A New Micro-holder Device for Local Drug Delivery during In Vivo Whole-cell Recordings. (15th June 2018)

• Record Type: Journal Article
• Authors: Sáez, María; Ketzef, Maya; Alegre-Cortés, Javier; Reig, Ramón; Silberberg, Gilad
• Is Part Of: Neuroscience. Volume 381(2018)
• Page Start: 115
• Page End: 123
• Publication Date: 2018-06-15
• Subjects: BMI bicuculline methiodide -- LFP local field potential -- M1 motor cortex -- S1 primary somatosensory cortex -- TTX tetrodotoxin; neuropharmacology -- cortex -- striatum -- slow oscillations -- in vivo patch-clamp -- bicuculline; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2018.04.011
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Versatile and cheap device for precise and stable drug application for in vivo intracellular recordings in deep brain areas. BMI modifies the properties of slow oscillations, changing duration, transitions and amplitude of the Up states. Local application of TTX blocks the slow oscillations in the striatal neurons with no effects in the cortical activity. Abstract: Focal administration of pharmacological agents during in vivo recordings is a useful technique to study the functional properties of neural microcircuits. However, the lack of visual control makes this task difficult and inaccurate, especially when targeting small and deep regions where spillover to neighboring regions is likely to occur. An additional problem with recording stability arises when combining focal drug administration with in vivo intracellular recordings, which are highly sensitive to mechanical vibrations. To address these technical issues, we designed a micro-holder that enables accurate local application of pharmacological agents during in vivo whole-cell recordings. The holder couples the recording and drug delivery pipettes with adjustable distance between the respective tips adapted to the experimental needs. To test the efficacy of the micro-holder we first performed whole-cell recordings in mouse primary somatosensory cortex (S1) with simultaneous extracellular recordings in S1 and motor cortex (M1), before and after local application of bicuculline methiodide (BMI 200 µM). The blockade of synaptic inhibition resulted in increased amplitudes and rising slopes of "Up states", and shortening of their duration. We then checked the usability of the micro-holder in a deeper brain structure, the striatum. We applied tetrodotoxin (TTX 10 µM) during whole-cell recordings in the striatum, while simultaneously obtaining extracellular recordings in S1 and M1. The focal application of TTX in the striatum blocked Up states in the recorded striatal neurons, without affecting the cortical activity. We also describe two different approaches for precisely releasing the drugs without unwanted leakage along the pipette approach trajectory.