Anti-DRD1 (aa 9-21) polyclonal antibody

Studies of personality have suggested that dissimilarities in ability to cope with stressful situations results in differing tendency to develop addictive behaviors. The present study used selectively bred stress-resilient, socially-dominant (Dom) and stress-vulnerable, socially-submissive (Sub) mice to investigate the interaction between environmental stress and inbred predisposition to develop addictive behavior to cocaine. In a Conditioned Place Preference (CPP) paradigm using cocaine, Sub mice displayed an aversion to drug, whereas Dom mice displayed drug attraction. Following a 4-week regimen of Chronic Mild Stress (CMS), Sub mice in CPP displayed a marked increase (>400%) in cocaine attraction, whereas Dom mice did not differ in attraction from their non-stressed state. Examination of hippocampal gene expression revealed in Sub mice, exposure to external stimuli, stress or cocaine, increased CRH expression (>100%), which was evoked in Dom mice only by cocaine exposure. Further, stress-induced decreases in DRD1 (>60%) and DRD2 (>50%) expression in Sub mice differed markedly from a complete lack of change in Dom mice. From our findings, we propose that social stratification dictates vulnerability to stress-induced attraction that may lead to addiction via differential regulation of hippocampal response to dopaminergic input, which in turn may influence differing tendency to develop addictive behaviors.

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 forin vivoexperiments. 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 bothin vitroandin 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.