Morphological Changes in Major Salivary Glands in Mice Treated With a Choline and Methionine Deficient Diet

It has been shown that the methionine-choline deficient (MCD) diet induces hepatocarcinogenesis, but not in extrahepatic organs, such as the testis, and pancreas, although may increase chemical-induced carcinogenesis in the colon, mammary gland, esophagus, and pancreas. Accumulating evidence suggests that salivary glands are very susceptible to stress conditions, such as radiation, hyperglycemia, and exposure to xenobiotics in vivo. This study aimed to analyze the histological changes on the major salivary glands (parotid, submandibular, and sublingual) after MCD diet administration.

Male Swiss mice were submitted to ad libitum access to the control (AIN-76) or MCD diet for 28 days. The rebound group received the MCD diet for 24 days and the control diet for 10 days. Using the AxioImager A2 microscope, the hematoxylin-eosin (HE) stained specimens (4 mm) were evaluated for tissue degeneration, nuclear hyperchromatism and atrophy.

In the parotid gland from the MCD group, tissue degeneration, pyknosis, apoptosis and atrophy were observed, which remained in the rebound group, associated with hyperchromatism. In the submandibular gland from both MCD and rebound groups, severe tissue disorganization was associated with cell pleomorphism, hyperchromatic cells, apoptosis, increased eosinophilia, and inflammatory infiltrate. Finally, in the sublingual gland, there were no histological alterations in the experimental groups compared to the control.

MCD can induce pre-neoplastic changes in the mouse parotid and submandibular glands, which are not reversed by a change in the diet.