Nicergoline, a drug used for age-dependent cognitive impairment, protects cultured neurons against β-amyloid toxicity

Abstract

Nicergoline, a drug used for the treatment of Alzheimer's disease and other types of dementia, was tested for its ability to protect neurons against β-amyloid toxicity. Pure cultures of rat cortical neurons were challenged with a toxic fragment of β-amyloid peptide (βAP 25–35) and toxicity was assessed after 24 h. Micromolar concentrations of nicergoline or its metabolite, MDL, attenuated βAP 25–35-induced neuronal death, whereas MMDL (another metabolite of nicergoline), the α 1-adrenergic receptor antagonist, prazosin, or the serotonin 5HT-2 receptor antagonist, methysergide, were inactive. Nicergoline increased the basal levels of Bcl-2 and reduced the increase in Bax levels induced by β-amyloid, indicating that the drug inhibits the execution of an apoptotic program in cortical neurons. In mixed cultures of rat cortical cells containing both neurons and astrocytes, nicergoline and MDL were more efficacious than in pure neuronal cultures in reducing β-amyloid neurotoxicity. Experiments carried out in pure cultures of astrocytes showed that a component of neuroprotection was mediated by a mechanism of glial–neuronal interaction. The conditioned medium of cultured astrocytes treated with nicergoline or MDL for 72–96 h (collected 24 h after drug withdrawal) was neuroprotective when transferred to pure neuronal cultures challenged with β-amyloid. In cultured astrocytes, nicergoline increased the intracellular levels of transforming-growth factor-β and glial-derived neurotrophic factor, two trophic factors that are known to protect neurons against β-amyloid toxicity. These results raise the possibility that nicergoline reduces neurodegeneration in the Alzheimer's brain.