Spontaneous behaviour, habituation, and sniffing responsiveness of aged female rats.

Wistar female rats of two age groups were tested with the aim to investigate whether changes in spontaneous behaviour, habituation and sniffing responsiveness can be considered to be a function of age. Compared with young animals (2 months), aged animals (24 months) had lower locomotor and exploratory as well as investigatory scores but higher grooming and relaxation scores when exposed to a novel environment. Further, aged animals were inferior in habituation as characterized by decreased retention scores in investigatory and grooming patterns when exposed to the same environment for the second time. Finally, they exhibited both lower sniffing behaviour in the scent-free box and lower sniffing responsiveness to scent stimuli coming from the adult male rats. Thus, age-related behavioural changes repeatedly reported in learning and memory function were sufficiently complemented by the changes in natural behavioural repertoire. These behavioural patterns may serve as a model for the study of functional aspects of brain ageing as well as for search for geriatric drugs.