Environmental Enrichment Improves the Recognition Memory in Adult Mice Following Social Isolation via Downregulation of Kv4.2 Potassium Channels.

Recognition memory is a cognitive process that enables us to distinguish familiar objects and situations from new items, which is essential for mammalian survival and adaptation to a changing environment. Social isolation (SI) has been implicated as a detrimental factor for recognition memory. The medial prefrontal cortex (mPFC) has been shown to carry information concerning the relative familiarity of individual stimuli, and modulating neuronal function in this region may contribute to recognition memory. The present study aimed to investigate the neuronal mechanisms in the mPFC of environmental enrichment (EE) on recognition memory in adult mice following SI. Mice were assigned into three groups: control, SI, and SI + EE groups. Novel location recognition (NLR) and novel object recognition (NOR) tests were performed to evaluate the recognition memory. The levels of Kv4 channels were assessed by qRT-PCR and western blotting. The effects of SI and SI + EE on the excitability of pyramidal neurons in the mPFC were measured using whole-cell recording. We found that SI led to a reduction in the excitability of pyramidal neurons. Specifically, we have identified that the reduction in the firing activity of pyramidal neurons resulted from alterations in the function and expression of Kv4.2 channels. Furthermore, EE regulated Kv4.2 channels, normalized the activity of pyramidal neurons, and restored the behavioral deficits following SI. Thus, the roles of Kv4.2 channels in excitability of pyramidal neurons suggest that the Kv4.2 channels present a promising therapeutic target for recognition memory impairment.

Grass carp (Ctenopharyngodon idellus) invariant chain of the MHC class II chaperone protein associates with the class I molecule.

The invariant chain (Ii) is an important immune molecule, as it assists major histocompatibility complex (MHC) class II molecules to present antigenic peptides. The relationship between the Ii and MHC molecules in teleosts remains poorly understood. This study focused on the molecular structure of grass carp Ii (gIi), its organ distribution, correlations with gene transcription, and the association with MHC. gIi cDNA was cloned using designed degenerate primers and the rapid amplification of cDNA ends method (RACE). The gIi sequence was 92%-96% similar to that of other teleosts, but only 52%-67% similar to that of mammals, respectively. The gIi gene was distributed in all 12 organs examined by PCR. The gIi gene transcription levels were markedly higher in organs enriched with immune cells than in other organs (P < 0.01). Moreover, positive correlations were detected between transcription levels of the gIi and gMhcI or II genes in different organs (r = 8.415-8.523, P = 0.001). The gIi co-localized on endomembrane systems with either class I or II molecules in co-transfected cells observed by a laser confocal. Further testing confirmed that the gIi bound gMHCI and II molecules. Taken together, these results indicate that the gIi is associated with MHC class I and II molecules, suggesting homology of both MHC molecules.

[Cloning of pigeon invariant chain (Ii) gene by RACE].

In order to compare the structure and function of pigeon invariant chain (pIi) gene with other avian's, pIi gene was cloned using a method of RACE (Rapid Amplification of cDNA Ends). Firstly, according to high conservative nucleotide sequence of homologous fragment in avian invariant chain (Ii) gene, a pair of degenerated primer was designed, and a special DNA fragment was gained from pigeon spleen cell RNA by PCR. Then based on the sequence of gained DNA fragment, some new primers were designed, and the 3'terminal and the 5'terminal of pIi gene were cloned by RACE respectively. Finally a complete cDNA of pIi was to extend with newly designed primer by PCR. The product was identified by electrophresis and sequence analysis. The results of sequencing indicate that pIi gene is 1,050 bp in length (GenBank No. AY904337), which includes an open reading frame of 633 bp encoding a precursor protein with 211 amino acid residues. In comparison with the nucleotide sequences of other species' Ii genes, pIi is similar to chicken's, showing an overall identity of 82.8 with chicken and over 52.0 with human and other mammalian animals. In addition, some amino acid residues in Ii molecule manifest extremely conservative among animals, which suggests that they could have an important biological function.

[The clinical evaluation of tinidazole-iodoform-phenocamphor paste as an intra-canal sterilization medication for acute periapical periodontitis].

OBJECTIVE: To compare the clinical effect of tinidazole-iodoform-phenocamphor paste on acute periapical periodontitis with of formocresol. METHODS: 80 permanent teeth of acute periapical periodontitis were selected and divided randomly into tinidazole-iodoform-phenocamphor paste group (T group) and formocresol group (C group). The periapical signs and symptoms were recorded. Radiographs were taken and periapical radiolucent areas were calculated. After root canal preparation,the tinidazole-iodoform-phenocamphor paste was used as an intra-canal dressing medication for 7 days in T group and the formocresol paper point was used in C group. During the course of root canal treatment,the standard paper-point sampling method was used to collect and quantify the periapical exudates and the clinical findings were assessed with clinical periapical index(CPI). All statistical analyses were finished with Sigmastat software. RESULTS: At the first visit, there was no significant difference between two groups of CPI indexes and exudates volumes (P>0.05). The stepwise regression results suggested that exudates volumes had a significant correlation to periapical percussion(P=0.0031). There was a close relationship between radiolucent areas and periapical percussion or swelling degree (P=0.1148, P<0.0001). After the root canal sterilization, there was a statistically significant decrease in exudates volumes and CPI indexes (P<0.01), but the difference of exudates volumes and CPI indexes between two groups was not statistically significant (P>0.05). CONCLUSION: It indicated that tinidazole-iodoform-phenocamphor paste had the same effect on controlling acute periapical periodontitis as that of formocresol.