Gastrectomy alters emotional reactivity in rats: neurobiological mechanisms

Egr-1 mediates chronic hypoxia-induced renal interstitial fibrosis via the PKC/ERK pathway

BACKGROUND

Chronic hypoxia-induced epithelial-to-mesenchymal transition (EMT) is a crucial process in renal fibrogenesis. Egr-1, as a transcription factor, has been proven to be important in promoting EMT. However, whether it functions in hypoxia-induced renal tubular EMT has not been fully elucidated.

METHODS

Egr-1 were detected at mRNA and protein levels by qPCR and Western blot analysis respectively after renal epithelial cells were subjected to hypoxia treatment. Meanwhile, EMT phenotype was also observed through identification of relevant EMT-specific markers. siRNA was used to knock down Egr-1 expression and subsequent changes were observed. Specific PKC and MAPK/ERK inhibitors were employed to determine the molecular signaling pathway involved in Egr-1-mediated EMT phenotype. In vivo assays using rat remnant kidney model were used to validate the in vitro results. Furthermore, Egr-1 expression was examined in the samples of CKD patients with the clinical relevance revealed.

RESULTS

Hypoxia treatment enhanced the mRNA and protein levels of Egr-1 in HK-2 cells, which was accompanied by a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker Fsp-1. Downregulation of Egr-1 with siRNA reversed hypoxia-induced EMT. Using the specific inhibitors to protein kinase C (calphostin C) or MAPK/ERK (PD98059), we identified that hypoxia induced Egr-1 expression through the PKC/ERK pathway. In addition, the upregulation of Egr-1 raised endogenous Snail levels, and the downregulation of Snail inhibited Egr-1-mediated EMT in HK-2 cells. Through in vivo assays using rat remnant kidney and CKD patients' kidney tissues, we found that Egr-1 and Snail were overexpressed in tubular epithelial cells with EMT.

CONCLUSION

Egr-1 may be an important regulator of the development of renal tubular EMT induced by hypoxia through the PKC/ERK pathway and the activation of Snail. Targeting Egr-1 expression or activity might be a novel therapeutic strategy to control renal fibrosis.

Surgery-induced behavioral changes in aged rats

Elderly patients may experience impairments in cognition or mood following surgery. To study the development and underlying mechanisms of these postoperative behavioral changes, young (3 months) and aged (18-20 months) male rats were subjected to abdominal surgery followed by behavioral testing during a period of 6 weeks. Microglia activation (IBA-1) and neurogenesis (DCX) were immunohistochemically determined. In separate experiments, the effects of anesthesia and the cytokine response (IL-6) following surgery were evaluated. Increased age was associated with changes in affective behavior, decreased cognitive flexibility and increased microglia activation as well as increased weight loss and plasma IL-6 following surgery. No effects of surgery on cognition were observed at either age. However, aged rats displayed long-term changes in affective behavior and had increased microgliosis in the CA1 hippocampal region following surgery. Microglia activation following surgery was positively correlated to parameters of behavior and spatial learning. These findings support the hypothesis that elderly patients have an increased behavioral and (neuro)inflammatory response to surgery and these factors may be related.

A possible association between panic disorder and a polymorphism in the preproghrelingene

The aim of the study was to investigate whether polymorphisms in the preproghrelin gene are associated with anxiety disorders, such as panic disorder, in humans. Panic disorder is a severe anxiety disorder, characterized by sudden attacks of intense fear or anxiety in combination with somatic symptoms. The preproghrelin gene codes for two gut-derived circulating peptides that have been linked to anxiety-like behaviour in rodents: ghrelin (an orexigenic, pro-obesity hormone) and obestatin. In the present study, we genotyped three missense mutations in the preproghrelin gene in 215 patients suffering from panic disorder and in 451 controls. The A allele of the rs4684677 polymorphism was significantly associated with panic disorder, while there were no significant associations with the two other polymorphisms studied. We conclude that the rs4684677 (Gln90Leu) polymorphism in the preproghrelin gene may be associated with increased risk of panic disorder. It will be important to confirm these findings in additional panic disorder patient groups.