Dexmedetomidine protects rats from postoperative cognitive dysfunction via regulating the GABABR‐mediated cAMP‐PKA‐CREB signaling pathway

This work attempts to discuss whether dexmedetomidine (Dex) can protect rats from postoperative cognitive dysfunction (POCD) through regulating the γ‐aminobutyric acid‐_B receptor (GABA_BR)‐mediated cyclic adenosine monophosphate (cAMP) – protein kinase A (PKA) – cAMP‐response element binding (cAMP‐PKA‐CREB) signaling pathway. Sprague‐Dawley rats were divided into a non‐surgical group (Control), a surgical group (Model), a surgical group treated with Dex (Model + Dex), a surgical group treated with GABA_BR antagonist (Model + CGP 35348) and a surgical group treated with Dex and GABA_BR agonist (Model + Dex + Baclofen). Cognitive and memory functions were evaluated by Y‐maze test and open‐field test. The neuronal morphology of the hippocampus was observed by hematoxylin and eosin staining and neuronal apoptosis was by terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick‐end labeling method. Inflammatory factors and cAMP levels were detected by enzyme‐linked immunosorbent assay while expressions of GABA_BR and PKA‐CREB pathway‐related molecules by Western blot. Compared with control rats, the model rats exhibited reduced alternation rates with a prolonged time spent in the central zone; meanwhile, levels of tumor necrosis factor‐α and interleukin‐1β and the apoptotic index, as well as GABA_BR1 and GABA_BR2 expressions were increased in the model rats, but the cAMP‐PKA‐CREB pathway was inhibited (all P < 0.05). When treated with either Dex or CGP 35348, the surgical rats displayed an opposite tendency concerning the above factors as compared to the model rats (all P < 0.05). Furthermore, Baclofen, the agonist of GABA_BR, could reverse the protective effect of Dex against POCD in rats. Dex protects rats from POCD possibly via suppressing GABA_BR to up‐regulate the cAMP‐PKA‐CREB signaling pathway, thereby alleviating the hippocampal inflammation caused by surgical trauma.     

Role of calcium in polycystic kidney disease: From signaling to pathology

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited monogenic kidney disease. Characterized by the development and growth of cysts that cause progressive kidney enlargement, it ultimately leads to end-stage renal disease. Approximately 85% of ADPKD cases are caused by mutations in the PKD1 gene, while mutations in the PKD2 gene account for the remaining 15% of cases. The PKD1 gene encodes for polycystin-1 (PC1), a large multi-functional membrane receptor protein able to regulate ion channel complexes, whereas polycystin-2 (PC2), encoded by the PKD2 gene, is an integral membrane protein that functions as a calcium-permeable cation channel, located mainly in the endoplasmic reticulum (ER). In the primary cilia of the epithelial cells, PC1 interacts with PC2 to form a polycystin complex that acts as a mechanosensor, regulating signaling pathways involved in the differentiation of kidney tubular epithelial cells. Despite progress in understanding the function of these proteins, the molecular mechanisms associated with the pathogenesis of ADPKD remain unclear. In this review we discuss how an imbalance between functional PC1 and PC2 proteins may disrupt calcium channel activities in the cilium, plasma membrane and ER, thereby altering intracellular calcium signaling and leading to the aberrant cell proliferation and apoptosis associated with the development and growth of renal cysts. Research in this field could lead to the discovery of new molecules able to rebalance intracellular calcium, thereby normalizing cell proliferation and reducing kidney cyst progression.     

Hypothalamic insulin and glucagon-like peptide-1 levels in an animal model of depression and their effect on corticotropin-releasing hormone promoter gene activity in a hypothalamic cell line

Background

In depression, excessive glucocorticoid action may cause maladaptive brain changes, including in the pathways controlling energy metabolism. Insulin and glucagon-like peptide-1 (GLP-1), besides regulation of glucose homeostasis, also possess neurotrophic properties. Current study was aimed at investigating the influence of prenatal stress (PS) on insulin, GLP-1 and their receptor (IR and GLP-1R) levels in the hypothalamus. GLP-1 and GLP-1R were assayed also in the hippocampus and frontal cortex – brain regions mainly affected in depression. The second objective was to determine the influence of exendin-4 and insulin on CRH promoter gene activity in in vitro conditions.

Effects of chlorogenic acid on carbachol-induced contraction of mouse urinary bladder

Chlorogenic acid (CGA) is a polyphenol found in coffee and medicinal herbs such as Lonicera japonica. In this study, the effect of CGA-induced relaxation on carbachol (CCh)-induced contraction of mouse urinary bladder was investigated. CGA (30–300 μg/ml) inhibited CCh- or U46619-induced contraction in a concentration-dependent manner. SQ22536 (adenylyl cyclase inhibitor) recovered CGA-induced relaxation of CCh-induced contraction; however, ODQ (guanylyl cyclase inhibitor) did not have the same effect. In addition, 3-isobutyl-1-methylxanthine (IBMX) enhanced CGA-induced relaxation; however, forskolin or sodium nitroprusside did not have the same effect. Moreover, Ro 20–1724, a selective phosphodiesterase (PDE) 4 inhibitor, enhanced CGA-induced relaxation, but vardenafil, a selective PDE5 inhibitor, did not have the same effect. In the presence of CCh, CGA increased cyclic adenosine monophosphate (cAMP) level, whereas SQ22536 inhibited the increase of cAMP levels. Moreover, higher cAMP levels were obtained with CGA plus IBMX treatment than the total cAMP levels obtained with separate CGA and IBMX treatments. In conclusion, these results suggest that CGA inhibited CCh-induced contraction of mouse urinary bladder by partly increasing cAMP levels via adenylyl cyclase activation.     

