Silica prevents the induction of diabetes with complete Freund's adjuvant and low-dose streptozotocin in rats.

Three weekly intraperitoneal injections of complete Freund's adjuvant (CFA) and, one day later, 25 mg/kg of STZ have been reported to cause a gradual onset of autoimmune diabetes. We have previously reported that the onset of diabetes in this model occurs too rapidly to be due to a specific immune reaction and that other compounds that activate macrophages also potentiate low-dose STZ in rats. We have proposed that mediators released from activated macrophages may enhance the cytotoxic effect of STZ. In the present study, we have observed that intraperitoneal injections of silica, a macrophage toxin, markedly decrease the incidence and severity of diabetes induced with CFA and low-dose STZ.

Effects of a zinc deficient diet upon fluid intake in the rat.

Zinc deficient rats demonstrate an increased intake of sodium chloride (NaCl) containing solutions as compared to normal rats, presumably related to decreased taste acuity. The purpose of this study was to determine if zinc deficient rats would show altered intake of other solutions since changes in NaCl intake may be reflective of serious pathophysiologic processes not related to taste. Eight littermate pairs of inbred Fisher CDF rats, 29 days of age, were divided into two groups and individually housed in stainless steel cages. One group was pair-fed a zinc deficient diet supplemented with ZnSO4, 100 ppm, while the second group was fed the zinc deficient diet, ad libitum. Using a two-bottle preference test, the rats fed the zinc deficient diet showed significantly increased preferences for 5 X 10(-2), 1.5 X 10(-1) and 3 X 10(-1) M NaCl as compared to controls, supporting previous observations. In addition, they showed significantly increased mean preferences for 3.0 X 10(-2) M sucrose, 1.3 X 10(-6) M quinine sulfate and 2.5 X 10(-3) M hydrochloric acid. Analysis of the individual water and fluid intakes showed that the altered preferences were generally the result of increased fluid intake with variable differences observed in water intake. The results demonstrate that zinc deficient rats exhibit altered intake of several different chemical compounds, and support the hypothesis that zinc deficient animals may have alterations in taste acuity.