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Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing.

ABSTRACT: 1. We investigated muscarinic receptors in the detrusor and mucosa of the human bladder body. Radioligand-binding studies with [(3)H]QNB were conducted using specimens collected from patients (36-77 years) with normal bladder function, undergoing surgery. For RT-PCR, biopsies of normal bladder were obtained from patients (30-88 years) undergoing check cystoscopy. 2. Binding of [(3)H]QNB in detrusor (n=20) was of high affinity (K(D) 77.1 (55.2-99.0) pM) and capacity (B(max) 181+/-7 fmol mg protein(-1)). Similar values were obtained in mucosa (n=6) (K(D) 100.5 (41.2-159.9) pM; B(max) 145+/-9 fmol mg protein(-1)). 3. Competition-binding experiments in detrusor membranes with muscarinic receptor antagonists including trospium, darifenacin, 4-DAMP, methoctramine, AQ-RA 741, AF-DX 116 and pirenzepine indicated a receptor population of 71% M(2), 22% M(3) and 7% M(1). In the mucosa, 75% of sites were M(2) receptors, with 25% M(3)/M(5). 4. Using RT-PCR, expression of M(1), M(2), M(3) and M(5) mRNA was demonstrated in both detrusor and mucosa. 5. The presence of a high density of mainly M(2) muscarinic receptors in the mucosa appears to be a novel finding and raises the question of their physiological significance and the source of their endogenous ligand. 6. There was a negative correlation of receptor number (B(max)) with age in detrusor muscle from male patients (P=0.02). Quantitative competitive RT-PCR demonstrated a selective age-related decrease in mRNA for muscarinic M(3) but not M(2) receptors, in both male (P<0.0001) and female (P=0.019) detrusor. These findings correspond with reports of decreased detrusor contractility with ageing.

SUBMITTER: Mansfield KJ

PROVIDER: S-EPMC1576093 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature

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Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing.

Mansfield Kylie J KJ Liu Lu L Mitchelson Frederick J FJ Moore Kate H KH Millard Richard J RJ Burcher Elizabeth E

British journal of pharmacology 20050401 8

1. We investigated muscarinic receptors in the detrusor and mucosa of the human bladder body. Radioligand-binding studies with [(3)H]QNB were conducted using specimens collected from patients (36-77 years) with normal bladder function, undergoing surgery. For RT-PCR, biopsies of normal bladder were obtained from patients (30-88 years) undergoing check cystoscopy. 2. Binding of [(3)H]QNB in detrusor (n=20) was of high affinity (K(D) 77.1 (55.2-99.0) pM) and capacity (B(max) 181+/-7 fmol mg protei ...[more]

PMID: 15723094

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Project description:An organ such as the bladder consists of complex, interacting set of tissues and cells. Inflammation has been implicated in every major disease of the bladder, including cancer, interstitial cystitis, and infection. However, scanty is the information about individual detrusor and urothelium transcriptomes in response to inflammation. Here, we used suppression subtractive hybridizations (SSH) to determine bladder tissue- and disease-specific genes and transcriptional regulatory elements (TRE)s. Unique TREs and genes were assembled into putative networks.It was found that the control bladder mucosa presented regulatory elements driving genes such as myosin light chain phosphatase and calponin 1 that influence the smooth muscle phenotype. In the control detrusor network the Pax-3 TRE was significantly over-represented. During development, the Pax-3 transcription factor (TF) maintains progenitor cells in an undifferentiated state whereas, during inflammation, Pax-3 was suppressed and genes involved in neuronal development (synapsin I) were up-regulated. Therefore, during inflammation, an increased maturation of neural progenitor cells in the muscle may underlie detrusor instability. NF-kappaB was specifically over-represented in the inflamed mucosa regulatory network. When the inflamed detrusor was compared to control, two major pathways were found, one encoding synapsin I, a neuron-specific phosphoprotein, and the other an important apoptotic protein, siva. In response to LPS-induced inflammation, the liver X receptor was over-represented in both mucosa and detrusor regulatory networks confirming a role for this nuclear receptor in LPS-induced gene expression.A new approach for understanding bladder muscle-urothelium interaction was developed by assembling SSH, real time PCR, and TRE analysis results into regulatory networks. Interestingly, some of the TREs and their downstream transcripts originally involved in organogenesis and oncogenesis were also activated during inflammation. The latter represents an additional link between inflammation and cancer. The regulatory networks represent key targets for development of novel drugs targeting bladder diseases.

Dataset Information

Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing.

Publications

Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing.

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