45 Androgen affects structural and functional perfection, such as NOS and PDE5 expression and activity of the corpus cavernosum and urinary tract.46,47 Reduced production of testosterone with age contributes to the occurrence of BPH/LUTS.48 Androgen receptors were expressed in the epithelial cells of the urethra and in the bladder of rabbits and in the urothelium, bladder smooth muscle, striated muscle cells of the proximal urethra and in the neurons in the autonomic ganglia of the prostatic plexus of the male rat.49,50 Testosterone and its metabolites maintain the reflex activity in the Erlotinib mouse pelvic part of the ANS in

rats.51 NOS-NO-cGMP pathway is partially androgen-dependent in the rat urinary tract.52 It is suggested that LUTS may be related to low androgen level.21,53 PS-341 Sleep deprivation is a significant problem among adult men who have BPH/LUTS, especially nocturia. After several days of prolonged physical and psychological stress and sleep deprivation, testosterone falls by 70–90%.53 Circulating testosterone levels increase during sleep, which start to rise on sleep onset and peak during the first episode of rapid eye movement (REM) sleep. A rise in testosterone in normal young men during continuous nocturnal sleep began at sleep onset and reached a plateau around

the time of the first REM sleep episode 90 min later.54 Sleep deprivation is a physiological stressor. Therefore, it is not surprising that serum testosterone was altered following sleep deprivation. Sleep deprivation causes secretion of serotonin. Serotonin binds to 5 HT 2 receptor resulting in production of corticotrophin-releasing hormone in Leydig cells. Corticotropin-releasing hormone inhibits cyclic adenosine monophosphate (cAMP) production and subsequent testosterone production.55 Nocturia-induced stress may be a cause of low testosterone. PDE5 mRNA is expressed in the bladder, urethra and prostate. PDE5 I inhibited the contraction of isolated bladder, urethra and prostate strips in an in vitro study.56 These results serve as a motive to attempt PDE5 I in patients with

BPH-induced LUTS. Multiple studies showed that PDE5 I improved BPH/LUTS. However, there has been debate about improvement in Qmax compared with placebo.57–70 of The first choice of management of ED using pharmacotherapy is PDE5 I.71 There have been many clinical studies of sildenafil in BPH/LUTS.57-63 Eryildirim et al.59 found that sildenafil has a positive effect in both LUTS and ED in men with LUTS and ED. The efficacy of tadalafil to relieve LUTS secondary to BPH has been reported in many clinical trials.64–66,70 In a recent clinical study, tadalafil was effective in treating BPH/LUTS. After 12 weeks of medication once daily, tadalafil produced great improvements over baseline in the IPSS, such as 13% for placebo versus 31% for 5 mg tadalafil, and improvement of IPSS was dose-dependent. However, the increase in peak flow rate did not reach statistical significance.