Je. Burkhardt et al., IMMUNOHISTOCHEMISTRY OF ARTICULAR-CARTILAGE FROM IMMATURE BEAGLE DOGSDOSED WITH DIFLOXACIN, Toxicologic pathology, 25(5), 1997, pp. 475-480
Effects of the fluoroquinolone difloxacin on articular-epiphyseal cart
ilage in growing beagle dogs have been described by light microscopic,
electron microscopic, and biochemical methods. Here we present data f
rom an immunohistochemistry study with humeral head cartilage from 3-m
o-old beagle dogs after treatment with 1 or 2 oral doses of 300 mg dif
loxacin/kg body weight. Dogs were euthanatized either 24 hr (single do
se) or 48 hr (2 doses) after onset of dosing, and cartilage tissue was
stored at -90 degrees C until it was studied by immunohistochemistry.
Antibodies against matrix components (collagen II, fibronectin) as we
ll as antibodies against cellular structures (integrins) were used. Af
ter single-dose treatment (24-hr group:), cartilage lesions such as cl
efts were not observed, but increased staining for fibronectin was fou
nd in cartilage samples from 5 of 6 animals. Markedly increased staini
ng for fibronectin was also demonstrated in the vicinity of clefts wit
hin cartilage of all animals of the 48-hr group. Collagen II staining
was homogeneously distributed in cartilage from controls and was sligh
tly reduced in territorial matrix in 2 of 6 dogs of the 48-hr group. I
ntegrin staining on chondrocytes was nor significantly affected by dif
loxacin under the given conditions with the exception of a slight redu
ction of the or, integrin chain in 1 of 5 dogs of the 48-hr group. Ove
rall, the most important result is the finding that fibronectin was a
sensitive immunohistochemical marker for change in cartilage samples d
ue to difloxacin treatment in dogs.