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Cyclooxygenase 2 and intermittent hypoxia-induced spatial deficits in the rat.. Richard C Li; Barry W Row; Evelyne Gozal; Leila Kheirandish; Qiang Fan; Kenneth R Brittian; Shang Z Guo; Leroy R SachlebenJr; David Gozal (2003) American journal of respiratory and critical care medicine display abstract
Intermittent hypoxia (IH) during sleep, a critical feature of sleep apnea, induces significant neurobehavioral deficits in the rat. Cyclooxygenase (COX)-2 is induced during stressful conditions such as cerebral ischemia and could play an important role in IH-induced learning deficits. We therefore examined COX-1 and COX-2 genes and COX-2 protein expression and activity (prostaglandin E2 [PGE2] tissue concentration) in cortical regions of rat brain after exposure to either IH (10% O2 alternating with 21% O2 every 90 seconds) or sustained hypoxia (10% O2). In addition, the effect of selective COX-2 inhibition with NS-398 on IH-induced neurobehavioral deficits was assessed. IH was associated with increased COX-2 protein and gene expression from Day 1 to Day 14 of exposure. No changes were found in COX-1 gene expression after exposure to hypoxia. IH-induced COX-2 upregulation was associated with increased PGE2 tissue levels, neuronal apoptosis, and neurobehavioral deficits. Administration of NS-398 abolished IH-induced apoptosis and PGE2 increases without modifying COX-2 mRNA expression. Furthermore, NS-398 treatment attenuated IH-induced deficits in the acquisition and retention of a spatial task in the water maze. We conclude that IH induces upregulation and activation of COX-2 in rat cortex and that COX-2 may play a role in IH-mediated neurobehavioral deficits.
Protease-activated receptor-2-mediated contraction of urinary bladder is enhanced in cyclophosphamide-treated rats.. Tsutomu Nakahara; Yuko Kubota; Maki Saito; Kenji Sakamoto; Kunio Ishii (2004) Naunyn-Schmiedeberg's archives of pharmacology display abstract
Protease-activated receptor-2 (PAR-2) is activated by serine proteases, such as trypsin and mast cell tryptase. Recently, we have shown that activators of PAR-2 contract the rat urinary bladder mainly by stimulating release of prostaglandins (PGs) from the mucosal layer. In the present study, we investigated how the PAR-2-mediated responses are altered in rats with cyclophosphamide (CYP)-induced cystitis. The contractile responses to trypsin and PAR-2 activating peptide (PAR-2 AP; SLIGRL-NH2) in the urinary bladders were augmented by treatment of rats with CYP. The contractile effects of these PAR-2 activators on the smooth muscles of the urinary bladder were also potentiated after induction of cystitis by CYP. On the other hand, CYP-induced cystitis significantly attenuated contractions produced by PGE2 in the smooth muscles of the urinary bladder. The PAR-2-mediated contractions were significantly prevented by indomethacin or NS-398, an inhibitor of cyclooxygenase-2. Both trypsin and PAR-2 AP increased the release of PGE2 from the urinary bladder mucosa and smooth muscle. CYP-induced cystitis enhanced the PAR-2 activators-induced PGE2 releases from the urinary mucosa without affecting those from the smooth muscle of the urinary bladder. The PGE2 releases were prevented by indomethacin or NS-398. The mRNAs for PAR-2 in the urinary bladder mucosa and smooth muscle preparations were not altered in CYP-induced cystitis. These results suggest that PAR-2-mediated responses were enhanced in bladders from CYP-treated rats. The enhancement of PAR-2-mediated contraction might be ascribed to the increased production of PGs and the altered sensitivity of smooth muscle to PAR-2 activators.
Prostaglandin F2alpha produced by inducible cyclooxygenase may contribute to the resolution of inflammation.. Paul R Colville-Nash; Derek W Gilroy; Dean Willis; Mark J Paul-Clark; Adrian R Moore; Derek A Willoughby (2005) Inflammopharmacology display abstract
Cyclooxygenase-2 may play a role in resolution of carrageenan-induced pleurisy in rats by generating anti-inflammatory prostanoids. Here, we show exudate prostaglandin F2alpha concentrations rise during resolution of this model. These were reduced by the selective cyclooxygenase-2 inhibitor NS-398, which exacerbated inflammation. Concomitant treatment with NS-398 and the synthetic FP receptor agonist fluprostenol reversed this exacerbation. This suggests prostaglandin F2alpha produced by cyclooxygenase-2 contributes to resolution of this inflammatory reaction.
Sphingosine 1-phosphate induces cyclooxygenase-2 via Ca2+-dependent, but MAPK-independent mechanism in rat vascular smooth muscle cells.. Akiko Nodai; Takuji Machida; Sachiko Izumi; Yumika Hamaya; Takayuki Kohno; Yasuyuki Igarashi; Kenji Iizuka; Masaru Minami; Masahiko Hirafuji (2007) Life sciences display abstract
The effects of sphingosine 1-phosphate (S1P) on prostaglandin I(2) (PGI(2)) production and cyclooxygenase (COX) expression in cultured rat vascular smooth muscle cells (VSMCs) were investigated. S1P stimulated PGI(2) production in a concentration-dependent manner, which was completely suppressed by NS-398, a selective COX-2 inhibitor, as determined by radioimmunoassay. S1P stimulated COX-2 protein and mRNA expressions in a concentration- and time-dependent manner, while it had no effect on COX-1 expression. S1P(2) and S1P(3) receptors mRNA were abundantly expressed in rat VSMCs. Suramin, an antagonist of S1P(3) receptor, almost completely inhibited S1P-induced COX-2 expression. Pretreatment of VSMCs with pertussis toxin (PTX) partially, but significantly inhibited S1P-induced PGI(2) production and COX-2 expression. S1P also activated extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). However, neither PD 98059, a selective inhibitor of ERK activation, nor SB 203580, a selective inhibitor of p38 MAPK, had a significant inhibitory effect on S1P-induced COX-2 expression, suggesting that the MAPK activation does not play main roles in S1P-induced COX-2 induction. S1P-induced COX-2 expression was inhibited by PP2, an inhibitor of Src-family tyrosine kinase, Ca(2+) depletion, and GF 109203X, an inhibitor of protein kinase C (PKC). These results suggest that S1P stimulates COX-2 induction in rat VSMCs through mechanisms involving Ca(2+)-dependent PKC and Src-family tyrosine kinase activation via S1P(3) receptor coupled to PTX-sensitive and -insensitive G proteins.