Abstract
BackgroundEarly life stress (ELS) in macaques in the form of insecure maternal attachment putatively induces epigenetic adaptations resulting in a “thrifty phenotype” throughout the life cycle. For instance, ELS induces persistent increases in insulin resistance, hippocampal and corpus callosum atrophy and reduced “behavioral plasticity”, which, taken together, engenders an increased risk for mood and anxiety disorders in humans but also a putative sparing of calories. Herein, we test the hypothesis whether a thrifty phenotype induced by ELS is peripherally evident as hypotrophy of cardiac structure and function, raising the possibility that certain mood disorders may represent maladaptive physiological and central thrift adaptations. Methods14 adult bonnet macaques (6 males) exposed to the maternal variable foraging demand (VFD) model of ELS were compared to 20 non-VFD adult subjects (6 males). Left ventricle end-diastolic dimension (LVEDD), Left ventricle end-systolic dimension (LVESD) and stroke volume (SV) were calculated using echocardiography. Blood pressure and heart rate were measured only in females. Previously obtained neurobehavioral correlates available only in males were analyzed in the context of cardiac parameters. ResultsReduced LVESD (p < 0.05) was observed when controlled for age, sex, body weight and crown-rump length whereas ejection fraction (EF) (p = 0.037) was greater in VFD-reared versus non-VFD subjects. Pulse pressure was lower in VFD versus non-VFD females (p < 0.05). Male timidity in response to a human intruder was associated with reduced LVEDD (p < 0.05). ConclusionsELS is associated with both structural and functional reductions of left ventricular measures, potentially implying a body-wide thrifty phenotype. Parallel “thrift” adaptations may occur in key brain areas following ELS and may play an unexplored role in mood and anxiety disorder susceptibility.
Highlights
general linear model (GLM) revealed that males were older and weighed more than females but no rearing effect or rearing x sex effects were noted for age and weight
The current study demonstrates that early life stress in bonnet macaques in the form of variable foraging demand (VFD)-rearing produced persistent LV hypotrophy as evidenced by a significant decrease in Left ventricle end-systolic dimension (LVESD) but not Left ventricle end-diastolic dimension (LVEDD)
The reduced pulse pressure was directly correlated with LV cardiac dimension, and arose from numerically lower systolic blood pressure (BP) and numerically higher diastolic BP, suggesting the LV of VFD was performing less cardiac “work”
Summary
While early adversity is a well-known cause of cardiomyopathy (Steptoe and Kivima€ki, 2013), few studies have assessed the long term effects of ELS directly on cardiac structure and function (Carlier et al, 1988). Life stress (ELS) in macaques in the form of insecure maternal attachment putatively induces epigenetic adaptations resulting in a “thrifty phenotype” throughout the life cycle. We test the hypothesis whether a thrifty phenotype induced by ELS is peripherally evident as hypotrophy of cardiac structure and function, raising the possibility that certain mood disorders may represent maladaptive physiological and central thrift adaptations. Results: Reduced LVESD (p < 0.05) was observed when controlled for age, sex, body weight and crownrump length whereas ejection fraction (EF) (p 1⁄4 0.037) was greater in VFD-reared versus non-VFD subjects. Parallel “thrift” adaptations may occur in key brain areas following ELS and may play an unexplored role in mood and anxiety disorder susceptibility
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