L-tyrosine ameliorates some effects of lower body negative pressure stress

Physiol Behav. 1995 Feb;57(2):223-30. doi: 10.1016/0031-9384(94)00278-d.


Tyrosine, a large neutral amino acid normally present in protein foods, is the precursor of the catecholamine neurotransmitters dopamine, norepinephrine, and epinephrine. Animal studies indicate that systemic administration of tyrosine in pharmacological quantities can reduce physiological and behavioral decrements induced by highly stressful conditions. The current study was designed to test the effects of tyrosine (100 mg/kg of body weight) on humans exposed to cardiovascular stress. Twenty participants were exposed to two Lower Body Negative Pressure (LBNP) sessions (-50 mm Hg for a maximum of 30 min) during each of two testing sessions of a repeated measure double-blind placebo-controlled study. The detected effects of tyrosine include an overall increase in pulse pressure (LBNP typically reduces pulse pressure) and an increase in auditory event related potential amplitude (P300-N300), an electro-physiological correlate of attention which may indicate enhanced cognitive activation.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Affect / drug effects
  • Cardiac Output / drug effects
  • Cross-Over Studies
  • Double-Blind Method
  • Electrocardiography / drug effects
  • Electroencephalography / drug effects
  • Electromyography / drug effects
  • Heart Rate / drug effects
  • Humans
  • Hydrocortisone / blood
  • Lower Body Negative Pressure / adverse effects*
  • Male
  • Psychomotor Performance / drug effects
  • Pulse
  • Stress, Physiological / physiopathology*
  • Stress, Physiological / psychology
  • Stroke Volume / drug effects
  • Tyrosine / pharmacology*
  • Ventricular Function, Left / drug effects


  • Tyrosine
  • Hydrocortisone