Dominique Pralet | PubMed Health

PubMed2006

Effect of GLC756, a novel mixed dopamine D1 receptor antagonist and dopamine D2 receptor agonist, on TNF-alpha release in vitro from activated rat mast cells.

Tumor necrosis factor-alpha (TNF-alpha) is released from activated mast cells via an IgE-dependent mechanisms, and plays a crucial role in ocular allergic inflammation. This study examined the influence of three antiglaucoma drugs differing in their chemical structure and pharmacological profile (i.e. latanoprost, timolol, GLC756) on TNF-alpha release from activated rat mast cells. A rat basophilic leukemia mast cell line (RBL-2H3) was activated via IgE/anti-IgE. Rat mast cells were incubated with latanoprost, timolol, GLC756 or betamethasone (positive control) at concentrations of 0.1, 1, 10 and 30 microM. TNF-alpha concentration in supernatant was measured by ELISA 5 h post-activation. Compared to controls, the prostaglandin derivative latanoprost and the beta-blocker timolol in the concentration range 0.1-30 microM, had no significant effect on TNF-alpha release from rat mast cells measured 5h after activation. By contrast, the dopaminergic drug GLC756 compared to controls in the concentration range 1-30 microM significantly inhibited TNF-alpha release from activated rat mast cells in a concentration-dependent manner. The positive control betamethasone inhibited TNF-alpha release almost completely at all concentrations tested. In conclusion, the results of this study suggest that latanoprost and timolol do not reduce inflammation triggered by activated mast cells. By contrast, the dopaminergic drug GLC756 inhibited TNF-alpha release from activated mast cells, suggesting an palliative potential of dopaminergic compounds on allergic conjunctivitis in topical glaucoma medication.

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Laser technologies in toxicopathology.

One of the main concepts in toxicology and risk assessment is the identification of compounds with the least toxicity, gaining increased understanding of the underlying mechanisms of efficacy and toxicity so as to accelerate the early selection of compounds for development. For this purpose, "cutting-edge" technologies, such as flow cytometry (FC), laser scanning cytometry (LSC) and confocal laser scanning microscopy (CLSM), have proved to be valuable tools. FC, LSC and CLSM have been successfully applied in a wide range of areas within toxicology and research including genetics, reproduction, dermatology, pathology and target organ toxicity. The scope of this paper is to give a short overview of the usefulness of the different laser applications. Specific examples of the impact of these technologies will be presented or can be found in the references. Flow cytometry methods have been successfully applied in immunophenotyping, micronuclei scoring, polyploidy determination, apoptosis and cell cycle evaluation, cell proliferation and quantification. A three-parameter FC method for the analysis of testicular toxicity has also been established as an alternative to traditional histopathological methods. This method allows a large number of cells to be analysed in a short time and provides quantitative values to evaluate testicular damage in the rat. Laser scanning cytometry has been used in our unit for rat blood cell immunophenotyping, tumor proliferation, apoptosis and cell cycle analysis on minipig and rat skin and cardiac cells identification. The wide range of applications that can be applied with the LSC shows the enormous potential of this technology in research and development. Confocal laser scanning microscope was used in our laboratory, in collaboration with the research department, to investigate the mechanisms underlying hepatic lesions found in dogs, to detect fibrinogen influx into rat lung, to explore the mechanism of eye toxicity and to quantify dopaminergic fibers in brain sections. Integrating these technologies within discovery pathology allowed us to understand disease processes with respect to their development and subsequent consequences. It contributes to descriptive pathologic diagnostic and allows a productive interaction with research and development. These technologies offer a range of novel applications and have been shown to be useful tools in terms of specificity, sensitivity, reliability, rapidity and quantification. Expertise in cutting-edge technologies, pathology and cell and molecular biology is essential to a successful and flexible interaction across all therapeutic areas in drug discovery.

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