Huntingtin in the amygdaloid basolateral complex is correlated with Vonsattel staging in Huntington’s disease

Huntington's disease has traditionally been considered a motor disorder, but it is currently classified as a multisystem neurodegenerative disease that involves brain regions, such as the amygdala, and causes depression. The aim of the present study was to analyse the distribution of huntingtin in the human amygdaloid basolateral complex, considering its nuclei, sex, triplet repeats and Vonsattel score, as well as to characterize the cellular relationships between huntingtin and associated copathologies. The present study included 23 human brain samples from patients (males and females) with and without Huntington's disease, Parkinson's disease and Alzheimer's disease. An unbiased stereology approach was used to quantify huntingtin deposits. Multiple immunofluorescence experiments were conducted to analyse the relationship between huntingtin and glial populations. Immunohistochemistry against pathological markers of other neurodegenerative diseases was also carried out. Quantification data did not reveal differences among different nuclei (basomedial, basolateral or lateral) in the basolateral complex or according to sex. Huntingtin deposits did not correlate with cytosine-adenine-guanine (CAG) repeats. However, these deposits were positively correlated with pathological Vonsattel grades. Additional aggregates of other pathological proteinopathies were also observed. This correlation between the human basolateral amygdaloid complex and the Vonsattel stage provides a new perspective for neuropathological diagnosis and helps in understanding nonmotor symptoms such as depression.