The impact of voluntary exercise on relative telomere length in a rat model of developmental stress

Abstract

BackgroundExposure to early adverse events can result in the development of later psychopathology, and is often associated with cognitive impairment. This may be due to accelerated cell aging, which can be catalogued by attritioned telomeres. Exercise enhances neurogenesis and has been proposed to buffer the effect of psychological stress on telomere length. This study aimed to investigate the impact of early developmental stress and voluntary exercise on telomere length in the ventral hippocampus (VH) and prefrontal cortex (PFC) of the rat. Forty-five male Sprague–Dawley rats were categorised into four groups: maternally separated runners (MSR), maternally separated non-runners (MSnR), non-maternally separated runners (nMSR) and non-maternally separated non-runners (nMSnR). Behavioural analyses were conducted to assess anxiety-like behaviour and memory performance in the rats, after which relative telomere length was measured using qPCR.ResultsMaternally separated (MS) rats exhibited no significant differences in either anxiety levels or memory performance on the elevated-plus maze and the open field compared to non-maternally separated rats at 49 days of age. Exercised rats displayed increased levels of anxiety on the day that they were removed from the cages with attached running wheels, as well as improved spatial learning and temporal recognition memory compared to non-exercised rats. Exploratory post-hoc analyses revealed that maternally separated non-exercised rats exhibited significantly longer telomere length in the VH compared to those who were not maternally separated; however, exercise appeared to cancel this effect since there was no difference in VH telomere length between maternally separated and non-maternally separated runners.ConclusionsThe increased telomere length in the VH of maternally separated non-exercised rats may be indicative of reduced cellular proliferation, which could, in turn, indicate hippocampal dysfunction. This effect on telomere length was not observed in exercised rats, indicating that voluntary exercise may buffer against the progressive changes in telomere length caused by alterations in maternal care early in life. In future, larger sample sizes will be needed to validate results obtained in the present study and obtain a more accurate representation of the effect that psychological stress and voluntary exercise have on telomere length.

Chronic early life stress induced by limited bedding and nesting (LBN) material in rodents: critical considerations of methodology, outcomes and translational potential

“…In addition, the LBN environment had consequences for brain telomere length that differ between males and females (Arun Asok, Bernard, Rosen, Dozier, & Roth, 2014; A Asok, Bernard, Roth, Rosen, & Dozier, 2013). Telomere length is another biomarker of stress emerging as highly sensitive to variations in the caregiving environment (Botha et al, 2012; Drury et al, 2012; Tyrka et al, 2010). …”

Training Performed Above Lactate Threshold Decreases p53 and Shelterin Expression in Mice

“…The role of exercise intensity has not being analyzed properly in the few studies investigating the effects of chronic exercise on telomere biology. Usually the studies have used voluntary wheel running as intervention, or individuals already adapted to exercise (cross-sectional studies) or individuals performing intervention at only one exercise intensity [5,40,47]. In this sense, the determination of lactate threshold (LT) has been used as a tool to distinguish limits of metabolic domains during exercise in humans and rodents, such that exercise intensity is considered moderate below the LT and of high-intensity above the LT [2,3].…”

Intrauterine exposure to maternal stress alters Bdnf IV DNA methylation and telomere length in the brain of adult rat offspring

“…Rats selectively bred for enhanced depressive‐like symptoms (i.e., the Flinders‐sensitive line) show reduced telomere length in the hippocampus (Wei et al, 2015), supporting a role for telomere shortening in the brain. In contrast, other studies have found that postnatal stress (e.g., maternal separation or caregiver maltreatment) is associated with longer telomeres in the ventral hippocampus and medial prefrontal cortex (Asok et al, 2014; Botha et al, 2012). The findings here complement our previous work with regard to stress effects on a common brain region (i.e., the mPFC), but differ in the direction of telomere change.…”