The heritability of schizophrenia (SCZ) has been estimated to be as high as 80%, suggesting that genetic factors may play an important role in the etiology of SCZ. Cav1.2 encoded by CACNA1C and Cav1.3 encoded by CACNA1D are dominant calcium channel-forming subunits of L-type Voltage-dependent Ca2+ channels, expressed in many types of neurons. The CACNA1C has been consistently found to be a risk gene for SCZ, but it is unknown for CACNA1D. To investigate the association of CACNA1D with SCZ, we designed a two-stage case-control study, including a testing set with 1117 cases and 1815 controls and a validation set with 1430 cases and 4295 controls in Han Chinese. A total of selected 97 tag single nucleotide polymorphisms (SNPs) in CACNA1D were genotyped, and single-SNP association, imputation analysis and gender-specific association analyses were performed in the two independent datasets. None was found to associate with SCZ. Further genotype and haplotype association analyses indicated a similar pattern in the two-stage study. Our findings suggested CACNA1D might not be a risk gene for SCZ in Han Chinese population, which add to the current state of knowledge regarding the susceptibility of CACNA1D to SCZ.

Mast cells play an important role in inflammatory and allergic diseases. MAS-related G protein-coupled receptor X2 (MRGPRX2) is a novel G protein-coupled receptor in mast cells that mediates drug-induced anaphylactoid reactions. Piperine has been reported to have anti-inflammatory and anti-allergic pharmacological activities. However, whether the pharmacological effects are regulated by MRGPRX2 has not yet been reported. The purpose of this study was to assess the anti-anaphylactoid effect of Piperine and to explore its potential mechanism. The anti-anaphylactoid effect of Piperine was assessed by an in vivo mouse hindpaw extravasation model. Mast cell intracellular calcium mobilization was measured by a calcium imaging assay. An enzyme immunoassay was used to evaluate the release of pro-inflammatory factors from stimulated mast cells. Activated mast cell related signals were assessed by western blot. A cell membrane chromatography assay was used to determine the binding characteristics of Piperine and MRGPRX2. The results showed that Piperine suppressed mast cell intracellular Ca 2+ mobilization, inhibited cytokines and chemokines release, and down-regulated the phosphorylation level of phospholipase Cγ1, protein kinase C, inositol 1,4,5-triphate receptor, P38, protein kinase B, and ERK. Meanwhile, Piperine can bind to MRGPRX2 as a specific antagonist. Hence, Piperine can be served as a novel therapeutic drug candidate for MRGPRX2-mediated anaphylactoid reactions. K E Y W O R D Santianaphylactoid effects, Ca 2+ influx, mast cells, MRGPRX2, Piperine

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Addiction is a debilitating, chronic psychiatric disorder that is difficult to cure completely owing to the high rate of relapse. Behavioral sensitization is considered to may underlie behavioral changes, such as relapse, caused by chronic abuse of psychomotor stimulants. Thus, its animal models have been widely used to explore the etiology of addiction. Recently, increasing evidence has demonstrated that N-methyl-D-aspartate receptors (NMDARs) play an important role in addiction to psychomotor stimulants. However, the role of GluN2B-containing receptors and their downstream signaling pathway(s) in behavioral sensitization induced by methamphetamine (METH) have not been investigated yet. In this study, we used different doses of ifenprodil (2.5, 5, 10 mg/kg), a selective antagonist of the GluN2B subunit, to investigate the role of GluN2B-containing NMDARs in METH-induced behavioral sensitization. We then examined changes in the levels of Ras, phosphorylated extracellular signal-regulated kinase (pERK)/ERK, and ∆FosB in the caudate putamen (CPu) by western blot. We found that 2.5 or 10 mg/kg ifenprodil significantly attenuated METH-induced behavioral sensitization, whereas the mice treated with a moderate dose of ifenprodil (5 mg/kg) displayed no significant changes. Further results of western blot experiments showed that repeated administration of METH caused the increases in the levels of Ras, pERK/ERK and ∆FosB in the CPu, and these changes were inhibited by only the 2.5 mg/kg dose of ifenprodil. In conclusion, these results demonstrated that 2.5 mg/kg ifenprodil could attenuate METH-induced behavioral sensitization. Moreover, GluN2B-containing NMDARs and their downstream Ras-ERK-∆FosB signaling pathway in the CPu might be involved in METH-induced behavioral sensitization.

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