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- Oxytocin treatment for amphetamine-induced social impairments. [Journal Article]
- J Neurosci 2014 Oct 29; 34(44):14503-5.
- CART in the regulation of appetite and energy homeostasis. [Journal Article, Review]
- Front Neurosci 2014.:313.
The cocaine- and amphetamine-regulated transcript (CART) has been the subject of significant interest for over a decade. Work to decipher the detailed mechanism of CART function has been hampered by the lack of specific pharmacological tools like antagonists and the absence of a specific CART receptor(s). However, extensive research has been devoted to elucidate the role of the CART peptide and it is now evident that CART is a key neurotransmitter and hormone involved in the regulation of diverse biological processes, including food intake, maintenance of body weight, reward and addiction, stress response, psychostimulant effects and endocrine functions (Rogge et al., 2008; Subhedar et al., 2014). In this review, we focus on knowledge gained on CART's role in controlling appetite and energy homeostasis, and also address certain species differences between rodents and humans.
- T-Lymphocyte Deficiency Exacerbates Behavioral Deficits in the 6-OHDA Unilateral Lesion Rat Model for Parkinson's Disease. [JOURNAL ARTICLE]
- J Neurol Neurophysiol 2014 May; 5(3)
T-lymphocytes have been previously implicated in protecting dopaminergic neurons in the substantianigra from induced cell death. However, the role of T-cells in neurodegenerative models such as Parkinson's disease (PD) has not been fully elucidated. To examine the role of T-lymphocytes on motor behavior in the 6-hydroxydopamine (6-OHDA) unilateral striatal partial lesion PD rat model, we assessed progression of hemi-parkinsonian lesions in the substantia nigra, induced by 6-OHDA striatal injections, in athymic rats (RNU-/-, T-lymphocyte-deficient) as compared to RNU-/+ rats (phenotypically normal). Motor skills were determined by the cylinder and D-amphetamine sulfate-induced rotational behavioral tests. Cylinder behavioral test showed no significant difference between unilaterally lesioned RNU-/- and RNU-/+ rats. However both unilaterally lesioned RNU-/- and RNU-/+ rats favored the use of the limb ipsilateral to lesion. Additionally, amphetamine-induced rotational test revealed greater rotational asymmetry in RNU-/- rats compared to RNU-/+ rats at two- and six-week post-lesion. Quantitative immunohistochemistry confirmed loss of striatal TH-immunopositive fibers in RNU-/- and RNU-/+ rat, as well as blood-brain-barrier changes associated with PD that may influence passage of immune cells into the central nervous system in RNU-/- brains. Specifically, GFAP immunopositive cells were decreased, as were astrocytic end-feet (AQP4) contacting blood vessels (laminin) in the lesioned relative to contralateral striatum. Flow cytometric analysis in 6-OHDA lesioned RNU-/+rats revealed increased CD4+ and decreased CD8+ T cells specifically within lesioned brain. These results suggest that both major T cell subpopulations are significantly and reciprocally altered following 6-OHDA-lesioning, and that global T cell deficiency exacerbates motor behavioral defects in this rat model of PD.
- Patterns of presentation and clinical features of toxicity after reported use of ([2-aminopropyl]-2,3-dihydrobenzofurans), the 'benzofuran' compounds. A report from the United Kingdom National Poisons Information Service. [JOURNAL ARTICLE]
- Clin Toxicol (Phila) 2014 Oct 27.:1-7.
