OBJECTIVETo investigate the role of cyclic adenosine monophosphate(cAMP) in the regulation of intestinal epithelial barrier function under hypoxia.

METHODSIntestinal epithelial barrier was established by Caco-2 monolayers. Cells were divided into four groups: normoxia (Nx), normoxia plus Forskolin(Nx+FSK), hypoxia(Hx), hypoxia plus SQ22536(Hx+SQ22536). cAMP concentrations of different groups were assessed by cAMP enzyme immunoassay kit. RT-PCR and Western blotting were used to detect the mRNA and protein expressions of claudin-1 and occludin under normoxic and hypoxic condition. Caco-2 monolayers were grown on Millicell filters, and transepithelial electrical resistance(TER) was measured using a Millipore electric resistance system.

RESULTSThe concentration of cAMP under hypoxic conditions(Hx group) was higher compared with Nx group [(6.30±0.50) pmol/L vs. (2.38±0.18) pmol/L, P<0.01]. At the same time, both mRNA and protein expressions of claudin-1 and occluding were lower in Hx group than those in Nx group(all P<0.05). TER decreased by 76.30±0.64(P<0.01). When the monolayers were exposed to hypoxia plus SQ22536 (Hx+SQ22536 group), the concentration of cAMP was(2.12±0.23) pmol/L, which was lower than that under hypoxic conditions(Hx group, P<0.01). Both mRNA and protein expressions of claudin-1 and occludin were higher compared to Hx group (all P<0.01). TER increased by 32.96±2.16 (P<0.05).

CONCLUSIONWhen Caco-2 cells are exposed to hypoxia, barrier function, claudin-1 and occludin expression are diminished in parallel with a high level of intracellular cAMP compared with the normoxic condition. Inhibition of the intracellular cAMP level under hypoxia can maintain the intestinal epithelial function through regulating the claudin-1 and occludin expression and attenuate the permeability of intestinal mucosa.

Adenosine Monophosphate ; Caco-2 Cells ; Claudin-1 ; metabolism ; Humans ; Intestinal Mucosa ; metabolism ; Intestines ; Occludin ; metabolism

OBJECTIVETo investigate the effect of hypoxia on the proliferation and occludin expression of primary rat Sertoli

METHODSWe constructed a primary Sertoli cell system by two-step enzymatic digestion in 18 -22 days old Wistar rats and identified it by oil red O and immunofluorescence methods. We randomly divided the Sertoli cells into five groups to be cultured in oxygen at the concentrations of 20%, 15%, 10%, 5% and 1%, respectively, for 6, 12, 24, 48 and 72 hours. We detected the proliferation of the Sertoli cells by CCK-8 assay, determined the expression of occludin by Western blot, and analyzed the differences among the five groups.

RESULTSOil red O staining revealed red lipid droplets in the cytoplasm of the Sertoli cells, and immunofluorescence showed the positive expression of the FasL protein, with the purity of Sertoli cells over 95% in vitro. Compared with the 20% normoxic group, the proliferation of the Sertoli cells was gradually reduced in the 15% and 10% hypoxia groups, and significantly declined in the 5% and 1% groups (P < 0.01). At 12 hours, the expression of occludin began to decrease with the prolonging of time and reduction of oxygen concentration (P < 0.01).

CONCLUSIONHypoxia suppresses the proliferation of Sertoli cells and reduces the expression of occludin. It could be inferred that hypoxia could damage the integrity of blood-testis barrier and spermatogenesis of the testis.

Animals ; Cell Hypoxia ; Cell Proliferation ; Cells, Cultured ; Male ; Occludin ; metabolism ; Rats ; Rats, Wistar ; Sertoli Cells ; metabolism

