In this study, we examined changes in hormonal status, oxidative status, antioxidant defense, and peripheral blood leukocyte telomere length in male Javanese macaques (Macaca fascicularis) following transfer from group housing to individual cages as a model of social isolation. The study was performed in ten male Javanese macaques aged 11-17 years using a longitudinal design: the parameters were assessed in the same animals before transfer to individual cages and after 60 days of isolation. Malondialdehyde (MDA) concentration, superoxide dismutase (SOD) and catalase activities, cortisol, testosterone, and thyroglobulin levels, as well as absolute mean telomere length, were measured. A statistically significant decrease in telomere length (p = 0.0062), MDA concentration, and catalase activity (p < 0.01), as well as an increase in SOD activity and cortisol level (p < 0.05), was observed. Testosterone showed a decreasing trend, whereas thyroglobulin showed an increasing trend. The obtained data indicate systemic changes in the studied parameters in response to isolation. Changes in telomere length and oxidative status may reflect the involvement of mechanisms related to DNA damage and antioxidant system function. The results are consistent with the concept of stages of the general adaptation syndrome.
