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Transient receptor potential vanilloid 1 (TRPV1) is highly expressed in primary afferent neurons. Tissue damage generates an array of chemical mediators that activate and sensitize afferent nerve fibers, and sensitization of afferent nerve fibers plays an important role in development of visceral pain. We investigated participation of TRPV1 in visceral pain associated with bladder inflammation induced in mice by systemic treatment with cyclophosphamide or intravesical instillation of acrolein. The effects of experimental cystitis on bladder function (an indicator of visceral pain) and the threshold of response to mechanical or thermal stimuli of the hind paws were investigated using TRPV1 knock-out (KO) and congenic wild-type (WT) mice. We found that cystitis induced bladder mechanical hyperreactivity and increased mechanical sensitivity of hind paws in WT, but not in TRPV1 KO mice. Lack of functional TRPV1 did not inhibit development of histological evidence of bladder inflammation, or increased expression of mRNAs for nerve growth factor, endothelial nitric oxide synthase, cyclooxygenase-2 and bradykinin receptors in urothelium. Cystitis did not affect the threshold of response to thermal stimuli in WT or KO mice. These results suggest that TRPV1 is essential for cystitis-induced bladder mechanical hyperreactivity. Also, TRPV1 participates in development of visceral pain, as reflected by referred increased mechanosensitivity in peripheral tissues in the presence of visceral inflammation.

Cannabinoid receptors 1 and 2 (CB1 and CB2) are G-protein coupled receptors that are expressed throughout the body. Cannabinoid receptor are expressed in the urinary bladder and may affect bladder function. The purpose of this study was twofold: to confirm the presence of cannabinoid receptors in the bladder, the L6/ S1 spinal cord, and dorsal root ganglia (DRG), and to determine the effects of acute and chronic bladder inflammation on expression of cannabinoid receptors. Acute or chronic bladder inflammation was induced in rats by intravesical administration of acrolein. Abundance of CB1 and CB2 protein and their respective mRNA was determined using immunoblotting and quantitative real-time PCR, respectively. We confirmed the presence of CB1 and CB2 receptor protein and mRNA in bladder, L6-S spinal cord, and DRG. Acute bladder inflammation induced increased expression of CB2, but not CB1, protein in the bladder detrusor. Chronic bladder inflammation increased expression of bladder CB2 protein and mRNA but not CB1 protein or mRNA. Expression of CB1 or CB2 in spinal cord or DRG was unaffected by acute or chronic bladder inflammation. CB1 and CB2 receptors are present in the bladder and its associated innervation, and CB2 receptors are up-regulated in bladder after acute or chronic inflammation. CB2 receptors may be a viable target for pharmacological treatment of bladder inflammation and associated pain.Cannabinoid receptors 1 and 2 (CB1 and CB2) are members of the G-protein coupled receptor (GPCR) superfamily. CB1 is expressed primarily in the central nervous system (CNS) and is the most abundant GPCR in the brain [19]. CB2 is expressed by leukocytes, including mast cells [6], lymphocytes, monocytes, and neutrophils [2], and CB2 is also expressed at low levels in the CNS in both microglia and some neurons [8,22]. Cannabinoid receptors have also been detected in peripheral tissues, including urinary bladder [10]. Endocannabinoids and cannabinoid agonists decrease motility in normal and inflamed bladder, suggesting that CB receptors may have functional effects on the bladder [4,12,13]. Hyperalgesia associated with turpentine-induced acute bladder inflammation was prevented by administration of a cannabinoid agonist [6]. While there is interest in the use of cannabinoids to treat bladder disorders, effects of inflammation on expression of cannabinoid receptors in the bladder have not been described.*Address correspondence to: Dr. Dale E. Bjorling, Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive Drive, Madison, WI 53706, bjorlind@svm.vetmed.wisc.edu, Tel: 608-263-4808, Fax: 608-263-7930. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the productio...

OBJECTIVES To determine (i) the presence of fatty acid amide hydrolase (FAAH) in the urinary bladder; (ii) whether or not endogenous fatty acid ethanolamides are synthesized by the bladder; (iii) the effects of FAAH inhibition on referred hyperalgesia associated with acute bladder inflammation in rats. MATERIALS AND METHODS Immunohistochemistry and immunoblotting were performed to detect FAAH in the bladder. Acrolein (1 mM, 400 µL) was instilled into bladders of female Wistar rats to induce cystitis. Referred mechanical hyperalgesia was assessed by application of Von Frey monofilaments to the hind paws. Animals were killed 4, 24, 48 and 72 h after acrolein instillation, and the fatty acid ethanolamide content of bladders was measured using isotope-dilution liquid chromatography/mass spectrometry. Other rats were treated with the FAAH inhibitor URB597 (0.3 mg/kg, i.p.) after the induction of cystitis, and the mechanical sensitivity of the hind paws was determined. RESULTS Immunohistochemistry and immunoblotting showed the presence of FAAH in the bladder, with greatest abundance in the urothelium. Acrolein-induced cystitis increased fatty acid ethanolamide content (including anandamide) in the bladder in a time-dependent manner. Inhibition of FAAH diminished referred hyperalgesia associated with acute bladder inflammation. CONCLUSIONS The results obtained in the present study indicate that (i) FAAH is present in the urinary bladder; (ii) fatty acid ethanolamides are increased during bladder inflammation; (iii) inhibition of FAAH could be an effective therapeutic approach for the treatment of bladder pain. These results raise the possibility that inhibitors of enzymes responsible for metabolism of fatty acid ethanolamides could inhibit pain associated with bladder inflammation.

Currently available β-cell replacement therapies for patients with diabetes, including islet and pancreas transplantation, are largely successful in restoring normal glucose metabolism, but the scarcity of organ donors restricts their more widespread use. To solve this supply problem, several different strategies for achieving β-cell mass restoration are being pursued. These include the generation of β cells from stem cells and their subsequent transplantation, or regeneration-type approaches, such as stimulating endogenous regenerative mechanisms or inducing reprogramming of non-β cells into β cells. Because these strategies would ultimately generate allogeneic or syngeneic β cells in humans, the control of alloimmunity and/or autoimmunity in addition to replacing lost β cells will be of utmost importance. We briefly review the recent literature on these three promising strategies toward β-cell replacement or restoration and point out the major issues impacting their translation to treating human diabetes.