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High-frequency electrical stimulation in the nucleus accumbens of morphine-treated rats suppresses neuronal firing in reward-related brain regions.

Hu WH, Bi YF, Zhang K, Meng FG, Zhang JG - Med. Sci. Monit. (2011)

Bottom Line: Conditioned place preference (CPP) behavior of the rats was evaluated to confirm morphine preference after morphine injection and CPP training for 10 days.The results suggest that electrical stimulation in the NAc can suppress neuronal firing in reward-related brain regions.The core and shell of the NAc play different roles in suppressing NAc neuronal firing as 2 stimulating targets.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.

ABSTRACT

Background: Previous studies have reported that high-frequency stimulation (HFS) in the nucleus accumbens (NAc) is a potential treatment modality for drug craving and relapse. We aimed to explore the electrophysiological changes in reward-related brain regions during NAc stimulation and reveal the effects of stimulation frequency and target changes on NAc neuronal activities.

Material/methods: Twenty-eight rats were randomized into saline (n=8) and morphine (n=20) groups. The morphine group was further divided into core (n=10, only the core of the NAc was stimulated) and shell (n=10, only the shell of the NAc was stimulated) subgroups. Conditioned place preference (CPP) behavior of the rats was evaluated to confirm morphine preference after morphine injection and CPP training for 10 days. We recorded NAc neuronal responses to NAc core stimulation at different frequencies, as well as changes in VP and VTA neuronal firing during NAc core stimulation, and changes in NAc neuronal firing during NAc shell stimulation.

Results: The results indicate that high frequency stimulation was more effective in suppressing NAc neuronal activities than low frequency stimulation and that core stimulation was more effective than shell stimulation. Most VP neurons were inhibited by NAc core stimulation, while VTA neurons were not.

Conclusions: The results suggest that electrical stimulation in the NAc can suppress neuronal firing in reward-related brain regions. The stimulation might be frequency- dependent in suppressing neuronal firing. The core and shell of the NAc play different roles in suppressing NAc neuronal firing as 2 stimulating targets.

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Related in: MedlinePlus

Magnified view of recording traces from a NAc neuron during HFS of the NAc core. The black arrows indicated action potentials being embedded into the artifacts. Since the neuron spike duration (1.2 ms) was much longer than the period during which the amplifier was saturated (0.4 ms), the spikes could be accurately detected. The black bars indicated the stimulation artifacts.
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f1-medscimonit-17-6-br153: Magnified view of recording traces from a NAc neuron during HFS of the NAc core. The black arrows indicated action potentials being embedded into the artifacts. Since the neuron spike duration (1.2 ms) was much longer than the period during which the amplifier was saturated (0.4 ms), the spikes could be accurately detected. The black bars indicated the stimulation artifacts.

Mentions: The duration spent in the drug-paired chamber in the CPP test was converted to CPP score. Neuronal firing patterns were defined by interspike interval histogram (ISIH). According to ISIH analysis, regular firing pattern shows symmetrical density distribution, irregular firing pattern shows Poisson distribution, and burst firing pattern shows gradual decay of skewness distribution [23]. Since the neuronal spike duration (1.0~1.5 ms) is much longer than the period during which the amplifier was saturated (0.2~0.45 ms), spikes were not occulted by the stimulation artifacts (Figure 1). The artifacts during stimulation were completely removed by template subtraction method [24,25] (Figure 2). During the stimulation period, neurons were considered as responsive when their firing rate showed more than 20% change from that of the pre-stimulation period [22]. The suppression rate was determined with the following formula: suppression rate = (firing rate during pre-stimulation period – firing rate during stimulation period)/firing rate during pre-stimulation period ×100%.


High-frequency electrical stimulation in the nucleus accumbens of morphine-treated rats suppresses neuronal firing in reward-related brain regions.

Hu WH, Bi YF, Zhang K, Meng FG, Zhang JG - Med. Sci. Monit. (2011)

Magnified view of recording traces from a NAc neuron during HFS of the NAc core. The black arrows indicated action potentials being embedded into the artifacts. Since the neuron spike duration (1.2 ms) was much longer than the period during which the amplifier was saturated (0.4 ms), the spikes could be accurately detected. The black bars indicated the stimulation artifacts.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539543&req=5

f1-medscimonit-17-6-br153: Magnified view of recording traces from a NAc neuron during HFS of the NAc core. The black arrows indicated action potentials being embedded into the artifacts. Since the neuron spike duration (1.2 ms) was much longer than the period during which the amplifier was saturated (0.4 ms), the spikes could be accurately detected. The black bars indicated the stimulation artifacts.
Mentions: The duration spent in the drug-paired chamber in the CPP test was converted to CPP score. Neuronal firing patterns were defined by interspike interval histogram (ISIH). According to ISIH analysis, regular firing pattern shows symmetrical density distribution, irregular firing pattern shows Poisson distribution, and burst firing pattern shows gradual decay of skewness distribution [23]. Since the neuronal spike duration (1.0~1.5 ms) is much longer than the period during which the amplifier was saturated (0.2~0.45 ms), spikes were not occulted by the stimulation artifacts (Figure 1). The artifacts during stimulation were completely removed by template subtraction method [24,25] (Figure 2). During the stimulation period, neurons were considered as responsive when their firing rate showed more than 20% change from that of the pre-stimulation period [22]. The suppression rate was determined with the following formula: suppression rate = (firing rate during pre-stimulation period – firing rate during stimulation period)/firing rate during pre-stimulation period ×100%.

Bottom Line: Conditioned place preference (CPP) behavior of the rats was evaluated to confirm morphine preference after morphine injection and CPP training for 10 days.The results suggest that electrical stimulation in the NAc can suppress neuronal firing in reward-related brain regions.The core and shell of the NAc play different roles in suppressing NAc neuronal firing as 2 stimulating targets.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.

ABSTRACT

Background: Previous studies have reported that high-frequency stimulation (HFS) in the nucleus accumbens (NAc) is a potential treatment modality for drug craving and relapse. We aimed to explore the electrophysiological changes in reward-related brain regions during NAc stimulation and reveal the effects of stimulation frequency and target changes on NAc neuronal activities.

Material/methods: Twenty-eight rats were randomized into saline (n=8) and morphine (n=20) groups. The morphine group was further divided into core (n=10, only the core of the NAc was stimulated) and shell (n=10, only the shell of the NAc was stimulated) subgroups. Conditioned place preference (CPP) behavior of the rats was evaluated to confirm morphine preference after morphine injection and CPP training for 10 days. We recorded NAc neuronal responses to NAc core stimulation at different frequencies, as well as changes in VP and VTA neuronal firing during NAc core stimulation, and changes in NAc neuronal firing during NAc shell stimulation.

Results: The results indicate that high frequency stimulation was more effective in suppressing NAc neuronal activities than low frequency stimulation and that core stimulation was more effective than shell stimulation. Most VP neurons were inhibited by NAc core stimulation, while VTA neurons were not.

Conclusions: The results suggest that electrical stimulation in the NAc can suppress neuronal firing in reward-related brain regions. The stimulation might be frequency- dependent in suppressing neuronal firing. The core and shell of the NAc play different roles in suppressing NAc neuronal firing as 2 stimulating targets.

Show MeSH
Related in: MedlinePlus