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Piccolo (PCLO) inhibits methamphetamine-induced neuropharmacological effects via modulation of dopamine (DA) uptake and regulation of the transport of synaptic vesicles in neuronal cells. Clinical studies have recently suggested that the single nucleotide polymorphism (SNP) rs13438494 in the intron 24 of the PCLO gene is associated with psychiatric disorder, in the meta-analysis of GWAS. Therefore, in this study, we attempted to evaluate the possible role of the PCLO SNP in the mechanisms of uptake of monoamines. To characterize rs13438494 in the PCLO gene, we constructed plasmids carrying either the C or A allele of the SNP and transiently transfected them into SH-SY5Y cells to analyze genetic effects on the splicing of PCLO mRNA. The C and A allele constructs produced different composition of the transcripts, indicating that the intronic SNP does affect the splicing pattern. We also transfected DA and serotonin (5-hydroxytryptamine; 5- HT) transporters into cells and analyzed their uptakes to elucidate the association to psychiatric disorders. In the cells transfected with the C allele, both the DA and 5-HT uptake were enhanced compared to the A allele. We also conducted a clinical study, in order to clarify the genetic associations. PCLO rs13438494 exhibits a relationship with the symptoms of drug dependence or related parameters, such as the age of first exposure to methamphetamine, eating disorders, tobacco dependence and fentanyl requirement. Our findings suggest that rs13438494 is associated with drug abuse and contributes to the pathogenesis of psychiatric disorders via modulation of neurotransmitter turnover.

The regulator of G-protein signaling (RGS) modulates the functioning of heterotrimeric G protein. RGS9-2 is highly expressed in the striatum and plays a role in modulating dopaminergic receptor-mediated signaling cascades. Previous studies suggested that the RGS9 gene might contribute to the susceptibility to psychotic diseases. Therefore, we investigated the association between the RGS9 gene and two related dopamine psychoses, schizophrenia and methamphetamine use disorders. The subjects comprised 487 patients of schizophrenia and 464 age- and sex-matched healthy controls and 220 patients of methamphetamine use disorder and 289 controls. We genotyped two nonsynonymous polymorphisms, rs12452285 (Leu225Ser) and rs34797451 (His498Arg), of the RGS9 gene. Rs34797451 showed monomorphism in the present Japanese population, but rs12452285 showed polymorphism. There were no significant differences in genotypic or allelic distributions of rs12452285 between patients with schizophrenia and the corresponding control or between patients with methamphetamine use disorder and the corresponding control. We also analyzed the clinical features of methamphetamine use disorder. We found a significant association in allelic distribution with the phenotypes of age at first consumption (p0.047). The present study suggested that the RGS9 gene is unlikely to play a major role in schizophrenia and methamphetamine dependence liability and/or the development of methamphetamine induced psychosis, at least in a Japanese population.

Several studies have suggested that the endocannabinoid system plays significant roles in the vulnerability to psychiatric disorders including drug abuse. To examine the possible association of the CNR1 and CNR2 genes, which encode cannabinoid receptors CB1 and CB2, with methamphetamine dependence, we investigated three single nucleotide polymorphisms (SNPs) (rs806379, rs1535255, rs2023239) in intron 2 of the CNR1 gene and a nonsynonymous SNP, Q63R, in the CNR2 gene. The study samples consisted of 223 patients with methamphetamine dependence and 292 age- and sex- matched controls. There were no significant differences between the patients and controls in genotypic or allelic distribution of any SNP of the CNR1 and CNR2 genes. We also analyzed the clinical features of methamphetamine dependence. Rs806379 of the CNR1 gene showed a significant association with the phenotype of latency of psychosis after the first consumption of methamphetamine. Patients with the T allele or T-positive genotypes (T/T or A/T) may develop a rapid onset of psychosis after methamphetamine abuse. The present study suggests a possibility that genetic variants of the CNR1 gene may produce a liability to the complication of psychotic state after abuse of methamphetamine; however, our findings need to be confirmed by future replications.

Experimental studies have demonstrated that not only dopaminergic signaling but also glutamatergic/NMDA receptor signaling play indispensable roles in the development of methamphetamine psychosis. Our recent genetic studies provided evidence that genetic variants of glutamate-related genes such as DTNBP1, GLYT1, and G72, which are involved in glutamate release and regulation of co-agonists for NMDA receptors, conferred susceptibility to methamphetamine psychosis. Serine racemase converts l-serine to d-serine, which is an endogenous co-agonist for NMDA receptors. Three single nucleotide polymorphisms (SNPs) in the promoter region of the serine racemase gene (SRR), rs224770, rs3760229, and rs408067, were proven to affect the transcription activity of SRR. Therefore, we examined these SNPs in 225 patients with methamphetamine psychosis and 291 age- and sex-matched controls. There was no significant association between methamphetamine psychosis and any SNP examined or between the disorder and haplotypes comprising the three SNPs. However, rs408067 was significantly associated with the prognosis for methamphetamine psychosis and multi-substance abuse status. The patients with C-positive genotypes (CC or CG) of rs408067 showed better prognosis of psychosis after therapy and less abuse of multiple substances than the patients with GG genotypes. Because the C allele of rs408067 reduces the expression of SRR, a lower d-serine level or reduced NMDA receptor activation may affect the prognosis of methamphetamine psychosis and multiple substance abuse. Our sample size is, however, not large enough to eliminate the possibility of a type I error, our findings must be confirmed by replicate studies with larger samples.

