51. Salivary alpha-amylase response to endotoxin administration in humans

Abstract

Salivary alpha-amylase (sAA) has been proposed as a non-invasive biomarker for stress-related activation of the sympathetic nervous system (SNS). However, there is still much debate concerning the validity and reliability of sAA as a surrogate measure of SNS activity. Since acute systemic inflammation leads to pronounced activation of the SNS, we investigated in a double-blind, randomized and placebo-controlled crossover study the influence of intravenous lipopolysaccharide (0.4 ng/kg body weight) or placebo injection on sAA activity in healthy male subjects. Endotoxin administration induced significant increases in sAA activity, plasma norepinephrine (NE) concentration, heart rate, and state anxiety. Both sAA activity and plasma NE reached maximum levels at the peak of the inflammatory response (2 h post injection) and rapidly returned to baseline whereas heart rate further increased and then gradually normalized until six hours post injection. Most importantly, sAA activity was significantly correlated with circulating NE levels but not with other markers of SNS activity. Together, these findings demonstrate that immunogenic stress is associated with a significant increase in sAA activity, but whether this reflects SNS activity remains to be elucidated.