Curcumin Ameliorates the Experimental Diabetic Peripheral Neuropathy through Promotion of NGF Expression in Rats.

Increasing evidence suggested that inhibiting the apoptosis of Schwann cells (SCs) and promoting nerve growth factor (NGF) expression in sciatic nerves play key roles in preventing the onset of diabetic peripheral neuropathy (DPN). Curcumin, a primary bioactive substance in turmeric with multiple characteristics, has been shown to have many therapeutic effects in a variety of diseases. However, curcumin is poorly studied in the DPN models. We aimed to explore the therapeutic benefits and underlying mechanism of curcumin in high fat/sugar diets joint streptozotocin (STZ)-induced DPN rat models. Sprague-Dawley (SD) rats were divided into five groups (6 rats per group), control group, DPN group, Curcumin groups (50, 100, and 150 mg/kg). Curcumin was administered intragastrically once per day for 4 continuous weeks. Body weight (BW) and fasting blood glucose (FBG) were monitored in all groups. The mechanical withdraw threshold (MWT) was measured. We also assessed neuropathic change by testing nerve conductance velocity (NCV) in sciatic nerves. TEM was applied to observe the sciatic nerves ultrastructure. The SCs apoptosis in sciatic nerves was stained using TUNEL kit. NGF contents in sciatic nerves and serum were detected using western blotting and ELISA analysis. The results showed curcumin had no obvious effect on the BW and FBG change. Curcumin (100 and 150 mg/kg) attenuated the MWT, NCV, and sciatic nerves ultrastructure in DPN rats. Curcumin (50, 100 and 150 mg/kg) reduced SCs apoptosis in sciatic nerves. In addition, curcumin at 150 mg/kg had the best efficacy in increasing protein expression of NGF in sciatic nerves and serum NGF level. Our work demonstrated that curcumin has neuroprotective effects for the treatment of DPN.

Exaggerated activities of TRPM7 underlie bupivacaine-induced neurotoxicity in the SH-SY5Y cells preconditioned with high glucose.

Hyperglycemia is considered a risk factor for the enhancement of local anesthetic-induced neurotoxicity. Transient receptor potential melastatin 7 (TRPM7), a kinase-coupled cation channel, has been implicated in a variety of neuropathological processes, including intracellular calcium disturbance and high glucose-induced neuropathy. In this study, we investigated whether TRPM7-related pathophysiology is involved in bupivacaine-induced neurotoxicity in SH-SY5Y cells and how hyperglycemia acts as a risk factor. For initial neurotoxicity evaluation, it was confirmed that cell damage and apoptosis induced by acute exposure to bupivacaine were dependent on its concentration and glucose preconditioning. High glucose preconditioning facilitated the bupivacaine-induced fast and temporary rise in intracellular free calcium concentration ([Ca2+ ]i ), which was attributed to both calcium influx through TRPM7 and calcium store release. Additionally, bupivacaine was shown to increase TRPM7-like currents, particularly in cells preconditioned with high glucose. Bupivacaine-induced neurotoxicity in hyperglycemia was correlated with extracellular signal-regulated kinase (ERK), but not protein kinase B (AKT) activation. Inhibition of TRPM7 and ERK activity alleviates bupivacaine neurotoxicity. These results suggest that therapeutically targeting TRPM7-related pathophysiological changes could be a potential strategy for treating local anesthetic-induced neurotoxicity exacerbated by hyperglycemia.

Neuroanatomical autonomic substrates of brainstem-gut circuitry identified using transsynaptic tract-tracing with pseudorabies virus recombinants.

To investigate autonomic substrates of brainstem-gut circuitry identified using trans-synaptic tracing with pseudorabies virus (PRV)-152, a strain that expresses enhanced green fluorescent protein, and PRV-614, a strain that expresses enhanced red fluorescent protein, injecting into the rat rectum wall. 3-7 days after PRV-152 injection, spinal cord and brainstem were removed and sectioned, and processed for PRV-152 visualization using immunofluorescence labeling against PRV-152. 6 days after PRV-614 injection, brainstem was sectioned and the neurochemical phenotype of PRV-614-positive neurons was identified using double immunocytochemical labeling against PRV-614 and TPH. We observed that the largest number of PRV-152- or PRV-614-positive neurons was located in the gigantocellular reticular nucleus (Gi), lateral paragigantocellular (LPGi), rostral ventrolateral reticular nucleus (RVL), solitary tract nucleus (Sol), locus coeruleus (LC), raphe magnus nucleus (RMg), subcoeruleus nucleus (SubCD). Double-labeled PRV-614/tryptophan hydroxylase (TPH) neurons were concentrated in the RMg, LPGi and Sol. These brainstem neurons are candidates for relaying autonomic command signals to the gut. The autonomic substrate of brainstem-gut circuitry likely plays an important role in mediating different aspects of stress behaviors.

The change in cerebral glucose metabolism after electroacupuncture: a possible marker to predict the therapeutic effect of deep brain stimulation for refractory anorexia nervosa.

Some reports have demonstrated that deep brain stimulation (DBS) is a promising treatment for patients who suffer from intractable anorexia nervosa. However, the nature of DBS may not be viewed as a standard clinical treatment option for anorexia nervosa because of the unpredictable outcome before DBS. Just like DBS in the brain, electroacupuncture at acupoints is also efficient in treating refractory anorexia nervosa. Some neuroimaging studies using functional magnetic resonance imaging, single-photon emission computed tomography (SPECT), and positron emission tomography (PET) had revealed that both DBS and electroacupuncture at acupoints with electrical stimulation are related to the changes in cerebral glucose metabolism. Therefore, we hypothesize that the changes in cerebral glucose metabolism after electroacupuncture might be useful to predict the therapeutic effect of deep brain stimulation for refractory anorexia nervosa.