COLLOIDAL GOLD LOCALIZATION OF METALLOTHIONEIN REACTIVITY IN HEPATOCYTES OF STREPTOZOTOCIN-INDUCED DIABETIC RATS

The colloidal gold technique for immunocytochemical localization of me tallothionein (MT) immunoreactivity was applied to hepatic tissue of c ontrol and streptozotocin (STZ)-induced diabetic rats. Diabetic animal s, as determined by blood glucose levels, were sacrificed 14 weeks aft er STZ injection. The hepatocytes from the control animals demonstrate d immunolabeling for MT in both the cytoplasm and nucleus. The cytopla smic labeling was limited to the free polysomes and mitochondria, wher eas the labeling of the nucleus was sparse. The hepatocytes of the STZ -induced diabetic animals also demonstrated immunolabeling for MT of t he cytoplasm and nucleus. The cytoplasmic labeling was more intense, w ith labeling of the free polysomes, mitochondria, and polysomes associ ated with the endoplasmic reticulum. The labeling of the nucleus was m ore intense than that observed in the control animals, with apparent s pecificity for the heterochromatin masses and nucleolus. It is our bel ief that this differential labeling indicates: (1) induction of MT in STZ-induced diabetes and a shift in the movement of MT from the intrac ellular to extracellular space for cellular uptake of trace metals, an d (2) an increase in the intranuclear MT by virtue of its role in the transport of trace metals through the nuclear envelope.