Muscarinic receptor transcript and protein density in hypertrophied and atrophied rat urinary bladder

Abstract

Aims-Our previous studies showed that bladder hypertrophy shifts the muscarinic receptor subtype mediating contraction from M 3 towards M 2 along with increased M 2 and decreased M 3 protein concentration. We quantified mRNA for M 1 through M 5 receptors to determine whether the changes in M 2 and M 3 protein levels was due to changes in transcription.Methods-Bladder hypertrophy was induced by bladder outlet obstruction (BOO), major pelvic ganglion electrocautery (DEN), and major pelvic ganglion decentralization (DEC). Bladder atrophy was induced by ureteral diversion (DIV). Additional groups included denervated and diverted (DEN-DIV), sham operated (SHAM), and normal (NOR) controls. Transcripts were quantified using a multiplex ribonuclease protection assay (RPA) and receptor protein density was determined by immunoprecipitation. Receptor transcripts were expressed per unit total RNA.Results-Although all five receptor subtype transcripts were detected in all experimental groups, the densities of M 1 , M 4 , and M 5 were much lower than for the M 2 and M 3 subtype. There were more M 2 receptor transcripts than all the others, consistent with M 2 protein determinations. M 2 transcripts were significantly increased in DEN and BOO bladders. Surprisingly, M 3 transcripts were also significantly increased in BOO. There was a significant correlation (r = 0.98, P < 0.001) between protein density and transcript density for the M 2 but not the M 3 receptor among the different experimental groups.Conclusions-Changes in mRNA concentration are reflected by changes in protein density for the M 2 receptor but not for the M 3 receptor. Extrapolation of functional effects from transcript density data is invalid for M 3 mediated bladder contractions.

Detection of muscarinic receptor subtypes in human urinary bladder mucosa: Age and gender‐dependent modifications

“…We would like to underline that the M 2 subtype expression showed a positive correlation between the amount of mRNA expressed and its transcription, as the protein quantification showed a similar trend observed by Q-RT-PCR. These results are in line with those reported by Braverman and Ruggieri, 30 indicating that, in the rat, the M 2 receptor protein density correlates directly with the respective transcripts, while no correlation exists between the protein and the transcripts regarding the M 3 subtype, suggesting that the muscarinic receptor subytpe translation is differentially regulated. Mechanisms underlying this phenomenon and whether or not this finding may have a clinical involvement would be a matter of further investigation.…”

The Loss and Progressive Recovery of Voiding after Spinal Cord Interruption in Rats is Associated with Simultaneous Changes in Autonomous Contractile Bladder Activity

“…The behaviour of M 3 mRNA in bladders post-SCI seems to correlate less with the expression of M 3 protein since in hypertrophied [22] and (spontaneous voiding) neurogenic [23] rat bladders a decrease of M 3 protein amount has been reported. Similar noncorrelating findings have been reported before [26] and suggest differences in the cascade from mRNA to protein between M 2 and M 3 . The observed changes at the mRNA level are likely to be involved in the increased sensitivity for muscarinic agonists post-SCI, but the exact mechanisms remain unclear from the present study.…”

Temporal Morphological and Functional Impact of Complete Urinary Diversion on the Bladder: A Model of Bladder Disuse in Rats

“…However, M3 and P2X1 receptor proteins were significantly decreased at 1 week and 8 weeks after UD compared with those of control and sham groups. Considering urinary diversion may reduce the tissue concentration of β-actin 13,14 , the results of the current study may overestimate the expression of the mentioned receptor proteins in the UD group.…”