Susceptibility of gerbils (Meriones unguiculatus) to weekly subcutaneous and single intravenous injections of N-diethylnitrosamine

Tumors of the nasal cavities induced in rats by 2,2-dioxopropyl-N-propylnitrosamine. Comparative aspects with man

Weekly SC administration of 2,2-dioxopropylnitrosamine to 88 Sprague-Dawley rats resulted in the induction of 76 separate neoplasms in the respiratory region of the nasal cavities. No tumors of the olfactory region were found. Histologically there were 37 squamous papillomas, 17 transitional papillomas, and 22 squamous cell carcinomas. These tumors were compared with a selected group of 53 related human tumors of the nasal and paranasal cavities, consisting of 11 squamous cell papillomas, 13 transitional papillomas, and 29 squamous cell carcinomas. While the experimental squamous cell papillomas showed a striking histological resemblance with the squamous papillomas observed in man, none of the experimental transitional papillomas had evidence of the characteristics inverted pattern seen in humans; nevertheless, the experimental tumors showed signs of incomplete squamous metaplasia and preservation of intraepithelial secretory glands, features commonly seen in transitional papillomas of man. The squamous cell carcinomas of this experiment were very similar to the corresponding human tumors in morphology and sex incidence. In both species a significant number of squamous cell carcinomas were keratinizing and of a high grade of histological malignancy. In addition, 69% of the human squamous cell carcinomas occurred in the male sex, and 72% of the experimental carcinomas developed in males. This comparative study suggests that further studies investigating the significance of nitrosamines as suspected etiologic factors of nasal carcinogenesis in man may be useful.

Immunocytological study of the distribution of C-cells calcitonin in the thyroid gland of the normal adult gerbil

The distribution of C-cells in the thyroid gland of the gerbil (Meriones inguiculatus) was studied on serial sections in the cranio-caudal direction. C-cells were visualized by immunofluorescence with an anti-calcitonin immune serum. A very heterogeneous distribution was found. C-cells first appear in the posterio-interior position. Then they progressively occupy the whole posterior part and finally are confined to the posterio-exterior position. No C-cells at all were detected in the upper and lower poles. According to the species, there is a wide variation in the relative distribution of C-cells in the thyroid gland. Our results add to the information available about the distribution of C-cells and its bearing on phylogenic evolution.

Effect of diazepam on microsomal diethylnitrosamine metabolism in gerbils

Dealkylation of diethylnitrosamine (DEN) by a liver microsomal fraction was measured after treatment of the Mongolian gerbil with DEN, Valium, or DEN plus Valium. Valium-dosed male and female animals showed strongly stimulated deethylase levels compared with the controls. This was also true of the DEN-treated females. Combined treatment (DEN + Valium) resulted in a significant loss of activity compared with treatment with DEN only, but was not significantly lower than that in the controls. Significant differences were also found between the experimental groups in microsomal enzymes. Metabolism of 14C-DEN to 14CO2 by gerbil liver slices in vitro showed dose-dependent inhibition by Valium. Kinetic analysis of DEN-dealkylation by purified gerbil microsomes revealed at least two Km values. In the microsomal system, diazepam inhibited DEN-dealkylation significantly at low substrate levels.

Carcinogenesis of N-nitrosodiethylamine (DENA) in chickens and domestic cats

The environmental carcinogen N-nitrosodiethylamine (diethylnitrosamine, DENA) has been found to be carcinogenic in 18 animal species. In this study we demonstrate that, after intramuscular injection in chickens, it induces hepatocellular carcinomas of the liver and adenocarcinomas of the kidney. Oral administration in domestic cats causes malignant hepatomas and tumors of the esophagus and kidney. Since DENA is carcinogenic in all species in which it has been tested adequately it can be expected to be a human carcinogen, too.

Morphology of diethylnitrosamine-induced lung tumours in Dzungarian dwarf hamsters

After transplacental application of 30 mg/kg b.w. diethylnitrosamine 16 out of 21 Dzungarian dwarf hamsters developed lung tumours. The histological picture of these tumours is described. The neoplasms are classified as papillary, tubular, or alveolar adenomas or adenocarcinomas, respectively. Different histological architectures occur in one and the same animal or even in different parts of the same tumour. The neoplasms derive from outgrowths of the epithelium of small bronchioles. The significance of the Dzungarian dwarf hamster as a suitable tool for transplacental and postnatal cancer research is discussed.

Histogenesis of tumors from the nasal cavities induced by diethylnitrosamine

Chronic subcutaneous (s.c.) or single intravenous (i.v.) injections of diethylnitrosamine (DEN) to gerbils (Meriones unguiculatus) led to the induction of carcinomas of the nasal cavities in a high incidence. These neoplasms were multifocal in origin, frequently showing mixed cellular patterns of the following cell types: large cuboidal cells, nonciliated columnar cells, ciliated columnar cells, small cells, and squamous epithelial cells. No sensory cells of the olfactory mucosa or neurofibrillar differentiations were found in these neoplasms, although several showed rosette- and pseudorosette-like formations. Dose and route of administration seemed to influence the site of origin and the patterns of cellularity of these tumors. Whereas chronic s.c. injections resulted in carcinomas of the olfactory region, being mostly composed of large cuboidal cells, single i.v. injections led to the development of carcinomas mainly originating from the respiratory-olfactory mucosal junction and composed preferentially of nonciliated and ciliated columnar cells.