Snake coiled fibres in rat soleus muscle in chloroquine induced myopathy share immunohistochemical characteristics with amyloid depositions in Alzheimer's disease brain tissue

Pathological and immunopathological studies were carried out on snake coiled fibres (SCF) which occurred in affected soleus muscle in chloroquine treated rats. The SCF began to appear in denervated soleus muscle by 8 days after chloroquine injection. By day 14, typical SCF were observed with an unusual swirling pattern of the myofibrils, presenting a bizarre appearance. By day 21 or later, the SCF became less remarkable, and were fragmented and broken apart to form large vacuoles. Immunopathological studies demonstrated that the amyloid β (Aβ ) and N and C‐terminal regions of amyloid precursor protein (APP), and the amyloid associated proteins tested, apolipoprotein E (apoE), SP‐40,40, α1‐antichymotrypsin (α1‐ACT), and ubiquitin, which are known to be components of amyloid depositions found in Alzheimer's disease (AD) affected brains, were present in the SCF. ApoE, SP‐40,40, α1‐ACT, and ubiquitin are induced following certain cell challenges (e.g. heat shock, various drugs and injury). The significance of APP, Aβ, and amyloid associated proteins are discussed in respect to snake coiled fibre formations in chloroquine rat myopathy and in the amyloidogenesis of AD.