Determinants of the diurnal course of salivary alpha-amylase.
OBJECTIVE
Previous data from our group and others have shown that salivary alpha-amylase activity increases in response to stress. It has been suggested that salivary alpha-amylase may be a marker for adrenergic activity. Less is known about other determinants of salivary alpha-amylase activation. The objective of the current study was to describe the diurnal pattern of salivary amylase and its determinants.


METHODS
Saliva samples were collected immediately after waking-up, 30 and 60 min later, and each full hour between 0900 and 2000 h by 76 healthy volunteers (44 women, 32 men). Compliance was controlled by electronic monitors. In order to control factors which might influence the diurnal profile of salivary alpha-amylase (such as momentary stress, mood, food, or body activity), at each sampling time point the subjects filled out a diary examining the activities they had carried out during the previous hour.


RESULTS
Salivary alpha-amylase activity shows a distinct diurnal profile pattern with a pronounced decrease within 60 min after awakening and a steady increase of activity during the course of the day. Mixed models showed a relative independence of diurnal salivary alpha-amylase from momentary stress and other factors, but significant associations with chronic stress and mood.


CONCLUSIONS
Our results suggest that diurnal profiles of salivary alpha-amylase are relatively robust against momentary influences and therefore may prove useful in the assessment of sympathetic nervous system activity. The findings underscore the need to control for time of day in studies using salivary alpha-amylase as a dependent variable.
Nater
Urs M
UM
Emory University School of Medicine, Atlanta, GA 30322, USA. unater@emory.edu
Rohleder
Nicolas
N
Schlotz
Wolff
W
Ehlert
Ulrike
U
Kirschbaum
Clemens
C
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D002940:Circadian Rhythm; D003940:Diagnostic Techniques, Endocrine; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D010349:Patient Compliance; D012107:Research Design; D012463:Saliva / Q000737:chemistry / Q000201:enzymology*; D012727:Sex Characteristics; D012907:Smoking; D013312:Stress, Physiological / Q000201:enzymology; D013564:Sympathetic Nervous System / Q000502:physiology; D000516:alpha-Amylases / Q000032:analysis*
D000516:alpha-Amylases; D006854:Hydrocortisone