Elderly Female Rhesus Macaques Preserve Lung Alveoli With Estrogen/Progesterone Therapy

The aging lung is associated with increased susceptibility to chronic inflammatory diseases such as chronic obstructive pulmonary disease where females have been reported to be more susceptible than males. The changes in reproductive hormones due to aging may directly or indirectly affect lung structure and function and little is known on the mechanism of these changes. Twenty female rhesus macaques were divided into four groups. Ovariectomy (OVX) was performed on eight animals with three receiving estrogen/progesterone therapy (HRT) and five animals given implants containing vehicle. The remaining 12 animals represented control groups of ages 10-14 years (n = 6) and ages 20-24 (n = 6). A design-based stereological method was employed to estimate the number of alveoli in the right middle lung lobe along with hormone analysis for possible correlation. A significant decrease was found in the number of alveoli in the vehicle OVX animals compared to intact younger adult females (P < 0.001). A significant increase in alveoli between OVX vehicle animals and those on HRT was also found (P < 0.0001). There was difference in the number of alveoli between younger adult animals and animals on HRT. The loss of ovaries and hormones had a significant effect on alveolar lung morphology. This result mimics what is seen in the aging process and could contribute to gender differences reported in the elderly. Hormone replacement, as reported here, could possibly slow the loss of alveoli due to the aging process or aid in alveolar regeneration through direct or indirect mechanisms. Anat Rec, 299:973-978, 2016. © 2016 Wiley Periodicals, Inc.