Innate Differences in Weight Gain and Associated Behaviour can Be Marked by Cortisol Responsivity (#125)
Three stressors were applied to LR and HR animals and energy homeostasis (food intake and thermogenesis) was measured. Thermogenesis was recorded with dataloggers implanted into muscle. Stressors were hypoglycaemia (0.125units/kg insulin, i.v.), a barking dog and immune challenge (200ng/kg Lipopolysaccharide–LPS, i.v.). LPS induced the greatest overall disturbance in energy homeostasis with reduction (p<0.01) in food intake in both groups (47%±7% in LR vs 26%±5% in HR); LR showed a greater (p<0.05) reduction in food intake and greater (p<0.05) rise in temperature measured by area under the curve (AUC) of temperature x time (LR, 20.4±2 vs HR, 14.7±2). Metabolic responses were minimal with the other 2 stressors. The change in energy homestasis was paralleled by cortisol responsiveness to stressors with the greatest effect and difference between HR and LR seen in LPS treatment (AUC 1543±273 ng/mL.6h in HR and 1051±138 ng/mL.6h, p<0.05).
Behavioural responses to (1) isolation in an enclosure (5x3m), (2) a human intruder and (3) competition for food were analysed. LR had greater (p<0.05) activity in Test(1) (Activity Score: LR, 6.5±1.4 vs HR, 2.9±1.5), spent more (P<0.05) time (109±25sec) facing the human (63±25sec) in Test(2) and competed for food more successfully than HR in Test(3). Greater activity and increased thermogenesis in LR may reduce their propensity to become obese on a high energy diet.
- 1 George SA, Khan S, Briggs H, Abelson JL. CRH-stimulated cortisol release and food intake in healthy, non-obese adults. Psychoneuroendocrinology 2010;35:607-12. 2 B. A. Henry and I. J. Clarke (2012) Characterizing the cellular mechanisms of post-prandial thermogenesis in skeletal muscle. Joint Annual Meeting: ASN-ADSA-ASAS Joint Symposium, Phoenix Arizona.