Estimation of adenosine and its major metabolites in brain tissues of rats using high-performance thin-layer chromatography–densitometry

Computational and Structural Biotechnology Journal

2015

Adenosine is a signaling molecule and downstream product of ATP that acts as a neuromodulator. Adenosine regulates physiological processes, such as neurotransmission and blood flow, on a time scale of minutes to hours. Recent developments in electrochemical techniques, including fast-scan cyclic voltammetry (FSCV), have allowed direct detection of adenosine with sub-second temporal resolution. FSCV studies have revealed a novel mode of rapid signaling that lasts only a few seconds. This rapid release of adenosine can be evoked by electrical or mechanical stimulations or it can be observed spontaneously without stimulation. Adenosine signaling on this time scale is activity dependent; however, the mode of release is not fully understood. Rapid adenosine release modulates oxygen levels and evoked dopamine release, indicating that adenosine may have a rapid modulatory role. In this review, we outline how FSCV can be used to detect adenosine release, compare FSCV with other techniques used to measure adenosine, and present an overview of adenosine signaling that has been characterized using FSCV. These studies point to a rapid mode of adenosine modulation, whose mechanism and function will continue to be characterized in the future.

Section: Biological Studies Of Adenosine With Fscvmentioning

confidence: 59%

Fast-scan Cyclic Voltammetry for the Characterization of Rapid Adenosine Release

Nguyen

Computational and Structural Biotechnology Journal

2015

“…When comparing evoked adenosine levels with basal levels reported in the literature, the rank order of evoked adenosine release is not the same as the trends for regional differences in basal levels. The caudate-putamen and nucleus accumbens have the highest evoked release but the lowest basal adenosine levels [25][26][27]. In the cortex and hippocampus, trends for stimulated and basal release are better correlated as basal Fig.…”

Section: Discussionmentioning

confidence: 85%

The mechanism of electrically stimulated adenosine release varies by brain region

Pajski

2012

Purinergic Signalling

Adenosine plays an important role in neuromodulation and neuroprotection. Recent identification of transient changes in adenosine concentration suggests adenosine may have a rapid modulatory role; however, the extent of these changes throughout the brain is not well understood. In this report, transient changes in adenosine evoked by one second, 60 Hz electrical stimulation trains were compared in the caudate-putamen, nucleus accumbens, hippocampus, and cortex. The concentration of evoked adenosine varies between brain regions, but there is less variation in the duration of signaling. The highest concentration of adenosine was evoked in the dorsal caudate-putamen (0.34± 0.08 μM), while the lowest concentration was in the secondary motor cortex (0.06±0.02 μM). In all brain regions, adenosine release was activity-dependent. In the nucleus accumbens, hippocampus, and prefrontal cortex, this release was partly due to extracellular ATP breakdown. However, in the caudate-putamen, release was not due to ATP metabolism but was ionotropic glutamate receptor-dependent. The results demonstrate that transient, activity-dependent adenosine can be evoked in many brain regions but that the mechanism of formation and release varies by region.

“…Inosine is the nucleoside of hypoxanthine and is also a downstream metabolite of adenosine. 5 Fig. 5 shows an example CV for each analyte before and after Nafion-CNT coating and Figure S3 shows calibration curves for 50 nM to 10 μM for all the analytes.…”

Section: Resultsmentioning

confidence: 99%

“…3 Traditionally, adenosine has been thought to act on a slow time scale and changes lasting minutes to hours have been measured in vivo with microdialysis sampling coupled to HPLC. 4,5 However, faster adenosine changes have recently been detected in vivo and in brain slices using both fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes and amperometric enzyme sensors. [6][7][8] FSCV can detect changes on the millisecond time scale which provides high temporal resolution for measuring transients in vivo.…”

Section: Introductionmentioning

confidence: 99%

Nafion–CNT coated carbon-fiber microelectrodes for enhanced detection of adenosine

Ross

2012

Analyst

109

Adenosine is a neuromodulator that regulates neurotransmission. Adenosine can be monitored using fast-scan cyclic voltammetry at carbon-fiber microelectrodes and ATP is a possible interferent in vivo because the electroactive moiety, adenine, is the same for both molecules. In this study, we investigated carbon-fiber microelectrodes coated with Nafion and carbon nanotubes (CNTs) to enhance the sensitivity of adenosine and decrease interference by ATP. Electrodes coated in 0.05 mg/mL CNTs in Nafion had a 4.2 ± 0.2 fold increase in current for adenosine, twice as large as for Nafion alone. Nafion-CNT electrodes were 6 times more sensitive to adenosine than ATP. The Nafion-CNT coating did not slow the temporal response of the electrode. Comparing different purine bases shows that the presence of an amine group enhances sensitivity and that purines with carbonyl groups, such as guanine and hypoxanthine, do not have as great an enhancement after Nafion-CNT coating. The ribose group provides additional sensitivity enhancement for adenosine over adenine. The Nafion-CNT modified electrodes exhibited significantly more current for adenosine than ATP in brain slices. Therefore, Nafion-CNT modified electrodes are useful for sensitive, selective detection of adenosine in biological samples.