Validation of a Preclinical Model of Diethylnitrosamine-Induced Hepatic Neoplasia in Yucatan Miniature Pigs.

OBJECTIVE: The purpose of this study was to reduce the time to tumor onset in a diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) swine model via partial liver embolization (PLE) and to characterize the model for use in translational research. METHODS: Eight Yucatan miniature pigs were injected intraperitoneally with either saline (n = 2) or DEN (n = 6) solution weekly for 12 weeks. Three of the DEN-treated pigs underwent PLE. The animals underwent periodic radiological evaluation, liver biopsy, and blood sampling, and full necropsy was performed at study termination (∼29 months). RESULTS: All DEN-treated pigs developed hepatic adenoma and HCC. PLE accelerated the time to adenoma development but not to HCC development. Biomarker analysis results showed that IGF1 levels decreased in all DEN-treated pigs as functional liver capacity decreased with progression of HCC. VEGF and IL-6 levels were positively correlated with disease progression. Immunohistochemical probing of HCC tissues demonstrated the expression of several important survival-promoting proteins. CONCLUSION: To our knowledge, we are the first to demonstrate an accelerated development of hepatic neoplasia in Yucatan miniature pigs. Our HCC swine model closely mimics the human condition (i.e., progressive disease stages and expression of relevant molecular markers) and is a viable translational model.

Overexpression of JAK2: a predictor of unfavorable prognosis for nasopharyngeal carcinoma.

PURPOSE: Analysis of the nasopharyngeal carcinoma public transcriptome revealed JAK2 was significantly upregulated in tumors, which encouraged us to investigate its prognostic significance and mutational status. MATERIALS & METHODS: We assessed the immune-expression of JAK2 and its relationships with various clinicopathological parameters. JAK2 mutation was detected by PCR followed by sequencing. RESULTS: High expression of JAK2 was significantly associated with advanced tumor staging (p = 0.019). JAK2 overexpression acted as an independent predictor for worse disease-specific survival (p = 0.005), distant metastasis-free survival (p = 0.036), local recurrence-free survival (p = 0.012) and overall survival (p = 0.007). JAK2 mutation was not detected in selected cases with JAK2 protein overexpression. CONCLUSION: JAK2 can serve as a valuable negative prognostic factor and a potential therapeutic target.

[Efficiency of interferon therapy in patients with essential thrombocythemia or polycythemia vera]. / Effektivnost' interferonoterapii u bol'nykh essentsial'noi trombotsitemiei i istinnoi politsitemiei.

AIM: To evaluate the efficiency of interferon (IFN) therapy in patients with essential thrombocythemia (ET) and polycythemia vera (PV). SUBJECTS AND METHODS: A total of 61 patients (41 with ET and 20 with PV) were examined. Prior to study enrolment, 44 (72%) patients with ET or PV received one or other therapy (aspirin was not taken into account). The mean Jak2V617F mutant allele at baseline was 23% (6-54%) in the patients with ET and 40% (11-88%) in those with PV. The median time from diagnosis to enrollment was 49 months. RESULTS: The paper presents the clinical and molecular findings of long-term INF-α therapy in patients with ET or PV. The median follow-up was 52 months. Recombinant IFN-α2 showed its ability to induce complete hematologic remission (ET (76%), PV (70%)) and a complete molecular response. 22 (69%) out of 32 patients were noted to have a smaller number of cells with the Jak2V617F mutation. In the patients with PV and in those with ET, the relative reduction in the proportion of cells with the Jak2V617F mutant gene averaged 85% and 56% of the baseline values, respectively. There was a reduction in the proportion of cells expressing the Jak2V617F mutation in both the ET (from 12 to 2.2%; p=0.001) and PV (from 32.7% to 3.2%) groups (р=0.001). Ten (31%) patients achieved a deep molecular remission (≤2% Jak2V617F allele); among them, 5 patients were not found to have Jak2V617F mutation. The obtained molecular response remained in 7 of the 10 patients untreated for 11 to 86 months. The long-term treatment with IFN-α led to normalization of the morphological pattern of bone marrow in 5 of the 7 PV or ET patients. CONCLUSION: Significant molecular remissions achieved by therapy with recombinant interferon-α2 confirm the appropriateness of this treatment option in in the majority of patients with ET or PV.

