Experimental lung research
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Comparative Study
Inhalation administration of all-trans-retinoic acid for treatment of elastase-induced pulmonary emphysema in Fischer 344 rats.
A past study demonstrated that all-trans-retinoic acid (ATRA) treatment by intraperitoneal injection in a rat model of elastase-induced emphysema caused tissue regeneration as evidenced by a decrease in alveolar size and lung volume and an increase in alveolar number. We postulated that treatment with this retinoid by nose-only inhalation exposure would be a more efficient means of targeting damaged lung tissue. Emphysema was induced in male Fischer 344 rats by intratracheal instillation of pancreatic elastase (0.5 IU/g body weight). ⋯ Neither inhaled nor injected ATRA reduced the enlarged lung volumes associated with this emphysema model. Stereology demonstrated that alveolar air space enlargement in ATRA-treated rats was similar to that in sham-treated emphysematous animals. Thus, while inhalation treatment caused greater levels of the drug in lung tissue in comparison to that of injection-treated animals, treatment with ATRA by either route of administration did not cause a reversal of lung tissue damage in this model of elastase-induced emphysema.