Improvement of impaired electrical activity in NPC1 mutant cortical neurons upon DHPG stimulation detected by micro-electrode array.

Niemann-Pick Type C1 (NPC1) disease is an autosomal recessive neurodegenerative disease characterized by an excessive accumulation of unesterified cholesterol in late endosomes/lysosomes. Patients with NPC1 disease show a series of symptoms in neuropathology, including a gradually increased loss of motor control and seizures. However, mechanism of the neurological manifestations in NPC1 disease is not fully understood yet. In this study, we utilized the micro-electrode array (MEA) to analyze the spontaneous extracellular electrical activity in cultivated cortical neurons of the NPC1 mutant (NPC1-/-) mouse. Our results show a decrease of the spontaneous electrical activity in NPC1-/- neuronal network when compared to wild type neurons, as indicated by the decreased spike rate, burst rate, event rate, and the increased burst period and event period. Application of 3,5-dihydroxyphenylglycine (DHPG), a specific agonist of group I metabotropic glutamate receptors, improved the electrical activity of the NPC1-/- neuronal network, suggesting that DHPG can be used as a potential therapeutic strategy for recovery of the electrical activity in NPC1 disease.

Superpotent [Dmt¹] dermorphin tetrapeptides containing the 4-aminotetrahydro-2-benzazepin-3-one scaffold with mixed µ/δ opioid receptor agonistic properties.

Novel dermorphin tetrapeptides are described in which Tyr(1) is replaced by Dmt(1), where d-Ala(2) and Gly(4) are N-methylated, and where Phe(3)-Gly(4) residue is substituted by the constrained Aba(3)-Gly(4) peptidomimetic. Most of these peptidic ligands displayed binding affinities in the nanomolar range for both µ- and δ-opioid receptors but no detectable affinity for the κ-opioid receptor. Measurements of cAMP accumulation, phosphorylation of extracellular signal-regulated kinase (ERK1/2) in HEK293 cells stably expressing each of these receptors individually, and functional screening in primary neuronal cultures confirmed the potent agonistic properties of these peptides. The most potent ligand H-Dmt-NMe-d-Ala-Aba-Gly-NH(2) (BVD03) displayed mixed µ/δ opioid agonist properties with picomolar functional potencies. Functional electrophysiological in vitro assays using primary cortical and spinal cord networks showed that this analogue possessed electrophysiological similarity toward gabapentin and sufentanil, which makes it an interesting candidate for further study as an analgesic for neuropathic pain.

Acute functional neurotoxicity of lanthanum(III) in primary cortical networks.

Because of its diverse physical and chemical properties, lanthanum has been used in various industrial and medical fields. However, until recently, its effects at the cellular and molecular level had hardly been investigated. Using primary cortical networks grown on microelectrode array neurochips, we investigated the acute functional neurotoxicity of lanthanum(III) chloride (LaCl(3)). Lanthanum caused a biphasic concentration-dependent decline in network activity resulting in a complete cessation of the activity at 3mM LaCl(3). However, the networks' oscillatory behavior and synchronicity between neurons remained unaffected until activity loss. The spike activity diminished at half effective concentration values for the two phases of 117 nM and 763 µM LaCl(3) corresponding to 16 ng/ml and 10.6 µg/ml lanthanum, respectively. Furthermore, under the experimental conditions, LaCl(3) did not affect voltage-dependent ion channels contributing to the shape and amplitude of the action potential. Further similarity analysis by pattern recognition exposed significant similarities of the activity changes caused by LaCl(3) to those induced by phenobarbital, gamma-aminobutyric acid, and the gap junction blocker carbenoxolone and sodium propionate. Overall, this study demonstrates inhibitory and potentially sedative toxicological effects of lanthanum(III) ions at concentrations comparable to the plasma concentrations observed in patients with kidney disease being treated with lanthanum carbonate for hyperphosphatemia. Therefore, given the lack of proof that the blood-brain barrier is completely impermeable in uremic patients and lanthanum cannot cross, caution is warranted.