BACKGROUND AND PURPOSEThe designer drug 1-(4-methylphenyl)-2-methylaminopropan-1-one (4-methylmethcathinone, mephedrone) is reported to possess psychostimulant, entactogenic and hallucinogenic effects. The purpose of this study was to examine the effects of acute administration of mephedrone on extracellular levels of dopamine (DA) and 5-HT in the nucleus accumbens of awake rats and compare these effects with those induced by 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and amphetamine. EXPERIMENTAL APPROACHMicrodialysis sampling was performed while simultaneously recording locomotor activity in rats and the monoamines were determined by HPLC with electrochemical detection. KEY RESULTSMephedrone (3 mg·kg -1 s.c.) and (+)-amphetamine (1 mg·kg -1 s.c.) caused rapid increases in extracellular DA levels of 496% and 412%, respectively, whereas MDMA (3 mg·kg -1 s.c.) showed only a moderate effect (235%). The corresponding 5-HT levels increased to 941% (mephedrone) and 911% (MDMA), but only to 165% following amphetamine. The calculated t1/2 values for elimination rate of mephedrone, MDMA and amphetamine-induced increases in extracellular DA levels were 25, 303 and 51 min, the corresponding t1/2 values for 5-HT were 26, 48 and 84 min, respectively. Locomotor activity was increased most by amphetamine, whereas both mephedrone and MDMA showed about three times lower and shorter-lasting effects. CONCLUSIONS AND IMPLICATIONSThe neurochemical and functional properties of mephedrone resemble those of MDMA, but it also shows an amphetamine-like effect in that it evokes a rapid release and elimination of DA in the brain reward system, a feature that may contribute to its potent re-inforcing properties.

After Golgi-Cajal mapped neural circuits, the discovery and mapping of the central monoamine neurons opened up for a new understanding of interneuronal communication by indicating that another form of communication exists. For instance, it was found that dopamine may be released as a prolactin inhibitory factor from the median eminence, indicating an alternative mode of dopamine communication in the brain. Subsequently, the analysis of the locus coeruleus noradrenaline neurons demonstrated a novel type of lower brainstem neuron that monosynaptically and globally innervated the entire CNS.Furthermore, the ascending raphe serotonin neuron systems were found to globally innervate the forebrain with few synapses, and where deficits in serotonergic function appeared to play a major role in depression. We propose that serotonin reuptake This will lead to the unified execution of information handling and trophism for optimal brain function and survival.

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At present, there are few means to track symptomatic stages of CNS aging. Thus, although metabolic changes are implicated in mtDNA mutation-driven aging, the manifestations remain unclear. Here, we used normally aging and prematurely aging mtDNA mutator mice to establish a molecular link between mitochondrial dysfunction and abnormal metabolism in the aging process. Using proton magnetic resonance spectroscopy and HPLC, we found that brain lactate levels were increased twofold in both normally and prematurely aging mice during aging. To correlate the striking increase in lactate with tissue pathology, we investigated the respiratory chain enzymes and detected mitochondrial failure in key brain areas from both normally and prematurely aging mice. We used in situ hybridization to show that increased brain lactate levels were caused by a shift in transcriptional activities of the lactate dehydrogenases to promote pyruvate to lactate conversion. Separation of the five tetrameric lactate dehydrogenase (LDH) isoenzymes revealed an increase of those dominated by the Ldh-A product and a decrease of those rich in the Ldh-B product, which, in turn, increases pyruvate to lactate conversion. Spectrophotometric assays measuring LDH activity from the pyruvate and lactate sides of the reaction showed a higher pyruvate → lactate activity in the brain. We argue for the use of lactate proton magnetic resonance spectroscopy as a noninvasive strategy for monitoring this hallmark of the aging process. The mtDNA mutator mouse allows us to conclude that the increased LDH-A/LDH-B ratio causes high brain lactate levels, which, in turn, are predictive of aging phenotypes.mtDNA mutator mouse | proton magnetic resonance spectroscopy | in situ hybridization | COX/SDH enzyme histochemistry | HPLC

