Parkinson’s disease is a progressive neurodegenerative disorder resulting from the degeneration of pigmented dopaminergic neurons in the substantia nigra pars compacta. It induces a series of functional modifications in the circuitry of the basal ganglia nuclei and leads to severe motor disturbances. The amino acid glutamate, as an excitatory neurotransmitter, plays a key role in the disruption of normal basal ganglia function regulated through the interaction with its receptor proteins. It has been proven that glutamate receptors participate in the modulation of neuronal excitability, transmitter release, and long-term synaptic plasticity, in addition to being related to the altered neurotransmission in Parkinson’s disease. Therefore, they are considered new targets for improving the therapeutic strategies used to treat Parkinson’s disease. In this review, we discuss the biological characteristics of these receptors and demonstrate the receptor-mediated neuroprotection in Parkinson’s disease. Pharmacological manipulation of these receptors during anti-Parkinsonian processes in both experimental studies and clinical trials are also summarized.

K2P potassium channels stabilize the resting membrane potential in nearly all cells and have been implicated in several neuronal, cardiovascular, and immune diseases. DCPIB, a known specific and potent inhibitor of volume-regulated anion channels (VRAC), has been reported to activate TREK1 and TREK2 in astrocytes and in vitro recently. In the present study, we demonstrated DCPIB also voltage dependently activated TRAAK besides TREK1/TREK2, showing DCPIB activated all TREK subfamily members. In contrast, the compound potently inhibited several other K2P channels with no voltage dependence, including TRESK, TASK1, and TASK3. DCPIB displayed superior selectivity toward TRESK with an IC50 of 0.14 μM, demonstrating at least 100-fold higher affinity over TREK1/TRAAK channels. Furthermore, the impaired ion selectivity filter region greatly impaired the activating effect of DCPIB on TREK1 but not the inhibitory effect of DCPIB on TRESK. This indicates distinct molecular determinants underlying the effect of DCPIB on TREK1 or TRESK channels. Our results showed that DCPIB played diverse effects on K2P channels and could be a useful tool for further investigating structure–function studies of K2P channels.

Background Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders. Enhancing hippocampal neurogenesis by promoting proliferation and differentiation of neural stem cells (NSCs) is a promising therapeutic strategy for AD. 20( S )-protopanaxadiol (PPD) and oleanolic acid (OA) are small, bioactive compounds found in ginseng that can promote NSC proliferation and neural differentiation in vitro . However, it is currently unknown whether PPD or OA can attenuate cognitive deficits by enhancing hippocampal neurogenesis in vivo in a transgenic APP/PS1 AD mouse model. Here, we administered PPD or OA to APP/PS1 mice and monitored the effects on cognition and hippocampal neurogenesis. Methods We used the Morris water maze, Y maze, and open field tests to compare the cognitive capacities of treated and untreated APP/PS1 mice. We investigated hippocampal neurogenesis using Nissl staining and BrdU/NeuN double labeling. NSC proliferation was quantified by Sox2 labeling of the hippocampal dentate gyrus. We used western blotting to determine the effects of PPD and OA on Wnt/GSK3β/β-catenin pathway activation in the hippocampus. Results Both PPD and OA significantly ameliorated the cognitive impairments observed in untreated APP/PS1 mice. Furthermore, PPD and OA significantly promoted hippocampal neurogenesis and NSC proliferation. At the mechanistic level, PPD and OA treatments resulted in Wnt/GSK-3β/β-catenin pathway activation in the hippocampus. Conclusion PPD and OA ameliorate cognitive deficits in APP/PS1 mice by enhancing hippocampal neurogenesis, achieved by stimulating the Wnt/GSK-3β/β-catenin pathway. As such, PPD and OA are promising novel therapeutic agents for the treatment of AD and other neurodegenerative diseases.

Colorectal cancer (CRC) is an aggressive cancer. Isoalantolactone (IATL) has been reported to exert cytotoxicity against various cancer cells, but not CRC. In this study, we explored the anti-CRC effects and mechanism of action of IATL in vitro and in vivo. Our results demonstrated that IATL inhibited proliferation by inducing G0/G1 phase cell cycle arrest, apoptosis and autophagy in CRC cells. Repression of autophagy with autophagy inhibitors chloroquine (CQ) and Bafilomycin A1 (Baf-A1) enhanced the anti-CRC effects of IATL, suggesting that IATL induces cytoprotective autophagy in CRC cells. Mechanistic studies revealed that IATL lowered protein levels of phospho-AKT (Ser473), phospho-mTOR (Ser2448), phospho-70S6K (Thr421/Ser424) in CRC cells. Inhibition of AKT and mTOR activities using LY294002 and rapamycin, respectively, potentiated the inductive effects of IATL on autophagy and cell death. In vivo studies showed that IATL suppressed HCT116 tumor growth without affecting the body weight of mice. In consistent with the in vitro results, IATL lowered protein levels of Bcl-2, Bcl-XL, phospho-AKT (Ser473), phospho-mTOR (Ser2448), and phsopho-70S6K (Thr421/Ser424), whereas upregulated protein levels of cleaved-PARP and LC3B-II in HCT116 tumors. Collectively, our results demonstrated that in addition to inhibiting proliferation, inducing G0/G1-phase cell cycle arrest and apoptosis, IATL initiates cytoprotective autophagy in CRC cells by inhibiting the AKT/mTOR signaling pathway. These findings provide an experimental basis for the evaluation of IATL as a novel medication for CRC treatment.