Contemporary management of fibrolamellar hepatocellular carcinoma: diagnosis, treatment, outcome, prognostic factors, and recent developments.

World J Surg Oncol. 2016;14(1):151

Authors: Kassahun WT

Abstract
Fibrolamellar hepatocellular carcinoma (FL-HCC) is a malignant liver tumor which is thought to be a variant of conventional hepatocellular carcinoma (HCC). It accounts for a small proportion of HCC cases and occurs in a distinctly different group of patients which are young and usually not in the setting of chronic liver disease. The diagnosis of FL-HCC requires the integration of clinical information, imaging studies, and histology. In terms of the treatment options, the only potentially curative treatment option for patients who have resectable disease is surgery either liver resection (LR) or liver transplantation (LT). When performed in a context of aggressive therapy, long-term outcomes after surgery, particularly liver resection for FL-HCC, were favorable. The clinical outcome of patients with unresectable disease is suboptimal with median survival of less than 12 months. The aim of this review is to update the available evidence on diagnosis, treatment options, outcome predictors, and recent developments of patients with this rare disease and to provide a summarized overview of the available literature.

PMID: 27215576 [PubMed - in process]

Free-thiamine is a potential biomarker of thiamine transporter-2 deficiency: a treatable cause of Leigh syndrome.

Brain. 2016 Jan;139(Pt 1):31-8

Authors: Ortigoza-Escobar JD, Molero-Luis M, Arias A, Oyarzabal A, Darín N, Serrano M, Garcia-Cazorla A, Tondo M, Hernández M, Garcia-Villoria J, Casado M, Gort L, Mayr JA, Rodríguez-Pombo P, Ribes A, Artuch R, Pérez-Dueñas B

Abstract
Thiamine transporter-2 deficiency is caused by mutations in the SLC19A3 gene. As opposed to other causes of Leigh syndrome, early administration of thiamine and biotin has a dramatic and immediate clinical effect. New biochemical markers are needed to aid in early diagnosis and timely therapeutic intervention. Thiamine derivatives were analysed by high performance liquid chromatography in 106 whole blood and 38 cerebrospinal fluid samples from paediatric controls, 16 cerebrospinal fluid samples from patients with Leigh syndrome, six of whom harboured mutations in the SLC19A3 gene, and 49 patients with other neurological disorders. Free-thiamine was remarkably reduced in the cerebrospinal fluid of five SLC19A3 patients before treatment. In contrast, free-thiamine was slightly decreased in 15.2% of patients with other neurological conditions, and above the reference range in one SLC19A3 patient on thiamine supplementation. We also observed a severe deficiency of free-thiamine and low levels of thiamine diphosphate in fibroblasts from SLC19A3 patients. Surprisingly, pyruvate dehydrogenase activity and mitochondrial substrate oxidation rates were within the control range. Thiamine derivatives normalized after the addition of thiamine to the culture medium. In conclusion, we found a profound deficiency of free-thiamine in the CSF and fibroblasts of patients with thiamine transporter-2 deficiency. Thiamine supplementation led to clinical improvement in patients early treated and restored thiamine values in fibroblasts and cerebrospinal fluid.

PMID: 26657515 [PubMed - indexed for MEDLINE]

Mutations in the MORC2 gene cause axonal Charcot-Marie-Tooth disease.

Brain. 2016 Jan;139(Pt 1):62-72

Authors: Sevilla T, Lupo V, Martínez-Rubio D, Sancho P, Sivera R, Chumillas MJ, García-Romero M, Pascual-Pascual SI, Muelas N, Dopazo J, Vílchez JJ, Palau F, Espinós C

