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| Author(s): |
Raphael Caio Tamborelli Garcia
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2009-09-28 |
| Examining board members: |
Tania Marcourakis;
Merari de Fatima Ramires Ferrari;
Roberto Frussa Filho
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| Advisor: | Tania Marcourakis |
| Abstract | |
Smoking crack has increased in the last years when compared to the other routes of cocaine administration. Its advantage is the quicker and stronger high effects and its ease of use without the need of needles. Smoking crack involves inhaling not only cocaine, but also its pyrolysis product, methylecgonidine (AEME). There are evidences that cocaine causes neurodegeneration, but AEME involvement in this process has not been studied yet. The aim of this study was to investigate AEME participation in neurodegeneration using a primary hippocampus culture made from rat fetuses. Cellular viability assays (MTT), lactate dehydrogenase activity (LDH) and morphological evaluations with fluorescence microscopy were performed. The involvement of oxidative injury in the neurodegeneration process was also studied through DNA adduct formation; the evaluation of antioxidants enzymes activities as glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST); and the production of malonaldehyde (MDA), a lipoperoxidation biomarker. Both cocaine and AEME showed neurotoxic effects. Through viability assays and morphologic evaluations we can suggest that, in hippocampal cells, cocaine cell death mechanism involves not only necrosis, but also apoptosis and that AEME pathway involved in neurodegeneration is only apoptosis. AEME did not produce a direct DNA injury, as no DNA adduct was observed with desoxyguanosine (d-G), the most reactive nitrogenous base, nor with commercial DNA. Moreover, our results showed that 1 and 2 mM of AEME and cocaine, respectively, were equipotent and the concomitant incubation of both compounds in those concentrations showed additive effect after 48 hours of exposure. Hippocampal cell death at 24 hours was preceded by a decrease in GPx activity after 3 hours of incubation with AEME, cocaine and association between these two compounds. GST activity also decreased but only after 6 hours of exposure, also before cell death. There was no alteration in GR activity. There was an increase, although not statistically significant, in MDA after 48 hours of exposure. As smoking crack abusers are exposed to both cocaine and AEME, our results suggest a higher susceptibility to neurodegeneration in smoking crack than with cocaine alone. (AU) | |