This study was performed to induce hepatic fibrosis and to elucidate the pathologic feature of the liver by intraperitoneal injection of MHV-2M virus and concomitant serial water immersion stress in ICR mice having normal immune system for T-cell
mediated cellular immunity.
The study was made of two experiments having three animal groups in each experiment to which the specific pathogen free animals of female mice were randomly assigned.
The animals of the group 1 in experiment 1 were injected with MHV-2M of 1×10E7 PFU in 0.2ml PBS at study initiation, and at 12, 24 hours after the first injection. Serial water immersion stress was provided to mice of group 2 by allowing them in
cold
water about 3 minutes a time, 2 times a day for 10 days. A combinated treatment were allowed to the mice of group 3 of the same experiment.
In experiment II, the same procedure were prepared except the differences of 2 times viral injection at 0 and 12 hour, and a 14 day stress period.
All animals were submitted to gross necropsy, and the livers of mice survived to the end of observation period were taken under the ether anesthesia.
All livers were examined macroscopically and microscopically. For histopathalogical examination of the liver tissues, hematoxylin and eosin, Masson's trichrome, Watanabe's silver staining, and immunohistochemical staining method were employed.
A transmission electron microscopic examination was performed after the staining of the specimen with uranyl acetate and lead citrate.
Histopathological observations showed increased collagen or reticulin fibers in the liver of group 3 in experiment I and II. During the initial stage of fibrosis desmine positive cells were increased at the necrotic lesion, but this tendency was
decreased according to the progress of fibrosis. Type IV collagen positive areas were increased at the liver tissue which had shown severe fibrosis.
The ratios of occurance of hepatic fibrosis were 61.5% and 42.7% at group 3 of experiment I and II, respectively.
Therefore, the results of this study may suggest that a new hepatic fibrosis model in ICR mouse could be available with further detailed study to settle the critical conditions to reach the uniformity of the biological response.
|