Objective. To characterise the patterns of presentation and clinical features of toxicity following reported recreational use of benzofuran compounds ((2-aminopropyl)-2,3-dihydrobenzofurans) in the UK, as reported to the National Poisons Information Service (NPIS), and to compare clinical features of toxicity with those after reported mephedrone use. Methods. NPIS patient-specific telephone enquiries and user sessions for TOXBASE(®), the NPIS online information database, related to (2-aminopropyl)-2,3-dihydrobenzofurans and associated synonyms were reviewed from March 2009 to August 2013. These data were compared with those of mephedrone, the recreational substance most frequently reported to NPIS, collected over the same period. Results. There were 63 telephone enquiries concerning 66 patients and 806 TOXBASE(®) user sessions regarding benzofuran compounds during the period of study. The first telephone enquiry was made in July 2010 and the highest numbers of enquiries were received in August 2010 (33 calls, 112 TOXBASE(®) sessions). Patients were predominantly male (82%) with a median age of 29 years; 9 reported co-ingestion of other substances. Comparing the 57 patients who reported ingesting benzofuran compounds alone with 315 patients ingesting mephedrone alone, benzofurans were more often associated with stimulant features, including tachycardia, hypertension, mydriasis, palpitation, fever, increased sweating, and tremor, (72% vs. 38%, odds ratio [OR] 4.2, 95% confidence interval [CI] 2.27-7.85, P < 0.0001) and mental health disturbances (58% vs. 38%, OR 2.3, 95% CI 1.29-4.07, P = 0.006). Other features reported after benzofuran compound ingestion included gastrointestinal symptoms (16%), reduced level of consciousness (9%), chest pain (7%), and creatinine kinase elevation (5%). Conclusions. Reported ingestion of benzofuran compounds is associated with similar toxic effects to those of amphetamines and cathinones. Mental health disturbances and stimulant features were reported more frequently following reported ingestion of benzofuran compounds than after ingestion of mephedrone.
- A One-Generation Reproductive Toxicity Study of 3,4-Methylenedioxy-N-Methamphetamine (MDMA, Ecstasy), an Amphetamine Derivative, in C57BL/6 Mice. [Journal Article]
- J Toxicol Environ Health A 2014; 77(22-24):1431-42.
3,4-Methylenedioxy-N-methamphetamine (MDMA, ecstasy) is an amphetamine derivative and is a popular type of drug that is abused due to its effects on the central nervous system (CNS), including alertness and euphoria. However, life-threatening (brain edema, heart failure, and coma) and fatal hyperthermia sometimes occur in some individuals taking MDMA. In a one-generation reproductive toxicity study, the potential toxicity of chronic exposure of MDMA was investigated on the reproductive capabilities of parental mice (F0), as well as the survival/development of their subsequent offspring (F1). Male and female C57BL/6 mice were administered orally MDMA at 0, 1.25, 5 or 20 mg/kg body weight (b.w.) throughout the study, beginning at the premating period, through mating, gestation, and lactation periods. MDMA did not produce any apparent clinical signs in F0 or F1 mice, and produced no significant changes in body weight, feed/water intake, or organ weights. In contrast, administration of MDMA produced external abnormalities in fetuses, stillbirth and labored delivery, and diminished viability and weaning indices in offspring, but these data were not significant. In addition, physical development of F1 mice was not markedly influenced by MDMA treatment. Nonetheless, serum biochemistry markers showed that levels of alkaline phosphatase (ALP), aspartate aminotransferase (AST), and blood urea nitrogen (BUN) were markedly elevated in a dose-dependent manner from 5 mg and higher MDMA/kg b.w., whereas levels of triglycerides (TG), potassium (K), and uric acid (UA) were reduced. Data suggest that MDMA may exert a weak reproductive and developmental toxicity, and the no-observed-adverse-effect level (NOAEL) of MDMA is estimated to be 1.25 mg/kg b.w./d.
- Delta-Like 1 Homologue (DLK1) Protein in Neurons of the Arcuate Nucleus that Control Weight Homeostasis and Role of Fasting on Hypothalamic DLK1 mRNA. [JOURNAL ARTICLE]
- Neuroendocrinology 2014 Oct 20.
