Shunnan Ge

Dopamine depletion increases the power and coherence of high-voltage spindles in the globus pallidus and motor cortex of freely moving rats☆

Studies on patients with Parkinsons disease and in animal models have observed enhanced synchronization of oscillations in several frequency bands within and between the cortical-basal ganglia (BG) structures. Recent research has also shown that synchronization of high-voltage spindles (HVSs) in the cortex, striatum and substantia nigra pars reticulate is increased by dopamine depletion. However, more evidence is needed to determine whether HVS activity in the whole cortex-BG network represents homologous alteration following dopamine depletion. As the globus pallidus (GP) is in a central position to propagate and synchronize oscillations in the cortical-BG circuits, we employed local-field potentials and electrocorticogram to simultaneously record oscillations in the GP and primary (M1) and secondary (M2) motor cortices on freely moving 6-hydroxydopamine (6-OHDA) lesioned and control rats. Results showed that HVS episodes recorded from GP, and M2 and M1 cortex areas were more numerous and longer in 6-OHDA lesioned rats compared to controls. Relative power associated with HVS activity in the GP, and M2 and M1 cortices of 6-OHDA lesioned rats was significantly greater than that for control rats. Coherence values for HVS activity between the GP, and M2 and M1 cortex areas were significantly increased by dopamine depletion. Time lag between the M1 cortex HVS and GP HVS was significantly shorter for dopamine depleted than normal rats. Findings indicate a crucial rule for dopamine in the regulation of HVS activity in the whole cortical-BG circuit, and suggest a close relationship between abnormally synchronized HVS oscillations in the cortex-BG network and Parkinsons disease.

Associations between bilateral subthalamic nucleus deep brain stimulation (STN-DBS) and anxiety in Parkinson's disease patients: a controlled study.

The authors explored the associations between subthalamic nucleus deep brain stimulation (STN-DBS) and anxiety in Parkinsons disease (PD) patients. Recent research suggests that anxiety may be one of the earliest manifestations of PD; however, the lack of a dopamine-medication control group is a major limitation of these studies. Authors paired a group of 31 bilateral STN-DBS PD patients (STN-DBS group) with 31 dopamine-medicated PD patients (Medication-control group) and used various psychological assessment scales for group evaluations. These were completed 1 month preoperatively, and 3 weeks, 5 weeks, 2 months, 4 months, 7 months, and 13 months postoperatively. As compared with the Medication group, the STN-DBS group improved in motor functioning and general status after 1 week Stimulator Power-On; State-Anxiety improved significantly at 1 week and 1 month after Stimulator Power-On, but was not significant at the subsequent time-points. Anxiety scores remained stable before 3rd-month Stimulator Power-On, but got worse after that time. In the STN-DBS group, S-AI was positively related to motor symptoms and life quality preoperatively and 4 months postoperatively, but, in the Medication group, this correlation existed throughout the study. PD-related anxiety decreased in STN-DBS patients because of the improvement in motor function for a short time; however, as the voltages and pulse-widths grew higher with time, the PD-related anxiety became worse.

Long-Term Changes in the Personality and Psychopathological Profile of Opiate Addicts after Nucleus Accumbens Ablative Surgery Are Associated with Treatment Outcome

Objective: To investigate the long-term outcome and changes of the personality and psychopathological profile of opiate addicts after bilateral stereotactic nucleus accumbens (NAc) ablative surgery. Methods: 60 patients were followed up for 5 years and abstinent status and adverse events were evaluated. NAc lesion volumes and locations were obtained by postoperative MRI scans. The Chinese version of the Eysenck Personality Questionnaire (EPQ-RSC), the Symptom Checklist-90-Revised (SCL-90-R), the Beck Depression Inventory (BDI), the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the World Health Organization’s Quality of Life Questionnaire – Brief Version (WHOQOL-BREF) were administered to the patients before and 5 years after the stereotactic surgery. Results: The total abstinence rate of all patients in their 5th postoperative year was 47.4%. The abstinent patients had a significantly larger lesion volume than the relapsed ones, but a larger lesion volume also increased the risk of adverse events. 5 years after surgery, the abstinent patients showed significant decreases on the Psychoticism (EPQ-P) and Neuroticism (EPQ-N) scores by EPQ-RSC, a significant decline on the Global Severity Index and the subscores in all 10 dimensions by SCL-90-R, significant decreases on the BDI and Y-BOCS scores, and significant improvements on the scores of all domains by WHOQOL-BREF, while for the relapsed patients, only the subscores of obsessive-compulsive by SCL-90-R and the Y-BOCS scores significantly decreased. Postoperative analysis revealed that the abstinent patients had a significantly better score than the relapsed ones by various instruments, and NAc lesion volumes and locations did not correlate with the outcome of any of these instruments. Conclusion: The bilateral ablation of NAc by stereotactic neurosurgery was a feasible method for alleviating psychological dependence on opiate drugs and preventing a relapse. Long-term follow-up suggested that surgery can improve the personality and psychopathological profile of opiate addicts with a trend towards normal levels, provided persistent abstinence can be maintained; relapse, on the other hand, may ruin this effect.

