Evaluation of Voltage-Sensitive Dyes for Long-Term Recording of Neural Activity in the Hippocampus

Abstract

We searched for an optimal voltage-sensitive dye for optical measurements of neural activity in the hippocampal slice by evaluating several merocyanine-rhodanine and oxonol dyes. The wavelength dependence (action spectra), pharmacological effects of staining, signal size, signal-to-noise ratio, and the utility of the dyes for long-term continuous recording were examined for four merocyanine-rhodanine dyes (NK2761, NK2776, NK3224 and NK3225), which had been reported to be optimal in embryonic nervous systems, and for two oxonol dyes (NK3630 (RH482) and NK3041 (RH155)), which have been among the most popular potentiometric probes for the hippocampal slice preparation. NK2761, NK3224 and NK3225 provided large signal-to-noise ratios, and proved to be useful for optical recordings lasting several hours. NK3630 was most suitable for long-term recording, although the signal-to-noise ratio was slightly inferior to that of the merocyanine-rhodanines. Using NK3630 (RH482) on the hippocampal slice preparation, we demonstrate here that long-term potentiation can be monitored stably for more than 8 hr.

Voltage Imaging Reveals the CA1 Region at the CA2 Border as a Focus for Epileptiform Discharges and Long-Term Potentiation in Hippocampal Slices

“…Slices were stored in a vial of 95% O 2 -5% CO 2 -bubbled artificial cerebrospinal fluid (ACSF) for 1 h. ACSF was identical to the cutting solution but contained 2.5 mM CaCl 2 and 1.3 mM MgSO 4 . Slices were stained with one of three different voltage-sensitive dyes: 0.2 mg/ml RH155, 100 M RH414 (Molecular Probes, Eugene, OR), or 0.02 mg/ml RH482 (NK3630, Hayashibara Biochemical Laboratories, Okayama, Japan) Jackson 2003, 2006;Momose-Sato et al 1999). Staining was accomplished by incubation in a solution of dye in 95% O 2 -5% CO 2 -bubbled ACSF for 1 h. During recording, hippocampal slices were continuously perfused with 95% O 2 -5% CO 2 -bubbled ACSF at a flow rate of 2-2.5 ml/min in a submerged recording chamber and maintained at 29 -31°C.…”

Propagating Wave and Irregular Dynamics: Spatiotemporal Patterns of Cholinergic Theta Oscillations in Neocortex In Vitro

“…Briefly, the slices were stained with ACSF containing 0.005-0.02 mg/ml of an oxonol dye, NK3630 [first synthesized by R. Hildesheim and A. Grinvald as RH482; available from Nippon Kankoh-Shikiso Kenkyusho, Japan) (see Momose-Sato et al (1999) for molecular structure], for 30 -60 min (22°C). During staining, the dye solution was gently bubbled with 95% O 2 -5% CO 2 .…”

Optical coherence tomography for cross-sectional imaging of neural activity

“…The action spectrum of NK3630 (RH482) absorption dye, as reported for a hippocampal slice preparation, 35 suggests that the maximum fractional change of transmitted light intensity is at around 700 nm (∼0.12%). Although the OCT measurement of backscattered light from particular depths can yield larger fraction with dye staining, 29 the measurements are still expected to vary with design wavelength, species, and staining procedure.…”