Nasrallah, Rania2013-11-082013-11-0820042004Source: Dissertation Abstracts International, Volume: 66-05, Section: B, page: 2372.http://hdl.handle.net/10393/29146http://dx.doi.org/10.20381/ruor-19619This study examined the distribution of prostacyclin (PGI2 ) receptors (IP) along the rat nephron, the signaling responses coupled to IP activation, and any alterations in this system in high-glucose treated (HG)-mesangial cells (MG) and streptozotocin (STZ)-diabetic rat kidneys. In situ hybridization, RT-PCR, RealTime RT-PCR, and Northern blot were used to study mRNA, and immunohistochemistry and Western blot for protein. IP mRNA was detected in glomeruli, vasculature, and cortical and medullary tubules on rat tissue sections, and in different preparations: kidney (C: cortex, OM: outer medulla, and IM: inner medulla), cultured MG (primary and transformed), proximal tubule (PT; fresh and cultured), and inner medullary collecting duct (fresh: f-IMCD and cultured: c-IMCD). IP protein was noted in PT, MG, IMCD, OM, and IM, but not cortex. Our work suggests that IP activation increases CAMP in: primary and immortalized MG, cultured PT, f-IMCD and c-IMCD. Inhibition of vasopressin-cAMP was obtained in f-IMCD. However IP was not linked to any calcium signaling in our studies. And we did not detect any IP subtypes or spliced variants. The role of PGI2/IP in MG was examined following 24 hr stimulation with cicaprost (CCP). A decrease in fibronectin and p27 was observed in cell lysates, and an increase in matrix metalloproteinase-2; CCP had no effect on thymidine or leucine incorporation. In response to 24 hr and 4 day HG, CCP- and iloprost (ILP)-cAMP was attenuated in MG: immortalized and primary cultures, respectively. CCP-CAMP was also diminished by anisomycin, a MAPK activator. PGI2 synthesis is dependent on cyclooxygenase (COX) and PGI 2 synthase (PGIS). We show increased COX-1 and -2 in the medulla of STZ rats, as well as HG-IMCD. Only COX-2 was elevated in HG-MG. While PGE 2 synthase was augmented in the OM of STZ rats, PGIS protein was reduced in HG-MG. HG did not affect IP mRNA in vitro, but reduced IP protein. However, IP mRNA was diminished in the OM of STZ rats, and all three-kidney regions in 6-mth uni-nephrectomized/STZ rats. The attenuation of PGI2/IP described in our work suggests that IP may serve as a target to prevent progressive injury to diabetic kidneys.331 p.enBiology, Cell.Thesis