PHD, Kent State University, 2024, College of Arts and Sciences / School of Biomedical Sciences

In nonhuman primates, the adrenal gland serves an important function in the stress response and as an additional source of steroid hormones: estrogens and testosterone. Therefore, the measurement of these adrenal steroids can provide valuable information regarding the relationship between stress and reproductive fitness. This research documented the hormonal maturation of the adrenal gland in small apes and explored how environmental, reproductive, and social changes influence adrenal hormone secretions in primates. The first objective was to determine the presence and pattern of adrenarche in the small apes. This objective collected cross-sectional fecal samples from 64 (35F, 29M) zoo-housed small apes and longitudinal fecal samples from 7 female zoo-housed small apes and measured dehydroepiandrosterone-sulfate (DHEAS) by enzyme immunoassay to determine the pattern of hormone secretion characteristic of the activation of the adrenal gland, or adrenarche. This study tested the effects of age, sex, and genus on fecal DHEAS levels using generalized linear mixed-effects models (GLMM). The results showed that age was positively correlated with a pre-pubertal increase in fecal DHEAS across all genera in the study (Hylobates spp., Hoolock spp., Nomascus spp., Symphalangus syndactylus) indicating that the small apes exhibit delayed adrenarche similar to the great apes. The second objective was to examine how reproductive state and social dominance impact fecal androgens and the glucocorticoid metabolite (GCM) to DHEAS ratio (GCM:DHEAS) in free-ranging Japanese macaques (Macaca fuscata) considering environmental factors (season and ambient temperature) and social behaviors (i.e., aggression, and affiliation) as potential variables influencing these steroid hormones. This objective measured fecal GCM and DHEAS in 354 samples by enzyme immunoassay in 11 female macaques (7 pregnant/lactating, 4 nonpregnant/nonlactating). Using GLMM, the results showed that pregnant and lactati (open full item for complete abstract)

Committee: Rafaela Takeshita (Advisor); Richard Meindl (Committee Member); Mary Ann Raghanti (Committee Member); Wilson Chung (Committee Member) Subjects: Animals; Behavioral Sciences; Biology; Developmental Biology; Ecology; Endocrinology; Evolution and Development; Physiology; Social Structure; Welfare; Zoology