Differential effects of endothelins on histological and ultrastructural changes and trypsinogen activation in the secretagogue-induced acute pancreatitis in rats

Therapeutic effects of Saussurea involucrata injection against severe acute pancreatitis- induced brain injury in rats

OBJECTIVES

To observe the therapeutic effects of Saussurea involucrata (Sau) injection against severe acute pancreatitis (SAP)-induced brain injury.

METHODS

Sodium taurocholate-induced SAP-modeled rats were equally randomized into an SAP model group (SAP group) and a Sau treated group (Sau  +  S group). Healthy rats were equally randomized into a Sau treated group (Sau  +  H group) and a sham operation group (SO group). Serum amylase levels, endothelin-1 (ET-1) and nitric oxide (NO) contents were determined by optical turbidimetry, ELISA and nitrate reductase method respectively. Western blot was used to detect protein expression levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), ET-1, inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) while mRNA levels of these biomarkers in brain tissue were measured by quantitative real-time PCR. Furthermore, pathological changes, as well as all above indexes of pancreas and brain, were observed at 6, 24 and 48 h after administration.

RESULTS

There was a significant difference in mortality between SAP and Sau  +  S groups (P  <  0.05). Serum amylase levels, ET-1 and NO contents, ET-1/NO ratio, relative expression levels of ET-1 and iNOS protein/mRNA of brain tissue in Sau + S group were lower than those in SAP group at 24 and 48 h post-operation (P  <  0.05 or 0.01), meanwhile, pancreas and brain pathological scores showed similar tendency (P  <  0.01). However, both protein and mRNA levels of PI3K, Akt and eNOS of brain tissue in Sau + S group were higher than those in SAP group (P  <  0.05 or P  <  0.01). There were no significant differences in all indexes between Sau + H and SO groups at all designated time points (P  >  0.05).

CONCLUSIONS

Sau injection has therapeutic effects on SAP-induced brain injury in rats.

Differentially expressed kinase genes associated with trypsinogen activation in rat pancreatic acinar cells treated with taurolithocholic acid 3-sulfate

Trypsinogen activation is the initial factor involved in the development of all types of acute pancreatitis (AP) and has been suggested to be regulated by protein kinases. In the present study, AR42J rat pancreatic acinar cells were treated with taurolithocholic acid 3-sulfate (TLC-S), and trypsinogen activation was detected with bis-(CBZ-L-isoleucyl-L-prolyl-L-arginine amide) dihydrochloride (BZiPAR) staining and flow cytometry. Differentially expressed protein kinase genes were screened by Gene Chip analysis, and the functions of these kinases were analyzed. A significantly increased activation of trypsinogen in AR42J cells following treatment with TLC-S was observed. A total of 22 differentially expressed protein kinase genes were found in the TLC-S group, among which 19 genes were upregulated and 3 were downregulated. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, kinase genes of the same KEGG pathways were connected to create a network through signaling pathways, and 10 nodes of kinases were identified, which were mitogen-activated protein kinase (Mapk)8, Mapk14, Map2k4, interleukin-1 receptor-associated kinase 3 (Irak3), ribosomal protein S6 kinase, 90 kDa, polypeptide 2 (Rps6ka2), protein kinase C, alpha (Prkca), v-yes-1 Yamaguchi sarcoma viral related oncogene homolog (Lyn), protein tyrosine kinase 2 beta (Ptk2b), p21 protein (Cdc42/Rac)-activated kinase 4 (Pak4) and FYN oncogene related to SRC, FGR, YES (Fyn). The interactions between signaling pathways were further analyzed and a network was created. MAPK and calcium signaling pathways were found to be located at the center of the network. Thus, protein kinases constitute potential drug targets for AP treatment.

Gene expression profiling and endothelin in acute experimental pancreatitis

AIM: To analyze gene expression profiles in an experimental pancreatitis and provide functional reversal of hypersensitivity with candidate gene endothelin-1 antagonists.

METHODS: Dibutyltin dichloride (DBTC) is a chemical used as a polyvinyl carbonate stabilizer/catalyzer, biocide in agriculture, antifouling agent in paint and fabric. DBTC induces an acute pancreatitis flare through generation of reactive oxygen species. Lewis-inbred rats received a single i.v. injection with either DBTC or vehicle. Spinal cord and dorsal root ganglia (DRG) were taken at the peak of inflammation and processed for transcriptional profiling with a cDNA microarray biased for rat brain-specific genes. In a second study, groups of animals with DBTC-induced pancreatitis were treated with endothelin (ET) receptor antagonists [ET-A (BQ123) and ET-B BQ788)]. Spontaneous pain related mechanical and thermal hypersensitivity were measured. Immunohistochemical analysis was performed using anti-ET-A and ET-B antibodies on sections from pancreatic tissues and DRG of the T10-12 spinal segments.

RESULTS: Animals developed acute pancreatic inflammation persisting 7-10 d as confirmed by pathological studies (edema in parenchyma, loss of pancreatic architecture and islets, infiltration of inflammatory cells, neutrophil and mononuclear cells, degeneration, vacuolization and necrosis of acinar cells) and the pain-related behaviors (cutaneous secondary mechanical and thermal hypersensitivity). Gene expression profile was different in the spinal cord from animals with pancreatitis compared to the vehicle control group. Over 260 up-regulated and 60 down-regulated unique genes could be classified into 8 functional gene families: circulatory/acute phase/immunomodulatory; extracellular matrix; structural; channel/receptor/transporter; signaling transduction; transcription/translation-related; antioxidants/chaperones/heat shock; pancreatic and other enzymes. ET-1 was among the 52 candidate genes up-regulated greater than 2-fold in animals with pancreatic inflammation and visceral pain-related behavior. Treatments with the ET-A (BQ123) and ET-B (BQ-788) antagonists revealed significant protection against inflammatory pain related mechanical and thermal hypersensitivity behaviors in animals with pancreatitis (P < 0.05). Open field spontaneous behavioral activity (at baseline, day 6 and 30 min after drug treatments (BQ123, BQ788) showed overall stable activity levels indicating that the drugs produced no undesirable effects on normal exploratory behaviors, except for a trend toward reduction of the active time and increase in resting time at the highest dose (300 μmol/L). Immunocytochemical localization revealed that expression of ET-A and ET-B receptors increased in DRG from animals with pancreatitis. Endothelin receptor localization was combined in dual staining with neuronal marker NeuN, and glia marker, glial fibrillary acidic protein. ET-A was expressed in the cell bodies and occasional nuclei of DRG neurons in naïve animals. However, phenotypic expression of ET-A receptor was greatly increased in neurons of all sizes in animals with pancreatitis. Similarly, ET-B receptor was localized in neurons and in the satellite glia, as well as in the Schwann cell glial myelin sheaths surrounding the axons passing through the DRG.

CONCLUSION: Endothelin-receptor antagonists protect against inflammatory pain responses without interfering with normal exploratory behaviors. Candidate genes can serve as future biomarkers for diagnosis and/or targeted gene therapy.