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The effect of phototherapy on intestinal mucosal enzyme activity in the Gunn rat
Insights
Phototherapy for infant jaundice does not cause diarrhea by affecting intestinal enzymes. Studies on Gunn rats found no evidence that light or bilirubin byproducts decrease lactase activity, refuting a common hypothesis.
Area of Science:
- Neonatal care
- Gastroenterology
- Biochemistry
Background:
- Infants treated with phototherapy for jaundice often experience loose stools.
- Acquired lactase deficiency secondary to phototherapy was hypothesized as the cause of diarrhea.
- The direct effects of light energy and indirect effects via bilirubin photooxidation products on intestinal enzymes were unknown.
Purpose of the Study:
- To investigate whether phototherapy directly impacts intestinal enzyme activity.
- To determine if bilirubin photooxidation products contribute to intestinal dysfunction.
- To elucidate the cause of diarrhea in infants undergoing phototherapy.
Main Methods:
- Adult Gunn rats (homozygote and heterozygote) were exposed to light for varying durations; controls were kept in the dark.
- Intestinal lactase, sucrase, and GGTP activities, along with serum bilirubin, were measured.
- Jaundiced and non-jaundiced 1-week-old suckling Gunn rats were exposed to light for 96 hours, and intestinal lactase activity was assessed.
Main Results:
- No significant decrease in intestinal lactase, sucrase, or GGTP activities was observed in adult rats treated with light.
- Light exposure did not alter enzyme activities, even in the presence of elevated bilirubin.
- Intestinal lactase activity remained unchanged in jaundiced and non-jaundiced suckling rats after phototherapy.
Conclusions:
- Phototherapy does not appear to cause diarrhea by decreasing intestinal lactase, sucrase, or GGTP activity.
- Light energy and bilirubin photooxidation products are unlikely to be responsible for the diarrheal state observed post-phototherapy.
- The etiology of loose stools in infants undergoing phototherapy requires further investigation beyond direct effects on intestinal enzymes.
Abstract:
Infants undergoing phototherapy may develop loose stools. Acquired lactase deficiency secondary to this treatment modality was suggested as a cause for the diarrhea. The effects of light energy directly on intestinal enzymes and indirectly through bilirubin photooxidation products were studied. Adult homozygote and heterozygote Gunn rats were treated with light for varying periods while littermate controls were kept in the dark. Intestinal lactase, sucrase and GGTP activities and serum bilirubin concentrations were determined. Jaundiced and non-jaundiced 1-week-old suckling Gunn rats were treated with light for 96 h, and intestinal lactase activity determined. No decreases in lactase, sucrase or GGTP activities were observed suggesting the reported diarrheal states following phototherapy are not related to light energy or photooxidation products.