 5 V and resolution was<1 mV. The current acquisition range was ±1μA and the minimum resolution was 0. 2 nA. This telemetry system was designed based on microprocessor ADuCM360, including a potentiostat, a current detection module and a radio module. And the size was only 24 mm × 13 mm × 11 mm. The computer software written in LabVIEW language was used for data storage and display. In order to verify the accuracy and reliability of this system, an electrical performance test was performed. The current response for ascorbic acid with different concentration was recorded by using the telemetry system. The potential of working electrode was set as 30 mV, and the current response of ascorbic acid electrode had a good linear relationship with its concentration within the concentration range of 50-300 μmol/L. Linear equation was I(nA) = 2. 98CAA(μmol/L)-137. 39, and linear correlation coefficient R2=0. 984. Moreover, the applicability of the instrument in the study for living animals was explored by using the cerebral ischemia as model.

A dual-mode recording system used for synchronous detection of neuroeletrical and neurochemical signals was developed, and a dual-mode synchronous detection experiment was carried out using the instrument. The device comprised 64-channel neuroelectricity recording module with voltage resolution of 0. 3 μV and 4-channel neurochemistry recording module with current resolution of 1 pA. The software had many basic features, including Spike separation and sort, chronoamperometry, cyclic voltammetry, etc. In particular, the software could observe and analyze the dual-mode neural signals synchronously. The performance of the system was demonstrated in the single mode detection experiments. In neuroeletrical experiments, 64-channel simulate neural signals were detected and the signal to noise ratio ( S/N) of Spike recorded from cortex of Sprague-Dawley ( SD ) rat was 6. In the K3 [ Fe ( CN )6 ] and ascorbic acid measurement experiments, the current response of K3 [ Fe ( CN)6 ] in the range of 0. 1-10 mmol/L was obtained by cyclic voltammetry, with a correlation coefficient of 0. 9889, and the current response of ascorbic acid ( concentration:10-800 μmol/L) by chronoamperometry increased linearly with a correlation coefficient of 0. 9841. Based on the rat model of global cerebral ischemia, a dual-mode detection experiment was carried out. In the experiment, the neuroelectrical and neurochemical signals were synchronously recorded in the SD rat primary visual cortex. According to the experimental results, we got the conclusion that the concentration of ascorbic acid negatively related to the Spike firing in the SD rat primary visual cortex.