Article
Frequency-dependent neuronal electrophysiology response to micro electrical stimulation of nucleus accumbens in acute rat brain slices
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Published: | June 4, 2012 |
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Objective: Acute rat brain slices consisting of caudate nucleus, putamen, nucleus accumbens.
Methods: The rat brain slice (250 μm thick) was kept in a chamber filled with artificial cerebro-spinal fluid (aCSF) on the top of a 3D multi electrode array (MEA). One of the electrodes in this MEA was selected as the stimulation electrode, which was in contact with the nucleus accumbens shell region, the remaining electrodes were used as recording electrodes. The current-driven electrical stimulation was generated by a stimulus generator from MultiChannelSystems. The stimuli was monopolar biphasic negative-first pulses train with (±)64 μA pulse amplitude, 100 μs pulse width, and various frequencies (10 Hz, 140 Hz). After 2–3 mins, the base line recording, two stimulation protocols were used in this study: 1) Frequencies from 2 to 140 Hz in an increasing manner (2, 5, 10, 60, 80, 100, 140 Hz) were evaluated within one slice; 2) Stimulations at a frequency of 140 Hz which was considered as high frequency stimulation and a frequency of 10 Hz which was considered to be the low frequency stimulation, were applied for 200 secs alternately in a randomized order.
Results: Spontaneous activity was recorded from 82 neurons in 15 rats. The average firing rate of these recorded neurons was 1.12 Hz. During the high frequency stimulation (HFS) of 140 Hz, the firing rate was suppressed to 50 % of the basal value. During low frequency stimulation (LFS) of 10 Hz, the firing rate was 108% of the basal value. The effects of accumbens nucleus, DBS by HFS and LFS were significantly different (p < 0.0001). Both on GABAa receptor antagonist bicuculline present and absent condition, HFS inhibit neuronal spontaneous activities up to 50% of the basal value.
Conclusions: High frequency electrical stimulation at 140 Hz significantly inhibits the neuronal spontaneous firing rate in the nucleus accumbens shell region in the acute rat brain slice.