title: Tyrosine ameliorates heat induced delay in event related potential P300 and contingent negative variation.
abstract: The efficacy of tyrosine, a catecholamine precursor, as a countermeasure in the reduction of cognitive decline during heat exposure (HE) using event-related potential P300, and contingent negative variation (CNV) was evaluated. Ten healthy males, age 20-30years participated in the study. Volunteers received placebo or tyrosine (6.5g) 90min prior to HE (1.5h in 45°C+30% RH). P300 latency was significantly increased (p<0.01) during exposure with placebo, which was reduced significantly (p<0.01) after tyrosine supplementation. There was an increase in CNV M100 latency (p<0.05) and reaction time (p<0.01) and decrease in M100 amplitude (p<0.01) during HE with placebo, which returns to near normal level with the tyrosine administration. A significantly higher plasma norepinephrine (p<0.05), dopamine and epinephrine levels were detected in tyrosine supplemented group post heat exposure. HE increases the brain catecholamine activity thereby reduces the plasma norepinephrine and dopamine level leading to a reduction in cognitive performances. Tyrosine supplementation increases the catecholamine level and reduces the impairment of cognitive performance during HE.
authors.affiliation: Neurophysiology Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi 110054, India.
authors.forename: Krishna
authors.initials: K
authors.lastname: Kishore
authors.forename: Koushik
authors.initials: K
authors.lastname: Ray
authors.forename: J P
authors.initials: JP
authors.lastname: Anand
authors.forename: Lalan
authors.initials: L
authors.lastname: Thakur
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Kumar
authors.forename: Usha
authors.initials: U
authors.lastname: Panjwani
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D002395:Catecholamines / Q000378:metabolism*; D003265:Contingent Negative Variation / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000097:blood; D004569:Electroencephalography; D004837:Epinephrine / Q000097:blood; D018913:Event-Related Potentials, P300 / Q000187:drug effects / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010919:Placebos; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome; D014443:Tyrosine / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D002395:Catecholamines; D010919:Placebos; D014443:Tyrosine; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine
keywords: CNV; Heat stress; P300; Reaction time; Tyrosine