OBJECTIVE: To explore the expression and distribution of barrier molecules in epithelium of various types of chronic rhinosinusitis and its significance. METHOD: There were four groups including control (13 samples), Eos-CRSwNP (10 samples), nonEos-CRSwNP (14 samples), CRSsNP (11 samples). The method of immunohistochemistry was used to detect the protein expression of E-cadherin and occludin in nasal mucosa. RESULT: There was positive staining extensively distributed among cells in nasal mucosa. There was no significant difference in these groups. However, the occludin mainly located on the top of epithelial cells. In normal nasal mucosa, the positive expression was continuous, however, it was discontinuous both in CRSwNP and CRSsNP groups. CONCLUSION There was no E-cadherin loss in the progression of pathophysiology of chronic rhinosinusitis. But the loss of occludin may correlate to the dysfunction of epithelial barrier, which was beneficial for the pathogen invasion.
Cadherins ; metabolism ; Chronic Disease ; Epithelial Cells ; Epithelium ; metabolism ; Humans ; Immunohistochemistry ; Nasal Mucosa ; Occludin ; metabolism ; Rhinitis ; metabolism ; Sinusitis ; metabolism

OBJECTIVE: To explore the molecular mechanisms of Porphyromonas gingivalis infection-induced umbilical vein endothelial barrier dysfunction in vitro. METHODS: Human umbilical vein endothelial cells (HUVECs) were cultured in vitro, and after the formation of the endothelial barrier, the cells were infected with P. gingivals at a multiplicity of infection (MOI). The transepithelial electrical resistance (TEER) of the cell barrier was measured, and FITC-dextran trans-endothelial permeability assay and bacterial translocation assay were performed to assess the endothelial barrier function. The expression levels of cell junction proteins including ZO-1, occludin and VE-cadherin in the cells were examined by qRT-PCR and Western blotting. RESULTS: In freshly seeded HUVECs, TEER increased until reaching the maximum on Day 5 (94 Ωcm²), suggesting the formation of the endothelial barrier. P. gingivals infection caused an increase of the permeability of the endothelial barrier as early as 0.5 h after bacterial inoculation, and the barrier function further exacerbated with time, as shown by significantly lowered TEER, increased permeability of FITC-dextran (40 000/70 000), and increased translocation of SYTO9-E. coli cross the barrier. MTT assay suggested that P. gingivals infection did not significantly affect the proliferation of HUVECs (P>0.05), but in P. gingivalsinfected cells, the expressions of ZO-1, occludin and VE-cadherin increased significantly at 24 and 48 h after bacterial inoculation (P < 0.05). CONCLUSION P. gingivals may disrupt the endothelial barrier function by down-regulating the expressions of the cell junction proteins (ZO-1, occludin, VE-cadherin) and increasing the permeability of the endothelial barrier.
Humans ; Cadherins/metabolism* ; Escherichia coli/metabolism* ; Human Umbilical Vein Endothelial Cells/metabolism* ; Occludin ; Porphyromonas gingivalis/metabolism* ; Umbilical Veins/metabolism*

OBJECTIVETo explore the action mechanisms of temperature in male infertility or subfertility by observing the effects of different temperatures on the proliferation of and occludin (OCLN) expression in rat Sertoli cells in vitro.

METHODSWe isolated Sertoli cells from the testis of male Wistar rats, and performed oil red O staining and immunohistochemistry to identify their FasL. We cultured the Sertoli cells at 34 degrees C (control group) and at 35, 36, 37, 38 and 39 degrees C (experimental groups) for 4 days. Then we measured their proliferation by CCK-8 assay, observed their morphology and structure by hematoxylin-eosin staining, and determined their OCLN expression level by Western blotting and immunofluorescence.

RESULTSThe purity of the isolated Sertoli cells was (96.20 +/- 1.95)%. CCK-8 assay indicated that the proliferation of the Sertoli cells was increased between 34 and 36 degrees C, and decreased at 36-39 degrees C. The pyknotic nuclei and fragmentation of the Sertoli cells were more obvious at > 36 degrees C. Western blot and immunofluorescence showed the highest level of OCLN expression at 36 degrees C, which, however, decreased while the temperature rose above 36 degrees C (P < 0. 01).

CONCLUSIONHigh temperature (> 36 degrees C) inhibited the proliferation of rat Sertoli cells in vitro, and decreased the expression of OCLN, which suggests that a higher temperature above 36 degrees C may reduce male fertility by affecting the proliferation of Sertoli cells and integrity of the tight junction among Sertoli cells or Sertoli cells and other cells.

