-94 G/A polymorphism in the dopamine D1 receptor gene is associated with schizophrenia in a Chinese Han population from Shandong province

The correlation between -94 G/A polymorphism in the dopamine D1 receptor gone and schizophrenia remains poorly understood despite extensive research. This study sought to evaluate the genotypes and allele frequencies of the -94 G/A polymorphism in the dopamine D1 receptor gone by real-time PCR using TaqMan fluorescent probes. One hundred and sixty-two patients with schizophrenia and 101 healthy controls living in Shandong province of China were evaluated. Experimental results showed that the G/A genotype distribution was significantly higher in the schizophrenia patients than in healthy controls. The frequencies of G allele and A allele were not significantly different between the schizophrenia patients and the controls. Thus, the -94 G/A polymorphism in the dopamine D1 receptor gone was found to be associated with schizophrenia in a Chinese Han population from Shandong province.

Effects of endogenous dopamine induced by low concentration atropine eye drops on choroidal neovascularization in high myopia mice

AIM:To evaluate effects of endogenous dopamine induced by low concentration atropine eye drops on choroidal neovascularization(CNV)in high myopia mice.METHODS:The C57BL/6J mice were deprived of the right eye for 4wk,and the high myopia was diagnosed by optometry,the diopter was less than-6.00 D,and CNV was induced by 532 nm laser.The changes of dopamine D1 receptor(DRD1),dopamine D2 receptor(DRD2),and vascular endothelial growth factor A(VEGFA)were detected by Western blot technology at 0.5,1,2h,and 7d after 0.01%,0.05%,and 0.1%atropine eye drops,respectively,the area of CNV was measured.RESULTS:Significant increases were observed on the expression of DRD2 in mouse high myopia model at 0.5,1,2h,7d with 0.05%and 0.1%atropine eye drops(P<0.05).Significant decreases were observed on the expression of DRD1 and VEGFA in mouse high myopia model at 0.5,1,2h,7d with 0.05%and 0.1%atropine eye drops(P<0.05).The area of CNV induced by laser in the drug-treated group was significantly smaller than that in the control group,and the higher the concentration,the more significant the inhibitory effect(P<0.05).CONCLUSION:The 0.01%,0.05%,0.1%atropine eye drops can decrease the level of VEGFA and inhibit high myopia CNV indirectly by up-regulating the level of DRD2 and down-regulating the level of DRD1,and the effect of 0.05%and 0.1%atropine eye drops is more significant.

New therapeutic strategies targeting D1-type dopamine receptors for neuropsychiatric disease

The neurotransmitter dopamine acts via two major classes of receptors, Dl-type and D2-type. D1 receptors are highly expressed in the striatum and can also be found in the cerebral cortex. Here we review the role of D1 dopamine signaling in two major domains： L-DOPA-induced dyskinesias in Parkinson＇s disease and cognition in neuropsychiatric disorders. While there are many drugs targeting D2-type receptors, there are no drugs that specifically target D1 receptors. It has been difficult to use selective Dl-receptor agonists for clinical applications due to issues with bioavailability, binding affinity, pharmacological kinetics, and side effects. We propose potential therapies that selectively modulate D1 dopamine signaling by targeting second messengers downstream of D1 receptors, aUosteric modulators, or by making targeted modifications to Dl-receptor machinery. The development of therapies specific to Dl-receptor signaling could be a new frontier in the treatment of neurological and psychiatric disorders.

