Antimuscarinic compounds are increasingly used to treat the symptoms of overactive bladder; however, their use is often restricted by peripheral adverse effects (AEs). On the other hand, data regarding their influence on the central nervous system (CNS) are limited. This randomized, single-blind, parallel-group quantitative-topographical EEG (qEEG) study of clinical phase I investigates the potential CNS adverse effects of the three antimuscarinic drugs--tolterodine, oxybutynin, and trospium chloride--in comparison to placebo. Overall, 4 x 16 (total 64) young, healthy male volunteers were included in the study. The subjects were given either placebo or the clinically recommended daily doses of the drugs dispensed in three doses on a single day (tolterodine 2 mg bid and once placebo, total 4 mg/d; oxybutynin 5 mg tid, total 15 mg/d; and trospium chloride 15 mg tid, total 45 mg/d). The qEEG was recorded prior to and up to 4 hours after each intake of the trial medication (a total of 10 qEEG sessions) under three different conditions: at rest with eyes open, eyes closed, and under mental demand. The drug tolerability was subjectively evaluated by the volunteer and the investigator. In comparison to placebo (10% confidence interval), tolterodine and trospium chloride did not induce changes of the qEEG power in five of the six frequency bands (i.e., delta, alpha 1, alpha 2, beta 1, and beta 2). Isolated power decreases were only observed in the theta frequency band. In contrast, oxybutynin caused significant power reductions in four frequency bands (theta, alpha 1, alpha 2, and beta 1; p < 0.01). The subjectively evaluated drug tolerability was comparable between all treatment groups, although differences in the AE occurrence existed, with the AE frequency being higher in the oxybutynin group. The results of this study support the findings that oxybutynin as a tertiary amine crosses the blood-brain barrier, causing significant qEEG activity changes and more pronounced central adverse effects. Although tolterodine is also a tertiary amine, it shows limited effects on qEEG activity (i.e., slight theta power reductions), comparable to the effects of trospium chloride, a quarternary amine, which barely crosses the blood-brain barrier. The minimal qEEG changes observed with tolterodine and trospium chloride reflect most probably a rebound message from the peripheral target organs. Prescription of oxybutynin thus implicates a higher risk of CNS side effects.

Abstract-Based on the presence of a functional retinoic acid receptor/retinoid X receptor transcription factor binding sequence (hormone-responsive element) in the renin gene enhancer and on the fact that the peroxisome proliferatoractivated receptors (PPARs) bind to DNA as heterodimers with retinoid X receptors, we speculated that PPARs are involved in the regulation of renin gene expression. To test this hypothesis, we used the human renin-producing cell line CaLu-6. Endogenous or pharmacological PPAR␥ agonists (unsaturated fatty acids and thiazolidinediones, respectively) stimulated renin gene expression. Surprisingly, we found that PPAR␥ targets a palindromic repeat with a 3-bp spacer (Pal3) in the proximal human renin promoter. Thus, renin is the first gene described with a functional Pal3 sequence. PPAR␥ agonists also stimulated renin gene expression in cultured native juxtaglomerular cells, which are the main source of renin in vivo. In summary, PPAR␥ was identified as a novel intracellular mediator involved in the upregulation of renin transcription. Key Words: basic science Ⅲ gene expression/regulation Ⅲ hypertension (kidney), renin Ⅲ cell signaling P lasma renin is aspartyl protease, produced by the juxtaglomerular (JG) cells of the kidney. Renin is the ratelimiting factor of the renin-angiotensin-aldosterone-system, which is of fundamental importance to the regulation of blood pressure. 1 Therefore, the mechanisms involved in the control of the renin gene are extensively characterized. An enhancer sequence, which activates transcription in a position-and orientation-independent manner, was identified in the 5Ј-flanking region of the mouse renin gene. 2 The renin enhancer contains an Ϸ50-bp-long region, which attracts much attention because it is involved in the regulation of renin transcription by virtually all cues tested until now. [2][3][4][5][6][7] A direct repeat 5Ј-AGGTCA-3Ј was identified within the 50-bp enhancer sequence. 7 This direct repeat is principally known as the hormone-responsive element (HRE), because it is the consensus DNA-binding site for the nuclear hormone receptor superfamily. 8 The nuclear hormone receptors represent ligand-activated transcription factors, which are the intracellular docking stations for membrane-permeable bioactive substances, such as corticoids, retinoids, vitamin D3, thyroid hormones, and free fatty acids. Retinoic acid (vitamin A) was found to stimulate renin transcription through retinoic acid receptor-␣ and retinoid X receptor (RXR)-␣. 7 Mice lacking the vitamin D3 receptor have elevated renin mRNA levels, and vitamin D3 inhibits renin promoter activity. 9 Thyroid hormone was also found to regulate renin transcription. 10 On the other hand, aldosterone does not influence renin transcription but stabilizes renin mRNA. 11 Thus, peroxisome proliferator-activated receptors (PPARs) remained as the last nuclear hormone receptor subfamily, which has not been studied for its impact on renin transcription. Such an effect is feasible because PPARs bind to DNA as ...