Propranolol versus prazosin on some aspects of lipid metabolism in rats exposed to cigarette smoke: a biochemical, histological and histochemical study

ABSTRACT

The effects of prazosin and propranolol monotherapy on serum lipids were compared in rats exposed to cigarette smoke. Cigarette smoke exposure for two weeks resulted in a significant increase in serum triglycerides and LDL-cholesterol. Changes in total cholesterol / LDL-cholesterol ratio were not statistically significant. Prazosin monotherapy [0.5 mg/kg/day p.o. for two weeks] resulted in a decrease [insignificant] in serum triglycerides, total and LDL-cholesterol concentrations and total cholesterol/LDL-cholesterol ratio. Propranolol monotherapy [70 mg/kg/day p.o. for two weeks] resulted in a significant increase in serum triglycrides, total cholesterol and LDL-cholesterol, while the total cholesterol/LDL-cholesterol ratio. Propranolol monotherapy [70 mg/kg/day p.o. for two weeks] resulted in a significant increase in serum triglycerides, total cholesterol and LDL-cholesterol, while the total cholesterol/LDL-cholesterol ratio showed a significant drop. Cigarette smoke exposure in rats treated by prazosin resulted in attenuation of the deleterious effects of smoke on triglycerides and LDL-cholesterol. However, potentiation of the effects of exposure to cigarette smoke was noted in the propranolol treated group. Histological study of the liver in the different groups by H and E, and both the enzymatic [succinic dehydrogenase, non-specific esterase, alkaline and acid phosphatases] and the non-enzymatic histochemical [Sudan black B, OTAN and Schultz reactions] findings sustantiate thebiochemical data obtained. It is suggested that the effects of prazosin on serum lipids may be mediated, at least in part, by blocking an action of either the sympathetic nervous system or sirculating catecholamines that normally modulate lipoprotein metabolism and might mediate the lipid alterations induced by smoking. Furthermore, the data suggest that propranolol may induce significant, potentially atherogenic changes in lipid metabolism, whereas prazosin may represent an advantageous alternative as an antihypertensive agent, especially in smoking subjects with an already atherogenic lipoprotein profile