Elevated low-density lipoprotein cholesterol (LDL-C) enhances pro-erectile neurotransmission in the corpus cavernosum

Hypercholesterolaemia is thought to foster atherosclerosis and impotence through its effects on vascular endothelium. In this study, we investigated the pharmacological changes in rabbit corpus cavernosum (CC) secondary to incubation with lysolecithin and hypercholesterolaemia. A daily egg yolk dietary supplement induced gross hypercholesterolaemia in our rabbits. Group A of test animals (n-12) was fed with the yolk content of single egg and group B (n-6), that from two eggs for eight weeks. Serum level estimation revealed a progressive elevation of cholesterol to 15 and 30 times respectively, in the two treated groups as compared to values in the control group (n-6). Early histological manifestations of atherosclerosis were perceived as fat cell lesions in the cavernosum of treated animals. In vitro pharmacological studies on CC strips from both groups of test animals demonstrated a profound accentuation of the contractile responses to noradrenaline and histamine and attenuation of relaxant response to acetylcholine. However, in contrast to single-egg treated group, which demonstrated a reduction in the relaxant response to electrical field stimulation (EFS), there was a marked and statistically significant potentiation of this nitrergic transmission, in the two-eggs group. Prior incubation of CC strips of normolipidaemic rabbits (n-7) with lysolecithin, reproduced similar exaggerated response to EFS. Therefore, from the results of our study, it is concluded that oxidised LDL or its major amphiphile lysolecithin, at some critical level or beyond, may be capable of reverting at least some of the adverse effects of hypercholesterolaemia on erectile function, through its mediating effect on nitrergic transmission.