Developmental transcription factors important in early neuron specification and differentiation often remain expressed in the adult brain. However, how these transcription factors function to mantain appropriate neuronal identities in adult neurons and how transcription factor dysregulation may contribute to disease remain largely unknown. The transcription factor Nurr1 has been associated with Parkinson's disease and is essential for the development of ventral midbrain dopamine (DA) neurons. We used conditional Nurr1 genetargeted mice in which Nurr1 is ablated selectively in mature DA neurons by treatment with tamoxifen. We show that Nurr1 ablation results in a progressive pathology associated with reduced striatal DA, impaired motor behaviors, and dystrophic axons and dendrites. We used laser-microdissected DA neurons for RNA extraction and next-generation mRNA sequencing to identify Nurr1-regulated genes. This analysis revealed that Nurr1 functions mainly in transcriptional activation to regulate a battery of genes expressed in DA neurons. Importantly, nuclear-encoded mitochondrial genes were identified as the major functional category of Nurr1-regulated target genes. These studies indicate that Nurr1 has a key function in sustaining high respiratory function in these cells, and that Nurr1 ablation in mice recapitulates early features of Parkinson's disease. NR4A2 | nuclear receptor | laser capture microdissection | RNA sequencing | orphan receptor U nder experimental conditions, somatic differentiated cells can undergo reprogramming into other cell types or induced pluripotent stem cells (1). This remarkable plasticity raises questions of how the differentiated cellular identity is maintained for extended periods in normal life (2). Of particular relevance is how neurons, which should retain their specific functions for decades in a human brain, stably maintain their unique differentiated properties, and how disrupted maintenance of the correct differentiated identity may be related to disease. Under embryonic development, signaling events induce the expression of transcription factors that combinatorially function to specify appropriate identities and differentiation of specific neuron types. Many of these transcription factors continue to be expressed in adult neurons as well; however, little is known of their functions in the adult brain, or the extent to which they contribute to the stability of the differentiated state (3).Degeneration of ventral midbrain (VMB) dopamine (DA) neurons, particularly neurons of the substantia nigra compacta (SNc), causes many of the characteristic symptoms in patients with Parkinson's disease (PD). PD is characterized by a progressive pathology involving the appearance of insoluble protein inclusions known as Lewy bodies and eventually the death of neurons. Several studies have indicated that loss of striatal DA and other dopaminergic properties cause symptoms in PD long before cell bodies within the SNc actually die (4). Thus, PD cell pathology may influence differentiated...

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Distinct midbrain dopamine (mDA) neuron subtypes are found in the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA), but it is mainly SNc neurons that degenerate in Parkinson's disease. Interest in how mDA neurons develop has been stimulated by the potential use of stem cells in therapy or disease modeling. However, very little is known about how specific dopaminergic subtypes are generated. Here, we show that the expression profiles of the transcription factors Sox6, Otx2, and Nolz1 define subpopulations of mDA neurons already at the neural progenitor cell stage. After cell-cycle exit, Sox6 selectively localizes to SNc neurons, while Otx2 and Nolz1 are expressed in a subset of VTA neurons. Importantly, Sox6 ablation leads to decreased expression of SNc markers and a corresponding increase in VTA markers, while Otx2 ablation has the opposite effect. Moreover, deletion of Sox6 affects striatal innervation and dopamine levels. We also find reduced Sox6 levels in Parkinson's disease patients. These findings identify Sox6 as a determinant of SNc neuron development and should facilitate the engineering of relevant mDA neurons for cell therapy and disease modeling.

Superparamagnetic iron oxide nanoparticles (SPION) with suitable bio-compatible coatings have been used in biomedicine, particularly in magnetic resonance imaging (MRI), tissue engineering, and drug delivery applications. In this study, we describe the synthesis of SPION and its use for experimental in-vivo applications in MRI. SPION with a mean size of 6 nm have been prepared under inert atmosphere, in a polymeric starch matrix, by controlled chemical coprecipitation of magnetite phase from aqueous solutions containing suitable salts of Fe 2+ and Fe 3+ . X-ray powder diffraction was used to confirm a pure magnetite phase for the SPION. The influence of oxidizing agents on the cleavage of the starch chains was investigated by changing the concentration of H 2 O 2 . An aqueous solution of H 2 O 2 /NaOH cleaves the glycosidic bonds and reduces the polymer chains to a critical average molecular weight. From the dynamic light scattering (DLS) size distribution, the bulk agglomeration size was decreased by approximately 50% of the bulk size when treated by H 2 O 2 . Freshly synthesized starch-coated SPION in buffered artificial cerebro-spinal fluid were injected into the brain parenchyma of anaesthetized rats for in-vivo monitoring. Analysis of T 2 *-weighted images and T 2 *-maps revealed formation of a concentration gradient for the SPION at the injection site, indicating SPION dispersion in the living brain parenchyma from the center of the injection site toward the periphery. The starch-coated SPION show a biocompatibility and possibility of being transported in the extracellular space as well as being internalized in nerve cells.