Several lines of evidence implicate serotonergic dysfunction in diverse psychiatric disorders including anxiety, depression, and drug abuse. Mice with a knock-out of the 5HT1b receptor gene (HTR1B) displayed increased locomotor response to cocaine and elevated motivation to self-administer cocaine and alcohol. Previous genetic studies showed significant associations of HTR1B with alcohol dependence and substance abuse, but were followed by inconsistent results. We examined a case-control genetic association study of HTR1B with methamphetamine-dependence patients in a Japanese population. The subjects were 231 patients with methamphetamine dependence, 214 of whom had a comorbidity of methamphetamine psychosis, and 248 age- and sex-matched healthy controls. The three single nucleotide polymorphisms (SNPs), rs130058 (A-165T), rs1228814 (A-700C) and rs1228814 (A1180G) of HTR1B were genotyped. There was no significant difference in allelic and genotypic distributions of the SNPs between methamphetamine dependence and the control. Genetic associations of HTR1B were tested with several clinical phenotypes of methamphetamine dependence and/or psychosis, such as age at first abuse, duration of latency from the first abuse to onset of psychosis, prognosis of psychosis after therapy, and complication of spontaneous relapse of psychotic state. There was, however, no asscocation between any SNP and the clinical phenotypes. Haplotype analyses showed the three SNPs examined were within linkage disequilibrium, which implied that the three SNPs covered the whole HTR1B, and distribution of estimated haplotype frequency was not different between the groups. The present findings may indicate that HTR1B does not play a major role in individual susceptibility to methamphetamine dependence or development of methamphetamine-induced psychosis.

Endothelial nitric oxide synthase (NOS3) is one of the enzymes influencing nitric oxide (NO) function in the human brain. NO is a gaseous neurotransmitter that is involved in a variety of mechanisms in the central nervous system, such as N-methyl-D-aspartate receptor activation and oxidative stress. The evidence from animal pharmacological studies and postmortem studies supports an association between NO and psychotic disorders. Methamphetamine (METH) use disorder is a known psychotic disorder, and we therefore conducted a gene-based case-control study between tagging single nucleotide polymorphisms (SNPs) (rs2070744, rs1799983) in NOS3 and METH-induced psychosis in Japanese subjects (183 with METH-induced psychosis and 267 controls). Written informed consent was obtained from each subject. No significant association was found between any tagging SNP in NOS3 and METH-induced psychosis in the allele/genotype-wise or haplotype-wise analyses. In conclusion, we suggest that NOS3 might not contribute to the risk of METH-induced psychosis in the Japanese population.

Summary To clarify clinical roles of s receptor binding affinity of neuroleptics, neck dystonia induced by microinjection of s receptor ligands and neuroleptics into rat red nucleus was investigated. DTG and (+)-3-PPP, putative s receptor agonists, induced neck dystonia in dose-dependent and reversible manner. Haloperidol and perphenazine induced dystonia in the same way as s receptor agonists, whereas zotepine and (-)-sulpiride did not. The rank order of potency in induction of dystonia and s receptor affinity of these compounds showed positive correlation. Although BMY-14802 has a high affinity for s receptors, it never produced dystonia by itself. On the other hand, combined injection of BMY-14802 with DTG attenuated DTG-induced dystonia. Therefore, it is suggested that typical neuroleptics such as haloperidol act agonistic and atypical neuroleptics such as BMY-14802 act antagonistic at rubral s receptors in the induction of neck dystonia.

To determine whether a mitochondrial mRNA deficiency exists in mitochondrial myopathies, muscle biopsies from a patient with chronic progressive external ophthalmoplegia (CPEO) and a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) were studied using in situ hybridization. Histochemistry and immunohistochemistry were performed along with hybridization. Hybridization reactions were widely distributed over the sarcoplasm of all muscle fibers in the patient with MELAS. In the patient with CPEO, 80% of the fibers showed a marked decrease in density of autoradiographic grains. This marked decrease corresponded to the histochemical and immunohistochemical findings of a very weak staining of cytochromec oxidase (CCO). The isotope-labeled cDNA probe used in in situ hybridization in this study complements a part of subunit I of CCO and a part of subunit II of complex I in the mitochondrial gene. Our results suggest a defect in the mRNA in this CPEO patient.

Summary Intraperitoneal injection of (+)-3-[3-hydroxyphenyl)-N-(1-propyl)piperidine ((+)-3PPP), a sigma receptor agonist, significantly reduced the striatal levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) measured by in vivo microdialysis. These reductions were significantly greater at (+)-3PPP doses of 12 and 24 mg/kg than at 1 mg/ kg. The levels of 5-hydroxyindoleacetic acid (5HIAA) were increased by the injection of (+)-3PPP in dose of 24 mg/kg, but were not affected at lower doses. BMY-14802, a sigma antagonist, alone at doses of 15 mg/kg and 30 mg/kg did not affect the levels of DA, DOPAC, HVA and 5HIAA. Pretreatment with 30 mg/kg BMY-14802 reversed the reduction of the levels of DA induced by 12 mg/kg (+)-3PPP. Although neither 30 mg/kg BMY-14802 nor 12 mg/kg (+)-3PPP affected the levels of striatal 5HIAA, combined treatment with both produced a significant elevation. These findings clearly demonstrate that sigma receptors may regulate DA release from the striatal presynapse.

LRRK2G2019S is the most common known cause of Parkinson disease (PD) in patients of European origin, but little is known about its distribution in other populations. The authors identified two of 586 Japanese patients with PD heterozygous for the mutation who shared a haplotype distinct from that observed in Europeans. This suggests that G2019S originated from separate founders in Europe and Japan and is more widely dispersed than previously recognized.