Delta-like 1 homologue (DLK1; also called preadipocyte factor 1; Pref1) is an epidermal growth factor (EGF) repeat-containing transmembrane protein that is cleaved by tumour necrosis factor-α-converting enzyme to generate a biologically active soluble form. DLK1 is involved in the differentiation of several cell types, including adipocytes. Lack of the dlk1 gene results in adiposity and polymorphism within the gene encoding DLK1 is associated with human obesity. The dlk1 gene is expressed in restricted areas of the adult brain, with an enrichment of cell bodies expressing DLK1 mRNA in the hypothalamus. Antibodies to DLK1 were used to study the cellular localization and chemical identity of DLK1-immunoreactive neuronal cell bodies in rat hypothalamus. DLK1 immunoreactivity was demonstrated in the cell soma and dendrites of cell bodies in the suprachiasmatic, supraoptic, paraventricular, dorsomedial, arcuate nuclei and in the perifornical/lateral hypothalamic area. In the arcuate nucleus (Arc), DLK1 immunoreactivity was mainly seen in many neurons of the ventromedial and to lesser extent in its ventrolateral division. Double-labeling showed that 93.7% of orexigenic agouti-related peptide (AgRP) and 94.1% of neuropeptide Y (NPY) neurons located in the ventromedial part of the Arc were DLK1-positive, whereas 36.1% of anorexigenic pro-opiomelanocortin (POMC) and 34.6% of cocaine- and amphetamine-regulated transcript (CART) neurons of the Arc contained DLK1 immunoreactivity. DLK1 mRNA was down-regulated in the hypothalamus of fasted animals. Presence of DLK1 in the majority of orexigenic Arc NPY/AgRP neurons and regulation of DLK1 mRNA by nutritional challenge, suggests that DLK1 has a role in hypothalamic regulation of body weight control. © 2014 S. Karger AG, Basel.
- Amphetamine in Adolescence Disrupts the Development of Medial Prefrontal Cortex Dopamine Connectivity in a dcc-Dependent Manner. [JOURNAL ARTICLE]
- Neuropsychopharmacology 2014 Oct 22.
Initiation of drug use during adolescence is a strong predictor of both the incidence and severity of addiction throughout the lifetime. Intriguingly, adolescence is a period of dynamic refinement in the organization of neuronal connectivity, in particular medial prefrontal cortex (mPFC) dopamine circuitry. The guidance cue receptor, DCC (deleted in colorectal cancer), is highly expressed by dopamine neurons and orchestrates their innervation to the mPFC during adolescence. Furthermore, we have shown that amphetamine in adolescence regulates DCC expression in dopamine neurons. Drugs in adolescence may therefore induce their enduring behavioral effects via DCC-mediated disruption in mPFC dopamine development. In this study we investigated the impact of repeated exposure to amphetamine during adolescence on both the development of mPFC dopamine connectivity and on salience attribution to drug context in adulthood. We compare these effects to those induced by adult exposure to an identical amphetamine regimen. Finally, we determine whether DCC signaling within dopamine neurons is necessary for these events. Exposure to amphetamine in adolescence, but not in adulthood, leads to an increase in the span of dopamine innervation to the mPFC, but a reduction of presynaptic sites present on these axons. Amphetamine treatment in adolescence, but not in adulthood, also produces an increase in salience attribution to a previously drug-paired context in adulthood. Remarkably, DCC signaling within dopamine neurons is required for both of these effects. Drugs of abuse in adolescence may therefore induce their detrimental behavioral consequences by disrupting mesocortical dopamine development through alterations in the DCC signaling cascade.Neuropsychopharmacology accepted article preview online, 22 October 2014. doi:10.1038/npp.2014.287.
- The rare DAT coding variant Val559 perturbs DA neuron function, changes behavior, and alters in vivo responses to psychostimulants. [JOURNAL ARTICLE]
- Proc Natl Acad Sci U S A 2014 Oct 20.
Despite the critical role of the presynaptic dopamine (DA) transporter (DAT, SLC6A3) in DA clearance and psychostimulant responses, evidence that DAT dysfunction supports risk for mental illness is indirect. Recently, we identified a rare, nonsynonymous Slc6a3 variant that produces the DAT substitution Ala559Val in two male siblings who share a diagnosis of attention-deficit hyperactivity disorder (ADHD), with other studies identifying the variant in subjects with bipolar disorder (BPD) and autism spectrum disorder (ASD). Previously, using transfected cell studies, we observed that although DAT Val559 displays normal total and surface DAT protein levels, and normal DA recognition and uptake, the variant transporter exhibits anomalous DA efflux (ADE) and lacks capacity for amphetamine (AMPH)-stimulated DA release. To pursue the significance of these findings in vivo, we engineered DAT Val559 knock-in mice, and here we demonstrate in this model the presence of elevated extracellular DA levels, altered somatodendritic and presynaptic D2 DA receptor (D2R) function, a blunted ability of DA terminals to support depolarization and AMPH-evoked DA release, and disruptions in basal and psychostimulant-evoked locomotor behavior. Together, our studies demonstrate an in vivo functional impact of the DAT Val559 variant, providing support for the ability of DAT dysfunction to impact risk for mental illness.