NMDA and dopamine D1 receptors within NAc-shell regulate IEG proteins expression in reward circuit during cocaine memory reconsolidation.

Reactivation of consolidated memory initiates a memory reconsolidation process, during which the reactivated memory is susceptible to strengthening, weakening or updating. Therefore, effective interference with the memory reconsolidation process is expected to be an important treatment for drug addiction. The nucleus accumbens (NAc) has been well recognized as a pathway component that can prevent drug relapse, although the mechanism underlying this function is poorly understood. We aimed to clarify the regulatory role of the NAc in the cocaine memory reconsolidation process, by examining the effect of applying different pharmacological interventions to the NAc on Zif 268 and Fos B expression in the entire reward circuit after cocaine memory reactivation. Through the cocaine-induced conditioned place preference (CPP) model, immunohistochemical and immunofluorescence staining for Zif 268 and Fos B were used to explore the functional activated brain nuclei after cocaine memory reactivation. Our results showed that the expression of Zif 268 and Fos B was commonly increased in the medial prefrontal cortex (mPFC), the infralimbic cortex (IL), the NAc-core, the NAc-shell, the hippocampus (CA1, CA2, and CA3 subregions), the amygdala, the ventral tegmental area (VTA), and the supramammillary nucleus (SuM) following memory reconsolidation, and Zif 268/Fos B co-expression was commonly observed (for Zif 268: 51-68%; for Fos B: 52-66%). Further, bilateral NAc-shell infusion of MK 801 and SCH 23390, but not raclopride or propranolol, prior to addictive memory reconsolidation, decreased Zif 268 and Fos B expression in the entire reward circuit, except for the amygdala, and effectively disturbed subsequent CPP-related behavior. In summary, N-methyl-d-aspartate (NMDA) and dopamine D1 receptors, but not dopamine D2 or β adrenergic receptors, within the NAc-shell, may regulate Zif 268 and Fos B expression in most brain nuclei of the reward circuit after cocaine memory reactivation. These findings indicated that the NAc played a key role in regulating addictive memory reconsolidation by influencing the function of the entire addictive memory network.

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 &mgr;s, 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.

Systemic Blockade of Dopamine D2-Like Receptors Increases High-Voltage Spindles in the Globus Pallidus and Motor Cortex of Freely Moving Rats

High-voltage spindles (HVSs) have been reported to appear spontaneously and widely in the cortical–basal ganglia networks of rats. Our previous study showed that dopamine depletion can significantly increase the power and coherence of HVSs in the globus pallidus (GP) and motor cortex of freely moving rats. However, it is unclear whether dopamine regulates HVS activity by acting on dopamine D1-like receptors or D2-like receptors. We employed local-field potential and electrocorticogram methods to simultaneously record the oscillatory activities in the GP and primary motor cortex (M1) in freely moving rats following systemic administration of dopamine receptor antagonists or saline. The results showed that the dopamine D2-like receptor antagonists, raclopride and haloperidol, significantly increased the number and duration of HVSs, and the relative power associated with HVS activity in the GP and M1 cortex. Coherence values for HVS activity between the GP and M1 cortex area were also significantly increased by dopamine D2-like receptor antagonists. On the contrary, the selective dopamine D1-like receptor antagonist, SCH23390, had no significant effect on the number, duration, or relative power of HVSs, or HVS-related coherence between M1 and GP. In conclusion, dopamine D2-like receptors, but not D1-like receptors, were involved in HVS regulation. This supports the important role of dopamine D2-like receptors in the regulation of HVSs. An siRNA knock-down experiment on the striatum confirmed our conclusion.

Clinical analysis and treatment of symptomatic intracranial hemorrhage after deep brain stimulation surgery

