Wireless Instantaneous Neurotransmitter Concentration System: electrochemical monitoring of serotonin using fast-scan cyclic voltammetry--a proof-of-principle study.
OBJECTIVE
The authors previously reported the development of the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for measuring dopamine and suggested that this technology may be useful for evaluating deep brain stimulation-related neuromodulatory effects on neurotransmitter systems. The WINCS supports fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for real-time, spatially resolved neurotransmitter measurements. The FSCV parameters used to establish WINCS dopamine measurements are not suitable for serotonin, a neurotransmitter implicated in depression, because they lead to CFM fouling and a loss of sensitivity. Here, the authors incorporate into WINCS a previously described N-shaped waveform applied at a high scan rate to establish wireless serotonin monitoring.


METHODS
Optimized for the detection of serotonin, FSCV consisted of an N-shaped waveform scanned linearly from a resting potential of +0.2 to +1.0 V, then to -0.1 V and back to +0.2 V, at a rate of 1000 V/second. Proof-of-principle tests included flow injection analysis and electrically evoked serotonin release in the dorsal raphe nucleus of rat brain slices.


RESULTS
Flow cell injection analysis demonstrated that the N waveform, applied at a scan rate of 1000 V/second, significantly reduced serotonin fouling of the CFM, relative to that observed with FSCV parameters for dopamine. In brain slices, WINCS reliably detected subsecond serotonin release in the dorsal raphe nucleus evoked by local high-frequency stimulation.


CONCLUSIONS
The authors found that WINCS supported high-fidelity wireless serotonin monitoring by FSCV at a CFM. In the future such measurements of serotonin in large animal models and in humans may help to establish the mechanism of deep brain stimulation for psychiatric disease.
Griessenauer
Christoph J
CJ
Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota 55905, USA.
Chang
Su-Youne
SY
Tye
Susannah J
SJ
Kimble
Christopher J
CJ
Bennet
Kevin E
KE
Garris
Paul A
PA
Lee
Kendall H
KH
D000818:Animals; D002138:Calibration; D002244:Carbon; D000077482:Carbon Fiber; D004298:Dopamine / Q000378:metabolism; D004558:Electric Stimulation; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D066298:In Vitro Techniques; D008297:Male; D008839:Microelectrodes; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011903:Raphe Nuclei / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors
D000077482:Carbon Fiber; D018377:Neurotransmitter Agents; D012701:Serotonin; D002244:Carbon; D004298:Dopamine