Epidermal growth factor in serum, urine, submandibular glands and kidneys of diabetic mice

Abstract

Levels of epidermal growth factor (EGF) in serum were significantly decreased in streptozotocin (STZ)-diabetic mice (446±168 pg/ml) after 1 week and 423±52 after 4 weeks vs 766±162 pg/ml in controls, P.002 and < .001. respectively) and in genetically diabetic ob/ob mice (455±285 vs 962±453 pg/ml in nondiabetic ob/+ controls, P.043). The urinary excretion of EGF was significantly increased in STZ mice (104±53 vs 51±23 ng/h, P.013) but unchanged in ob/ob mice (33±9 vs 45±16 ng/h, P.134). However, when expressed per mg creatinine it was decreased in both cases: in STZ mice to 680±250 ng/mg at 1 week and 684±211 at 4 weeks vs 1250±303 ng/mg in controls (P<.01); and in the ob/ob mice to 552±117 vs 1237±300 ng/mg in ob/+ controls (P<.01). EGF content of the submandibular glands of STZ mice remained unchanged at 1 week (13.1±2.9 vs 11.0±1.8 μg/mg protein, P. 170) but dropped by 4 weeks (4.7±1.2 μg/mg, P<.001); in the ob/ob mice it was less than 20% that of controls (2.1±0.8 vs 12.2±3.6 μg/mg protein). In kidneys, the EGF content was not altered in either ob/ob (524±50 vs 571±33 pg/mg protein) or STZ mice (652±183 vs 665±80 pg/mg). The preproEGF mRNA level in STZ-treated mice was reduced after 4 weeks in submandibular glands but not in kidneys. The results show that diabetes affects EGF production, utilization and/or excretion in mice and that kidneys are spared from suppressionof EGF synthesis that is pronounced in the submandibular glands.