Age-related alterations in respiratory burst activation induced by various stimuli in mouse peritoneal macrophages treated with thermal stress.
The respiratory burst stimuli zymosan, opsonized zymosan (OZ), or phorbol myristate acetate (PMA) were used in order to assess the ability of thioglycolate elicited peritoneal macrophages (PM) from young and senescent mice to generate superoxide anions. The amount of superoxide generated by PM from senescent mice in response to zymosan was higher by 20% than in PM from young mice. However, superoxide release in response to stimulation by OZ or PMA was 30% and 60% higher in PM from young mice. Thermal stress reduced the amounts of superoxide generated in response to zymosan in both age groups. However, while at 42.5 degrees C PM from senescent mice demonstrated irreversible loss of activity. PM from young mice recovered up to 70% of their superoxide generating activity. Thermal stress also affected protein synthesis in a temperature and age-dependent manner. Macrophage activation level increased in the old but remained unaffected in the young as attested by transglutaminase activity. This suggests that the mechanisms of up- or down-regulation of superoxide release in the old differ under heat stress conditions.
Lavie
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Department of Morphological Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, P.O. Box 9649, Haifa 31096, Israel.