Oestrogen-mediated hormonal imbalance precipitates erectile dysfunction

Declining testosterone (T) in an aging male offsets the equilibrium between androgen and oestrogen (oestradiol, E(2)) with a resultant increase in E(2)-T ratio. Similar functional hormone imbalance is existent in clinical states of hypogonadism and is likely to arise from exposure of males to environmental oestrogens. The pathophysiological significance of this derangement on erectile function, hitherto unknown, was estimated in sexually mature male rats following acute and chronic treatment with oestrogen. A total of 60 male Sprague-Dawley rats (200-250 g) were divided into control and two treatment groups, administered 0.01 and 0.1 mg of oestradiol through oral gavage daily for 1 week (n=30, acute study) and 12 weeks (n=30, long-term study), respectively. Sexual activity in the presence of hormonally primed female rats and intracavernous pressure (ICP) response to electrical stimulation estimated treatment-induced changes, which were correlated with hormone levels and penile morphology at 12 weeks. Following two to five-fold elevation in serum E(2) levels (and simultaneous reduction in testosterone), there was a significant prolongation of mount, intromission, ejaculation latencies and some decrease in frequencies. The ICP response to nerve stimulation was also impaired in all the treated groups. Histologically, trichrome staining highlighted the cavernosal connective tissue hyperplasia in the long-term study groups. Results of this investigation indicate that oestradiol causes pathophysiological changes in erectile function. These observations provide an indirect evidence for the possible sexual health hazards in man upon inadvertent exposure to environmental oestrogens, ageing and derangement of E(2)-T ratio.