Genetic merit for fertility traits in Holstein cows: III. Hepatic expression of somatotropic axis genes during pregnancy and lactation.

The objective of this study was to characterize the circulating concentrations of insulin-like growth factor-I (IGF-I) and the hepatic expression of key genes regulating the somatotropic axis in cows divergent in genetic merit for fertility traits but with similar genetic merit for milk production traits. A total of 11 cows with good genetic merit for fertility (Fert+) and 12 cows with poor genetic merit for fertility (Fert-) underwent liver biopsy by percutaneous punch technique on d 20 (±6.7 d) prepartum and on d 2 (±1.5 d), d 58 (±3.7 d), d 145 (±13 d), and d 245 (±17.1 d) postpartum. Total RNA was isolated and the mRNA expression of growth hormone receptor (GHR 1A and GHRtot), IGF-I, janus tyrosine kinase 2 (JAK2), signal transducer and activator of transcription 5B (STAT5B), suppressor of cytokine signaling 3 (SOCS-3), acid-labile subunit (ALS), and IGF-binding proteins (IGFBP1 to IGFBP6) were measured by real-time quantitative PCR. During lactation, the circulating concentrations of IGF-I were 34% greater in Fert+ cows. The Fert+ cows had increased mean expression of IGF-I mRNA during the study; however, the difference in IGF-I mRNA abundance between Fert+ and Fert- cows was most pronounced at d 145 and 245. The expression of IGFBP3 and ALS transcript was similar in Fert+ and Fert- cows for the duration of the study. The Fert- cows, however, had greater expression of IGFBP2, IGFBP4, IGFBP5, and IGFBP6. Genotype had no effect on mRNA abundance of GHR 1A, STAT5B, JAK2, or SOCS-3. Genetic merit for fertility traits affects hepatic expression of key genes of the somatotropic axis regulating the synthesis, bioavailability, and stability of circulating IGF-I.

IL-17 induces AKT-dependent IL-6/JAK2/STAT3 activation and tumor progression in hepatocellular carcinoma.

BACKGROUND: The Th17 subset and IL-17 have been found in increased frequencies within certain tumors. However, their relevance in cancer biology remains controversial. This study aimed to clarify the biological action of IL-17 on hepatocellular carcinoma (HCC). METHODS: Effects and underlying molecular mechanisms of IL-17 on human HCC were explored in vitro using exogenous IL-17 stimulation and in nude mice by implanting IL-17 overexpressed HCC cells. The clinical significance of IL-17 was investigated in tissue microarrays containing HCC tissues from 323 patients following hepatectomy using immunohistochemistry. RESULTS: Although exogenous IL-17 showed no direct effect on the growth rate of HCC cells in vitro, PCR and ELISA showed that IL-17 selectively augmented the secretion of diverse proinvasive factors and transwell showed a direct promotion of invasion of HCC cells by IL-17. Furthermore, transfection of IL-17 into HCC cells significantly promoted neoangiogenesis, neutrophil recruitment and tumor growth in vivo. Using siRNA mediated knockdown of AKT and STAT3, we suggested that the effects of IL-17 were operated through activation of the AKT signaling in HCC, which resulted in IL-6 production. Then, IL-6 in turn activated JAK2/STAT3 signaling and subsequently up-regulated its downstream targets IL-8, MMP2, and VEGF. Supporting these findings, in human HCC tissues, immunostaining indicated that IL-17 expression was significantly and positively associated with STAT3 phosphorylation, neutrophil infiltration and increased tumor vascularity. The clinical significance of IL-17 was authenticated by revealing that the combination of intratumoral IL-17+ cells and phospho-STAT3 served as a better prognosticator for postoperative tumor recurrence than either marker alone. CONCLUSIONS: IL-17 mediated tumor-promoting role involves a direct effect on HCC cells through IL-6/JAK2/STAT3 induction by activating the AKT pathway.

Leptin activates human B cells to secrete TNF-α, IL-6, and IL-10 via JAK2/STAT3 and p38MAPK/ERK1/2 signaling pathway.