Animals ; Cell Proliferation ; Male ; Occludin ; metabolism ; Rats ; Rats, Wistar ; Sertoli Cells ; cytology ; metabolism ; Temperature ; Testis ; cytology ; metabolism

OBJECTIVE: To investigate the effects of diethylhexyl phthalate (DEHP) exposure on anxiety-like behaviors and learning and memory ability in mice and explore the underlying mechanism. METHODS: Forty male ICR mice were randomized equally into control group (0 mg/kg) and 10, 50 and 100 mg/kg DEHP exposure groups, in which the mice were exposed to DEHP at the indicated doses by gavage for 4 weeks. After the treatments, the mice were assessed for behavioral changes using open filed test, elevated plus-maze and Morris water maze test. Brain tissues were collected from the mice for determination of malondialdehyde (MDA) content, pathologies and expressions of ZO-1 and occludin in the hippocampus. RESULTS: Compared with the control group, the mice with DEHP exposure for 4 weeks exhibited no significant body weight change (P>0.05) but presented with obvious behavioral changes, manifested by reduced movement distance (P < 0.05) and time spent in the center of the open field (P < 0.05), reduced movement distance (P < 0.05) and time spent in the open arm of the elevated maze (P < 0.05), significantly increased latency of searching for the platform (P < 0.05), and decreased frequency of crossing the platform (P < 0.05). HE staining showed obvious vertebral cell death in the hippocampal CA1 to CA3 regions of the mice with DEHP exposure. The exposed mice showed significantly increased MDA content and decreased expressions of ZO-1 and occludin at both the mRNA and protein levels in the hippocampus (P < 0.05 or 0.01). Multivariate linear regression analysis suggested a close correlation between anxiety-like behaviors and learning and memory abilities in DEHP-exposed mice. CONCLUSION DEHP exposure may cause damages of the blood-brain barrier and the pyramidal cells in the hippocampus of mice, thereby inducing anxiety-like behaviors and learning and memory impairment.
Animals ; Anxiety/chemically induced* ; Blood-Brain Barrier/metabolism* ; Diethylhexyl Phthalate/toxicity* ; Male ; Maze Learning ; Mice ; Mice, Inbred ICR ; Occludin/pharmacology*

OBJECTIVETo observe the effect of SIRT1 on intestinal barrier function of epithelial Caco-2 cells under hypoxia and investigate its mechanism.

METHODSCaco-2 cells were randomly divided into three groups: normoxia group (Nx), hypoxia group (Hx,1%O2 for 6 h) and hypoxia plus 40 μmol/L Resveratrol (agonist of SIRT1) group (Hx+Res). Transepithelial electrical resistance (TER) was determined. mRNA and protein expressions of SIRT1 and tight junctions (ZO-1, Occludin, Claudin-1) were examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting.

RESULTSBoth mRNA and protein expressions of SIRT1 were significantly reduced in Hx group as compared with Nx group (0.40±0.02 vs. 0.70±0.07, P=0.001; 0.37±0.03 vs. 0.76±0.03, P=0.001). The mRNA and protein expressions of SIRT1 were significantly increased in Hx+Res group as compared with Hx group(0.50±0.02 vs. 0.40±0.02, P=0.026; 0.54±0.02 vs. 0.37±0.03, P=0.011). The expression levels of ZO-1, Occludin and Claudin-1 in Hx group were lower than those in Nx group (P<0.05), however, pretreatment with Resveratrol could attenuate the decreased expression of above 3 molecules under hypoxia(P<0.05). TERs of Nx group, Hx group and Hx+Res group were (142±7) Ohm/cm(2), (94±3) Ohm/cm(2) and (119±7) Ohm/cm(2) respectively. Compare with the Nx group, the TER of Hx group was significantly decreased(P<0.05). TER of Hx+Res group was significantly increased compare with Hx group, but it was still significantly lower than that in Nx group(P<0.05).

CONCLUSIONSExpression of SIRT1 is significantly reduced under hypoxia. Activation of SIRT1 can maintain the epithelial barrier function through regulating the expression of tight junctions under hypoxia.

Caco-2 Cells ; Cell Hypoxia ; Claudin-1 ; metabolism ; Epithelial Cells ; metabolism ; Humans ; Intestinal Mucosa ; cytology ; Occludin ; metabolism ; Sirtuin 1 ; metabolism ; Zonula Occludens-1 Protein ; metabolism

OBJECTIVETo explore the changes in the expressions of the tight junction related protein occludin and junctional adhesion molecule-1 (JAM-1) of the blood-testis barrier and their significance in rats after microwave radiation.

