Inhibition of corticosterone synthesis impairs cued water maze consolidation, but it does not affect the expression of BDNF, CK2 and SGK1 genes in dorsal striatum.

Corticosterone (CORT) release during learning experiences is associated with strong memories and activity of the glucocorticoid receptor. It has been shown that lesions of the dorsal striatum (DS) of rats trained in the cued version of the Morris water maze impair memory, and that local injection of CORT improves its performance, suggesting that DS activity is involved in procedural memory which may be modulated by CORT. We trained rats in cued Morris water maze and analyzed the effect of CORT synthesis inhibition on performance, CORT levels, expression of plasticity-involved genes, such as the brain derived neurotrophic factor (BDNF), casein kinase 2 (CK2), and the serum/glucocorticoid regulated kinase 1 (SGK1), as well as the presence of phosphorylated nuclear glucocorticoid receptor in serine 232 (pGR-S232) in the DS. The inhibition of CORT synthesis by metyrapone reduced CORT levels in plasma, prevented its increment in DS and impaired the performance of cued water maze. Additionally, there was an increase of CK2 and SGK1 mRNAs expression in trained subjects, which was unrelated to CORT levels. Finally, we did not observe changes in nuclear pGR-S232 in any condition. Our findings agree with evidence demonstrating that decreasing CORT levels hinders acquisition and consolidation of the spatial version of the Morris water maze; these novel findings broaden our knowledge about the involvement of the DS in the mechanisms underlying procedural memory.

Intense inhibitory avoidance training increases nuclear-phosphorylated glucocorticoid receptors in neurons of CA1 of hippocampus and ventral caudate putamen.

Corticosterone (CORT), the principal glucocorticoid in rodents, is released after stressful experiences such as training with high foot-shock intensities in the inhibitory avoidance task (IA). CORT reaches the glucocorticoid receptor (GR) located in almost all brain cells; the GR is subsequently phosphorylated at serine 232 (pGRser232). This has been reported as an indicator of ligand-dependent activation of the GR, as well as a requirement for its translocation into the nucleus for its transcription factor activity. The GR is present in the hippocampus with a high concentration in CA1 and dentate gyrus (DG), and a smaller proportion in CA3, and sparsely present in the caudate putamen (CPu); both structures are involved in memory consolidation of IA. To study the participation of CORT in IA, we quantified the ratio of pGR-positive neurons in both dorsal hippocampus (CA1, CA3 and DG) and dorsal and ventral regions of CPu of rats trained in IA, using different foot-shock intensities. Brains were dissected 60 min after training for immunodetection of pGRser232 positive cells. The results show that the groups trained with 1.0 and 2.0 mA had higher retention latencies than the 0.0 mA or 0.5 mA groups. An increase in the ratio of pGR-positive neurons was found in CA1 and ventral region of CPu only for the 2.0 mA trained group. These findings suggest that activation of GRs in CA1 and ventral CPu is involved in the consolidation of a stronger memory of IA, possibly through the modulation of gene expression.

Inactivation of HSV-2 by ascorbate-Cu(II) and its protecting evaluation in CF-1 mice against encephalitis.

Ascorbate is an important antioxidant. However, in the presence of transition metals such as Cu(II) or Fe(III), it also has pro-oxidant capabilities. The effect of ascorbate-Cu(II) in the in vitro infection of herpes simplex virus type 2 (HSV-2) and its protecting effect in a murine model was investigated. HSV-2 was treated with different concentrations of ascorbate in the presence of Cu(II). A group of CF-1 mice were treated with the inactivated virus and other treated with maintenance medium containing only ascorbate-Cu(II). Weeks later, mice were challenged intranasally with infectious viruses. HSV-2 was completely inactivated by 2mM ascorbate plus 1mM Cu(II). Ascorbate or Cu(II) alone did not inactivate the virus. Compared with the control group, 60% of the immunized animals did not show any sign of encephalitis and survived the herpes virus infection, while a 7% survival rate was observed in the control group (P = 0.056). We concluded that the in vitro treatment of HSV-2 with ascorbate-Cu(II) is not only able to inactivate the virus, but also suggested that the viral particles induced a protective response against herpes encephalitis. This inactivation may provide an alternative method to develop new agents therapeutics.

Specific mutation screening of TP53 gene by low-density DNA microarray.

TP53 is the most commonly mutated gene in human cancers. Approximately 90% of mutations in this gene are localized between domains encoding exons 5 to 8. The aim of this investigation was to examine the ability of the low density DNA microarray with the assistance of double tandem hybridization platform to characterize TP53 mutational hotspots in exons 5, 7, and 8 of the TP53. Nineteen capture probes specific to each potential mutation site were designed to hybridize to specific site. Virtual hybridization was used to predict the stability of hybridization of each capture probe with the target. Thirty-three DNA samples from different sources were analyzed for mutants in these exons. A total of 32 codon substitutions were found by DNA sequencing. 24 of them a showed a perfect correlation with the hybridization pattern system and DNA sequencing analysis of the regions scanned. Although in this work we directed our attention to some of the most representative mutations of the TP53 gene, the results suggest that this microarray system proved to be a rapid, reliable, and effective method for screening all the mutations in TP53 gene.