[Effect of propranolol on lipid metabolism in rats]

The effects of propranolol on lipid metabolism were studied in rats. Male Sprague Dawley rats at 5 weeks of age were used. Rats were given 5-10 mg/kg/day of propranolol subcutaneously or 10 mg/kg/day orally for 8 weeks. Serum non-esterified fatty acids and triglyceride were lowered in the oral treatment with propranolol but not changed in the subcutaneous one. Total serum cholesterol tended to decrease at the early weeks of treatment and increased at later weeks of treatment as compared with the control group. alpha-Lipoprotein was higher and beta-lipoprotein was lower in propranolol-treated groups than that in the control group. Serum lecithin cholesterol acyl transferase activity and high density lipoprotein were higher in propranolol-treated groups at 1st and 8th week of treatment. Total cholesterol in the liver decreased at the 8th week of treatment, but triglyceride in the liver did not change. These results suggest that propranolol inhibits the hormone sensitive lipase activity through adenyl cyclase at the early weeks of treatment, but this effect is reduced by homeostasis at the later weeks of treatment. There were some differences in serum lipids and enzyme activities between the oral and subcutaneous treatments. This would be related to the first pass effect of propranolol.