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CHAPTER 3
Hamsters in Toxicological Research
There are at least six species of Old World
hamsters being bred in the laboratories. These
include the Syrian hamster (Mesocricetus
auratus), Chinese hamster (Cricetus gridseus),
Armenian hamster (Cricetus migratorius), Trans
caucasian or Kurdistan hamster (Mesocricetus
brandii), Rumanian hamster and the Djzungarian
hamster (Phodopus songorus). Among these, the
three first species qualify as inbreds and are used
primarily in laboratories. Newcomers include the
Russian Dwarf Campbell, Russian Dwarf Winter
White and Roborovski Hamster, European
Hamster and the Mouse-like Hamster. (Contact
information
http://www.southernshamsterclub.co.uk)
The Syrian Golden hamster (SGH) was
introduced by Adler in 1931, who obtained it from
Aleppo, a large city in northwestern Syria. It was
to be mainly used for research on Kala Azar and
Chinese hamsters as a suitable host for various
Leishmanae germs. Among the many species of
mice, the hamsters are the most susceptible to
the Leishmania germ. Contrary to other assorted
hamsters, the breeding of Syrian and Chinese
hamsters was successful. Therefore, they were
preferentially disseminated in America and in the
British Empire 70 .
In the United States and European laboratories,
SGH were used as the pancreatic cancer disease
model because of the reproducibility and
predictability of the disease in this species. They
were also used as models for anemia 71 and the
pathology of radiation syndrome 72 . Several inbred
lines of hamsters were produced, including those
with dystrophy-like myopathy and
cardiomyopathy, obesity in line with multiple
endocrine abnormalities, progressive hind-leg
paralysis and cystic prostatic hypertrophy, 73 to
name a few. Due to their various coat colors, they
also became a favored pet.
6
In chemical carcinogenesis, the cheek pouch of
SGH presented a suitable target for various
carcinogens. Such studies led to the discovery of
the sensitivity of the hamster’s respiratory tract to
certain carcinogens. This provided an ideal
model for testing suspected environmental
respiratory tract carcinogens, including tobacco,
because of its resistance to pulmonary injections
and its ability to decompose nicotine 74 . So, for a
long time, SGH presented itself as a species of
choice for respiratory tract carcinogenesis 75 .
Induction of melanoma, gastrointestinal, renal and
urinary bladder tumors in hamster, and its unique
cheek pouch for the development and
maintenance of tumors added to the value of this
animal for toxicological testing 76 . Unfortunately,
the usefulness of SGH for toxicological (drug)
testing was hampered due to its short survival.
Toxicological work (drug testing) sponsored by
the National Cancer Institute and major
pharmaceutical industries required the use of
animals with a general survival of about two
years. The survival of commonly used
commercial or institutional hamster colonies was
short. In the SGH colony of the Eppley Institute,
the survival time around 1974 was about 40-60
weeks. (As will be described later, the short
survival was unrelated to genetic but rather to the
lack of knowledge about the housing and dietary
conditions, the improvement of which raised the
survival to 18 months). Nevertheless, naturallyoccurring,
hormone-, viral- and carcinogeninduced
tumors in a variety of tissues, including
melanoma and lymphoma, by injection, digestion
and inhalation, had opened an avenue for
understanding carcinogenicity. The susceptibility
of hamster fetuses to toxic substances given to
their mothers provided a novel and important tool
for trans placental drug testing. This species
became the main focus of several major
institutions in the U.S. and abroad, including the
National Cancer Institute (Washington DC),