Electrical Stimulation Of Nucleus Accumbens Research Articles

Effect of electrical stimulation of nucleus accumbens with low, median and high currents intensities on conditioned place preference induced by morphine in rats.

Background:Some investigators indicated the effect of electrical or chemical stimulation on different parts of the brain and its effect on animal's behaviors. Furthermore, drug addiction is known to be associated with dysfunction of memory and motivational systems. In this study, we aimed to evaluate the effect of electrical stimulation of nucleus accumbens (NAc) with different currents intensities on conditioned place preference (CPP) induced by morphine.Materials and Methods:Male Wistar rats were randomly divided for experimental groups (n = 8). We investigated the influence of electrical stimulation with different current intensities (low: 15 μA, median: 50 μA and high: 100 μA) on NAc with ineffective and effective dose of morphine (0.5 and 5 mg/kg, respectively) on acquisition and expression of morphine-induced place conditioning in male rats.Results:The doses of subcutaneous administration morphine (2.5 and 5 mg/kg, P < 0.05 and P < 0.001; respectively) induced CPP compared with saline group. Furthermore, our findings are showed that electrical stimulation (100 μA) of NAc suppressed morphine-induced CPP. It revealed impairment of learning and memory formation in conditioning process due to morphine administration.Conclusion:It is possible that high current intensity (100 μA) had an accompanied effect by a reversal of the increased tissue contents of dopamine and its metabolites in the NAc of morphine-induced CPP rats. Furthermore, high current intensity in combination with ineffective dose of morphine (0.5 mg/kg) increased morphine-induced CPP probability via the prove reward system.

Deep brain stimulation of the bilateral nucleus accumbens in normal rhesus monkey

The nucleus accumbens (NAc) has been considered as a novel target of deep brain stimulation (DBS) for intractable psychiatric disorders. Quite a few questions exist about this new treatment, and might be explored in nonhuman primate models. There are several reports on DBS of brain nucleus other than NAc in nonhuman primates. Therefore, we stereotactically implanted the electrodes into bilateral NAc under the guidance of MRI using a clinical Leksell stereotactic system in normal rhesus monkeys. NAc could be recognized as the area of continuity between the caudate nucleus and putamen in the coronal sections, which is beneath the internal capsule, and the gray matter nucleus between the ventromedial prefrontal cortex and anterior commissure in axial sections, which is medial to the putamen. NAc is mainly at a point 2.0-3.0 mm inferior, 3.0-4.0 mm anterior, and 4.5-5.5 mm lateral to the anterior commissure. The electrodes were implanted accurately and connected to an implantable pulse generator subcutaneously. After recovery from surgery, stimulation with a variety of parameters was trialed, and continuous stimulation at 90 μs, 3.5 V, 160, or 60 Hz was administered individually for 7 days. The behaviors and spontaneous locomotor activity of the animals did not change significantly during stimulation. This is the first report on DBS of NAc in nonhuman primates to the best of our knowledge. Bilateral electrical stimulation of NAc is a safe treatment. This model could be helpful in further studies on the clinical use of NAc stimulation for psychiatric disorders and for a better understanding of the functions of this nucleus.

Effect of picrotoxin and nipecotic acid on inhibitory response of dopaminergic neurons in the ventral tegmental area to stimulation of the nucleus accumbens

Electrical stimulation of nucleus accumbens inhibited the activity of neurons in the ventral tegmental area (VTA). Inhibition was potentiated by nipecotic acid, a GABA uptake inhibitor, and was attenuated by picrotoxin, a GABA antagonist. Four units inhibited by nucleus accumbens stimulation were also antidromically activated. These observations suggest that neurons in the VTA, including specifically those projecting to the nucleus accumbens, receive a descending GABAergic input from that area.