title: Intravenous tryptophan administration attenuates cortisol secretion induced by intracerebroventricular injection of noradrenaline.
abstract: This study was conducted to investigate the possibility of suppression of stress-induced cortisol (CORT) secretion by tryptophan (TRP) administration and to better understand its regulatory mechanisms by using a noradrenaline (NA) injection into the third ventricle (3V) as a stress model in cattle. A total of 25 Holstein steers with a cannula in the 3V were used. First, the increase in CORT secretion was observed following a NA injection into the 3V in a dose-dependent manner, verifying the appropriateness of this treatment as a stress model of CORT secretion (Experiment 1). The effect of prior-administration of TRP into peripheral blood with a dose that has been demonstrated to increase brain 5-hydroxytryptamine levels on the elevation of plasma CORT induced by NA or corticotropin-releasing hormone (CRH) was then examined (Experiment 2). The prior administration of TRP suppressed NA-induced, but not CRH-induced, CORT elevation. These results suggest that an increase in TRP absorption into peripheral blood could suppress the stress-induced CORT secretion in cattle via the attenuation of the stimulatory effect of NA on the hypothalamic CRH release.
authors.affiliation: Animal Physiology and Nutrition Research Division, National Institute of Livestock and Grassland Science, Tsukuba, Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Sutoh
authors.affiliation: Animal Physiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Kasuya
authors.affiliation: Animal Physiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Yayou
authors.affiliation: Animal Physiology and Nutrition Research Division, National Institute of Livestock and Grassland Science, Tsukuba, Japan.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Ohtani
authors.affiliation: Animal Physiology and Nutrition Research Division, National Institute of Livestock and Grassland Science, Tsukuba, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D002417:Cattle; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006854:Hydrocortisone / Q000378:metabolism*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage* / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D013315:Stress, Psychological / Q000139:chemically induced / Q000503:physiopathology; D014364:Tryptophan / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D014364:Tryptophan; D006854:Hydrocortisone; D009638:Norepinephrine
keywords: cattle; cortisol; noradrenaline; stress; tryptophan