Calcium binding proteins in motoneurons at low and high risk for degeneration in ALS

Recent reports challenge the hypothesis that expression of calcium binding proteins contributes to the greater resistance of some motoneurons to degen eration in amyotrophic lateral sclerosis (ALS). We therefore re-examined, u sing immunohistochemistry, the expression of calbindin, calretinin and parv albumin in vulnerable (hypoglossal, XII; and cervical spinal) and resistant (oculomotor, III) motoneurons of adult rats. Calbindin immunoreactivity wa s lacking in motor nuclei but strong in the dorsal horn. Calretinin was exp ressed in spinal, but not III or XII, motoneurons. Parvalbumin immunoreacti vity, tested with a polyclonal antibody, was intense in spinal and ill, but not XII, motoneurons; however, no staining in the ventral horn was observe d with a monoclonal antibody. Differential expression of calretinin and par valbumin within vulnerable motoneurons suggests that immunoreactivity for t hese proteins is not a reliable marker for resistance to degeneration in AL S. NeuroReport 11:3305-3308 (C) 2000 Lippincott Williams & Wilkins.