AUTHOR=Appleman Maria-Luisa , Thomas Jeremy L. , Weiss Alison R. , Nilaver Benjamin I. , Cervera-Juanes Rita , Kohama Steven G. , Urbanski Henryk F. 

TITLE=Effect of hormone replacement therapy on amyloid beta (Aβ) plaque density in the rhesus macaque amygdala

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2023.1326747

DOI=10.3389/fnagi.2023.1326747

ISSN=1663-4365

ABSTRACT=<sec><title>Background</title><p>Amyloid beta (Aβ) plaque density was examined in the amygdala of rhesus macaques, to elucidate the influence of age, diet and hormonal environment.</p></sec><sec><title>Methods</title><p>Luminex technology was used to measure cerebrospinal fluid (CSF) concentrations of Aβ<sub>40</sub> and Aβ<sub>42</sub> across three decades, while immunohistochemistry was used to examine Aβ plaque density in the amygdala.</p></sec><sec><title>Results</title><p>Aβ<sub>40</sub> was found to be the predominant isoform of Aβ in the CSF, but neither Aβ<sub>40</sub> or Aβ<sub>42</sub> concentrations showed an age-related change, and the ratio of Aβ<sub>42</sub> to Aβ<sub>40</sub> showed only a marginal increase. Significantly fewer Aβ plaques were detected in the amygdala of old ovariectomized animals if they received estradiol HRT (<italic>p</italic> &lt; 0.001); similar results were obtained regardless of whether they had been maintained on a regular monkey chow for ∼48 months or on a high-fat, high-sugar, Western-style diet for ∼30 months.</p></sec><sec><title>Conclusion</title><p>The results demonstrate that HRT involving estrogen can reduce Aβ plaque load in a cognitive brain region of aged non-human primates. The results from this translational animal model may therefore have clinical relevance to the treatment of AD in post-menopausal women, whether used alone, or as a supplement to current pharmacological and monoclonal antibody-based interventions.</p></sec>