Abstract
Charcot-Marie-Tooth disease (CMT) is a complex disorder with wide genetic heterogeneity. Here we present a new axonal Charcot-Marie-Tooth disease form, associated with the gene microrchidia family CW-type zinc finger 2 (MORC2). Whole-exome sequencing in a family with autosomal dominant segregation identified the novel MORC2 p.R190W change in four patients. Further mutational screening in our axonal Charcot-Marie-Tooth disease clinical series detected two additional sporadic cases, one patient who also carried the same MORC2 p.R190W mutation and another patient that harboured a MORC2 p.S25L mutation. Genetic and in silico studies strongly supported the pathogenicity of these sequence variants. The phenotype was variable and included patients with congenital or infantile onset, as well as others whose symptoms started in the second decade. The patients with early onset developed a spinal muscular atrophy-like picture, whereas in the later onset cases, the initial symptoms were cramps, distal weakness and sensory impairment. Weakness and atrophy progressed in a random and asymmetric fashion and involved limb girdle muscles, leading to a severe incapacity in adulthood. Sensory loss was always prominent and proportional to disease severity. Electrophysiological studies were consistent with an asymmetric axonal motor and sensory neuropathy, while fasciculations and myokymia were recorded rather frequently by needle electromyography. Sural nerve biopsy revealed pronounced multifocal depletion of myelinated fibres with some regenerative clusters and occasional small onion bulbs. Morc2 is expressed in both axons and Schwann cells of mouse peripheral nerve. Different roles in biological processes have been described for MORC2. As the silencing of Charcot-Marie-Tooth disease genes have been associated with DNA damage response, it is tempting to speculate that a deregulation of this pathway may be linked to the axonal degeneration observed in MORC2 neuropathy, thus adding a new pathogenic mechanism to the long list of causes of Charcot-Marie-Tooth disease.

PMID: 26497905 [PubMed - indexed for MEDLINE]

Distinct cardiac phenotype between two homozygotes born in a village with accumulation of a genetic deficiency of adipose triglyceride lipase.

Int J Cardiol. 2015 Aug 1;192:30-2

Authors: Higashi M, Hirano K, Kobayashi K, Ikeda Y, Issiki A, Otsuka T, Suzuki A, Yamaguchi S, Zaima N, Hamada S, Hanada H, Suzuki C, Nakamura H, Nagasaka H, Miyata T, Miyamoto Y, Kobayashi K, Naito H, Toda T

PMID: 25985012 [PubMed - indexed for MEDLINE]

17 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results:

("orphan disease" OR "rare disease" OR "orphan diseases" OR "rare diseases")

These pubmed results were generated on 2016/05/24

PubMed comprises more than 24 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

Update on the safety of second generation antipsychotics in youths: a call for collaboration among paediatricians and child psychiatrists.

Ital J Pediatr. 2016;42(1):51

Authors: Pisano S, Catone G, Veltri S, Lanzara V, Pozzi M, Clementi E, Iuliano R, Riccio MP, Radice S, Molteni M, Capuano A, Gritti A, Coppola G, Milone A, Bravaccio C, Masi G

Abstract
During the past decade, a substantial increase in the use of second generation antipsychotics (SGAs) has occurred for a number of juvenile psychiatric disorders, often as off-label prescriptions. Although they were thought to be safer than older, first generation antipsychotics, mainly due to a lower risk of neurological adverse reactions, recent studies have raised significant concerns regarding their safety regarding metabolic, endocrinological and cardiovascular side effects. Aim of this paper is to update with a narrative review, the latest findings on safety of SGAs in youths. Results suggest that different SGAs may present different safety profiles. Metabolic adverse events are the most frequent and troublesome, with increasing evidences of heightened risk for type II diabetes mellitus. Results are discussed with specific emphasis on possible strategies of an active monitoring, which could enable both paediatricians and child psychiatrists to a possible prevention, early detection, and a timely management of such effects.

PMID: 27209326 [PubMed - as supplied by publisher]

Mixed Phenotype Acute Leukemia (MPAL) Exhibits Frequent Mutations in DNMT3A and Activated Signaling Genes.

Exp Hematol. 2016 May 18;

Authors: Eckstein OS, Wang L, Punia JN, Kornblau SM, Andreeff M, Wheeler DA, Goodell MA, Rau RE

Abstract
Mixed phenotype acute leukemia (MPAL) is a heterogeneous group of poor-prognosis leukemias with immunophenotypic features of at least two cell lineages. The full spectrum of genetic mutations in this rare disease has not been elucidated, limiting our understanding of disease pathogenesis and our ability to devise targeted therapeutic strategies. We sought to define the mutational landscape of MPAL by performing whole exome sequencing on samples from 23 adult and pediatric MPAL patients. We identified frequent mutations of epigenetic modifiers, most notably mutations of DNMT3A in 33% of adult MPAL patients. Mutations of activated signaling pathways, tumor suppressors and transcription factors were also frequent. Importantly, many of the identified mutations are potentially therapeutically targetable with agents currently available or in various stages of clinical development. Therefore, the mutational spectrum we identified provides potential biological insights and is likely to have clinical relevance for patients with this poor-prognosis disease.