PACAP38 improves airway epithelial barrier destruction induced by house dust mites allergen

PurposeThis study aimed to investigate the mechanism of PACAP38 on house dust mite (HDM)-induced asthmatic airway epithelial barrier destruction.MethodsThe HDM-induced asthma mice model and 16HBE cell model was established respectively. The enzyme linked immunosorbent assay (ELSIA), cell count and immunohistochemical assay were performed on mice in control group, HDM group and PACAP38 + HDM group.The cAMP/PKA activity, p-CREB and total CREB expression, TEER and the FITC-DX were investigated on cells in control-16HBE group, HDM-16HBE group and PACAP38 + HDM-16HBE group.ResultsThe levels of IL-4 and IL-5 in the HDM group were significantly higher than those in the control group (P < 0.05), while the above indexes in the PACAP38 + HDM group were lower than those in the HDM group (P < 0.05). E-cadherin, β-catenin, ZO-1 and occludin in the control group were highly immunoreactive in airway epithelial cells, whereas connexin staining was attenuated after HDM induction. The TEER level, cAMP levels and PKA activity were decreased, while FITC-DX transmittance was increased in HDM-16HBE group (P < 0.05) compared with the control-16HBE group.ConclusionPACAP38 could reduce the airway inflammation, weaken the AJC protein heterotopia and activate cAMP/PKA signaling pathway in HDM-induced asthma, which indicate that PACAP38 may be an important contributor in HDM-induced asthma.     

Conditioned-medium of stem cells from human exfoliated deciduous teeth prevent apoptosis of neural progenitors

PurposeThis study aimed to evaluate the neuroprotective ability of the conditioned medium of stem cells from human exfoliated deciduous teeth (CM-SHED) to prevent glutamate-induced apoptosis of neural progenitors.Materials and methodsNeural progenitors were isolated from two-day-old rat brains, and the conditioned medium was obtained from a mesenchymal stem cell SHED. Four groups were examined: neural progenitor cells cultured in neurobasal medium with (N + ) and without (N-) glutamate and glycine, and neural progenitor cells cultured in CM-SHED with (K + ) and without (K-) glutamate and glycine.ResultsThe expression of GABA A1 receptor (GABAAR1) messenger RNA (mRNA) in neural progenitor measured by real-time quantitative PCR. GABA contents were measured by enzyme-linked immunosorbent assay, whereas the apoptosis markers caspase-3 and 7-aminoactinomycin D were analysed with a Muse® cell analyzer. The viability of neural progenitor cells in the K + group (78.05 %) was higher than the control group N- (73.22 %) and lower in the N + group (68.90 %) than in the control group. The K + group showed the highest GABA content, which significantly differed from that in the other groups, whereas the lowest content was observed in the N + group. The expression level of GABAAR1 mRNA in the K + group was the highest compared to that in the other groups. CM-SHED potently protected the neural progenitors from apoptosis.ConclusionsCM-SHED may effectively prevent glutamate-induced apoptosis of neural progenitors.     

Prostaglandin E2 and I2 regulate intercellular adhesion molecule-1 expression in interleukin-1 beta-stimulated human gingival fibroblasts

The present study investigated the effect of prostaglandin (PG) E₂ and PGI₂ on intercellular adhesion molecule-1 (ICAM-1) expression in interleukin-1β (IL-1β)-stimulated human gingival fibroblasts (HGF). IL-1β potently induced ICAM-1 expression in HGF and indomethacin, a cyclooxygenase inhibitor, enhanced ICAM-1 expression in the cells. These data showed that endogenous PGs generated by HGF stimulated with IL-1β downregulated ICAM-1 expression. IL-1β significantly increased the levels of PGE₂ and, to a lesser extent, those of 6-keto-PGF_1α (a stable metabolite of PGI₂) in the culture media of HGF. Indomethacin completely inhibited the production of PGE₂ and 6-keto-PGF_1α in IL-1β-stimulated HGF. Exogenous PGE₂ and carbacyclin (a stable derivative of PGI₂) in the presence of indomethacin dose-dependently suppressed ICAM-1 expression in IL-1β-challenged HGF. Since PGE₂ and PGI₂ are known to elevate intracellular cyclic AMP (cAMP) levels, we examined the effect of dibutyryl cAMP, a cAMP analogue, and isobutylmethylxanthine, a phosphodiesterase inhibitor, on ICAM-1 expression. Both agents downregulated ICAM-1 expression in IL-1β-stimulated HGF. These results suggest that PGE₂ and PGI₂ downregulate ICAM-1 expression in IL-1β-stimulated HGF through a cAMP-dependent mechanism and that intracellular cAMP elevation in HGF may control inflammatory and immune responses in periodontal disease.     

小剂量左旋多巴上调pCREB及CD39蛋白表达发挥抗氧化应激损伤作用的研究

目的明确左旋多巴对PC12细胞生长及应激状态下存活的影响,探讨其抗氧化应激损伤的机制。方法不同浓度左旋多巴处理PC12细胞,用MTT法检测PC12细胞增长率及加入过氧化氢后细胞存活率;免疫荧光、Western blot方法测定磷酸化环单磷酸腺苷反应元件结合蛋白(pCREB)及CD39蛋白表达。结果低浓度左旋多巴(20μmol·L-1)促进PC12细胞生长,且可抗氧化应激损伤,而蛋白激酶抑制剂减弱此保护作用。免疫荧光及Western blot结果显示CD39及pCREB表达升高。结论低浓度左旋多巴可通过上调CD39及pCREB表达发挥抗氧化应激神经保护作用。