GPR177 in A-fiber sensory neurons drives diabetic neuropathic pain via WNT-mediated TRPV1 activation.

Diabetic neuropathic pain (DNP) is a common and devastating complication in patients with diabetes. The mechanisms mediating DNP are not completely elucidated, and effective treatments are lacking. A-fiber sensory neurons have been shown to mediate the development of mechanical allodynia in neuropathic pain, yet the molecular basis underlying the contribution of A-fiber neurons is still unclear. Here, we report that the orphan G protein-coupled receptor 177 (GPR177) in A-fiber neurons drives DNP via WNT5a-mediated activation of transient receptor potential vanilloid receptor-1 (TRPV1) ion channel. GPR177 is mainly expressed in large-diameter A-fiber dorsal root ganglion (DRG) neurons and required for the development of DNP in mice. Mechanistically, we found that GPR177 mediated the secretion of WNT5a from A-fiber DRG neurons into cerebrospinal fluid (CSF), which was necessary for the maintenance of DNP. Extracellular perfusion of WNT5a induced rapid currents in both TRPV1-expressing heterologous cells and nociceptive DRG neurons. Computer simulations revealed that WNT5a has the potential to bind the residues at the extracellular S5-S6 loop of TRPV1. Using a peptide able to disrupt the predicted WNT5a/TRPV1 interaction suppressed DNP- and WNT5a-induced neuropathic pain symptoms in rodents. We confirmed GPR177/WNT5A coexpression in human DRG neurons and WNT5A secretion in CSF from patients with DNP. Thus, our results reveal a role for WNT5a as an endogenous and potent TRPV1 agonist, and the GPR177-WNT5a-TRPV1 axis as a driver of DNP pathogenesis in rodents. Our findings identified a potential analgesic target that might relieve neuropathic pain in patients with diabetes.

Synthesis and Evaluation of Phenyliminoindolin-Containing Phenylacetamide Derivatives with the Antidepressant and Anticonvulsant Effects.

BACKGROUND: To discover a novel antidepressant-like effect and anticonvulsant compound, seventeen new 2-oxo-3-phenyliminoindolin-1-Nphenylacetamide compounds were synthesized and screened for the antidepressant activity and anticonvulsant effects. METHOD: 2-oxo-3-phenyliminoindolin-1-N-phenylacetamide derivatives were synthesized with indoline-2, 3-dione as the starting material, through a nucleophilic substitution reaction and a nucleophilic addition-elimination reaction. The target derivatives 2a-2q were evaluated the antidepressant-like activity using the FST, TST, and evaluated anticonvulsant effect by MES test. The main monoamine neurotransmitters and their metabolites in mouse brain regions were also simultaneously determined by HPLC-ECD. RESULTS: It was observed that 13 compounds showed significant reductions in the immobility time in the FST at a concentration of 50 mg/kg. Compound 2b was found to have the most potent antidepressant activity in the FST and the TST for 30 min after treatment. Compound 2b significantly increased the concentrations of the main neurotransmitters 5-HT, NE and the metabolite (5-HIAA, suggesting that the effects of compound 2b may be mediated through these neurotransmitters. As assessed using maximal electroshock, 13 compounds showed the anticonvulsant effects administered at the concentration levels of 100 or 300 mg/kg. Compound 2b showed anticonvulsant effect. Compound 2b could potentially be used as adjuncts of the antidepressants to treat depression in patients with epilepsy. CONCLUSION: In conclusion, compound 2b produced significant antidepressant-like activity and the mechanism of action may be due to increased 5-HT and NE in the mouse. Compound 2b showed more anticonvulsant effect. Compound 2b could potentially be used as adjuncts of the antidepressants to treat depression in patients with epilepsy.

Practical Synthesis, Antidepressant, and Anticonvulsant Activity of 3-Phenyliminoindolin-2-one Derivatives.

Herein, a series of 3-phenyliminoindolin-2-one derivatives were designed, synthesized, and screened for their antidepressant and anticonvulsant activities. The IR spectra of the compounds afforded NH stretching (3340-3346 cm(-1)) bands and C=O stretching (1731-1746 cm(-1)). In the (1)H-NMR spectra of the compounds, N-H protons of indoline ring were observed at 10.65-10.89 ppm generally as broad bands, and (13)C-NMR spectra of the compounds C=O were seen at 161.72-169.27 ppm. Interestingly, compounds 3o, 3p and 3r significantly shortened immobility time in the The forced swimming test (FST) and The tail suspension test (TST) at 50 mg/kg dose levels. In addition, compound 3r exhibited higher levels of efficacy than the reference standard fluoxetine but had no effect on locomotor activity in the open-field test. Compound 3r significantly increased serotonin and norepinephrine and the metabolite 5-hydroxyindoleacetic acid in mouse brain, suggesting that the effects of compound 3r may be mediated through these neurotransmitters. In the seizure screen, 15 compounds showed some degree against PTZ-induced seizure at a dose of 100 mg/kg, and the tested compounds did not show any neurotoxicity at a dose of 300 mg/kg in the rotarod test.

Design, Synthesis, and Potential Antidepressant-like Activity of 7-prenyloxy-2,3-dihydroflavanone Derivatives.

A series of 7-prenyloxy-2, 3-dihydroflavanone derivatives were synthesized and screened for their antidepressant-like activity. Among them, it was observed that compounds 5j and 5k were found to be the most antidepressant-like activity. In addition, it was found that compounds 5j and 5k significantly increased the concentrations of the main neurotransmitters 5-HT and NE in the hippocampus, hypothalamus, and cortex. Compounds 5j and 5k also significantly increased the contents of 5-HIAA in the hippocampus and cortex, shut down 5-HT metabolism compared with mice treated with stress vehicle. These results suggested that compounds 5j and 5k displayed potent antidepressant-like properties that were mediated via neurochemical systems.

Fucosterol, a sterol extracted from Sargassum fusiforme, shows antidepressant and anticonvulsant effects.

We previously showed that extracts of Sargassum fusiforme significantly reduce immobility time in the forced swim test and tail suspension test, suggesting that these extracts possess antidepressant-like effects. Here, fucosterol extracted from S. fusiforme was evaluated for antidepressant and anticonvulsant activities in mice. Fucosterol (10, 20, 30 and 40mg/kg) significantly shortened immobility time in the forced swim test and tail suspension test for30min after treatment but had no effect on locomotor activity in the open field test. Fucosterol significantly increased serotonin, norepinephrine and the metabolite 5-hydroxyindoleacetic acid in mouse brain, suggesting that the effects of fucosterol may be mediated through these neurotransmitters. As assessed using maximal electroshock, fucosterol (20, 40, 100mg/kg) possessed anticonvulsant activity, whereas rotarod toxicity test results indicated that fucosterol did not induce neurotoxicity at the same dose levels in mice. Thus, fucosterol may be a useful antidepressant adjunct candidate for treating depression in patients with epilepsy. A significant increase in hippocampal brain-derived neurotrophic factor (BDNF) levels was found in the fucosterol 20mg/kg group (P<0.05). Our findings suggested that fucosterol may possess an antidepressant-like effect, which may be mediated by increasing central BDNF levels.