CHARACTERIZATION OF DERMATOLOGICAL CHANGES IN GERIATRIC RHESUS MACAQUES

Nonhuman primates are frequently used for aging studies. We observed a high prevalence of skin disease among a group of geriatric rhesus mon keys (mean age = 25 years; n = 9) used in aging behavioral studies, Gr oss and histopathologic changes in the skin of these geriatric rhesus were compared with skin from control adult monkeys (mean age = 10; n = 4) and sun-exposed monkeys (mean age = 11; n = 4) to characterize age -related skin changes. Biopsy specimens were taken from four specified skin locations (lateral to bridge of nose, ventral midline, dorsal mi dline, perineal area) and from additional areas where skin lesions wer e present. Samples were routinely processed and evaluated by light mic roscopy. Blood samples were collected and tested for estrogen, thyroid -stimulating hormone, triiodothyronine, thyroxine, and cortisol levels , The axilla was swabbed and samples were obtained for bacterial cultu ring. All nine of the geriatric monkeys had notable dermal lesions, wh ile one of the control monkeys and one of the sun-exposed monkeys had abnormal findings. Major gross findings included increased areas of er ythematous skin, wrinkling, focal skin scaling, thinning of hair, foot calluses, and exudative lesions, Histologic skin changes included sub acute dermatitis, acanthotic dermatitis, and a lesion resembling an ea rly solar lentigo in the sun-exposed animal. These changes were not as sociated with hormonal abnormalities or bacterial pathogens, Histologi c changes are compatible with nonspecific skin changes observed in eld erly humans. This study establishes a baseline of dermatologic changes of the aging rhesus macaque.