Oleuropein supplementation increases urinary noradrenaline and testicular testosterone levels and decreases plasma corticosterone level in rats fed high-protein diet.
The effects of oleuropein, a phenolic compound in extra virgin olive oil, on protein metabolism were investigated by measuring testicular testosterone and plasma corticosterone levels in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 and 10 g/100 g casein) with or without 0.1 g/100 g oleuropein. After 28 days of feeding, the testosterone level in the testis was significantly higher and the plasma corticosterone level was significantly lower in rats fed the 40% casein diet with oleuropein than in those fed the same diet without oleuropein. The urinary noradrenaline level, nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with oleuropein supplementation than in those fed the 40% casein diet without oleuropein supplementation. In Experiment 2, the effects of oleuropein aglycone (a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein ingested in the gastrointestinal tracts) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, were investigated in anesthetized rats. Plasma LH level increased dose dependently after the administration of oleuropein aglycone (P<.001, r=0.691). These findings suggest that dietary supplementation with 0.1 g/100 g oleuropein alters the levels of hormones associated with protein anabolism by increasing urinary noradrenaline and testicular testosterone levels and decreasing plasma corticosterone level in rats fed a high-protein diet.
Laboratory of Nutrition Chemistry, Faculty of Home Economics, Kobe Women's University, Suma-ku, Kobe 654-8585, Japan. oi@suma.kobe-wu.ac.jp
Yuriko
Y
Oi-Kano
Teruo
T
Kawada
Tatsuo
T
Watanabe
Fumihiro
F
Koyama
Kenichi
K
Watanabe
Reijirou
R
Senbongi
Kazuo
K
Iwai
D000818:Animals; D002364:Caseins / Q000008:administration & dosage; D003345:Corticosterone / Q000097:blood*; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D057888:Iridoid Glucosides; D039823:Iridoids; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000652:urine*; D000069463:Olive Oil; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D010938:Plant Oils / Q000008:administration & dosage; D011714:Pyrans / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013737:Testis / Q000187:drug effects*; D013739:Testosterone / Q000032:analysis*
D002364:Caseins; D004041:Dietary Fats; D004044:Dietary Proteins; D057888:Iridoid Glucosides; D039823:Iridoids; D000069463:Olive Oil; D010938:Plant Oils; D011714:Pyrans; C002769:oleuropein; D013739:Testosterone; D007986:Luteinizing Hormone; D003345:Corticosterone; D009638:Norepinephrine