Microanatomical localization of dopamine receptor protein immunoreactivity in the rat cerebellar cortex
ABSTRACT Dopamine (DA) receptor subtype localization was investigated in rat cerebellar cortex using immunohistochemical techniques with antibodies raised against D1–D5 receptor protein. A faint D1 receptor protein immunoreactivity was developed in molecular and Purkinje neurons layers. D2 receptor protein immunoreactivity was found primarily in cerebellar white matter followed by molecular and granular layers and Purkinje neurons. Antibodies against D2S receptor protein were localized in molecular layer and to a lesser extent, in granular layer. A few Purkinje neurons displayed a faint D2S receptor protein immunoreactivity. D3 receptor protein immunoreactivity was observed primarily in molecular and in Purkinje neurons layers of lobules 9 and 10. A faint D3 receptor protein immunoreactivity was also localized in Purkinje neurons and to a lesser extent, in molecular and granular layers of cerebellar lobules 1–8. D4 receptor protein immunoreactivity was found in cerebellar white matter. A pale immunostaining was also visualized in molecular layer. D5 receptor protein immunoreactivity was localized primarily in molecular and Purkinje neurons layers and to a lesser extent, in granular layer and in white matter. The above results indicate that rat cerebellar cortex expresses the DA receptor subtypes so far identified. Purkinje neurons, which are the only efferent neurons of cerebellum, are richest in DA receptor protein immunoreactivity. This suggests that dopaminergic neurotransmission may modulate efferent inputs from cerebellum. The localization of the majority of D2 and D4 and of a faint D5 protein receptor immunoreactivity in cerebellar white matter suggests that these receptors may be presynaptic and transported axonally.
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ABSTRACT: Homeodomain-interacting protein kinase 2 (Hipk2) is an emerging player in cell response to genotoxic agents that contributes to the cell's decision between cell cycle arrest or apoptosis. HIPK2 acts as co-regulator of an increasing number of transcription factors and modulates many different basic cellular processes such as apoptosis, proliferation, DNA damage response, differentiation. Idiopathic pulmonary fibrosis (IPF) is characterized by an anatomical disarrangement of the lung due to fibroblast proliferation, extracellular matrix deposition and lung function impairment. Although the role of inflammation is still debated, attention has been focused on lung cell functions as fibroblast phenotype and activity. Aim of the present study was to analyze the loss of heterozygosity (LOH) at HIPK2 locus 7q32.34 in human lung fibroblasts and the HIPK2 expression in 15 IPF samples and in four primary fibroblast cell cultures isolated from IPF biopsies using semi-quantitative RT-PCR, Western blots and immunohistochemistry. We demonstrated a frequency of LOH in IPF fibroblasts of 46% for the internal D7S6440 microsatellite and 26.6% for the external D7S2468 microsatellite. Furthermore, we demonstrated low HIPK2 protein expression in those fibroblasts from IPF patients that present the HIPK2 LOH. The restoration of HIPK2 expression in IPF derived cells induced a significant reduction of chemoresistance after treatment with cisplatin. The results obtained allow us to hypothesize that HIPK2 dysfunction may play a role in fibroblasts behavior and in IPF pathogenesis. HIPK2 may be considered as a novel potential target for anti-fibrosis therapy. J. Cell. Physiol. 228: 235-241, 2013. © 2012 Wiley Periodicals, Inc.Journal of Cellular Physiology 01/2013; 228(1):235-41. DOI:10.1002/jcp.24129 · 3.87 Impact Factor
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ABSTRACT: Methylphenidate (MP) is widely used to treat attention deficit hyperactivity disorder (ADHD). Variable number of tandem repeats polymorphisms in the dopamine D4 receptor (D(4)) gene have been implicated in vulnerability to ADHD and the response to MP. Here we examined the contribution of dopamine D4 receptors (D4Rs) to baseline brain glucose metabolism and to the regional metabolic responses to MP. We compared brain glucose metabolism (measured with micro-positron emission tomography and [(18)F]2-fluoro-2-deoxy-D-glucose) at baseline and after MP (10 mg/kg, i.p.) administration in mice with genetic deletion of the D(4). Images were analyzed using a novel automated image registration procedure. Baseline D(4)(-/-) mice had lower metabolism in the prefrontal cortex (PFC) and greater metabolism in the cerebellar vermis (CBV) than D(4)(+/+) and D(4)(+/-) mice; when given MP, D(4)(-/-) mice increased metabolism in the PFC and decreased it in the CBV, whereas in D(4)(+/+) and D(4)(+/-) mice, MP decreased metabolism in the PFC and increased it in the CBV. These findings provide evidence that D4Rs modulate not only the PFC, which may reflect the activation by dopamine of D4Rs located in this region, but also the CBV, which may reflect an indirect modulation as D4Rs are minimally expressed in this region. As individuals with ADHD show structural and/or functional abnormalities in these brain regions, the association of ADHD with D4Rs may reflect its modulation of these brain regions. The differential response to MP as a function of genotype could explain differences in brain functional responses to MP between patients with ADHD and healthy controls and between patients with ADHD with different D(4) polymorphisms.European Journal of Neuroscience 08/2010; 32(4):668-76. DOI:10.1111/j.1460-9568.2010.07319.x · 3.67 Impact Factor
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ABSTRACT: Brief strong depolarization of cerebellar Purkinje cells produces a slow inward cation current. This current, called depolarization-induced slow current (DISC), is triggered by Ca influx in the Purkinje cell and is attenuated by a blocker of vesicular fusion. Previous work in other brain regions, such as the substantia nigra and ventral tegmental area, has shown that dopamine can be released from dendrites to produce paracrine and autocrine signaling. Here, we test the hypothesis that postsynaptic release of dopamine and autocrine activation of dopamine receptors is involved in DISC. Light immunohistochemistry showed that D(3) dopamine receptors, vesicular monoamine transporter type 2 (VMAT2), and dopamine plasma membrane transporters (DATs) were all expressed in cerebellar Purkinje cells. However, their expression was strongest in the gyrus region of cerebellar lobules IX and X. Comparison of DISC across lobules revealed that it was weak in the anterior portions of the cerebellum (lobules II, V, and VI) and strong in lobules IX and X. DISC was blocked by dopamine receptor antagonists (haloperidol, clozapine, eticlopride, and SCH23390). Likewise, DISC was strongly attenuated by inhibitors of VMAT (reserpine and tetrabenazine) and DAT (GBR12909 and rimcazole). These drugs did not produce DISC attenuation through blockade of depolarization-evoked Purkinje cell Ca transients. Purkinje cells in cerebellar slices derived from DAT-null mice expressed DISC, but this DISC ran down at a significantly higher rate than littermate controls. Together, these results suggest that strong Purkinje cell depolarization produces Ca-dependent release of vesicular postsynaptic dopamine that then excites Purkinje cells in an autocrine manner.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 08/2009; 29(26):8530-8. DOI:10.1523/JNEUROSCI.0468-09.2009 · 6.75 Impact Factor