Related Experiment Video
Updated: Aug 12, 2026
The Left Pneumonectomy Combined with Monocrotaline or Sugen as a Model of Pulmonary Hypertension in Rats
Published on: March 8, 2019
Suppression of polyamine biosynthesis prevents monocrotaline-induced pulmonary edema and arterial medial thickening
Abstract:
Previous work in our laboratory has shown that the continuous administration of alpha-difluoromethylornithine (DFMO), a highly specific irreversible inhibitor of ornithine decarboxylase (ODC), which is the rate-limiting enzyme in polyamine biosynthesis, prevented the development of pulmonary hypertension and right ventricular hypertrophy induced in rats 21 days after a single injection of monocrotaline (MCT). We now report that DFMO treatment did not influence the proposed first step of MCT pneumotoxicity, that is, the hepatic metabolism of MCT to toxic pyrrolic metabolites. In contrast, DFMO treatment blunted the development of lung perivascular edema at Day 7, inhibited the respective four- and twofold increases in lung putrescine and spermidine contents at Day 21 without significantly altering spermine content, and prevented the arterial medial thickening at Day 21. It thus appears that increased lung polyamine biosynthesis may be essential for the expression of MCT-induced perivascular edema as well as the development of the medial thickening stage of MCT-induced hypertensive pulmonary vascular disease.
Insights
Alpha-difluoromethylornithine (DFMO) prevents pulmonary hypertension by inhibiting polyamine synthesis in the lungs, not by altering initial toxic metabolite formation. This suggests polyamine pathways are crucial for developing this condition.
Area of Science:
- Pharmacology
- Pulmonary Medicine
- Biochemistry
Background:
- Monocrotaline (MCT) injection in rats induces pulmonary hypertension and right ventricular hypertrophy.
- Alpha-difluoromethylornithine (DFMO) is a specific inhibitor of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis.
- Previous studies indicated DFMO prevents MCT-induced pulmonary hypertension.
Purpose of the Study:
- To investigate the role of polyamine biosynthesis in the development of MCT-induced pulmonary hypertension.
- To determine if DFMO affects the initial hepatic metabolism of MCT.
- To elucidate the specific stages of MCT pneumotoxicity influenced by DFMO.
Main Methods:
- Continuous administration of DFMO to rats previously injected with MCT.
- Assessment of hepatic metabolism of MCT.
- Measurement of lung perivascular edema, polyamine content (putrescine, spermidine, spermine), and arterial medial thickening at various time points post-MCT injection.
Main Results:
- DFMO treatment did not affect the hepatic metabolism of MCT to toxic pyrrolic metabolites.
- DFMO administration blunted lung perivascular edema at Day 7.
- DFMO inhibited increases in lung putrescine and spermidine at Day 21 and prevented arterial medial thickening, without significantly altering spermine levels.
Conclusions:
- Increased lung polyamine biosynthesis is essential for the development of MCT-induced perivascular edema.
- Inhibition of polyamine synthesis by DFMO prevents the medial thickening stage of MCT-induced hypertensive pulmonary vascular disease.
- DFMO's protective effects appear downstream of initial MCT hepatic metabolism, targeting polyamine-dependent pathways in the lung.