Leptin, one of the adipokines, functions as a hormone and a cytokine. In this investigation, we show for the first time that leptin, in a concentration-dependent manner, activates human peripheral blood B cells to induce secretion of IL-6, IL-10, and TNF-α. Leptin increased B cells expressing CD25 and HLA-DR. Leptin induces phosphorylation of Janus activation kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), p38 mitogen-activated protein kinase (p38MAPK), and extracellular signal-regulated kinase (ERK1/2). Furthermore, leptin-induced cytokine secretion by B cells was blocked by inhibitors of JAK2, STAT3, p38MAPK, and ERK1/2. These data demonstrate that leptin activates human B cells to secrete cytokines via activation of JAK2/STAT3 and p38MAPK/ERK1/2 signaling pathways, which may contribute to its inflammatory and immunoregulatory properties.

JAK2V617F mutation for the early diagnosis of Ph- myeloproliferative neoplasms in patients with venous thromboembolism: a meta-analysis.

Recent studies suggested that JAK2V617F mutation is frequent in patients with splanchnic vein thrombosis (SVT) but not in patients with other venous thromboembolic events (VTE). However, whether screening for the JAK2V617F mutation in VTE patients is justified remains unclear. Therefore, we performed a systematic review to assess the frequency of JAK2 mutation in VTE patients and the role of JAK2V617F mutation in the diagnosis of myeloproliferative neoplasms. MEDLINE and EMBASE databases were searched. Two reviewers independently performed study selection and extracted study characteristics. Pooled odds ratios of case-control studies and weighted mean proportion of the prevalence of JAK2V617F mutation of uncontrolled series were calculated. Twenty-four studies involving 3123 patients were included. Mean prevalence of JAK2 mutation was 32.7% (95% confidence interval, 25.5%-35.9%) in SVT patients. JAK2 mutation was associated with increased risk of SVT (odds ratio, 53.98; 95% confidence interval, 13.10-222.45). Mean prevalence of JAK2 mutation in other VTE patients was low (range, 0.88%-2.57%). Presence of JAK2V617F mutation in SVT patients was associated with a subsequent diagnosis of myeloproliferative neoplasm in many patients. JAK2 mutation is strongly associated with SVT, and routine screening of JAK2 mutation appears to be indicated in these patients.

The impact of bone marrow fibrosis and JAK2 expression on clinical outcomes in patients with newly diagnosed multiple myeloma treated with immunomodulatory agents and/or proteasome inhibitors.

We determined the impact of bone marrow fibrosis (BMF) on the clinical outcomes of newly diagnosed multiple myeloma (NDMM) patients in the current era of myeloma therapy. A total of 393 MM patients were included in the final analysis. The median followup was 83 months (range: 3.9 to 212 months). BMF was noted in 122 (48.2%) evaluable patients. Median progression free survival (PFS) in patients without BMF was 30.2 (95% CI: 24.7-38.0) months, and 21.1 (95% CI: 18.8-27.5) months in patients with BMF present (P = .024). Median overall survival (OS) was 61.2 (95% CI: 51.5-81.2) months in patients without BMF, and 45.1 (95% CI: 38.7-57.0) months in patients with BMF (P = .0048). A subset of 99 patients had their bone marrow biopsies stained for JAK1 and JAK2 by immunohistochemistry. Of these samples 67 (67.7%) patients had detectable JAK2 expression predominantly noted on bone marrow megakaryocytes. JAK2 expression correlated with myeloma disease stage (P = .0071). Our study represents the largest dataset to date examining the association of BMF with prognosis in the era of novel therapies and widespread use of hematopoietic stem cell transplant (HSCT). Our data suggest that MM patients with BMF (particularly those with extensive BMF) have a poorer prognosis even when treated with immunomodulatory agents and proteasome inhibitors.

Concordance of assays designed for the quantification of JAK2V617F: a multicenter study.

