Amyotrophic lateral sclerosis (ALS) is the collective term for a fatal motoneuron disease of different etiologies, with oxidative stress as a common molecular denominator of disease progression. Melatonin is an amphiphilic molecule with a unique spectrum of antioxidative effects not conveyed by classical antioxidants. In preparation of a possible future clinical trial, we explored the potential of melatonin as neuroprotective compound and antioxidant in: (1) cultured motoneuronal cells (NSC-34), (2) a genetic mouse model of ALS (SOD1(G93A)-transgenic mice), and (3) a group of 31 patients with sporadic ALS. We found that melatonin attenuates glutamate-induced cell death of cultured motoneurons. In SOD1(G93A)-transgenic mice, high-dose oral melatonin delayed disease progression and extended survival. In a clinical safety study, chronic high-dose (300 mg/day) rectal melatonin was well tolerated during an observation period of up to 2 yr. Importantly, circulating serum protein carbonyls, which provide a surrogate marker for oxidative stress, were elevated in ALS patients, but were normalized to control values by melatonin treatment. This combination of preclinical effectiveness and proven safety in humans suggests that high-dose melatonin is suitable for clinical trials aimed at neuroprotection through antioxidation in ALS.

Beta-amyloid peptides (A beta peptides) form the main protein component of the amyloid deposits found in the brains of Alzheimer's disease (AD) patients. Soluble A beta peptides, which are proteolytic fragments of the amyloid-precursor protein (APP) are constitutively secreted by cells expressing APP during normal metabolism [1] and are also present in human plasma and cerebrospinal fluid [2]. Missense mutations in Codon 717 of the APP gene are responsible for a small percentage of inherited AD cases (FAD) and increase the amount of A beta peptides containing additional carboxy terminal amino acids (A beta 1-42, A beta 1-43) [3, 4]. Recent findings indicate that FAD mutations in the presenilin 1 and 2 genes also increase the amount of these longer A beta peptides [5]. A beta 1-42 polymerizes more rapidly in vitro [6] than A beta 1-40 and has been identified as the major component of the brain amyloid deposits [7-9]. We recently developed a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) system [10] for the separation of these two peptides. Here we describe a modified version of the original SDS-PAGE procedure, which allows the separation of A beta 1-40, A beta 1-42, and A beta 1-43 for the first time. Detection of the three A beta peptides in the lower ng and pg range is realized by optimized silver staining or immunoblot procedures. These nonradioactive methods may validate results obtained by ELISA procedures used to study the metabolic fate of APP. They may help to define the neurotoxic potential of the longer A beta peptides in relation to their aggregation state.

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