Motor neuronal death in sporadic amyotrophic lateral sclerosis (ALS) is not apoptotic. A comparative study of ALS and chronic aluminium chloride neurotoxicity in New Zealand white rabbits

Abstract

Whether diseased motor neurones in sporadic amyotrophic lateral sclerosis (ALS) die via apoptosis is unknown. Because this relates primarily to difficulties in utilizing post-mortem tissue from end-stage disease, motor neurone degeneration in ALS spinal cord was compared with that of a model of a chronic motor neurone degeneration. Degenerating motor neurones in ALS, identified by ubiquitin immunoreactivity, did not demonstrate the morphological characteristics of apoptosis and were not c-Jun immunoreactive or TUNEL positive. A temporal analysis of spinal motor neurone death in the chronic AlCl3 neurotoxicity model of motor neurone degeneration was also undertaken. AlCl3 was administered intracisternally every 4 weeks and, at intervals of 51, 107, 156 and 267 days, evidence of apoptosis was sought by morphology, TUNEL hybridization or DNA laddering. Double-labelling immunostudies were also performed with antibodies to either c-Jun, ubiquitin or high molecular weight neurofilament (NFH) with TUNEL hybridization. Although significant neurone loss was evident, apoptosis was not found. These studies demonstrate a lack of apoptosis in ALS spinal motor neurones and suggest that this observation does not relate to the utilization of post-mortem tissue in which apoptotic neurones may have been lost.

Programmed cell death in amyotrophic lateral sclerosis

“…The author of that study has also documented DNA fragmentation in anteriorhorn gray matter of the spinal cord and motor cortex of ALS cases by gel electrophoresis (38), a technique not frequently used in the nervous system to identify apoptosis since, in many neurological situations, it is difficult to obtain samples with a sufficiently high proportion of dying cells. In contrast to all these positive findings, other groups, using similar techniques and tissue samples, have failed to provide any evidence of internucleosomal cleavage of DNA in postmortem tissue from human ALS cases or from animal models of the disease (32,41,42). Although the actual reason for these divergent results is unclear, they cast doubt on the reliability and even the specificity of such findings.…”

Species-dependent neuropathology in transgenic SOD1 pigs

“…Real-time PCR of transgene copy numbers revealed that transgenic pigs carried various numbers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) of the transgene (Supplementary information, Table S1). Using immunohistochemistry staining with an antibody specific to hSOD1, we could confirm the expression of transgenic hSOD1 in the lumbar spinal cords of a stillborn transgenic pig, but not in a wild-type one ( Figure Figure 1 Generation of hSOD1 (G93A) transgenic pigs.…”

“…These transgenic SOD1 mouse models carry a greatly elevated protein load compared with human ALS tissues, and these animals exhibit some phenotypic features, such as intracytoplasmic vacuoles derived from the mitochondria and the endoplasmic reticulum, which are rarely found in human ALS tissues [11][12][13]. In terms of the mechanisms of neuronal death in ALS, most evidence from mouse models suggests that apoptosis may play a crucial role in the death of motor neurons [14][15][16]; however, conclusive evidence of apoptosis has been difficult to detect in humans [17][18][19][20]. In addition, intranuclear inclusions were seen in the brains of ALS patient with SOD1 mutations [21][22][23], which have nevertheless not been found in transgenic mutant SOD1 mouse models.…”

Cell death mechanisms in neurodegeneration

“…These include cell shrinkage, chromatic condensation, DNA fragmentation, and increased expression of both proapototic (c-Jun, c-Fax, Bax, p53, APO-1/Fas-CD95, Fas, Fas-L, caspase 8 and 9, activated caspase 3, tumor necrosis factor R1/p55), and antiapoptotic proteins (Bcl-2, Bcl-x), or DNA repair enzymes, such as Ref-1 and the co-expressed GADD45 [13, 16,20,[23][24][25][26][27][28][29][30][31][32][33][34][35][36]. However, other groups have observed little or no evidence of apoptotic neuronal cell death associated with neurodegenerative diseases [24,[37][38][39][40][41][42][43]. These studies have relied on the presence of Table 2).…”