title: Responses of plasma glucose metabolism to exogenous insulin infusion in sheep-fed forage herb plantain and exposed to heat.
abstract: The use of herbal plants as traditional medicines has a century long history. Plantain (Plantago lanceolata L.) is a perennial herb containing bioactive components with free radical scavenging activities. An isotope dilution technique using [U-13C]glucose was conducted to determine the effect of plantain on the responses of plasma glucose metabolism to exogenous insulin infusion in sheep. Six crossbred sheep (three wethers and three ewes; mean initial BW=40±2 kg) were fed either a mixed hay of orchardgrass (Dactylis glomerata) and reed canarygrass (Phalaris arundinacea) (MH-diet) or mixed hay and fresh plantain (1 : 1 ratio, dry matter basis, PL-diet) and exposed to a thermoneutral (TN, 20°C; 70% relative humidity (RH)) environment or a heat exposure (HE, 30°C; 70% RH) for 5 days using a crossover design for two 23-day periods. The isotope dilution was conducted on days 18 and 23 of the experimental period during TN and HE, respectively. Plasma concentration of α-tocopherol was greater (P<0.0001) for the PL-diet than the MH-diet and remained comparable between environmental treatments. Plasma glucose concentration before isotope dilution technique was reduced for sheep (P=0.05) during HE compared with TN and remained comparable between diets. Plasma glucose turnover rate during the preinfusion period of insulin did not differ (P=0.10) between dietary treatments and between environments (P=0.65). The response of plasma glucose utilization to exogenous insulin administration was lower (P=0.04) for the PL-diet than the MH-diet. Under present experimental conditions, the plantain group was found to be resistant to the effects of insulin infusion.
authors.affiliation: 1Deptartment of Animal Science,Iwate University,Morioka 020-8550,Japan.
authors.forename: M
authors.initials: M
authors.lastname: Al-Mamun
authors.affiliation: 1Deptartment of Animal Science,Iwate University,Morioka 020-8550,Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shibuya
authors.affiliation: 1Deptartment of Animal Science,Iwate University,Morioka 020-8550,Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kajita
authors.affiliation: 2Forage Production and Utilization Research Team,Tohoku Agricultural Experimental Station, Morioka 020-0123,Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: 1Deptartment of Animal Science,Iwate University,Morioka 020-8550,Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sano
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects*; D031745:Dactylis; D004032:Diet / Q000662:veterinary; D005260:Female; D006358:Hot Temperature; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D031783:Phalaris; D010943:Plantago; D012756:Sheep / Q000502:physiology*; D024502:alpha-Tocopherol / Q000097:blood
chemical_list: D001786:Blood Glucose; D007328:Insulin; D024502:alpha-Tocopherol
keywords: glucose metabolism; heat stress; insulin; plantain; sheep