Neuroprotektion durch Nikotin, Clenbuterol, Memantin und Prolin-reiches Peptid in einer Primärkultur von postnatalen Hippocampuszellen der Ratte

It is known that nicotine and nicotinereceptoragonists (Epibatidine, ABT-494) induce neuroprotection by induction of bFGF mRNA and bFGF protein. In the present study no changes in the expression of the growth factor TGF-ß1 caused by nicotine were seen in vivo and in vitro. In postnatal hippocampal cells nicotine did not influence the expression of the TGF-ß1 mRNA or the TGF-ß1 protein. We also could not see any influence of nicotinetartrat on the expression of TGF-ß1 in different brain regions (hippocampus, cortex, striatum) after immunhistochemical staining. Nicotine and nicotinereceptoragonists did not influence the level of mRNA and of protein of TGF-ß1. Clenbuterol is neuroprotective by induction of growth factors like NGF, bFGF or TGF-ß1. Clenbuterol protected cells against apoptosis induced by staurosporine and necrosis induced by glutamate. The infarct volume after cerebral ischemia in mice could also be reduced by clenbuterol. The combination of the ß2-adrenergic agonist clenbuterol and the NMDA-receptor antagonist memantine were examined regarding the neuroprotective effect in vivo and in vitro. In vivo and in vitro the combination of these drugs was more neuroprotective than the single drug alone. In a postnatal hippocampal cell culture the concentrations of 10 nM clenbuterol and 10 nM memantine were more protective than 10 nM clenbuterol or memantine alone against an apoptotic cell death. The combination of 1 nM clenbuterol and memantine was more protective against the necrotic cell death than each drug alone. Usually one enantiomere of the racemate mediates the pharmacological effect. The enantiomere, which shows an effect, is called eutomere, the other one is called distomere. In vivo and in vitro the (+)-enantiomere of clenbuterol was neuroprotective. The (-)-enatiomere showed no protective effect. In a postnatal hippocampal cell culture only the (+)-enantiomere is neuroprotective against an apoptotic and necrotic cell death. In vivo the dosis of 0.3 and 1.0 mg/kg body weight (+)-clenbuterol reduced the infarct volume after cerebral ischemia in mice. In vitro no differences in activation of astroctyts and expression of NGF could be seen between both the enantiomeres. Neuroprotection could also be reached by proline-rich peptide (PRP). A primary culture of postnatal hippocampal cells was pretreated for 8 h with 10-5 g/ml PRP. After their pretreatment apoptotic cell death was induced by staurosporine. Under these conditions this peptide was protective against an apoptotic cell death. PRP has a structure similar to vasopressin. However, vasopressin was not neuroprotective under these conditions. Studies on the mechanism of neuroprotection of PRP were performed. It was of interest to study, where this peptide was localized in the cell. Is this peptide localized in the cytosol or in the nucleus? For these studies immunocytochemical analysis should have been used. Moreover the monoclonal antibody against this peptide was not specific enough. In a Western-Blot, a lot of unspecific signals were detected.