Decreased anxiety levels related to aging

Abstract

The present experiment investigated the effects of aging on emotional behavior, without concomitant influences from any previous behavioral manipulation apart from weighing the rats. Anxiety-related behaviors were measured in the elevated plus-maze (EPM). Performance in the open field (OF) was also assessed to control for any effect of aging on exploratory behavior that could account for changes in emotional behavior. Fifty-two naïve male Wistar rats of 3 (3MO), 17 (17MO), or 24 (24MO) months, were submitted to two sessions (5 min each) of EPM, followed by two sessions (2 min each) of OF, on 4 consecutive days. The main emotional indices (open arm entries, ratio of open arm entries to total entries, time spent in open arms, ratio of time in open arms to time in four arms, open arm ends, and head dips) measured in the EPM indicated a lower level of anxiety in aged (24MO) than in young (3MO) rats, whereas middle-aged (17MO) rats showed intermediate values between those of 3MO and 24MO rats; 3MO rats showed higher general motor activity (number of rearings in closed arms of EPM and in OF, and higher number of areas crossed in OF) than 17MO and 24MO rats. We conclude that aging is associated with a decrease in anxiety and in general motor activity.

Synergistic effects of age and stress in a rodent model of stroke

“…Similar findings have been made in experimental studies showing greater reduction in motor activity [16] and diminished performance in skilled and unskilled motor tasks in aged rats [17,28]. Sustained high levels of glucocorticoids may compromise the ability to overcome ischemia-induced deficits both on the neuronal and functional level [18][19][20][21][22].…”

Elevated plus-maze performance of Fischer-344 rats as a function of age and of exposure to 56Fe particles

“…While these results differ from those of some experiments which report that rats normally avoid the open arms of the maze (Andrade et al, 2003;Baguszewski and Zagrodzka, 2002;Torras-Garcia et al, 2004), other investigators (Imhof et al, 1993) have also reported that their younger rats spent more time in the open arms of the maze than in the closed arms. As the age of the rats increases, there are corresponding increases in the preference for the closed arms of the maze, which would indicate an increase in baseline anxiety levels.…”

The role of anxiety in the development of levodopa-induced dyskinesias in an animal model of Parkinson’s disease, and the effect of chronic treatment with the selective serotonin reuptake inhibitor citalopram

“…There were several reasons for this: firstly, older animals better correspond to the clinical situation of LID in patients with PD. Secondly, previous studies have reported that older rats display a significantly lower basal anxiety level than younger animals (Boguszewski and Zagrodzka 2002;Torras-Garcia et al 2005), which ensured that sufficient animals had a low anxiety state. Thirdly, older rats have stable weight and, as rats are prandial drinkers and citalopram was administered via drinking water in the present study, it ensured that all rats received equivalent doses.…”