Light microscopy study of cisplatin-induced ototoxicity in rats.

BACKGROUND: Although most studies on animal ototoxicity employ scanning electron microscopy, all cochlear structures may be identified with light microscopy. This paper describes a simple method of histological assessment of cisplatin-induced ototoxicity in rats, and relates morphological changes to functional changes in hearing detected by distortion product evoked otoacoustic emissions. MATERIALS AND METHODS: Male Wistar rats were injected with 8 mg/kg/day cisplatin, or with an equivalent volume of saline solution, for three consecutive days. They underwent distortion product evoked otoacoustic emission testing at baseline and at 24 or 48 hours after the last administration. At the end of the experiment, the animals were sacrificed and their cochleae were retrieved and prepared for haematoxylin and eosin staining. RESULTS: A four-point scoring system was used to grade injury to the external ciliated cells, as indicated by the number of cells absent from the basal turn of the cochlear duct. A four-point scoring system was also used to grade stria vascularis injury, as indicated by the degree of shrinkage of the intermediate cells. Scores were significantly higher in groups treated with cisplatin compared with controls. Morphological changes were confirmed by decreased distortion product evoked otoacoustic emission amplitudes in animals treated with cisplatin. CONCLUSION: This method is simple to perform with routine histology equipment and is appropriate for the study of acute, cisplatin-induced ototoxicity in rats.

Effects of chlorpromazine on alveolar bone loss in experimental periodontal disease in rats.

Chlorpromazine (CPZ), a phenothiazine derivative, possesses anti-inflammatory properties, inhibition of tumor neurosis factor-alpha (TNF-alpha) synthesis and bone resorption. TNF-alpha promotes inflammatory changes and bone resorption in periodontitis. We have studied the effect of CPZ in experimental periodontitis. Wistar rats were subjected to a ligature placement around the cervix of the right second upper molars. Alveolar bone loss was evaluated by the sum of the distances between the cusp tip and the alveolar bone along the axis of each molar root, which was subtracted from the contralateral side. Histopathological analysis of the periodontium was based on cell influx, osteoclast number, and alveolar bone and cementum integrity. Animals were weighed daily and total and differential peripheral white blood cell counts were performed 6 h and 1, 7 and 11 d after periodontitis induction. Groups were treated with CPZ 1 h before and daily up to the 11th d of periodontitis. Alveolar bone loss was inhibited 46%, 55.4%, and 76.5% by CPZ at 1, 3 and 9 mg/kg, respectively. Histological analysis showed a significant reduction of cell influx and osteoclast number, as well as preservation of the alveolar process and cementum. CPZ reversed leukocytosis but not weight loss. In conclusion, CPZ reduces bone loss in experimental periodontitis, probably via TNF-alpha blockade.