Response of the Hypothalamic-Pituitary-Adrenocortical System to Oxidative Stress in Mice of Different Age

Response of the hypothalamic-pituitary-adrenocortical system (HPAS) of aged (15 month-old) and young (2 month-old) mice to oxidative stress has been studied. The objects of the study were magnocellular neurosecretory centers (NSC) of hypothalamus, the supraoptic (SON) and paraventricular (PVN) nuclei, as well as the adrenals. We studied distribution of neurosecretory cells (NSC) that synthesize protein c-fos participating in the initial stage of apoptosis. Besides, the number of cells submitted to apoptosis was determined using luminescent microscopy. The obtained results showed that the activity of NSC and the number of apoptotic cells in the SON of young and aged mice did not changes at hyperoxia. Thus, the oxidative stress does not seem to be specific of this nucleus. However, oxygen increased the number of c-fos-immunoreactive NSC in the PVN of animals of both ages. The obtained data indicate that oxygen can cause development of apoptosis of the NSC and that protein c-fos is synthesized at one of the initial stages of this process.