Functional expression of muscarinic and purinoceptors in the urinary bladder of male and female rats and guinea pigs

Abstract

Purpose: The objectives of this study were to compare the functional expression of muscarinic and purinergic receptors in the urinary bladder of 2 species, rat and guinea pig under comparable experimental conditions; and to test whether the receptors in males and females differ. Methods: Reverse transcription-polymerase chain reaction (RT-PCR) techniques were used to identify gene expression profiles in bladder smooth muscle (total n=8 rats, 7 guinea pigs) and mechanical responses to nerve stimulation and applied acetylcholine (ACh) in the presence of specific antagonists were used to identify functional receptor sub-types (total n=12 rats, 16 guinea pigs). Results: RT-PCR indicated that M2 and M3 were the predominant muscarinic receptor genes in both the male and female rat and guinea pig bladders. M) caused a significant reduction in the amplitude of the phasic response to nerve stimulation in all groups, and this effect was significantly greater in male vs. female rats. mRNA for the purinergic P2X1, P2X2, P2X4, P2X5 and P2X7 receptors was detected in both male and female rats, whereas P2X3 and P2X6 were inconsistently detected in male rats. The P2X1 purinoceptor antagonist pyridoxal-5'-phosphate-6-(2'-naphthylazo-6'-nitro-4', 8'-disulphonate) (PPNDS), only inhibited nerve induced contractions at high concentrations (up to 10 -4 M). Conclusions: While only minor functional differences were documented in cholinergic and purinergic bladder contractile responses between male and female animals, and between rats and guinea pigs, data such as presented in this study are critical in determining how relative functional contributions may change in the diseased state, providing valuable information towards new treatment options.

A possible role of the cholinergic and purinergic receptor interaction in the regulation of the rat urinary bladder function

“…They were not activated by the application of α,β-methylene-ATP, 2-methyl-thio-ATP (data not shown) and UTP, consistent with the idea that ATP-induced Ca 2+ transients are generated via activating P2X 2 receptors in the cultured urinary bladder smooth muscle cells. The presence of P2X 2 receptors on these cells has already been described (Creed et al, 2010;Dutton et al, 1999;Lee et al, 2000;Studeny et al, 2005) and were also detected through immunostaining in this study.…”

“…Based on previous reports (Creed et al, 2010;Dutton et al, 1999;Lee et al, 2000;Studeny et al, 2005) and the pharmacological profile of the ATP-evoked calcium transients presented above, we suspected the presence of P2X 2 receptors in the rat urinary bladder smooth muscle. This was indeed confirmed using immunocytochemical and immunohistochemical surveys (Fig.…”

Effects of caveolae depletion and urothelial denudation on purinergic and cholinergic signaling in healthy and cyclophosphamide-induced cystitis in the rat bladder

“…All seven P2X-purinoceptors have been identified by immunohistochemistry or RT-PCR in the rat and human urinary bladder (Creed et al, 2010;Moore et al, 2001). However, conflicting evidence exist.…”

Autonomic nervous control of the urinary bladder

“…No gender differences were found in the expression of the M 2 and M 3 receptor genes in rats and guinea‐pigs (Creed et al . ). While we are not aware of human expression data, clinical studies suggest that there is an improvement in bladder function upon muscarinic receptor antagonists (Dmochowski et al .…”