Salivary alpha amylase (sAA) response to psychological stress in lean and overweight/obese men (#62)
We have shown in humans that overweight/obesity does not affect salivary cortisol responses to psychological stress(1). Nevertheless, it is unknown if there are differences between lean and overweight/obese men in the activity of the sympatho-adrenal medullary system in response to psychological stress. The activity of the sympatho-adrenal medullary system can be ascertained by measuring salivary alpha amylase (sAA)(2). We tested the hypothesis that overweight/obese men will have a greater sAA response to psychological stress compared to lean men.
Lean (BMI=20-25kgm-2; n=19) and overweight/obese (BMI=27-35kgm-2; n=17) men (50-70 years) were subjected to a well characterised psychological stress (Trier Social Stress Test; TSST) at 3pm. Saliva samples were collected every 7-15min from 2pm-5pm. Concentrations of sAA were determined by a kinetic assay and were compared within and between groups using repeated measures ANOVA.
BMI, body weight, percentage body fat, resting systolic and diastolic blood pressures were significantly (p<0.05) higherin overweight/obese men compared to lean men. Both groups responded to the TSST with a significant(p<0.05) elevation of sAA (overweight/obese=111% increase, lean=138% increase) but this response did not differ significantly between lean and overweight/obese men (time*treatment, p=0.261). There were no significant differences between lean and overweight/obese men in pre-treatment sAA concentrations (112.1±16.1vs140.8±16.5U/ml, respectively), delta sAA (155.1±51.2vs156.9±31.0U/ml, respectively), peak sAA concentration during stress (267.3±55.5vs297.7±41.0U/ml, respectively) or area under the curve (5220.5±2735.1vs3130.7±1525.4U/ml/min, respectively) (p>0.05 for all).
Both groups had a substantial but similar sAA response to psychological stress. The results did not support the hypothesis that overweight/obese men will have a greater sAA response to psychological stress compared to lean men. Our data suggest that elevated sympatho-adrenal medullary system responses to acute psychological stress (measured by sAA) may not be a major mechanism that increases the risk of overweight/obese men developing stress-related disease. Further research is required to verify this.1 2
- Jayasinghe SU, Torres SJ, Townsin E, Nowson CA, Tilbrook AJ, Turner AI (2010) Salivary cortisol responses to acute psychological stress in lean and overweight/obese men Proceedings of the Australian Health and Medical Research Congress 5: 507
- Nater UM, La Marca R, Florin L, Moses A, Langhans W, Koller MM & Ehlert U (2006) Stress-induced changes in human salivary alpha-amylase activity-associations with adrenergic activity, Psychoneuroendocrinology 31: 49-58