Dactinomycin isolated from the culture broth of Strepeomyces chrysomallus or Slrep-
p tomyces antibioticus, is one of the effective antibiotic anticancer drug. Since the flat
portion of the molecule intercalates into the double helical DNA strands between suc-
cessive guanine-cytocine base pair, it inhibits the action of DNA dependent RNA
polymerase altering the biosynthesis of RNA and protions. Although dactinomycin
is very effective against tumor cell proliferation, it may also damage on the normally
proliferative tissues of the body and develope the toxic effects during treatment of
- -- cancer partients.
The author has investigated the effect of dactinomycin on the mose duodenum
y`. histochemically observing changes in the activities of alkaline phosphatase. The
animals treated with 1 mg per kg of dactinomycin were sacrificed at 12, 24 and 48
hours after drug administration and fasted for 12 hours before sacrificing animals of
control and experimental groups. The animals of control group were administered
only water for injection. The duodenum specimens were fixed in 10%-neutral formalin
at 4C and sectioned in 161im thickness in frozen cryostat. The acitivity of alkaline
phosphatase was evaluated histochemically by Gomori´s method and incubation time
of sliced specimen was 20 minutes.
The results were as follows.
1. The activities of alkaline phosphatase were moderately positive in the epithelium
of duodenum of the control group, weakly positive in the 12 hours dactinomycin
treated group strongly positive in the 24 hours dactinomycin treated group and
f moderately positive in the 48 hours dactinomycin treated group. The weakely
´a positive reaction of alkaline phosphatase in the lamine propria, trace positive reac-
tion in the submucosa and trace positive or negative reaction in the muscle layer
j were observed in the control group and all dactinomycin treated goup. Consequent-
ly, it is suggested that dactinomycin decreases activities of alkaline phosphatase
i in the epithelium of the duodenum in mouse.
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