Diurnal variation of gamma-glutamyl transpeptidase activity during DMBA-induced hamster buccal pouch carcinogenesis.

OBJECTIVE The aim of the present study is to assess the diurnal variation of gamma-glutamyl transpeptidase (GGT) during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. MATERIALS AND METHODS The right buccal pouches of 108 Syrian golden hamsters, divided into three experimental groups, were treated three times weekly with 0.5% DMBA in mineral oil over an 11-week treatment regimen. The left buccal pouches were untreated and served as the controls. Within each group, six animals were killed at 4-h intervals (04.00, 08.00, 12.00, 16.00, 20.00 and 24.00) for 24 h. GGT histochemical stain, according to the method of Ruthenberg and coworkers, was applied. The number of GGT-positive foci in the pouch mucosa was recorded at 3, 7 and 11 experimental weeks. RESULT Diurnal variation of GGT histochemical activity during DMBA-induced hamster buccal pouch carcinogenesis was substantiated in the present study. CONCLUSION This investigation highlights the importance of the diurnal variation in experimental oral carcinogenesis.