AP124 Sigma-AldrichGoat Anti-Mouse IgG Antibody

Dopamine is integral to cognition, learning and memory, and dysfunctions of the frontal cortical dopamine system have been implicated in several developmental neuropsychiatric disorders. The dorsolateral prefrontal cortex (DLPFC) is critical for working memory which does not fully mature until the third decade of life. Few studies have reported on the normal development of the dopamine system in human DLPFC during postnatal life. We assessed pre- and postsynaptic components of the dopamine system including tyrosine hydroxylase, the dopamine receptors (D1, D2 short and D2 long isoforms, D4, D5), catechol-O-methyltransferase, and monoamine oxidase (A and B) in the developing human DLPFC (6 weeks -50 years).Gene expression was first analysed by microarray and then by quantitative real-time PCR. Protein expression was analysed by western blot. Protein levels for tyrosine hydroxylase peaked during the first year of life (p less than 0.001) then gradually declined to adulthood. Similarly, mRNA levels of dopamine receptors D2S (p less than 0.001) and D2L (p = 0.003) isoforms, monoamine oxidase A (p less than 0.001) and catechol-O-methyltransferase (p = 0.024) were significantly higher in neonates and infants as was catechol-O-methyltransferase protein (32 kDa, p = 0.027). In contrast, dopamine D1 receptor mRNA correlated positively with age (p = 0.002) and dopamine D1 receptor protein expression increased throughout development (p less than 0.001) with adults having the highest D1 protein levels (p ≤ 0.01). Monoamine oxidase B mRNA and protein (p less than 0.001) levels also increased significantly throughout development. Interestingly, dopamine D5 receptor mRNA levels negatively correlated with age (r = -0.31, p = 0.018) in an expression profile opposite to that of the dopamine D1 receptor.We find distinct developmental changes in key components of the dopamine system in DLPFC over postnatal life. Those genes that are highly expressed during the first year of postnatal life may influence and orchestrate the early development of cortical neural circuitry while genes portraying a pattern of increasing expression with age may indicate a role in DLPFC maturation and attainment of adult levels of cognitive function.

Agmatine, the decarboxylated metabolite of l-arginine, is considered to be a novel putative neurotransmitter. Recent studies have demonstrated that endogenous agmatine may directly participate in the processes of spatial learning and memory. Agmatine-immunoreactivity has been observed within synaptic terminals of asymmetric excitatory synapses in the hippocampal CA1 stratum radiatum (SR), suggesting that agmatine may be colocalized with glutamate. In the present study we demonstrate, using immunofluorescence confocal microscopy, that agmatine is colocalized with glutamate within CA1-CA3 hippocampal pyramidal cell bodies, in young Sprague-Dawley rats. Subcellular investigation, using postembedding electron microscopy-immunogold cytochemistry, has also revealed that agmatine is colocalized with glutamate in most synaptic terminals in the SR region of CA1. Ninety-seven percent of all agmatinergic profiles were found to contain glutamate, and 92% of all glutamatergic profiles contained agmatine (n=6; 300 terminals). Alterations in colocalized agmatine and glutamate levels in the SR synaptic terminals, following 4 days Morris water maze training, were also investigated. Compared with swim only control rats, water maze-trained rats had statistically significant increases in both agmatine (78%; P<0.01) and glutamate (41%; P<0.05) levels within SR terminals synapsing onto CA1 dendrites. These findings provide the first evidence that agmatine and glutamate are colocalized in synaptic terminals in the hippocampal CA1 region, and may co-participate in spatial learning and memory processing.

Superparamagnetic iron oxide (SPIO) nanoparticles are very useful for monitoring cell trafficking in vivo and distinguish whether cellular regeneration originated from an exogenous cell source, which is a key issue for developing successful stem cell therapies. However, the impact of SPIO labeling on stem cell behavior remains uncertain. Here, we show the inhibitory effect of Ferucarbotran, an ionic SPIO, on osteogenic differentiation and its signaling mechanism in human mesenchymal stem cells. Ferucarbotran caused a dose-dependent inhibition of osteogenic differentiation, abolished the differentiation at high concentration, promoted cell migration, and activated the signaling molecules, beta-catenin, a cancer/testis antigen, SSX, and matrix metalloproteinase 2 (MMP2). An iron chelator, desferrioxamine, suppressed all the above Ferucarbotran-induced actions, demonstrating an important role of free iron in the inhibition of osteogenic differentiation that is mediated by the promotion of cell mobilization, involving the activation of a specific signaling pathway. (c) 2010 Elsevier Inc. All rights reserved.