Sistemas purinérgico e colinérgico e perfil oxidativo no encéfalo de roedores: influência do alumínio e de diferentes dietas

Abstract

In this study, the effects of Aluminium (Al) and of different diets, both individually and in association, were investigated through the determination of NTPDase, 5 -nucleotidase and acetylcholinesterase (AChE) activities in rat brain. In addition, we investigated said effects on oxidative stress by determining activity of the antioxidant enzyme catalase as well as lipid peroxidation by measuring TBARS levels. Male rats were exposed to Al (50 mg/kg/day) by gavage during three months. NTPDase and 5 -nucleotidase activities were then determined in synaptosomes of cerebral cortex and hippocampus, as well as in platelets. ATP, ADP and AMP hydrolysis was increased in both synaptosomes of cerebral cortex and hippocampus, as well as in platelets. AChE activity and TBARS levels were determined in homogenate of different brain structures in mice exposed to Al (2.7 mg/kg/day) by gavage during three months. The group that received Al+sodium citrate presented an increase in AChE activity in hippocampus, striatum, cortex and hypothalamus. On the other hand, the group that received only Al presented a decrease in AChE activity in hypothalamus and an increase in striatum. Moreover, AChE was determined in S1 of different brain structures, synaptosomes of cerebral cortex and erythrocytes of male rats exposed to Al (50 mg/kg/day) by gavage during three months. There was an increase in AChE activity in S1 of striatum and hypothalamus and in synaptosomes of cerebral cortex and erythrocytes. However, in S1 of cerebellum, hippocampus and cortex there was a decrease. In addition, the effect of diets rich in saturated fat and refined sugar on AChE activity in homogenate of different brain structures, on catalase activity in liver and on TBARS levels in plasma and liver were determined in female and male rats. There was a decrease in AChE activity in hippocampus, cortex and hypothalamus of male and female rats given both a diet rich in saturated fat and a diet rich in refined sugar. There was no alteration of AChE activity in cerebellum and striatum. For both diets, catalase activity was increased in liver of male and female rats. In addition, considering the alterations brought about by the individual exposure to both environmental factors, Al and diets, the effect of the association of both factors was evaluated. Thus, after a period of three months of exposure to both Al (50 mg/kg/day) by gavage and diets rich in saturated fat and saturated/polyunsaturated fat ad libitum, NTPDase and 5 -nucleotidase activities were determined in synaptosomes of cerebral cortex and platelets of rats. Animals receiving both diets in association with Al and Al/Ci presented an increase in ATP, ADP and AMP hydrolysis in synaptosomes of cerebral cortex and platelets. The results obtained in the present study demonstrate that exposure to both environmental factors, Al and diets rich in saturated fat and refined sugar, either individually or in association, affected the purinergic and cholinergic systems and caused oxidative stress in rats.