PMID: 27208809 [PubMed - as supplied by publisher]

Childhood epidermolysis bullosa acquisita during squaric acid dibutylester (SADBE) immunotherapy for alopecia areata.

Br J Dermatol. 2016 May 21;

Authors: Guerra L, Pacifico V, Calabresi V, De Luca N, Castiglia D, Angelo C, Zambruno G, Di Zenzo G

Abstract
Epidermolysis bullosa acquisita (EBA) is a rare acquired subepidermal blistering disease associated with autoantibodies against type VII collagen. Although EBA manifests more frequently in adults, it can occur in childhood. We describe a 6-year-old male who developed the inflammatory variant of EBA shortly after the initiation of immunotherapy with squaric acid dibutylester (SADBE) for scalp alopecia areata (AA). The disease rapidly regressed following SADBE discontinuation and starting of a combined steroid and dapsone therapy and never recurred after treatment tapering and withdrawal. The association of EBA with other autoimmune diseases is common, but EBA occurring during AA has not been previously described. The development of EBA during SADBE treatment is also noticeable: the clinical history and therapeutic response in our patient point to a possible role of SADBE in EBA onset. This article is protected by copyright. All rights reserved.

PMID: 27208509 [PubMed - as supplied by publisher]

Leptin substitution in patients with lipodystrophy: neural correlates for long-term success in the normalization of eating behavior.

Diabetes. 2016 May 10;

Authors: Schlögl H, Müller K, Horstmann A, Miehle K, Püschel J, Villringer A, Pleger B, Stumvoll M, Fasshauer M

Abstract
Lipodystrophy (LD) is a rare disease with a paucity of subcutaneous adipocytes and leptin-deficiency. Patients often develop severe diabetes mellitus and show disturbed eating behavior with reduced satiety that can be restored by substitution with the leptin analogue metreleptin. However, long-term effects of metreleptin on resting-state brain connectivity in treatment-naïve LD patients have not been assessed. In this study, resting-state functional magnetic resonance imaging (fMRI) scans and extensive behavioral testing assessing changes in hunger/satiety regulation were performed during the first 52 weeks of metreleptin treatment in nine LD patients. Resting-state connectivity significantly increased over the course of metreleptin treatment in three brain areas, i.e. hypothalamus, insula/superior temporal gyrus, and medial prefrontal cortex. Behavioral tests demonstrated that perceived hunger, importance of eating, eating frequencies, and liking ratings of food pictures significantly decreased during metreleptin therapy. Taken together, leptin substitution was accompanied by long-term changes of hedonic and homeostatic central nervous networks regulating eating behavior, as well as decreased hunger feelings and diminished incentive value of food. It needs to be assessed in future studies whether metreleptin treatment in LD restores physiological processes important for the development of satiety.

PMID: 27207511 [PubMed - as supplied by publisher]

Pharmaceutical expenditure on drugs for rare diseases in Canada: a historical (2007-13) and prospective (2014-18) MIDAS sales data analysis.

Orphanet J Rare Dis. 2016;11(1):68

Authors: Divino V, DeKoven M, Kleinrock M, Wade RL, Kim T, Kaura S

Abstract
BACKGROUND: Health Canada has defined rare diseases as life-threatening, seriously debilitating, or serious chronic conditions affecting a very small number of patients (~1 in 2,000 persons). An estimated 9 % of Canadians suffer from a rare disease. Drugs treating rare diseases (DRDs) are also known as orphan drugs. While Canada is currently developing an orphan drug framework, in the United States (US), the Orphan Drug Act (ODA) of 1983 established incentives for the development of orphan drugs. This study measured total annual expenditure of orphan drugs in Canada (2007-13) and estimated future (2014-18) orphan drug expenditure.
METHODS: Orphan drugs approved by the US Food and Drug Administration (FDA) in the US were used as a proxy for the orphan drug landscape in Canada. Branded, orphan drugs approved by the FDA between 1983 through 2013 were identified (N = 356 unique products). Only US orphan drugs with the same orphan indication(s) approved in Canada were included in the analysis. Adjustment via an indication factoring was applied to products with both orphan and non-orphan indications using available data sources to isolate orphan-indication sales. The IMS Health MIDAS database of audited biopharmaceutical sales was utilized to measure total orphan drug expenditure, calculated annually from 2007-2013 and evaluated as a proportion of total annual pharmaceutical drug expenditure (adjusted to 2014 CAD).
RESULTS: Between 2007 and 2013, expenditure was measured for a final N = 147 orphan drugs. Orphan drug expenditure totaled $610.2 million (M) in 2007 and $1,100.0 M in 2013, representing 3.3- 5.6 % of total Canadian pharmaceutical drug expenditure in 2007-2013, respectively. Future trend analysis suggests orphan drug expenditure will remain under 6 % of total expenditure in 2014-18.
CONCLUSIONS: While the number of available orphan drugs and associated expenditure increased over time, access remains an issue, and from the perspectives of society and equity, overall spending on orphan drugs is lower relative to the number of patients affected with an orphan disease in Canada. The overall budget impact of orphan drugs is small and fairly stable relative to total pharmaceutical expenditure. Concerns that growth in orphan drug expenditure may lead to unsustainable drug expenditure do not appear to be justified.

