Real time adenosine fluctuations detected with fast-scan cyclic voltammetry in the rat striatum and motor cortex

Abstract

Background Adenosine serves many functions within the CNS, including inhibitory and excitatory control of neurotransmission. The understanding of adenosine dynamics in the brain is of fundamental importance. The goal of the present study was to explore subsecond adenosine fluctuations in the rat brain in vivo. Method Long Evans rats were anesthetized and a carbon fiber electrode was positioned in the motor cortex or dorsal striatum. Real time electrochemical recordings were made at the carbon fiber electrodes every 100 ms by applying a triangular waveform (−0.4 to +1.5 V, 400 V/s). Adenosine spikes were identified by the background-subtracted cyclic voltammogram. Results The frequency of detected adenosine spikes was relatively stable in both tested regions, and the time intervals between spikes were regular and lasted from 1 to 5 seconds within an animal. Spike frequency ranged from 0.5 to 1.5 Hz in both the motor cortex and the dorsal striatum. Average spike amplitudes were 85 ± 11 and 66 ± 7 nM for the motor cortex and the dorsal striatum, respectively. Comparison with Existing Methods The current study established that adenosine signaling can operate on a fast time scale (within seconds) to modulate brain functions. Conclusions This finding suggests that spontaneous adenosine release may play a fast, dynamic role in regulating an organism’s response to external events. Therefore, adenosine transmission in the brain may have characteristics similar to those of classical neurotransmitters, such as dopamine and norepinephrine

Regional Variations of Spontaneous, Transient Adenosine Release in Brain Slices

“…Changes in extracellular adenosine concentrations have been observed on time scales ranging from minutes to hours. − However, a faster form of transient adenosine release has recently been characterized, which lasts only a few seconds . While adenosine release can be electrically stimulated, recent studies have found transient adenosine events that are not stimulated, but spontaneous, and occur randomly. ,, Rapid adenosine can modulate electrically stimulated dopamine release . There is also a correlation between transient adenosine and transient oxygen events, supporting the hypothesis that rapid adenosine serves a neuroprotective role .…”

“…11 While adenosine release can be electrically stimulated, 12 recent studies have found transient adenosine events that are not stimulated, but spontaneous, and occur randomly. 11,13,14 Rapid adenosine can modulate electrically-stimulated dopamine release. 15 There is also a correlation between transient adenosine and transient oxygen events, supporting the hypothesis that rapid adenosine serves a neuroprotective role.…”

Analytical Techniques in Neuroscience: Recent Advances in Imaging, Separation, and Electrochemical Methods

“…177 Recently, the Budygin group also reported spontaneous adenosine release in rat striatum and motor cortex. 178 Although they used the same waveform, there is a discrepancy in the data as they did not observe a secondary oxidation peak. Their spontaneous transients were at much higher frequencies than previously reported, and they also detected adenosine efflux in response to a brief tail pinch.…”

“…Spontaneous adenosine transients were detected for the first time in vivo , with a characteristic electrochemical signature of a primary oxidation peak at +1.4 V and a second oxidation peak at +1.0 V in subsequent scans . Recently, the Budygin group also reported spontaneous adenosine release in rat striatum and motor cortex . Although they used the same waveform, there is a discrepancy in the data as they did not observe a secondary oxidation peak.…”

Transient Adenosine Release Is Modulated by NMDA and GABAB Receptors

“…Our lab has recently discovered a new mode of adenosine signaling: spontaneous, transient release that lasts for only about three seconds. 7–10 These spontaneous transients are modulated by A 1 receptors 7 and A 2a receptors 11 in the caudate and prefrontal cortex but regulation by other neurotransmitter receptors has not been studied.…”