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.
Highlights
Exposure to early adverse events can result in the development of later psychopathology, and is often associated with cognitive impairment
There were no significant differences in anxiety levels, as measured in the open field (OF) and elevated plus maze (EPM), in maternally separated (MS) and non-maternally separated rats at postnatal day 49 (PND49)
Exercised rats (MSR and non-maternally separated runners (nMSR)) performed significantly better in the Morris water maze (MWM) and the temporal order task in comparison to non-exercised rats (MSnR and non-maternally separated non-runners (nMSnR))
Summary
Exposure 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. The exact mechanisms through which stress influences physical and psychological wellbeing are presently unclear, increasing evidence supports the involvement of accelerated cell aging in this process [4]. The extent of this progressive aging in eukaryotic organisms can be catalogued by means of telomeres, the guaninerich sections of recurring DNA sequences at the extremities of chromosomes [4,5,6]. Telomere length (TL) can serve as an indicator of a cell’s biological age [4] and predict its future proliferative potential [6]
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