Differential expression of mGluR5 in human lumbosacral motoneurons

Glutamatergic excitotoxicity is one of the main hypotheses to explain motoneuronal degeneration in amyotrophic lateral sclerosis (ALS). Interestingly, autonomic motoneurons remain almost unaffected, even in late stages of the disease. Since glutamate receptors may mediate neurotoxic as well as neuroprotective effects, different expression patterns may contribute to neuronal vulnerability. We and others have previously described a significantly higher expression of group I metabotropic glutamate receptors (mGluRs) in rat autonomic motoneurons compared to somatic motoneurons. Here we show a selective expression of the group I receptor mGluR5 in human parasympathetic Onuf's nucleus. These results are in accordance with previous findings in rat and strengthen the hypothesis that mGluR expression may provide a possible clue to the selective vulnerability in ALS.