BACKGROUND: Many different techniques have been designed for the quantification of JAK2V617F allelic burden, sometimes producing discrepant results. DESIGN AND METHODS: JAK2V617F quantification techniques were compared among 16 centers using 11 assays based on quantitative polymerase chain reaction (with mutation-specific primers or probes, or fluorescent resonance energy transfer/melting curve analysis), allele-specific polymerase chain reaction, conventional sequencing or pyrosequencing. RESULTS: A first series of blinded samples (granulocyte DNA, n=29) was analyzed. Seven assays (12 centers) reported values inside the mean +/- 2SD; the mean coefficient of variation was 31%. Sequencing techniques lacked sensitivity, and strong discrepancies were observed with four techniques, which could be attributed to inadequate standards or to different modes of expression of results. Indeed, quantification of JAK2V617F in relation to another control gene produced higher than expected values, suggesting the possibility of more than two JAK2 copies/cell. After calibration of assays with common 1% to 100% JAK2V617F standards (dilutions of UKE-1 cells in normal leukocytes), 14 centers tested ten new samples. JAK2V617F allelic burdens greater or equal than 1% were then reliably quantified by five techniques -- one allele specific-polymerase chain reaction and four TaqMan allele-specific quantitative polymerase chain reaction assays, including one previously giving results outside the mean +/- 2SD -- with a lower mean coefficient of variation (21%). Of these, only the two TaqMan allele-specific quantitative polymerase chain reaction assays with primer-based specificity could detect 0.2% JAK2V617F. CONCLUSIONS: Techniques expressing the allelic burden as JAK2V617F/total JAK2 and using a common set of standards produced similar quantification results but with variable sensitivity. Calibration to a reference standard improved reproducibility.

Quantitative assay for Janus kinase 2 (JAK2) mutation in Chinese patients with chronic myeloproliferative disorders.

The Janus kinase 2 (JAK2) V617F mutation has considerably helped understanding of the molecular pathogenesis of chronic myeloproliferative disorders (MPD), hence this study investigated for the first time the mutational status and relative quantitation of JAK2 V617F mRNA in Chinese patients with chronic MPD. The study cohort comprised 123 chronic MPD patients (35 with polycythaemia vera [PV], 85 with essential thrombocythaemia [ET], three with idiopathic myelofibrosis [IMF]). Blood samples examined by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and capillary electrophoresis showed that the prevalence of the JAK2 V617F mutation was 100%, 62.4% and 66.7% in PV, ET and IMF patients, respectively. The proportion of JAK2 V617F mutated mRNA was 89.5% in homozygotes and 57.9% in heterozygotes; 18 PV heterozygous patients showed significantly higher mutated JAK2 mRNA levels than 36 heterozygous ET patients. Six of 93 patients exhibited abnormal karyotypes, but specific chromosomal abnormality was not found. The combination of ARMS-PCR and capillary electrophoresis enables quantitative assay of JAK2 V617F mutation, which helps in chronic MPD diagnosis and estimation of minimal residual disease.

Fedratinib: First Approval.

Fedratinib (INREBIC®) is a JAK2-selective inhibitor that has been developed as an oral treatment for myelofibrosis. In August 2019, fedratinib received its first global approval in the USA for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis. Phase III clinical development for myelofibrosis is ongoing worldwide. This article summarizes the milestones in the development of fedratinib leading to this first approval for myelofibrosis.

Rapid identification of JAK2 exon 12 mutations using high resolution melting analysis.

Diverse JAK2 exon 12 mutations have been described in patients with V617F-negative polycythemia vera. Development of a sensitive detection assay capable of identifying any of these mutations is required for medium-throughput diagnostic screens. Non-mutated and mutant JAK2 exon 12 alleles were amplified from patient samples and cloned into plasmid vectors, then used to determine the sensitivity of a novel high-resolution melting-curve assay designed to detect all mutant JAK2 exon 12 alleles tested. High resolution melting analysis was more sensitive than direct sequencing and capable of detecting exon 12 mutations in granulocytes at moderate levels. In a blinded analysis of DNAs from V617F-negative erythrocytosis patients, with direct sequencing and allele-specific PCR used in one laboratory and high resolution melting analysis in another, high resolution melting successfully identified JAK2 exon 12 mutations in all 4 mutation-positive patients. High resolution melting analysis is a rapid, sensitive and high-throughput technique that is suitable for screening for JAK2 exon 12 mutations.

Characterization of a highly effective protein substrate for analysis of JAK2(V617F) Activity.

