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Combined dopamine D 2 receptor antagonism and serotonin (5-HT) 1A receptor agonism may improve efficacy and alleviate some side effects associated with classical antipsychotics. The present study describes the in vitro and in vivo characterization of 1-(2,3-dihydrobenzo[1,4]dioxin-5-yl)-4-[5-(4-fluoro-phenyl)-pyridin-3-ylmethyl]-piperazine monohydrochloride (SLV313), a D 2/3 antagonist and 5-HT 1A agonist. SLV313 possessed high affinity at human recombinant D 2 , D 3 , D 4 , 5-HT 2B , and 5-HT 1A receptors, moderate affinity at 5-HT 7 and weak affinity at 5-HT 2A receptors, with little-no affinity at 5-HT 4 , 5-HT 6 , a 1 , and a 2 (rat), H 1 (guinea pig), M 1 , M 4 , 5-HT 3 receptors, and the 5-HT transporter. SLV313 had full agonist activity at cloned h5-HT 1A receptors (pEC 50 ¼ 9.0) and full antagonist activity at hD 2 (pA 2 ¼ 9.3) and hD 3 (pA 2 ¼ 8.9) receptors. In vivo, SLV313 antagonized apomorphine-induced climbing and induced 5-HT 1A syndrome behaviors and hypothermia, the latter behaviors being antagonized by the 5-HT 1A antagonist WAY100635. In a drug discrimination procedure SLV313 induced full generalization to the training drug flesinoxan and was also antagonized by WAY100635. In the nucleus accumbens SLV313 reduced extracellular 5-HT and increased dopamine levels in the same dose range. Acetylcholine and dopamine were elevated in the hippocampus and mPFCx, the latter antagonized by WAY100635, suggesting possible 5-HT 1A -dependent efficacy for the treatment of cognitive and attentional processes. SLV313 did not possess cataleptogenic potential (up to 60 mg/kg p.o.). The number of spontaneously active dopamine cells in the ventral tegmental area was reduced by SLV313 and clozapine, while no such changes were seen in the substantia nigra zona compacta following chronic administration. These results suggest that SLV313 is a full 5-HT 1A receptor agonist and full D 2/3 receptor antagonist possessing characteristics of an atypical antipsychotic, representing a potential novel treatment for schizophrenia. Neuropsychopharmacology (2007) 32, 78-94.

Abstract. In this study we have examined the influence of perturbation of endothelial cells on the amounts of fibronectin and von Willebrand factor in their extracellular matrix and the consequences of a changed composition of the matrix on platelet adhesion. For this purpose, we have used an in vitro perfusion system with which we can investigate the interactions of platelets in flowing blood with cultured endothelial cells and their extracellular matrix (Sakariassen, K. S., P. A. M. M. Aarts, P. G. de Groot, W. P. M. Houdgk, and J. J. Sixma, 1983, J. Lab. Clin Med. 102:522-535). Treatment of endothelial cells with 0.1-1.0 U/ml thrombin for 2 h increased the reactivity of the extracellular matrix, isolated after the thrombin treatment, towards platelets by ,o50%. The increased reactivity did not depend on de novo protein synthesis but was inhibited by 3-deazaadenosine, an inhibitor of phospholipid methylation, which also inhibits the stimulus-induced instantaneous release of von Willebrand factor from endothelial cells. However, no changes in the amounts of von Willebrand factor and fibronectin in the matrix were detected. Thrombin may change the organization of the matrix proteins, not the composition.When endothelial cells were perturbed with the phorbol ester PMA or thrombin for 3 d, the adhesion of platelets to the extracellular matrix of treated cells was strongly impaired. This impairment coincided with a decrease in the amounts of von Willebrand factor and fibronectin present in the matrix. These results indicate that, after perturbation, endothelial cells regulate the composition of their matrix, and that this regulation has consequences for the adhesion of platelets.

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Production of prostacyclin by endothelial cells is considered to be important in rendering the vessel wall nonthrombogenic. Cigarette smoking is an important risk factor in the pathogenesis of atherosclerosis. Here we show that the incubation of cultured human endothelial cells with a cigarette smoke condensate impaired the basal prostacyclin release. Also, the enhanced release of prostacyclin provoked by phorbol myristate acetate was inhibited by cigarette smoke condensate. Furthermore, cigarette smoke condensate impaired the thrombin-induced prostacyclin production. The production of prostacyclin from exogenous arachidonate was not affected by cigarette smoke condensate, indicating that cigarette smoke condensate constituents exert their inhibitory properties on the level of arachidonate mobilization from cellular phospholipids, rather than on cyclooxygenase or prostaglandin synthetase. The effects noted for cigarette smoke condensate could not be attributed to the cigarette smoke constituents nicotine and cadmium. While inhibiting the endothelial cell prostacyclin production significantly, cigarette smoke condensate did not cause cell death or impairment of secretory function, as measured by the release of von Willebrand factor. This in vitro study shows that impairment of an endothelial cell function is related to a risk factor for atherosclerosis.