Gut-brain crosstalk regulates craving for fatty food

Patients undergoing Roux-en-Y gastric bypass(RYGB)surgery elicit striking loss of body weight. Anatomical restructuring of the gastrointestinal(GI) tract, leading to reduced caloric intake and changes in food preference, are thought to be the primary drivers of weight loss in bariatric surgery patients. However, the mechanisms by which RYGB surgery causes a reduced preference for fatty foods remain elusive. In a recent report, Hankir et al described how RYGB surgery modulated lipid nutrient signals in the intestine of rats to blunt their craving for fatty food. The authors reported that RYGB surgery restored an endogenous fat-satiety signaling pathway, mediated via oleoylethanolamide(OEA), that was greatly blunted in obese animals. In RYGB rats, high fat diet(HFD) led to increased production of OEA that activated the intestinal peroxisome proliferation activator receptors-α(PPARα). In RYGB rats, activation of PPARα by OEA was accompanied by enhanced dopamine neurotransmission in the dorsal striatum and reduced preference for HFD. The authors showed that OEA-mediated signals to the midbrain were transmitted via the vagus nerve. Interfering with either the production of OEA in enterocytes, or blocking of vagal and striatal D1 receptors signals eliminated the decreased craving for fat in RYGB rats. These studies demonstrated that bariatric surgery led to alterations in the reward circuitry of the brain in RYGB rats and reduced their preference for HFD.

Disruption of dopamine D1 receptor phosphorylation at serine 421 attenuates cocaine-induced behaviors in mice

Dopamine D1 receptors（D1Rs） play a key role in cocaine addiction, and multiple protein kinases such as GRKs, PKA, and PKC are involved in their phosphorylation. Recently, we reported that protein kinase D1 phosphorylates the D1 R at S421 and promotes its membrane localization. Moreover, this phosphorylation of S421 is required for cocaineinduced behaviors in rats. In the present study, we generated transgenic mice over-expressing S421A-D1 R in the forebrain. These transgenic mice showed reduced phospho-D1R（S421） and its membrane localization, and reduced downstream ERK1/2 activation in the striatum. Importantly, acute and chronic cocaine-induced locomotor hyperactivity and conditioned place preference were significantly attenuated in these mice. These findings provide in vivo evidence for the critical role of S421 phosphorylation of the D1 R in its membrane localization and in cocaine-induced behaviors. Thus, S421 on the D1 R represents a potential pharmacotherapeutic target for cocaine addiction and other drug-abuse disorders.

Increased dopamine and its receptor dopamine receptor D1 promote tumor growth in human hepatocellular carcinoma

Background:Dopamine and dopamine receptor D1(DRD1),a member of the dopamine receptor family,have been indicated to play important roles in cancer progression,but dopamine secretion in hepatocellular carcinoma(HCC)and the effects of DRD1 on HCC remain unclear.This study was designed to explore the contribution of the dopaminergic system to HCC and determine the relationship between DRD1 and prognosis in HCC patients.Methods:The dopamine metabolic system was monitored using enzyme-linked immunosorbent assays(ELISAs).The expression of DRD1 was detected by microarray analysis,immunohistochemistry(IHC),and quantitative real-time PCR(qRT-PCR).Stable DRD1 knockout and overexpression cell lines were established for investigation.Transwell,colony formation,and Cell Counting Kit 8(CCK8)assays were performed to assess the malignant behaviors of cancer cells.The cAMP/PI3K/AKT/cAMP response element-binding(CREB)signaling pathway was evaluated by Western blot.This pathway,which is agitated by DRD1 in striatal neurons,had been proven to participate in tumor progression.Xenograft HCC tumors were generated for in vivo experiments.Results:Dopamine secretion increased locally in HCC due to an imbalance in dopamine metabolism,including the upregulation of dopa decarboxylase(DDC)and the downregulation of monoamine oxidase A(MAOA).Dopamine promoted the proliferation and metastasis of HCC.DRD1 was highly expressed in HCC tissues and positive DRD1 expression was related to a poor prognosis in HCC patients.The upregulation of DRD1 agitated malignant activities,including proliferation and metastasis in HCC by regulating the cAMP/PI3K/AKT/CREB pathway,and the downregulation of DRD1 had opposing effects.The effects of dopamine on HCC was reversed by depleting DRD1.SCH23390,a selective DRD1 antagonist,inhibited the proliferation and metastasis of HCC cells both in vitro and in vivo.Conclusion:Dopamine secretion was locally increased in HCC and promoted HCC cell proliferation and metastasis.DRD1 was found to exert positive effects on HCC progression and play a vital role in the dopamine system,and could be a potential therapeutic target and prognostic biomarker for HCC.