Locoweed-induced neuronal storage disease characterized by meganeurite formation.

Golgi staining was performed on cerebral cortex and thalamus of adult animals chronically intoxicated with an alpha-mannosidase inhibitor found in locoweed (Astragalus lentiginosus). The widespread occurrence of large, aspiny meganeurites was discovered on cortical pyramidal and thalamic principal neurons but aberrant spines and neurite growth were not observed. Ectopic neurite growth is known to be characteristic of alpha-mannosidosis of early onset in inherited and induced feline models. The absence of neuritogenesis in a storage disease known to be so characterized when induced in younger animals suggests that this unusual phenomenon is in some way linked to normal developmental processes associated with brain maturation.