​Alpha-Amylase (or α-Amylase) is a digestive enzyme that hydrolyses alpha-1,4 bonds of large polysaccharides such as starch and glycogen, yielding the smaller by-products of glucose and maltose. (1) Alpha amylase is synthesized in the acinar cells of the saliva glands and stored in secretory granules inside the cells. (2)  Its release from the salivary cells is greatly increased in response to taste or chewing motions of the jaw. (3,4,5)  Salivary α-amylase levels are not related to α-amylase levels in blood, which are derived from pancreatic secretion. (1)  In addition to its digestive function, alpha-amylase also plays an important anti-bacterial role in the oral cavity; for this reason it is present in lower levels in non-stimulated saliva between meals. (6,7) Salivary α-amylase exhibits a diurnal rhythm, with a pronounced decrease within 60 minutes after awakening and a steady increase of activity during the course of the day. (8)  Alpha-amylase production in the saliva glands increases in response to psychological and physical stress through interactions with the autonomic nervous system, and it has been found to be a useful as a marker of activity in the autonomic nervous system. (9,10,11)  Salivary alpha-amylase levels have been used as a biomarker of ANS activity in various fields of biobehavioral research. (12,13,14,15)

References

1. Schenkels, L.C., Veerman, E.C., Nieuw Amerongen, A.V. (1995). Biochemical composition of human saliva in relation to other mucosal fluids.  Crit Rev Oral Biol Med, 6(2), 161-75.
2. Gorr, S.U., Venkatesh, S.G., Darling, D.S. (2005).  Parotid secretory granules: Crossroads of secretory pathways and protein storage. J Dent Res, 84(6), 500-9.
3. Ekstrom, J. (2001). Gustatory-salivary reflexes induce non-adrenergic, non-cholinergic acinar degranulation in the rat parotid gland.  Exp Physiol, 86(4), 475-80.
4. Jensen, J.L., Brodin, P., Berg, T., Aars, H. (1991).  Parotid secretion of fluid, amylase and kallikrein during reflex stimulation under normal conditions and after acute administration of autonomic blocking agents in man.  Acta Physiol Scand, 143(3), 321-29.
5. Mackie, D.A., Pangborn, R.M. (1990). Mastication and its influence on human salivary flow and alpha-amylase secretion.  Physiol Behav, 47(3), 593-95.
6. Scannapieco, F.A., Torres, G., Levine, M.J. (1993).  Salivary alpha-amylase: Role in dental plaque and caries formation.  Crit Rev Oral Biol Med, 4(3-4), 301-07.
7. Douglas, C.W. (1983) The binding of human salivary α-amylase by oral strains of streptococcal bacteria.  Arch Oral Biol, 28(7), 567-73.
8. Nater, U.M., Rohleder, N., Schlotz, W., et al. (2007).  Determinants of the diurnal course of salivary alpha-amylase.  Psychoneuroendocrinology, 32(4), 392-401.
9. Nater, U.M., Rohleder, N. (2009).  Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: Current state of research.  Psychoneuroendocrinology, 34(4), 486-96.
10. van Stegeren, A., Rohleder, N., Everaerd, W., Wolf, O.T. (2006).  Salivary alpha amylase as marker for adrenergic activity during stress:  Effect of betablockade.  Psychoneuroendocrinology, 31(1), 137-41.
11. Proctor, G.B., Carpenter, G.H. (2007).  Regulation of salivary gland function by autonomic nerves.  Auton Neurosci, 133(1), 3-18.
12. Keller, P.S., El-Sheikh, M., Vaughn, B., Granger, D.A. (2009). Salivary alpha-amylase as a longitudinal predictor of children’s externalizing symptoms: Respiratory sinus arrhythmia as a moderator of effects.  Psychoneuroendocrinology, 34(5), 633-43.
13. Gordis, E.B., Margolin, G., Spies, L., et al. (2010).  Interparental aggression and parent-adolescent salivary alpha amylase symmetry.  Physiol Behav,  100(3), 225-33.
14. Gordis, E.B., Granger, D.A., Susman, E.J., Tickett, P.K. (2008). Salivary alpha amylase-cortisol asymmetry in maltreated youth.  Horm Behav, 53(1), 96-103.
15. Granger, D.A., Kivlighan, K.T., El-Sheikh, M., et al. (2007).  Salivary α-amylase in biobehavioral research: Recent developments and applications.  Ann N Y Acad Sci, 1098, 122-44.)