Quantitative enzyme histochemistry of rat foetal brain and trigeminal ganglion

Apoptosis induced in rat hepatocytes by in vivo exposure to taurochenodeoxycholate

Enzymatic and molecular cytochemistry was used to detect and follow the hepatotoxic effects caused in overnight-fasted Sprague-Dawley rats by a 1-h continuous intrafemoral infusion of taurochenodeoxycholate at 0.4 and 0.8 mumol-1 min-1 100 g-1 body weight dose levels. Rats were killed at 0, 1 and 24 h from the end of perfusion. Their livers were examined for morphology, DNA fragmentation (by a TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP-nick end-labelling assay), cell regeneration (by in vivo bromodeoxydurine incorporation), reduced glutathione, calcium and several enzyme cytochemical activities. Isolated injured hepatocytes randomly scattered throughout the liver were already evident at the end of perfusion. DNA fragmentation and cytoplasm shrinkage were prominent and early features of injured hepatocytes, which later showed calcium loading and chromatin clumping. Preserved cytochemical enzymatic activities indicated that plasma and mitochondria membranes were not severely damaged. Inflammatory response was absent. These observations indicate that an acute exposure to taurochenodeoxycholate induces a cell death process with apoptotic features.

A quantitative cytochemical study on the pathogenesis of streptozotocin-induced epithelial tumors in rat kidney

We investigated the development of early neoplastic lesions preceding the appearance of kidney epithelial tumors in rats treated with a single iv injection of 35 mg/kg of streptozotocin (STZ). Most of these lesions were associated with segments of atrophied and regenerative nephrons surrounded by a thick basal membrane that appear precociously in chronic progressive nephropathy. Cytochemical periodic acid-Schiff, Alcian blue, and colloidal iron reactions did not indicate an excessive storage of glycogen or acid mucopolysaccharides in early neoplastic lesions and tumors. Quantitative cytochemistry of mitochondrial succinate, alpha-glycerophosphate, and reduced nicotinamide adenine dinucleotide-dehydrogenases revealed a shift in metabolism toward glycolysis in atrophied and regenerative nephrons as well as in early neoplastic lesions and tumors. These correlative cytomorphological and cytochemical findings raise the possibility that changes associated with the initial stages of chronic progressive nephrosis may provide favorable conditions for the selective growth of STZ-initiated cells that generate focal collections of proliferating cells and then progress to tumor growth. Tumor prevalence was remarkably constant in animals sacrificed 33, 48, and 54 wk after treatment, suggesting that the prominent inflammatory and scarring reaction later developing in the course of progressive nephrosis might contribute to control the growth of STZ-induced cancer.

Biochemical quantitation and histochemical localization of glucose-6-phosphate dehydrogenase activity in the olfactory system of adult and aged rats

The activity of glucose-6-phosphate dehydrogenase, the rate-limiting enzyme of the hexose monophosphate shunt, was examined in olfactory epithelium, respiratory epithelium, olfactory bulb, and occipital cortex in Fisher 344 rats aged 4 and 24 months. Marked differences in this enzyme were found in olfactory compared to nonolfactory tissues. Olfactory epithelium and olfactory bulb have much greater glucose-6-phosphate dehydrogenase activity than respiratory epithelium and occipital cortex at both ages. Glucose-6-phosphate dehydrogenase remains fairly constant between adulthood and senescence in respiratory epithelium and occipital cortex. However, glucose-6-phosphate dehydrogenase activity decreases during the same time in both of the olfactory tissues examined. Previous studies of changes in this enzyme with aging have shown increases in enzyme activity in some brain regions, but never the decreases that we describe in olfactory tissues. Glucose-6-phosphate dehydrogenase histochemistry revealed intense staining of both the apical layer of olfactory epithelium and of Bowman's glands along with their ducts. Histochemistry of the olfactory bulb showed strongest staining in the nerve and glomerular layers of the bulb. The functional implications of these findings are discussed.