Hibernation Records on the Incisor Surface in the Turkish Hamster (Mesocricetus brandti) (Rodentia, Cricetidae)

The teeth of an adult female of the Turkish hamster (Mesocricetus brandti) after hibernation in semi-natural conditions were examined to reveal a relationship between the hibernation pattern on the incisor surface and the data of a temperature logger. The female spent the winter in a burrow prepared by herself inside a wintering cage from October 2018 till May 2019. A temperature logger was implanted to the animal intraperitoneally to record body temperature at 20-min intervals. Regular bouts of hypothermia started in mid-October. The longevity of each hypothermia bout increased whereas the minimum body temperature decreased and reached its lowest value in March. Later, the process proceeded backwards until the end of the heterothermia period. In the apical region of the incisor, daily increments were wide and well-distinguished which indicates that they had formed before the onset of the heterothermal period. In the basal region, closer to the growth zone, the increments were narrow and distinct, and their number corresponded in general to the number of normothermia episodes bouts. At the very base of the incisor as well as at its apical part, typical daily increments were revealed again. However, no correlation between the longevity of normothermia bouts and the width of increments was found. These data varied greatly from two other hamsters. In the Ciscaucasian hamster (Mesocricetus raddei) the number and character of increments comply with the number and duration of normothermia bouts, in the Common hamster (Cricetus cricetus), the “hibernation zone” was not recorded on the incisor surface. The Turkish hamster demonstrate an intermediate pattern, which we explain by quite different hibernation conditions of these species.

Female protein, amyloidosis, and hormonal carcinogenesis in Turkish hamster: differences from Syrian hamster

The Syrian hamster (Mesocricetus auratus) has been widely used as an experimental animal and is a unique model for three sex hormone-regulated events: 1) estrogen-initiated renal carcinogenesis, 2) sex-limited expression of amyloidosis, a ubiquitous disease, and 3) sex hormone control of a serum amyloid P component (SAP) called female protein (FP). In this study, we evaluated the closely related Turkish hamster (Mesocricetus brandti) for these three events and found some very different responses: 1) estrogen-initiated renal carcinogenesis was not found in Turkish hamster, 2) amyloidosis was not sex limited and actually was a rare disease in the Turkish hamster, and 3) Turkish hamsters did express a sex-limited SAP-FP in serum that was antigenically identical and structurally very similar (97.5%) to Syrian hamster SAP-FP. However, acute phase regulation of SAP-FP synthesis was different, and serum levels of this pentraxin were much lower than those found in the Syrian hamster. On the other hand, in contrast to findings in the Syrian hamster, hepatic tumors were relatively common in normal and especially in estrogen-treated Turkish hamsters. Therefore, although they are closely related, these two Mesocricetus hamster species have markedly dissimilar responses to sex hormones.