PMID: 27207271 [PubMed - as supplied by publisher]

A Decade of Change: Recent Developments in Pharmacotherapy of Hereditary Angioedema (HAE).

Clin Rev Allergy Immunol. 2016 May 20;

Authors: Bork K

Abstract
Hereditary angioedema (HAE) due to C1 esterase inhibitor (C1-INH) deficiency (HAE-C1-INH) is a rare but medically significant disease that can be associated with considerable morbidity and mortality. Research into the pathogenesis of HAE-C1-INH has expanded greatly in the last six decades and has led to new clinical trials with novel therapeutic agents and treatment strategies. Mechanisms of pharmacotherapy include (a) supplementing C1-INH, the missing serine-protease inhibitor in HAE; (b) inhibiting the activation of the contact system and the uncontrolled release of proteases in the kallikrein-kinin system, by blocking the production/function of its components; (c) inhibiting the fibrinolytic system by blocking the production/function of its components; and (d) inhibiting the function of bradykinin at the endothelial level. Strategies for managing HAE-C1-INH are aimed at treating acute attacks, or preventing attacks, through the use of prophylactic treatment. Available agents for treating acute attacks include plasma-derived C1-INH concentrates, a recombinant C1-INH, a bradykinin B2 receptor antagonist, and a plasma kallikrein inhibitor. Long-term prophylactic treatments include attenuated androgens, plasma-derived C1-INH concentrates, and anti-fibrinolytics. Plasma-derived C1-INH and a bradykinin B2 receptor antagonist are already approved for self-administration at home. The number of management options for HAE-C1-INH has increased considerably within the past decade, thus helping to alleviate the burden of this rare disease.

PMID: 27207174 [PubMed - as supplied by publisher]

26 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results:

("orphan disease" OR "rare disease" OR "orphan diseases" OR "rare diseases")

These pubmed results were generated on 2016/05/21

PubMed comprises more than 24 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

Whole Exome Sequencing in a Rare Disease: A Patient with Anomalous Left Coronary Artery from the Pulmonary Artery (Bland-White-Garland Syndrome).

OMICS. 2016 May;20(5):325-327

Authors: Hekim N, Batyraliev T, Trujillano D, Wang W, Dandara C, Karben Z, Saygılı Eİ, Çetin Z, Mıhcıoğlu D, Türkmen S, İkidağ MA, Cüce MA, Rolfs A

PMID: 27195969 [PubMed - as supplied by publisher]

A Novel ECM1 Splice Site Mutation in Lipoid Proteinosis: Case Report plus Review of the Literature.

Mol Syndromol. 2016 Apr;7(1):26-31

Authors: Rey LK, Kohlhase J, Möllenhoff K, Dekomien G, Epplen JT, Hoffjan S

Abstract
Lipoid proteinosis (LP) is an autosomal recessive genodermatosis known to be caused by mutations in ECM1. Nonsense and missense mutations are the most common variations in LP. Up to date, only 6 splice site mutations have been observed. We report on a 26-year-old female LP patient from a Turkish consanguineous family carrying a novel homozygous splice site mutation in intron 8 of the ECM1 gene and summarize the current knowledge on ECM1 mutations and possible genotype-phenotype correlations.

PMID: 27194970 [PubMed]

First reported association of chronic lymphocytic leukaemia and interstitial granulomatous dermatitis.

