Methamphetamine Causes Differential Alterations in Gene Expression and Patterns of Histone Acetylation/Hypoacetylation in the Rat Nucleus Accumbens

Methamphetamine (METH) addiction is associated with several neuropsychiatric symptoms. Little is known about the effects of METH on gene expression and epigenetic modifications in the rat nucleus accumbens (NAC). Our study investigated the effects of a non-toxic METH injection (20 mg/kg) on gene expression, histone acetylation, and the expression of the histone acetyltransferase (HAT), ATF2, and of the histone deacetylases (HDACs), HDAC1 and HDAC2, in that structure. Microarray analyses done at 1, 8, 16 and 24 hrs after the METH injection identified METH-induced changes in the expression of genes previously implicated in the acute and longterm effects of psychostimulants, including immediate early genes and corticotropin-releasing factor (Crf). In contrast, the METH injection caused time-dependent decreases in the expression of other genes including Npas4 and cholecystokinin (Cck). Pathway analyses showed that genes with altered expression participated in behavioral performance, cell-to-cell signaling, and regulation of gene expression. PCR analyses confirmed the changes in the expression of c-fos, fosB, Crf, Cck, and Npas4 transcripts. To determine if the METH injection caused post-translational changes in histone markers, we used western blot analyses and identified METH-mediated decreases in histone H3 acetylated at lysine 9 (H3K9ac) and lysine 18 (H3K18ac) in nuclear sub-fractions. In contrast, the METH injection caused time-dependent increases in acetylated H4K5 and H4K8. The changes in histone acetylation were accompanied by decreased expression of HDAC1 but increased expression of HDAC2 protein levels. The histone acetyltransferase, ATF2, showed significant METH-induced increased in protein expression. These results suggest that METH-induced alterations in global gene expression seen in rat NAC might be related, in part, to METH-induced changes in histone acetylation secondary to changes in HAT and HDAC expression. The causal role that HATs and HDACs might play in METH-induced gene expression needs to be investigated further

Transcription, Epigenetics and Ameliorative Strategies in Huntington’s Disease: a Genome-Wide Perspective

ease (HD) is an early event that shapes the brain transcriptome by both the depletion and ectopic activation of gene products that eventually affect survival and neuronal functions. Disrup-tion in the activity of gene expression regulators, such as transcription factors, chromatin-remodeling proteins, and non-coding RNAs, accounts for the expression changes observed in multiple animal and cellular models of HD and in samples from patients. Here, I review the recent advances in the study of HD transcriptional dysregulation and its causes to finally discuss the possible implications in ameliorative strategies from a genome-wide perspective. To date, the use of genome-wide approaches, predominantly based on microar-ray platforms, has been successful in providing an extensive catalog of differentially regulated genes, including biomarkers aimed at monitoring the progress of the pathology. Although still incipient, the introduction of combined next-generation sequencing techniques is enhancing our comprehension of the mechanisms underlying altered transcriptional dysregulation in HD by providing the first genomic landscapes associated with epigenetics and the occupancy of transcription factors. In addition, the use of genome-wide approaches is becoming more and more necessary to evaluate the efficacy and safety of ameliorative strategies and to identify novel mechanisms of amelioration that may help in the improvement of current preclinical therapeutics. Finally, the major conclusions obtain-ed from HD transcriptomics studies have the potential to be extrapolated to other neurodegenerative disorders

The effects of chronic neuroleptic treatment on neurotensin-like immunoreactivity in the rat central nervous system.

The dopamine receptor antagonist fluphenazine decanoate, when administered for a total period of 10 months, produced a large increase in neurotensin-like immunoreactivity in dopamine-rich brain areas, such as the nucleus accumbens, the striatum and the frontal cortex. A smaller, non-significant increase was observed in the substantia nigra with no change in either the hypothalamus or the spinal cord. The present results provide further evidence in favour of a functional interaction between neurotensin and dopamine in the central nervous system

Studies on the localization and expression of nitric oxide synthase using histochemical techniques

This review provides an update on the variety of histochemical techniques available for the cellular localization and expression of nitric oxide synthase in formalin-fixed tissue sections. The techniques of immunohistochemistry and NADPH-diaphorase histochemistry are discussed and the suitability of various types of probes and reporters which are useful for in situ detection of nitric oxide synthase mRNA expression are assessed. Figures are also included which illustrate the techniques described and protocols for in situ hybridization and NADPH-diaphorase histochemistry

Calcium homeostasis in ageing: studies on the calcium binding protein calbindin D-28K

Calbindin D-28K is a neuronal calcium binding protein which may act as a buffer of neuronal calcium. Evidence suggests that disturbance of calcium homeostasis is important in neurodegeneration, possibly via changes in calbindin D-28K. Immunoreactivity of calbindin D-28K is compared in Alzheimer's disease and age-matched controls. The size and number of calbindin D-28K positive neurons in Alzheimer's disease tissue is reduced. There is also shrinkage of the dendritic tree. Continuing work examines the function of calbindin D-28K using transgenic mice

Evolution of a homopurine-homopyrimidine pentanucleotide repeat sequence upstream of the human inducible nitric oxide synthase gene.

We have identified a highly polymorphic pentanucleotide repeat (CCTTT)n within the 5'-putative promoter region of the human inducible nitric oxide synthase gene (iNOS, NOS2). Using a pair of specific primers derived from the human iNOS gene, we have also amplified this iNOS repeat in DNA from the following species: chimpanzee, gorilla, orangutan and macaque. As is found in man, both chimpanzees and gorillas are polymorphic at this locus. In contrast, the locus is monomorphic in macaques and orangutans. While the average number of repeats is similar in gorilla and man, there are considerably fewer repeats in chimpanzees. A comparison of the sequences flanking the (CCTTT)n repeats among these closely related species demonstrates the presence of long stretches of homopurine-homopyrimidine residues. Similar polypurine/polypyrimidine stretches have been identified in the promoter regions of a number of other vertebrate genes where they have been associated with transcriptional regulation, although a role for the (CCTTT)n repeat array in the human iNOS gene has not yet been demonstrated

Cellular calcium handling in brain slices from calbindin D(28K)- deficient mice

CELLULAR calcium handling was examined in brain slices from transgenic antisense mice with a regional deficiency in the neuronal calcium binding protein calbindin D-28k and from their non transgenic wild type litter mate controls. Depolarization of brain slices with NMDA or potassium produced a prolonged elevation of neuronal calcium signal in neurons in brain slices from calbindin D-28k-deficient transgenic mice. This effect was selective and was seen only in brain areas where the antisense construct produced a significant depletion of calbindin D-28k protein. In other regions where calbindin D28k protein was not modified by the construct and in all glial cells whether from wild type or transgenic mice, cellular calcium handling was normal. NeuroReport 10:2367-2372CELLULAR calcium handling was examined in brain slices from transgenic antisense mice with a regional deficiency in the neuronal calcium binding protein calbindin D(28k) and from their non transgenic wild type litter mate controls. Depolarization of brain slices with NMDA or potassium produced a prolonged elevation of neuronal calcium signal in neurons in brain slices from calbindin D(28k)-deficient transgenic mice. This effect was selective and was seen only in brain areas where the antisense construct produced a significant depletion of calbindin D(28k) protein. In other regions where calbindin D(28k) protein was not modified by the construct and in all glial cells whether from wild type or transgenic mice, cellular calcium handling was normal