Thyroid hormones affect reactions in almost all pathways of lipid metabolism. It has been reported that plasma free fatty acid (FFA) concentration in hypothyroidism is generally within the normal range. In this study, however, we show that plasma FFA concentration in some hypothyroid patients is higher than the normal range. Symptoms of thyroid dysfunction in these individuals were less severe than those of patients with lower plasma FFA concentrations. From these findings we hypothesized that the change in FFA concentration must correlate with thyroid function. Using an animal model, we then examined the effect of highly purified eicosapentaenoic acid ethyl ester (EPA-E), a n-3 polyunsaturated fatty acid derived from fish oil, on thyroid function in 1-methyl-2-imidazolethiol (MMI)-induced hypothyroid rats. Oral administration of EPA-E inhibited reduction of thyroid hormone levels and the change of thyroid follicles in MMI-induced hypothyroid rats. These findings suggest that FFA may affect thyroid functions and EPA-E may prevent MMI-induced hypothyroidism.
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- Author: S Imamura x
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M Makino, N Oda, N Miura, S Imamura, K Yamamoto, T Kato, K Fujiwara, Y Sawai, K Iwase, A Nagasaka, and M Itoh
Y Itoh, S Imamura, K Yamamoto, Y Ono, M Nagata, T Kobayashi, T Kato, M Tomita, A Nakai, M Itoh, and A Nagasaka
Endothelin-1 (ET-1) concentrations are increased in patients with diabetes mellitus, particularly those with diabetic retinopathy, or essential hypertension. We hypothesized that ET-1 might participate in the development and progression of diabetic microangiopathy. In this study, the effects of the angiotensin converting enzyme (ACE) inhibitor, enalapril maleate, on diabetic angiopathy were examined in streptozotocin (STZ)-induced diabetic (STZ-DM) rats by monitoring variations in renal function and ET-1 concentrations in blood and organ tissues. Significant increases in kidney weight and in concentrations of urinary albumin, N-acetyl-fl-d-glucosamidase (NAG) and serum ET-1 were observed in the STZ-DM rats as compared with the non-diabetic rats, and the concentration of ET-1 in the kidneys tended to be increased. Microscopic and electron microscopic analyses showed increased mesangial cell proliferation, matrix expansion and enlarged mesangial area in the kidney of the diabetic rats. After administration of the ACE inhibitor, increased concentrations of urinary albumin and NAG in the STZ-DM rats were reduced to the control values with a slight improvement in the electron microscopic changes. These data suggest that ET-1 may be involved in the development and progression of diabetic nephropathy and may explain, in part, why diabetes is liable to complicate hypertension. ACE inhibitor may help to restore diabetic nephropathy in the STZ-induced diabetic rats.