Chronic mitochondrial energy impairment produces selective striatal degeneration and abnormal choreiform movements in primates.

TLDR

The pathogenesis of Huntington disease remains unclear, but impaired energy metabolism leading to excitotoxic injury is a proposed mechanism. The study aimed to determine whether chronic administration of 3‑nitropropionic acid could reproduce Huntington disease–like neuropathology and behavior in nonhuman primates. Researchers chronically administered 3‑nitropropionic acid, an irreversible succinate dehydrogenase inhibitor, to primates to induce metabolic impairment. Chronic 3‑NP treatment produced choreiform movements, dystonia, spontaneous dyskinesia, caudate and putamen lesions, loss of calbindin neurons, astrogliosis, preserved NADPH‑diaphorase neurons, dendritic proliferation, and spared striosomal organization, mirroring Huntington disease pathology.

Abstract

Although the gene defect responsible for Huntington disease (HD) has recently been identified, the pathogenesis of the disease remains obscure. One potential mechanism is that the gene defect may lead to an impairment of energy metabolism followed by slow excitotoxic neuronal injury. In the present study we examined whether chronic administration of 3-nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase, can replicate the neuropathologic and clinical features of HD in nonhuman primates. After 3-6 weeks of 3-NP administration, apomorphine treatment induced a significant increase in motor activity as compared with saline-treated controls. Animals showed both choreiform movements, as well as foot and limb dystonia, which are characteristic of HD. More prolonged 3-NP treatment in two additional primates resulted in spontaneous dystonia and dyskinesia accompanied by lesions in the caudate and putamen seen by magnetic resonance imaging. Histologic evaluation showed that there was a depletion of calbindin neurons, astrogliosis, sparing of NADPH-diaphorase neurons, and growth-related proliferative changes in dendrites of spiny neurons similar to changes in HD. The striosomal organization of the striatum and the nucleus accumbens were spared. These findings show that chronic administration of 3-NP to nonhuman primates can replicate many of the characteristic motor and histologic features of HD, further strengthening the possibility that a subtle impairment of energy metabolism may play a role in its pathogenesis.