OBJECTIVE: Identification of JAK2V617F in myeloproliferative disorders makes JAK2 an important marker for disease diagnosis and a highly attractive target for therapeutic drug development. This study is intended to identify a sensitive and specific substrate for assays of the JAK2 enzymatic activity. METHODS: We expressed a glutathione S-transferase (GST) fusion protein designated GST-JAKS, which carries a peptide sequence derived from the autophosphorylation sites of human JAK2. The protein was purified from Escherichia coli cells and was used to analyze to tyrosine kinase activities of purified enzymes and crude cell extracts from cells, including mononuclear cells of JAK2V617F -positive polycythemia vera blood. It was also used to perform JAK2 kinase assays to screen inhibitors of JAK2. RESULTS: GST-JAKS is strongly phosphorylated by activated forms of JAK2 including JAK2V617F and recombinant protein containing its catalytic domain alone. It showed minimal responses to wild-type JAK2 and was not phosphorylated by the epidermal growth receptor and the insulin receptor tyrosine kinases. Kinase assays with GST-JAKS provide a sharp contrast between wild-type and mutant JAK2,V617F and are sensitive enough to detect minute amounts of JAK2V617F found in crude cell extracts. Assays can be scaled up to screen for inhibitors of JAK2 in a dot blot format. CONCLUSION: GST-JAKS is sensitive and specific protein substrate for JAK2 assays. It may have clinical applications in diagnosis of diseases related to abnormal JAK2 activity. It is also an excellent substrate for development of large scale assays to screen JAK2 inhibitors.

Epigenetic control of PRV-1 expression on neutrophils.

OBJECTIVE: Polycythemia rubra vera-1 (PRV-1) is a GPI-linked protein that is expressed on a subgroup of neutrophils. The number of PRV-1-expressing neutrophils increases in pregnancy and sepsis, or after administration of granulocyte colony-stimulating factor. Expression of the PRV-1 gene is also increased in patients with polycythemia vera (PV) and essential thrombocythemia (ET). We investigated whether DNA methylation of the PRV-1 gene has a role in regulation of transcription and expression of the PRV-1 protein. METHODS: We compared the level of methylation of the PRV-1 gene and expression of the PRV-1 mRNA in normal neutrophils expressing PRV-1 to those that are PRV-1-negative. We also studied PRV-1 methylation and mRNA expression in patients with Philadelphia chromosome-negative myeloproliferative disorders and in an in vitro model of DNA demethylation. RESULTS: We found that methylation of CpG dinucleotides close to initiation codon of the PRV-1 gene was inversely related to expression of PRV-1 in normal neutrophils. Furthermore, overexpression of the PRV-1 gene in PV and ET is associated with a decrease in methylation of this gene. Among patients with PV and ET, methylation of the PRV-1 gene is also inversely correlated with the presence of the JAK2(V617F) somatic mutation. In an in vitro model, exposure of KG1 and KG1a cells to a DNA demethylating agent caused a decrease in methylation of the PRV-1 gene and increased its mRNA level. CONCLUSION: DNA methylation regulates PRV-1 expression under physiologic and pathologic conditions.

Amplification refractory mutation system, a highly sensitive and simple polymerase chain reaction assay, for the detection of JAK2 V617F mutation in chronic myeloproliferative disorders.

An acquired mutation in Janus kinase 2 (JAK2), V617F, has recently been identified in human myeloproliferative disorders. Detection of the mutation is helpful in differential diagnosis, prognosis, and predication of therapeutic response. Because the mutation can be present in a small proportion of granulocytic populations in myeloproliferative disorder patients, a highly sensitive detection method is required. In this study, we systematically optimized the reaction conditions of a published amplification refractory mutation system-polymerase chain reaction research protocol to make it a robust clinical diagnostic test. The modifications led to a clear demonstration of the V617F mutation in a patient who would have been easily missed by the original amplification refractory mutation system-polymerase chain reaction assay. The test detects the V617F mutation not only with a high analytic sensitivity of 0.05 to 0.1% but also with a high diagnostic specificity of 99%. In addition, the assay has the ability to distinguish cases with only mutant alleles from cases with mixed normal and mutant alleles. The assay is fast and easy to perform, and no special equipment other than thermocyclers is required. All these features make the assay readily and broadly applicable in clinical molecular diagnostic laboratories.

A potential role for HSP90 inhibitors in the treatment of JAK2 mutant-positive diseases as demonstrated using quantitative flow cytometry.

