Abstract
Dietary effects of freeze-dried bovine thymus powder (FDT) and a low-molecular-weight fraction of thymus (LMT) on the blood pressure of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were studied. LMT was prepared. from acetone-defatted FDT by water extraction, heat treatment, centrifugation and spray-drying of the supernatant solution. SHR and WKY were fed a diet containing 2% LMT or 10% FDT from 3 weeks of age. Systolic blood pressure of these SHR and WKY was measured at 6, 8, 10 and 12 weeks of age. Both FDT feeding and LMT feeding caused suppression of the rise in blood pressure of SHR from 8 weeks of age, whereas the blood pressure of WKY was not affected by dietary FDT or LMT. Several physiological parameters of rats at 14-16 weeks of age were also examined. Liver weight, serum α1-globulin content, and GPT activity in SHR were increased, and plasma renin concentration was decreased, by dietary FDT. Serum cholesterol levels were decreased by FDT or LMT. Serum angiotensin-converting enzyme activity and mitogen reactivity of spleen cells were not affected by dietary FDT or LMT. These results suggest that bovine thymus contains some factors that affect the mechanism of spontaneous hypertension develogment in SHR.
