Prostacyclin (PGI2) is a cyclooxygenase metabolite with antithrombotic properties found in vascular endothelial cells. The half-life is short both in vivo and in vitro, ranging from 30 seconds to a few minutes. CG 4305 is a stable carbacyclic analog of PGI2 that inhibits ADP-induced platelet aggregation 25% at a concentration of 50 nM. Doses of 10 mg/kg (oral) or 1 mg/kg (intraduodenal) have been shown to prevent rabbit carotid artery thrombosis.
The growth factors, platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) play major roles in enhanced smooth muscle cells growth in rodent blood vessels after vascular injury. Tyrosine kinase inhibition has been shown to be effective in blocking tyrosine phosphorylation at the PDGF and bFGF receptors in cultured fibroblast and vascular smooth muscle cells which in turn inhibits their proliferation[1]. CGP 53716 is a specific PDGFR tyrosine kinase inhibitor on SMC (smooth muscle cell) proliferation and migration in vitro and in neointimal formationin vivo[3]. CGP 53716 inhibited serum-induced cell growth in RASMC (rat aortic smooth muscle cells). And it completely blocked PDGF-BB tyrosine receptor autophosphorylation in RASMC and 3T3 cells, PDGF-BB-induced phosphorylation of mitogen-activated protein kinase at 1 μM in RASMC and inhibited PDGF-BB-induced c-Fos protein expression at 1 μM in RASMC; consistent with inhibition of PDGF-BB-induced DNA synthesis. Further, CGP 53716 inhibited PDGF-BB-, bFGF- and EGF-induced DNA synthesis in a concentration-dependent manner in each cell line. And it showed a 2- to 4-fold selectivity for PDGF-BB-stimulated DNA synthesis over bFGF or EGF in RASMC or 3T3 cells[1]. CGP 53716 inhibited dose dependently tyrosine phosphorylation of both the known PDGFRs: the PDGFR-α and PDGFR-β. After rat carotid artery ballooning injuryin vivo, the migration of alpha-actin-positive cells on the luminal side of internal elastic lamina was decreased with 50 mg kg day of CGP 53716 from 38 ± 10 (control group) to 4 ± 2. Intima media ratio was inhibited by 40% after 14 days in the CGP 53716-treated group (P=0.028) after rat aortic denudation[3].
Thrombin receptor peptide ligand is antagonist of the thrombin receptor (EC50s = 16-33 μM to inhibit platelet aggregation in vitro). It inhibits α-thrombin and platelet aggregation induced by thrombin receptor activating peptide in vitro when used at a concentration of 32 μM but does not affect platelet aggregation induced by ADP or collagen. It also inhibits thrombin- and TRAP-induced proliferation of vascular smooth muscle cells (VSMCs). Thrombin receptor peptide ligand (100 μmol/kg bolus, i.v., plus 900 μmol/kg infusion) inhibits arterial thrombosis in a rabbit model of partial carotid artery occlusion without increasing bleeding time.
N-Methyl-D-aspartate (NMDA) receptors are Ca2+ permeable ligand-gated channels of the central nervous system that are activated after binding of the co-agonists glutamate and glycine. CAY10608 is a propanolamine that potently, selectively, and non-competitively antagonizes the NR2B subunit of NMDA receptors (IC50 = 50 nM). It does not inhibit NR1, NR2A, NR2C, and NR2D subunits and has no significant effects on α-amino-3-hydroxy-5-methyl-4-isoxazolepropioinic acid (AMPA) or kainate receptors. CAY10608 is neuroprotective, since it prevents NMDA-triggered release of lactate dehydrogenase from cultured cortical neurons. Also, CAY10608, when administered intraperitoneally, reduces brain infarct volume resulting from transient ischemia via carotid artery occlusion.
Kynurenic acid, an active metabolite of tryptophan, is synthesized through a kynurenine intermediate by kynurenine aminotransferases (KATs). It acts as an antagonist of both NMDA and AMPA receptors, as well as α7 nicotinic acetylcholine receptors (nAChRs; EC50s = 235, 101, and 7 µM, respectively), and functions as an agonist for the aryl hydrocarbon receptor (AhR) and G protein-coupled receptor 35 (GPR35; EC50s = 1.4 and 39 µM, respectively). In a neonatal rat model of cerebral hypoxic-ischemia, induced by carotid artery ligation, administration of kynurenic acid at 300 mg kg prevents weight loss in the lesioned hemisphere. Additionally, at concentrations of 1 and 5 mg ml, it protects against neurodegeneration in the rhabdomere of the eye in an Htt93QtransgenicDrosophila model of Huntington's disease. Elevated levels of kynurenic acid in the cerebrospinal fluid have been observed in patients with schizophrenia.