BMJ Case Rep. 2016;2016

Authors: Riaz IB, Kamal MU, Segal RJ, Anwer F

Abstract
Interstitial granulomatous dermatitis (IGD), a rare disease, is well known to be associated with connective tissue disorders, malignancies and several drugs. We describe this first case of IGD in association with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL). A 66-year-old woman with a 6-year history of untreated CLL/SLL, presented with a 2-month history of progressively worsening eruption of the left thigh, along with fatigue, lymphadenopathy and night sweats. Skin biopsy showed findings consistent with IGD and infiltration of CLL. The eruption was non-responsive to treatment with antibiotics and local steroids. There was a significant improvement in the rash after an initial cycle of chemotherapy (combination therapy with bendamustine and rituximab) and complete resolution by the third cycle, for the treatment of her CLL. We suggest that the possibility of an underlying haematological malignancy should be investigated in patients with a skin rash non-responsive to conventional therapy.

PMID: 27194675 [PubMed - in process]

The partnership of patient advocacy groups and clinical investigators in the rare diseases clinical research network.

Orphanet J Rare Dis. 2016;11(1):66

Authors: Merkel PA, Manion M, Gopal-Srivastava R, Groft S, Jinnah HA, Robertson D, Krischer JP, Rare Diseases Clinical Research Network

Abstract
BACKGROUND: Among the unique features of the Rare Diseases Clinical Research Network (RDCRN) Program is the requirement for each Consortium to include patient advocacy groups (PAGs) as research partners. This development has transformed the work of the RDCRN and is a model for collaborative research. This article outlines the roles patients and PAGs play in the RDCRN and reports on the PAGs' impact on the Network's success.
METHODS: Principal Investigators from the 17 RDCRN Consortia and 28 representatives from 76 PAGs affiliated with these Consortia were contacted by email to provide feedback via an online RDCRN survey. Impact was measured in the key areas of 1) Research logistics; 2) Outreach and communication; and 3) Funding and in-kind support. Rating choices were: 1-very negative, 2-somewhat negative, 3-no impact, 4-somewhat positive, and 5-very positive.
RESULTS: Twenty-seven of the PAGs (96 %) disseminate information about the RDCRN within the patient community. The Consortium Principal Investigators also reported high levels of PAG involvement. Sixteen (94 %) Consortium Principal Investigators and 25 PAGs (89 %) reported PAGs participation in protocol review, study design, Consortium conference calls, attending Consortium meetings, or helping with patient recruitment.
CONCLUSIONS: PAGs are actively involved in shaping Consortia's research agendas, help ensure the feasibility and success of research protocols by assisting with study design and patient recruitment, and support training programs. This extensive PAG-Investigator partnership in the RDCRN has had a strongly positive impact on the success of the Network.

PMID: 27194034 [PubMed - as supplied by publisher]

Portosystemic Shunt Surgery in Patients with Idiopathic Noncirrhotic Portal Hypertension.

Ann Transplant. 2016;21:317-20

Authors: Karagul S, Yagci MA, Tardu A, Ertugrul I, Kirmizi S, Sumer F, Isik B, Kayaalp C, Yilmaz S

Abstract
BACKGROUND Idiopathic noncirrhotic portal hypertension (INCPH) is a rare disease characterized by increased portal venous pressure in the absence of cirrhosis and other causes of liver diseases. The aim of the present study was to present our results in using portosystemic shunt surgery in patients with INCPH. MATERIAL AND METHODS Patients who had been referred to our Liver Transplantation Institute for liver transplantation and who had undergone surgery from January 2010 to December 2015 were retrospectively analyzed. Patients with INCPH who had undergone portosystemic shunt procedure were included in the study. Age, sex, symptoms and findings, type of portosystemic shunt, and postoperative complications were assessed. RESULTS A total of 1307 patients underwent liver transplantation from January 2010 to December 2015. Eleven patients with INCPH who did not require liver transplantation were successfully operated on with a portosystemic shunt procedure. The mean follow-up was 30.1±19 months (range 7-69 months). There was no mortality in the perioperative period or during the follow-up. Two patients underwent surgery again due to intra-abdominal hemorrhage; one had bleeding from the surgical site except the portacaval anastomosis and the other had bleeding from the h-graft anastomosis. No patient developed encephalopathy and no patient presented with esophageal variceal bleeding after portosystemic shunt surgery. Shunt thrombosis occurred in 1 patient (9.9%). Only 1 patient developed ascites, which was controlled medically. CONCLUSIONS Portosystemic shunt surgery is a safe and effective procedure for the treatment of patients with INCPH.

PMID: 27194018 [PubMed - in process]

Altered localization and functionality of TAR DNA Binding Protein 43 (TDP-43) in niemann- pick disease type C.