Abstract Background: Symptomatic intracranial hemorrhage (ICH) may lead to permanent neurological disability of patients and has impeded the extensive clinical application of deep brain stimulation (DBS). The present study was conducted to discuss the incidence, prevention, and treatment of symptomatic ICH after DBS surgery. Methods: From January 2009 to December 2014, 396 patients underwent DBS with a total of 691 implanted leads. In all, 10 patients had symptomatic ICH. We analyzed these cases’ clinical characteristics, including comorbid diagnoses and coagulation profile. We described the onset of ICH, imaging features, clinical manifestations, treatment, neurological impairment, and outcome of DBS. Results: Of the 10 patients with symptomatic ICH, 2 had hypertension. Three cases of ICH occurred within 12 h of the procedure; four cases within 24 h. Five experienced grand mal seizures concurrently with hemorrhage. Unilateral frontal lobe hemorrhage occurred in all cases. In seven cases, hematomas occurred around the electrodes. Some hematomas were not well-circumscribed and had perihematomal edema. Conservative therapy was administered to 8 patients, and 2 patients underwent craniotomy and hematoma evacuation. All electrodes were successfully preserved. Neurological dysfunction in all patients gradually improved. Nine patients ultimately experienced effective symptom relief of Parkinson’s disease with DBS. Conclusions: Symptomatic ICH should be identified as soon as possible after implantation surgery and treated effectively to limit neurological deficit and preserve DBS leads.

Neuroprotective effects of nitidine in Parkinson's disease models through inhibiting microglia activation: role of the Jak2–Stat3 pathway

Parkinsons disease (PD) is the second most common neurodegenerative disorder; currently, no effective therapy is available to halt the progression of this disease. Neuroinflammation significantly contributes to the pathogenesis of PD. Recent studies have demonstrated that nitidine possesses anti-inflammatory activity. However, the role of nitidine in neuroinflammation of PD and the mechanism of its action, if any, are still unknown. In the present study, our results showed that nitidine significantly suppressed neurotoxin induced microglial activation in vitro. Further, we demonstrated that the inhibitory effect of nitidine on microglial activation is mediated by the Jak2–Stat3 pathway and that nitidine can suppress the nuclear translocation of p-Stat3 via enhancing the binding activity of αB-crystalline (CRYAB). Importantly, nitidine could inhibit reactive microgliosis and protect dopaminergic neurons in two Parkinsons disease animal models. Finally, our data showed that nitidine significantly improved neurobehavioral activity in PD animal models. Our results indicated that nitidine could significantly suppress microglial activation via the Jak2–Stat3 pathway and obviously improve behavioral function in PD animal models, which sheds some light on a promising therapeutic strategy for PD.

High frequency stimulation of the STN restored the abnormal high-voltage spindles in the cortex and the globus pallidus of 6-OHDA lesioned rats

Many studies showed that abnormal oscillations in the cortical-basal ganglia loop is involved in the pathophysiology of Parkinsons disease (PD). In contrast to the well-studied beta synchronization, high-voltage spindles (HVSs), another type of abnormal oscillation observed in PD, are neglected. To explore the role of subthalamic nucleus-deep brain stimulation (STN-DBS) in HVSs regulation, we simultaneously recorded the local field potential (LFP) in the globus pallidus (GP) and electrocorticogram (ECoG) in the primary motor cortex(M1) in freely moving 6-hydroxydopamine (6-OHDA) lesioned or control rats before, during, and after STN-DBS. Consistent with our previous study, HVSs occurrence, duration, and relative power and coherence between the M1 cortex and GP increased in 6-OHDA lesioned rats. We found that high but not low frequency stimulation restored the abnormal HVSs activity and motor deficit. These results suggest that the STN is involved in the abnormal oscillation between the M1 cortex and GP.

Decreased HCN2 expression in STN contributes to abnormal high-voltage spindles in the cortex and globus pallidus of freely moving rats.

Abnormal oscillation in the cortical-basal ganglia loop is involved in the pathophysiology of parkinsonism. High-voltage spindles (HVSs), one of the main type abnormal oscillations in Parkinsons disease, are regulated by dopamine D2-like receptors but not D1-like receptors. However, little is known about how dopamine D2-like receptors regulate HVSs and the role of hyperpolarization-activated cyclic nucleotide-gated2 (HCN2) in HVSs regulation. We simultaneously recorded the local field potential (LFP) in globus pallidus (GP) and electrocorticogram (ECoG) in primary motor cortex (M1) in freely moving 6-hydroxydopamine (6-OHDA) lesioned or control rats. The expression of HCN2 and dopamine D2 receptor in the subthalamic nucleus (STN) was examined by immunochemical staining and Western blotting. We also tested the role of HCN2 in HVSs regulation by using pharmacological and shRNA methodology. We found that dopamine D2-like receptor agonists suppressed the increased HVSs in 6-OHDA lesioned rats. HCN2 was co-expressed with dopamine D2 receptor in the STN, and dopamine depletion decreased the expression of HCN2 as well as dopamine D2 receptor which contribute to the regulation of HVSs. HCN2 was down regulated by HCN2 shRNA, which thereby led to an increase in the HVSs in naïve rats while HCN2 agonist reduced the HVSs in 6-OHDA lesioned rats. These results suggest that HCN2 in the STN is involved in abnormal oscillation regulation between M1 cortex and GP.