Comparative study of perception and processing of socially or sexually significant odor information in male rats with normal or accelerated senescence using fMRI.

Olfaction plays an important role in mammals while aging causes olfactory dysfunction. Here the features of olfactory function in aging male rats were studied. We compared brain activity of regions involved in the perception (olfactory bulbs) and processing (cerebral cortex, hippocampus, hypothalamus) of sexually or socially significant odor stimulus with 11.7 T MR-scanner and odor perception using behavioral tests in 5-month old males with normal (Wistar rats) or accelerated senescence (d-galactose-treated Wistar rats (150 mg/kg/day, i.p., 12 weeks) or OXYS rats with hereditary defined accelerated aging). d-galactose-treated Wistar males had altered BOLD-response in the centers processing socially significant odor information and changed patterns of the functional connectivity. We detected no significant changes in the olfactory function of OXYS males probably due to compensatory processes. In saline-treated Wistar rats, the correlation of BOLD-responses to both types of stimuli in the olfactory bulbs and cerebral cortex indicated changes in odor differentiation. Behavioral tests showed no significant differences between groups. However, the time of odor exploration increased in d-galactose-treated males indicating changes in odor recognition. Thus, we first revealed that in animal model of pharmacologically induced aging olfactory dysfunction occurred at the level of the centers processing socially significant odor information while the centers of odor perception (olfactory bulbs) remained unaffected. Alterations observed in Wistar rats chronically treated with saline evidenced the influence of long-term manipulations with experimental animals on olfactory function per se.