title: Adrenergic signaling elements in the bladder wall of the adult rat.
abstract: A growing body of work is describing the absence of a significant sympathetic innervation of the detrusor implying little sympathetic regulation of bladder contractility. However, low doses of adrenergic agonists are capable of relaxing the bladder smooth muscle. If these effects underpin a physiological response then the cellular nature and operation of this system are currently unknown. The present immunohistochemistry study was done to explore the existence of alternative adrenergic signaling elements in the rat bladder wall. Using antibodies to tyrosine hydroxylase (TH) and vesicular mono-amine transporter (vmat), few adrenergic nerves were found in the detrusor although TH immunoreactive (IR) nerves were apparent in the bladder neck. TH-IR and vmat-IR nerves were however abundant surrounding blood vessels. A population of vmat-IR cells was found within the network of interstitial cells that surround the detrusor muscle bundles. These vmat-IR cells were not or only weakly TH-IR. This suggests that these interstitial cells have the capacity to store and release catecholamines that may involve noradrenaline. Cells expressing the β1-adrenoceptor (β1AR-IR) were also detected within the interstitial cell network. Double staining with antibodies to β1AR and vmat suggests that the majority of vmat-IR interstitial cells show β1AR-IR indicative of an autocrine signaling system. In conclusion, a population of interstitial cells has the machinery to store, release and respond to catecholamines. Thus, there might exist a non-neuronal β-adrenergic system operating in the bladder wall possibly linked to one component of motor activity, micro-contractions, a system that may be involved in mechanisms underpinning bladder sensation.
authors.affiliation: Department of Urology, Antwerp University Hospital and University of Antwerp, Faculty of Medicine, Antwerp, Belgium. Electronic address: sarapersyn@hotmail.com.
authors.forename: Sara
authors.initials: S
authors.lastname: Persyn
authors.affiliation: Uro-physiology Research Group, The Dental and Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, England. Electronic address: j.e.eastham@newcastle.ac.uk.
authors.forename: Jane
authors.initials: J
authors.lastname: Eastham
authors.affiliation: Department of Urology, Antwerp University Hospital and University of Antwerp, Faculty of Medicine, Antwerp, Belgium. Electronic address: stefan.dewachter@uantwerpen.be.
authors.forename: Stefan
authors.initials: S
authors.lastname: De Wachter
authors.affiliation: Department of Urology, Antwerp University Hospital and University of Antwerp, Faculty of Medicine, Antwerp, Belgium. Electronic address: james.gillespie@uantwerpen.be.
authors.forename: James
authors.initials: J
authors.lastname: Gillespie
mesh_terms: D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D001743:Urinary Bladder / Q000098:blood supply / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism
chemical_list: D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D050493:Vesicular Monoamine Transport Proteins; D014446:Tyrosine 3-Monooxygenase
keywords: Catecholamines; Interstitial cells; Rat; Urinary bladder; β-Adrenoceptors