ABSTRACT
Objective To study improvement of cognitive function impairment of vascular dementia rats induced by a permanent bilateral ligation of common carotid arteries (2VO) after administration of leptin in brain. Methods Hippocampal neurons was isolated and cultured from SD rats. At oxygen-glucose deprivation condition, protection role of leptin on hippocampal neurons was observed and expression of leptin receptor was detected. Animal model of rats was established by 2VO. Pre-treatment VaD model of leptin was established by administration leptin into hippocampus region. The Morris water test was performed to detect difference in the cognitive function between VaD group and control group. Neuron apoptosis in hippocampus tissue were determined with TUNEL. Results Leptin receptor expression could be seen in hippocampal neurons. After oxygen-glucose deprivation cultured for 12 h , plenty of apoptotic cells were seen in hippocampal neurons, apoptosis rat was up to (72.96 ± 6.25) % , while apoptosis rate was (46.33 ±7.85)% and (23.58 ±5.08)% in 1 ( μg and 5μg leptin treatment group,respectively. Compared leptin treatment group with control group,difference had a statistical significance(P<0.01). Compared with untreated VaD group, latency time was shorter and average velocity was increased in leptin-treat-ment VaD group. Neuron apoptosis in hippocampus tissue of leptin-treated group were different significantly from those of untreated group (P < 0.01). Conclusion Leptin could protect hippocampal neurons from apoptosis in vitro. Cognitive function impairment could be improved by administration of leptin into brain in VaD rats.
ABSTRACT
<p><b>OBJECTIVE</b>To study the human dystrophin gene molecular deletion mechanism, we analyzed breakpoint regions within junction fragments of deletion-type patients and investigated whether the dystrophin gene's intron structure might be related to intron instability.</p><p><b>METHODS</b>Junction fragments corresponding to exon 46 and 51 deletions were cloned. The breakpoint regions were sequenced, and the features of introns with available Genebank sequences were analyzed.</p><p><b>RESULTS</b>An analysis of junction fragment sequences corresponding to exon 46 and 51 deletions showed that all 5' and 3' breakpoints are located within repeat sequences. No small insertions, small deletions, or point mutations are located near the breakpoint junctions. By analyzing the secondary structure of the junction fragments, we demonstrated that all junction fragment breakpoints are located in non-matching regions of single-stranded hairpin loops. A high concentration of repetitive elements is found to be a key feature of many dystrophin introns. In total, 34.8% of the overall dystrophin intron sequences is composed of repeat sequences.</p><p><b>CONCLUSION</b>Repeat elements in many dystrophin gene introns are the key to their structural bases and reflect intron instability. As a result of the primary DNA sequences, single-stranded hairpin loops form, increasing the instability of the gene, and forming the base for breaks in the DNA. The formation of the single-stranded hairpins can result in reattachment of two different breakpoints, producing a deletion.</p>