Resumo

Effect of Huperzine-A on S100B secretion in primary astrocyte cultures Paula S. Lunardi, Patrícia Nardin, Marina C. Leite, Maria Cristina B. Guerra, Daniela F. Souza, Paulo Roberto Klein, Carlos Alberto Gonçalves Key words: Alzheimer’s disease, Huperzine-A, S100B Objectives: Alzheimer´s disease (AD) involves in multiple pathogenic events, including neuroinflammation and oxidative stress, leading to a neuronal population decrease, especially of cholinergic neurons. This cholinergic hypothesis justifies the use of acetylcholinesterase inhibitors (IAChE) as the strategy for patients with AD. Huperzine A (HupA), a novel Lycopodium alkaloid isolated originally from a traditional Chinese medicine, seems to be an alternative. HupA is a reversible, potent and selective IAChE. Its potency and duration of AChE inhibition rival those of physostigmine, galanthamine, donepezil and tacrine, approved for treatment of DA. S100B is a calcium-binding protein, produced and secreted by astrocytes in the central nervous system (CNS) and plays a regulatory role in the cytoskeleton and cell cycle. Moreover, extracellular S100B, a marker of glial activation in several conditions of brain injury, for example in AD, has a trophic or apoptotic effect on neurons, depending on its concentration. Here we investigated the effect of HupA, tacrine and acetylthiocholine on S100B secretion and content of S100B and GFAP in cortical astrocyte cultures. Methods: Primary astrocyte cultures were prepared from cerebral cortex of newborn Wistar rats and were allowed to grow to confluence. S100B secretion was determined in culture medium by ELISA at 1 and 24 h of exposure to HupA, tacrine and acetylthiocholine at 10 and 100 µM. Cell integrity and viability was evaluated by MTT reduction assay and LDH release. Results: HupA and acetylthiocholine (100 µM) increased S100B secretion after 1 h of treatment (175% ± 24.1, n=6 and 182.7% ± 10.1, n=4 respectively). In 24 h of treatment, tacrine (100 µM) was able to reduce the S100B intracellular content in astrocyte cultures (78.2% ± 4.9, n=6), but it was not observed with HupA or acetylthiocholine. The GFAP immunocontent did not change after these treatments. No alteration in cell integrity and viability was observed. Conclusion: Our data show that HupA can regulate S100B secretion mechanisms and this modulation could be activated by cholinergic receptors. In fact, this was the first observation, to our knowledge, that S100B secretion could be modulated by cholinergic mechanism. This effect of HupA on S100B secretion could represent a trophic and therapeutic useful effect of this compound in AD. Financial Support: CNPq, CAPES.