- D4 Dopamine Receptor-Specific Antagonist Improves Reversal Learning Impairment in Amphetamine-Treated Male Rats. [JOURNAL ARTICLE]
- Exp Clin Psychopharmacol 2014 Oct 20.
The Attentional Set-Shifting Task (ASST) is a rodent analog of the Wisconsin Card Sorting Task, which measures executive functioning. The ASST tests for reversal of stimulus-response learning and the formation and maintenance of attentional sets. Depletion of dopamine has been shown to improve performance on attentional shifts. The study presented here questioned whether a D4-specific antagonist, L-745,870, could have a similar effect on animals, even after being treated with repeated doses of amphetamine. Three groups of male rats were given either 10 saline injections (n = 12), 10 amphetamine injections (2 mg/kg; n = 8), or 10 amphetamine injections plus 1 pretreatment injection of L-745,870 (0.1 mg/kg; n = 8) 20 min prior to testing. One-way ANOVA results showed that amphetamine-only rats were impaired on all 3 reversals (Ms = 19, 16.4, and 17.1) compared with L-745,870-treated rats (Ms = 9.8, 10.9, and 9.6) and controls (Ms = 8.6, 9.6, 9.3; all ps < .01). L-745,870-treated rats also displayed reduced latencies to respond compared with both saline controls and amphetamine rats. It is thought that D4 receptors play a role in cue salience, and that by blocking these receptors, animals display less attachment to previously rewarded cues. The results presented support this idea and imply that blocking of D4 receptors can reverse the impairment in reversals caused by amphetamine. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
- Treatment Receipt and Outcomes from a Clinic Employing the Attention-Deficit/Hyperactivity Disorder Treatment Guideline of the Children's Medication Algorithm Project. [JOURNAL ARTICLE]
- J Child Adolesc Psychopharmacol 2014 Oct 20.
Abstract Objective: Little is known about the pattern of service receipt and outcomes from clinics implementing best practice guidelines in child mental health. This study aimed to determine these variables for a clinic that implemented an attention-deficit/hyperactivity disorder (ADHD) treatment guideline proposed by the Children's Medication Algorithm Project (CMAP). Methods: Secondary analyses of medical record extracts were conducted for children who received treatment from 2007 to 2012 in a specialty clinic linked to a public children's hospital in Canada. Patterns of medication selection and dosing were compared with CMAP guidelines. Outcomes were based on parent and teacher ratings on the ADHD portion of the Multimodal Treatment Study for ADHD (MTA)- Swanson, Nolan, and Pelham, Version IV (SNAP-IV). Results: Data were available for 132 children (ages 5-14), 81.8% of whom had no previous ADHD medication exposure, and 97.0% of whom had started at least one medication. Methylphenidate was used first for 59.8% of children, whereas 33.3% started with an amphetamine product. Of the 47.0% of children who progressed to a second medication trial, 88.7% tried a stimulant from a second class. In total, 19.7% tried atomoxetine, which was typically used as a third stage choice (i.e., after two different stimulant exposures). Stage four to six medications were rarely used, rather stimulants were retried after atomoxetine and/or medication combinations were tried. Symptomatic remission at the end of treatment was achieved by 70.4% and 82.4%, according to parents and teachers respectively, for those with outcome data and who completed treatment. Outcomes for those further along the treatment algorithm were similar to discharges at the beginning of the algorithm. Conclusions: The high rates of symptomatic remission observed within this clinical service may be a function of adherence to CMAP recommendations. However, the lack of a comparison group or experimental design prevents determination of causality. Additional investigations of the impacts of implementing evidence-based guidelines are critically needed, with proposed benchmarks to inform outcome evaluations.