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Tissue phosphatase changes following triamcinolone associated with cleft palate in rats
Insights
Triamcinolone-induced cleft palates in rats show elevated lysosomal enzyme activity, specifically acid phosphatase and beta-glucuronidase, during palate fusion. This imbalance with protein synthesis suggests a key mechanism in cleft palate development.
Area of Science:
- Developmental biology
- Biochemistry
- Teratology
Background:
- Cleft palate is a common birth defect.
- Lysosomal enzymes are theorized to play a role in palatal shelf fusion.
- Triamcinolone is a known teratogen that can induce cleft palate in animal models.
Purpose of the Study:
- To investigate the role of lysosomal enzymes in triamcinolone-induced cleft palate development in rats.
- To analyze the biochemical changes in palatal tissue during the critical period of palate fusion.
Main Methods:
- Wistar rats were administered triamcinolone on gestation day 14.
- Fetal palatal tissue was collected daily from day 14 to 19.
- Activity of acid phosphatase, beta-glucuronidase, and alkaline phosphatase was measured.
- Protein concentration was also determined.
Main Results:
- Triamcinolone administration resulted in approximately 50% cleft palates.
- Elevated concentrations of acid phosphatase and beta-glucuronidase were observed in cleft palates compared to controls during days 17-18.
- Alkaline phosphatase was also elevated in control tissue on day 17.
- Protein levels were depressed in cleft palates, leading to an elevated enzyme activity to protein synthesis ratio.
Conclusions:
- Imbalanced lysosomal enzyme activity relative to protein synthesis during palate closure is implicated in triamcinolone-induced cleft palate.
- These findings support the theory that lysosomal enzyme action is crucial in palatal fusion.
- The study highlights specific enzymatic changes associated with teratogen-induced craniofacial defects.
Abstract:
One theory of the development of cleft palate in rats involves the action of lysosomal enzymes secreted by epithelial cells at the time of fusion of the palatal shelves. To test this theory we studied the biochemistry of the palates of fetal rats daily between days 14 and 19 (from 3 days before to 3 days after palate closure). Triamcinolone was administered once im on gestation day 14 to Wistar rats; 0.5 mg/kg body weight produced approximately 50% cleft palates. Pooled control palatal tissue was compared with pooled experimental tissue; that from fetuses with clefts being pooled separately from those not affected. Acid phosphatase and beta-glucuronidase were assayed. Concentration vs. time curves for both enzymes were very similar. Prior to the time of palate closure both enzymes were present in low concentration. Between days 16 and 17, the normal time of closure, there was an abrupt increased in enzyme concentration, with experimental tissue showing a significant elevation over control tissue on days 17 and 18. Alkaline phosphatase was also present in small amounts before closure and significantly higher in control tissue on day 17. Protein was depressed in palates having clefts on day 17; thus the ratio of enzyme activities to protein synthesis was significantly elevated at a critical time. Unaffected experimental palates had a normal ratio. These results suggest imbalanced acid phosphatase, beta-glucuronidase, and alkaline phosphatase activity compared with protein synthesis at the time of palate closure following triamcinolone in rats.