Acta Neuropathol Commun. 2016;4(1):52

Authors: Dardis A, Zampieri S, Canterini S, Newell KL, Stuani C, Murrell JR, Ghetti B, Fiorenza MT, Bembi B, Buratti E

Abstract
Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by the occurrence of visceral and neurological symptoms. At present, the molecular mechanisms causing neurodegeneration in this disease are unknown. Here we report the altered expression and/or mislocalization of the TAR-DNA binding protein 43 (TDP-43) in both NPC mouse and in a human neuronal model of the disease. We also report the neuropathologic study of a NPC patient's brain, showing that while TDP-43 is below immunohistochemical detection in nuclei of cerebellar Purkinje cells, it has a predominant localization in the cytoplasm of these cells. From a functional point of view, the TDP-43 mislocalization, that occurs in a human experimental neuronal model system, is associated with specific alterations in TDP-43 controlled genes. Most interestingly, treatment with N-Acetyl-cysteine (NAC) or beta-cyclodextrin (CD) can partially restore TDP-43 nuclear localization. Taken together, the results of these studies extend the role of TDP-43 beyond the Amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD)/Alzheimer disease (AD) spectrum. These findings may open novel research/therapeutic avenues for a better understanding of both NPC disease and the TDP-43 proteinopathy disease mechanism.

PMID: 27193329 [PubMed - in process]

Novel European SLC1A4 variant: infantile spasms and population ancestry analysis.

J Hum Genet. 2016 May 19;

Authors: Conroy J, M Allen N, Gorman K, O'Halloran E, Shahwan A, Lynch B, Lynch SA, Ennis S, King MD

Abstract
SLC1A4 deficiency is a recently described neurodevelopmental disorder associated with microcephaly, global developmental delay, abnormal myelination, thin corpus callosum and seizures. It has been mainly reported in the Ashkenazi-Jewish population with affected individuals homozygous for the p.Glu256Lys variant. Exome sequencing performed in an Irish proband identified a novel homozygous nonsense SLC1A4 variant [p.Trp453*], confirming a second case of SLC1A4-associated infantile spasms. As this is the first European identified, population ancestry analysis of the Exome Aggregation Consortium database was performed to determine the wider ethnic background of SLC1A4 deficiency carriers. p.Glu256Lys was found in Hispanic and South Asian populations. Other potential disease-causing variants were also identified. Investigation for SLC1A4 deficiency should be performed regardless of ethnicity and extend to include unexplained early-onset epileptic encephalopathy.Journal of Human Genetics advance online publication, 19 May 2016; doi:10.1038/jhg.2016.44.

PMID: 27193218 [PubMed - as supplied by publisher]

A partial trace amine-associated receptor 1 agonist exhibits properties consistent with a methamphetamine substitution treatment.

Addict Biol. 2016 May 19;

Authors: Pei Y, Asif-Malik A, Hoener M, Canales JJ

Abstract
Recent evidence suggests that the trace amine-associated receptor 1 (TAAR1) plays a pivotal role in the regulation of dopamine (DA) transmission and psychostimulant action. Several selective TAAR1 agonists have previously shown efficacy in models of cocaine addiction. However, the effects of TAAR1 activation on methamphetamine (METH)-induced behaviours are less well understood, as indeed are the underlying neurochemical mechanisms mediating potential interactions between TAAR1 and METH. Here, in a progressive ratio schedule of reinforcement the partial TAAR1 agonist, RO5263397, reduced the break-point for METH self-administration, while significantly increasing responding maintained by food reward. Following self-administration and extinction training, RO5263397 completely blocked METH-primed reinstatement of METH seeking. Moreover, when used as a substitute, unlike a low dose of METH, which sustained vigorous responding when substituting for the training dose of METH, RO5263397 was not self-administered at any dose, thus exhibiting no apparent abuse liability. Fast-scan cyclic voltammetry experiments showed that RO5263397 prevented METH-induced DA overflow in slices of the nucleus accumbens, while having no effect on DA transmission in its own right. Collectively, the present observations demonstrate that partial TAAR1 activation decreases the motivation to self-administer METH, blocks METH-primed reinstatement of METH seeking and prevents METH-induced DA elevations in the nucleus accumbens, and strongly support the candidacy of TAAR1-based medications as potential substitute treatment in METH addiction.

PMID: 27193165 [PubMed - as supplied by publisher]