METHODSEighty male Wistar rats were exposed to microwave radiation with average power density of 0, 10, 30 and 100 mW/cm2 for five minutes, and dynamic changes in the expressions of testicular occludin and JAM-1 were observed by Western blot and image analysis at 6 h, 1 d, 3 d, 7 d and 14 d after the radiation.

RESULTSThere was a significant down-regulation in the expression of the occludin protein at 3 - 7 d, 6 h - 7 d and 6 h - 14 d (P < 0. 05), as well as in that of JAM-1 at 3 - 7 d, 1 - 7 d and 1-14 d (P < 0.05) after exposure to 10, 30 and 100 mW/cm2 microwave radiation.

CONCLUSIONThe decreased protein expressions of occludin and JAM-1 may play an important role in the microwave radiation induced-damage to the blood-testis barrier.

Animals ; Blood-Testis Barrier ; metabolism ; radiation effects ; Cell Adhesion Molecules ; metabolism ; Down-Regulation ; Male ; Membrane Proteins ; metabolism ; Microwaves ; Occludin ; Rats ; Rats, Wistar ; Testis ; metabolism ; radiation effects

OBJECTIVETo explore the mechanism of electroacupuncture at Zusanli (ST 36) on regulation of intestinal inflammatory reaction in rats with acute pancreatitis.

METHODSFifty-four SD rats were randomly divided into a severe acute pancreatitis (SAP) group, an electroacupuncture (EA) group and a sham-operation (SO) group, 18 cases in each group. 3.5% sodium cholate was used to made SAP model by retrograde injecting in cholangiopancreatic duct. After the success of model making, the EA group was treated with EA at bilateral Zusanli (ST 36) for 30 min. The SO group and the SAP group were fixed at the same time for 30 min without treatment. All the rats were killed at 3 h, 6 h and 12 h after modeling in batches. The pathological changes of pancreatic tissue and intestinal epithelium were observed, and the expression of small intestinal occludin protein and nuclear factor kappa-B (NF-kappaB) were detected by immunohistochemical SP method.

RESULTSThe pathologic score and the expression of small intestinal NF-kappaB p65 at 3 h, 6 h and 12 h after modeling in the EA group and the SO group were significantly lower than those in the SAP group (all P < 0.05), and the expression of small intestinal occludin protein in the EA group and the SO group were significantly higher than that in the SAP group (all P < 0.05).

CONCLUSIONElectroacupuncture at Zusanli (ST 36) can alleviate pancreatic injury by reducing the expression of NF-kappaB p65 and enhancing the expression of occludin protein in the intestinal epithelium in the SAP model rats.

Acupuncture Points ; Acute Disease ; therapy ; Animals ; Electroacupuncture ; Humans ; Intestine, Small ; metabolism ; Male ; NF-kappa B ; genetics ; metabolism ; Occludin ; genetics ; metabolism ; Pancreatitis ; genetics ; metabolism ; therapy ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo.

METHODSIn situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section.

RESULTSOccludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively normal gastric tissue and gastric cancer as well as between paracancerous gastric tissue and gastric cancer. The expression of occludin mRNA in moderately and poorly differentiated groups was gradually reduced when compared with well differentiated group, which suggests that there be a significant correlation between tumor differentiation and the expression of occludin mRNA. Furthermore, the positive signals of occludin mRNA distributed extensively in the cytoplasm of SGC7901/VCR cell, being vincristine resistant, derived from parental gastric cell line SGC7901. The positive signals of SGC7901/VCR were stronger than those of SGC7901 cells.

CONCLUSIONOccludin mRNA, being mainly located in epithelial cells and its expression correlated with tumor differentiation, may be involved in the development of multi-drug resistance in gastric cancer.

Drug Resistance, Multiple ; physiology ; Drug Resistance, Neoplasm ; physiology ; Humans ; In Situ Hybridization ; Membrane Proteins ; genetics ; metabolism ; Occludin ; RNA, Messenger ; metabolism ; Stomach Neoplasms ; metabolism ; Tight Junctions ; metabolism