Salivary α-amylase stability, diurnal profile and lack of response to the cold hand test in young women

Abstract

Salivary cortisol measurement has proved useful for the non-invasive study of the hypothalamic–pituitary–adrenocortical axis, and salivary α-amylase has been suggested as a comparable marker for the sympathetic system. Despite some studies showing an increase in salivary α-amylase after challenges that stimulate the sympathetic nervous system, questions remain about interpretation. The aims of this study were to explore the stability of salivary α-amylase, its diurnal profile, response to the cold hand test, and correlation with cortisol. Salivary α-amylase was stable following 5 days at room temperature, and five freeze-thaw cycles. Its diurnal profile was opposite to that of cortisol. There was no salivary α-amylase response to the cold hand stress test, in the morning (11am) or afternoon (3pm), unlike cortisol which showed a response in the afternoon in the same samples. There was no correlation between salivary α-amylase and cortisol at any time. In conclusion, salivary α-amylase is stable to a range of conditions. Its diurnal pattern is compatible with sympathetic stimulation. Lack of response to the cold hand test suggests that secretion of salivary alpha-amylase is controlled by mechanisms more complex than sympathetic regulation alone.

Keywords::

• Salivary
• α-amylase
• cortisol
• diurnal variation
• cold pressor test

Acknowledgements

The authors are most grateful to the participants of this study. They would like to thank Diana Adams, Imperial College London, for technical assistance and support throughout this study. They thank Dr Maureen Marks, Institute of Psychiatry, King's College London, for statistical advice.

The authors are grateful to Eli Lilly Suisse (SA) and Pfizer Schweiz (AG) for Independent Medical Research Grants to author MK which enabled data collection.

Declaration of interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.