Obesity-induced hyperplastic lung growth.

The effects of overnutrition on lung growth were studied in newborn male Long-Evans rats made obese by nursing in small litters with subsequent feeding of a high fat diet. Control rats were nursed in normal-sized litters and then fed standard rat chow. The animals were killed at 8 wk of age. When compared with control rats, obese rats had significant increases in body weight (24%); fat pad weight (118%); fat pad weight/body weight ratio (77%); snout-to-anus length (11%); total lung weight (11%); lung content of DNA (19%), protein (22%), RNA (22%), total lipids (31%), cholesterol (20%), and triglycerides (141%); and the lung triglyceride/DNA ratio (217%). Serum levels of insulin (71%), total lipids (60%), cholesterol (64%), and triglycerides (90%) were also elevated in obese rats as compared with those in control rats. Unchanged were the ratios of lung protein/DNA, RNA/DNA, lipid/DNA, and cholesterol/DNA; lung phospholipid content; and serum concentrations of glucose and phospholipids. The results indicate the presence of cellular hyperplasia in lungs of young rats made obese by diet. Lipid deposition in the obese lungs suggests metabolic alterations in pulmonary composition occurring with obesity.