title: Aging accelerates dietary lard-induced increase in blood pressure in rats.
abstract: We investigated whether the dietary lard-induced increase in blood pressure (BP) is accelerated in aged rats compared to young ones. Three-month-old (young group), 10-month-old (middle-age group), and 18-month-old (older group) F344/N male rats were used. The rats were fed either chow alone or chow in which 50% of the energy content was from substituted lard. Systolic BP (SBP) and body weights (BW) were determined weekly during each 7-week feeding period. A Steady-state plasma glucose (SSPG) method was used to determine the insulin sensitivity. Bilateral testicular fat mass (epididymal fat; Epi-F) was removed in order to evaluate weight (Epi-FW). SBP began to increase at 2 weeks in the older lard-fed group, at 4 weeks in the middle-age lard-fed group, and at 5 weeks in the young lard-fed group after feeding was begun. There was no significant difference in the basal values of SBP among any ages-groups of the rats. After 4 weeks of lard feeding, increases in SBP, plasma insulin, leptin level, SSPG and Epi-FW/BW were observed in the older lard-fed group. In the younger rats, however, only hyperinsulinemia developed. At 7 weeks, increased BP in the younger rats was accompanied by increased plasma leptin level, SSPG and Epi-FW/BW. In summary, aging accelerates development of a dietary lard-induced increase in BP, which may be caused by the hyperleptinemia that may be the result of increased susceptibility to insulin resistance and/or visceral adiposity in older rats.
authors.affiliation: Department of Geriatrics, Medicine in Growth and Aging, Program in Health and Community Medicine, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan. ntamaya@med.nagoya-u.ac.jp
authors.forename: Norika
authors.initials: N
authors.lastname: Tamaya-Mori
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Uemura
authors.forename: Shin
authors.initials: S
authors.lastname: Tanaka
authors.forename: Akihisa
authors.initials: A
authors.lastname: Iguchi
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004041:Dietary Fats / Q000009:adverse effects*; D004837:Epinephrine / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006973:Hypertension / Q000097:blood / Q000209:etiology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D007328:Insulin; D020738:Leptin; D011433:Propranolol; D005947:Glucose; D004837:Epinephrine