Histo- And Biochemical Studies on Dehydrogenases in Tumorigenesis in Rat Zymbal Glands Induced With Dmba and Das

Abstract

Wistar SLC male rats were injected with 25 mg/Kg of 7,12-Dimethylbenz(a)anthracene intravenously twice at 51 and 66 days of age, and also fed on a commercial diet containing 4-Dimethylaminostilbene, 0.004%, from the age of 57 days to the respective days of their decapitations.Fresh cryostat serial sections of Zymbal glands were examined by histochemical methods for SDH, LDH and G6PDH 6, 11 and 17 weeks after the first injection.Either atypical hyperplasia of the acinar cells or microtumor was detected in the Zymbal glands of almost all treated rats 11 weeks after the first injection. An ear duct tumor was induced in all treated animals 17 weeks after treatment. SDH and G6PDH activities decreased progressively in the tumorigenesis, but moderate LDH activity remained in the tumor tissues.Biochemical determinations for LDH and MDH in the Zymbal glands harvested serially 4-20 weeks after the first injection of DMBA indicated that the quotient of LDH/MDH began to elevate 5-11 weeks after injection and elevated in the tumorigenesis owing to a progressively lower MDH.There have been numerous histo-and cytochemical observations on the enzymes of different tumors (2). These studies provide very useful information not only about the presence and activities of enzymes in relation to tumor growth, but also analysis of neoplastic transformation. Experimentally, in rats, special tumors in the auditory organs have been induced by the administration of aromatic hydrocarbons, aromatic amines, azo compounds or other chemical agents (7), and they are commonly called ear duct tumors. The induction of ear duct tumor with 7, l 2-Dimethylbenz(a)anthracene (DMBA) was greatly accelerated by feeding the animals a diet containing 4-Dimethylaminostilbene (DAS) ; none of the rats in these studies developed dual tumor growths at different locations (4). It would be reasonable to assume from our histological investigations that the ear duct tumor arises not from the squamous epithelium of the external auditory canal, but from cells which constitute the acini of the Zymbal gland. Systemic administration of DMBA and DAS evoked exclusively in the Zymbal gland the growth of tumors so minute as to be

Dehydrogenases in Local Carcinogenesis in Rat Mammary Gland by Dusting of Dmba-Powder

“…Biochemical determinations of dehydrogenases in the local tumorigenesis indicated that LDH increased prominently in the malignant tissues. It is useful to relate the concentration of LDH in tissues to MDH when both enzymes are assayed concurrently on the same solution of tissue constituents, with respect to malignant transformation in rats (10,13,14). The quotients were higher on the more malignant tissues of the present experiment, owing to the higher LDH activities.…”

“…Histochemically, atypisms of ALP and LDH activities were observed on the apparent malignant tissues induced by DMBA-dusting. Biochemical observations on the activities of LDH and MDH and on the pattern of LDH isoenzymes were done for the induced nodules with DMBA-dusting over females aged [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] weeks, which were harvested 5-18 weeks after the local application. The quotients of LDH/MDH in the same sample elevated on the malignant tissues prominently owing to higher LDH activity, and the elevation was moderate on the earlier-harvested, granulomatous tissues.…”