Rise in plasma lactate concentrations with psychosocial stress: a possible sign of cerebral energy demand.
OBJECTIVE
It is known that exogenous lactate given as an i.v. energy infusion is able to counteract a neuroglycopenic state that developed during psychosocial stress. It is unknown, however, whether the brain under stressful conditions can induce a rise in plasma lactate to satisfy its increased needs during stress. Since lactate is i) an alternative cerebral energy substrate to glucose and ii) its plasmatic concentration is influenced by the sympathetic nervous system, the present study aimed at investigating whether plasma lactate concentrations increase with psychosocial stress in humans.


METHODS
30 healthy young men participated in two sessions (stress induced by the Trier Social Stress Test and a non-stress control session). Blood samples were frequently taken to assess plasma lactate concentrations and stress hormone profiles.


RESULTS
Plasma lactate increased 47% during psychosocial stress (from 0.9 ± 0.05 to 1.4 ± 0.1 mmol/l; interaction time × stress intervention: F = 19.7, p < 0.001). This increase in lactate concentrations during stress was associated with an increase in epinephrine (R(2) = 0.221, p = 0.02) and ACTH concentrations (R(2) = 0.460, p < 0.001).


CONCLUSIONS
Plasma lactate concentrations increase during acute psychosocial stress in humans. This finding suggests the existence of a demand mechanism that functions to allocate an additional source of energy from the body towards the brain, which we refer to as 'cerebral lactate demand'.
Medical Clinic 1, University of Lübeck, Lübeck, Germany.
Britta
B
Kubera
Christian
C
Hubold
Saskia
S
Otte
Ann-Sophie
AS
Lindenberg
Irena
I
Zeiss
Regina
R
Krause
Mirja
M
Steinkamp
Johanna
J
Klement
Sonja
S
Entringer
Luc
L
Pellerin
Achim
A
Peters
D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000328:Adult; D001921:Brain / Q000378:metabolism*; D004734:Energy Metabolism; D004837:Epinephrine / Q000097:blood*; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D013315:Stress, Psychological / Q000097:blood*; D013564:Sympathetic Nervous System; D055815:Young Adult
D019344:Lactic Acid; D000324:Adrenocorticotropic Hormone; D004837:Epinephrine