Abstract
It has been demonstrated that AMP is hydrolyzed to adenosine(ADO) in the synaptic cleft by 5'-nucleotidase. This enzyme in the central nervous system is known to participate in neuroprotective properties. However, little is known about the relationship between 5'-nucleotidase activity and nicotine effects. Nicotine significantly increased 5'-nucleotidase in synaptosomes from hippocampus of adult rats. This activity was significantly inhibited by AMPCP which was a 5'-nucleotidase inhibitor. Nicotine significantly increased the hydrolysis of ATP, ADP, AMP and ADO by analysis with HPLC. These hydrolysis of adenine nucleotides were completely blocked in EGTA Ca2+-free buffer solution. We also examined the effect of ovariectomy (OVX) and estrogen replacement therapy (ER) on the activity of the enzyme that degrade adenine nucleotides in female rats. The release of ATP, ADP, AMP and ADO from hippocampus slice preparations by nicotine application in the buffer solution tended to decrease in the OVX group when compared to a control group. ER reversed the inhibition of the release of these nucleotides observed in OVX rats. The regulation of enzymes that hydrolyze these nucleotides in the hippocampus is essential in the modulation of the processes of neuronprotective properties. Results suggest the presence of a strong relationship between 5'-nucleotidase activity and nicotine effects to the ADO formation, and also to estrogen binding-sites. [J Physiol Sci. 2006;56 Suppl:S165]
