Simultaneous wireless and high-resolution detection of nucleus accumbens shell ethanol concentrations and free motion of rats upon voluntary ethanol intake.

Highly sensitive detection of ethanol concentrations in discrete brain regions of rats voluntarily accessing ethanol, with high temporal resolution, would represent a source of greatly desirable data in studies devoted to understanding the kinetics of the neurobiological basis of ethanol's ability to impact behavior. In the present study, we present a series of experiments aiming to validate and apply an original high-tech implantable device, consisting of the coupling, for the first time, of an amperometric biosensor for brain ethanol detection, with a sensor for detecting the microvibrations of the animal. This device allows the real-time comparison between the ethanol intake, its cerebral concentrations, and their effect on the motion when the animal is in the condition of voluntary drinking. To this end, we assessed in vitro the efficiency of three different biosensor designs loading diverse alcohol oxidase enzymes (AOx) obtained from three different AOx-donor strains: Hansenula polymorpha, Candida boidinii, and Pichia pastoris. In vitro data disclosed that the devices loading H. polymorpha and C. boidinii were similarly efficient (respectively, linear region slope [LRS]: 1.98 ± 0.07 and 1.38 ± 0.04 nA/mM) but significantly less than the P. pastoris-loaded one (LRS: 7.57 ± 0.12 nA/mM). The in vivo results indicate that this last biosensor design detected the rise of ethanol in the nucleus accumbens shell (AcbSh) after 15 minutes of voluntary 10% ethanol solution intake. At the same time, the microvibration sensor detected a significant increase in the rat's motion signal. Notably, both the biosensor and microvibration sensor described similar and parallel time-dependent U-shaped curves, thus providing a highly sensitive and time-locked high-resolution detection of the neurochemical and behavioral kinetics upon voluntary ethanol intake. The results overall indicate that such a dual telemetry unit represents a powerful device which, implanted in different brain areas, may boost further investigations on the neurobiological mechanisms that underlie ethanol-induced motor activity and reward.

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