The V617F mutation of the JAK2 tyrosine kinase is found in a majority of patients with myeloproliferative disorders. Flow cytometry assays for quantitation of phosphorylated and total protein for JAK2, STAT5, and heat shock proteins (HSPs) were developed to facilitate the study of the JAK/STAT pathway. A cell line homozygous for V617F (HEL) was treated with inhibitors of JAK2 tyrosine kinase activity and the HSP90 inhibitor 17-AAG. 17-AAG reduced HSP90 levels, but increased HSP70 levels. Phospho-STAT5, total STAT5, and total AKT levels were also reduced by 17-AAG treatment. Further, phospho-JAK2, total JAK2, and cell viability were reduced to a greater extent by 17-AAG than by the pan-JAK kinase family inhibitor JKII or the JAK2-specific inhibitor AG490, and these inhibitors failed to synergize with 17-AAG. Flow-cytometry-based assays for JAK/STAT signaling pathway and HSPs are likely to have broad clinical utility for monitoring patients with abnormalities in the JAK2 pathway.

Evaluation of JAK2 in B and T cell neoplasms: identification of JAK2(V617F) mutation of undetermined significance (JMUS) in the bone marrow of three individuals.

BACKGROUND/AIMS: The JAK2(V617F) mutation, which has been found in patients with myeloproliferative disorders (MPD), has not yet been evaluated in lymphoproliferative disorders by any adequately sensitive techniques. METHODS: We investigated whether low levels of JAK2(V617F) are present in lymphoid neoplasms using a highly sensitive and highly specific amplification refractory mutation system PCR (ARMS-PCR) assay. RESULTS: While 234 of 237 cases did not carry the JAK2(V617F) allele, it was identified in the bone marrow of 3 B cell lymphoma patients. The mutation was found to be neither associated with the lymphomas per se, nor with any signs, symptoms or laboratory findings of MPD. Moreover, JAK2(V617F) appeared subsequently in the peripheral blood of 2 of the 3 patients. CONCLUSION: These findings suggest that JAK2(V617F) arises in the bone marrow of individuals before clinical manifestation of any myeloid disorders. Presence of JAK2(V617F) in bone marrow might therefore increase the risk of future MPD development, just as monoclonal gammopathy of undetermined significance (MGUS) increases the risk of multiple myeloma. We term this phenomenon 'JAK2(V617F) of undetermined significance' (JMUS). Its clinical significance remains to be determined. To our knowledge, these findings represent the first identification of JAK2(V617F) in the bone marrow of patients without myeloid malignancies.

Mediating effect of dopamine D3 receptors on Jak2 and GABAAalpha1 expression in mouse brains induced by cocaine.

BACKGROUND: Cocaine addiction may involve complex neuroadaptations, including many changes of genes expression. Dopamine D3 receptors play an important role in cocaine addiction; however, its role in cocaine induced gene expression change is poorly understood. To identify the changes in gene expression induced by repeated cocaine exposure through D3 dopamine receptors, we compared the expression of four molecules: Janus kinase 2 (Jak2), g-aminobutanoic acid receptor subunit alpha 1 (GABAAalpha1), glutamate receptor AMPA3 alpha 3 (GluR 3) and stromal cell derived factor 1 (SDF1). These four have been implicated in mediating the actions of cocaine in the nucleus accumbens (NAc) and caudoputamen (CPu) in mice after acute and repeated cocaine exposure. METHODS: For the acute and repeated injections, the mice were divided into four groups: 30 mg/kg cocaine, nafadotride 0.5 mg/kg + cocaine 30 mg/kg, nafadotride 0.5 mg/kg, and saline as the basal group. The expression of Jak2, GABAAalpha1, GluR 3 and SDF1 were assayed by Western blot, quantitative real-time RT-PCR and immunohistochemistry. RESULTS: Twenty-four hours after seven consecutive days of repeated cocaine exposure, the expression of GABAAalpha1 decreased in cocaine group compared with basal line and further decreased in the cocaine + nafadotride group and remained at basal level in the nafadotride group. Similarly, the Jak2 expression decreased in cocaine group compared with base line. However, the levels of Jak2 increased in cocaine + nafadotride group compared with cocaine group, while remained at basal level in nafadotride group. CONCLUSIONS: GABAAalpha1 and Jak2 may be involved in chronic cocaine induced neuroadaptations. D3 dopamine receptors play an important role in the expression of these genes.