Efeito da curcumina sob a atividade das enzimas ntpdase e acetilcolinesterase em linfócitos de ratos expostos à fumaça do cigarro

Abstract

The exposure to the cigarette smoke xenobiotics is related with a compromised immune system and the development of many diseases such as Chronic Obstructive Pulmonary Disease (COPD) and lung cancer. The NTPDase and acetylcholinesterase (AChE) are important enzymes involved in the regulation of immune system and alterations in their activities have been showed in many diseases including the related with cigarette smoke-exposure. The curcumin (Cur), polyphenol isolated from the rhizomes of Curcuma longa and widely employed in the culinary and oriental traditional medicine, has many biological activities such as antioxidant, anticarcinogenic and antiinflammatory. Considering the relevance of lymphocytes in the establishment and progression of immune responses, the purpose of this study was to evaluate the effect of curcumin in the NTPDase and AChE activities in peripheral lymphocytes (PL) and lung lymphocytes (LL) from rats exposed to cigarette smoke. The establishment of a protocol to lung lymphocytes separation using the lung tissue was performed with the objective of optimize the cellular viability and the purity of separation, using as references the protocols for separation of human peripheral and lung lymphocytes. The experimental procedure to evaluate the effect of curcumin on the NTPDase and AChE in lymphocytes from rats exposed to the cigarette smoke was divided in two sets of experiments. In the first set, the animals were randomly divided into four groups: Vehicle; Cur 12.5 mg/kg; Cur 25 mg/kg; Cur 50 mg/kg. In the second experimental set, the animals were divided into 5 groups: Vehicle; smoke exposed; smoke and Cur 12.5 mg/kg; smoke and Cur 25 mg/kg; smoke and Cur 50 mg/kg. Curcumin was diluted with corn oil, administered by oral gavage, not exceeding 1 ml/kg body weight. The treatment with curcumin and cigarette smoke was carried out once a day, 5 days each week, during 30 days. It was administered the curcumin or corn oil, and approximately 10 minutes later, the smoking groups were exposed to the sidestream smoke of four commercial cigarettes (nicotine 0.9 mg, tar 10 mg each) inside a whole-body smoke exposure chamber. Control animals were placed in an equal chamber for the same amount of time. After thirty days, the animals were euthanized, the lung was removed and the peripheral blood collected for separation of lymphocytes. With the standardization of the protocol to the separation of lung lymphocytes it was achieved a percentage of lymphocytes higher than 82% and it was observed a strong correlation between the enzyme activity using ATP and ADP as substrates, which indicates that the results can be expressed in milligram of protein, millions of cells and millions of viable cells. The results from the experiments with the cigarette smoke exposure demonstrated that the treatment with curcumin prevented the alterations observed in the cigarette smoke-exposed animals such as the decrease of ATP and ADP hydrolysis in PL and LL, and the increase of AChE activity in PL. We suggest that the treatment with curcumin was protective, since the high concentrations of ATP are positively related with inflammation and tissue damage, and the emphysematous damages observed in cigarette smoke-exposed was not observed in the groups treated with curcumin.