Diabetes‐Induced Dysregulation of Purinergic Signaling in the Bladder Mucosa: Accelerated ATP Hydrolysis and Impaired Adenosine Uptake Promote Underactive Bladder Phenotype
Mahsa Borhani Peikani, Brian A. Perrino, Violeta N. Mutafova‐YambolievaABSTRACT
Objective
To explore molecular mechanisms underlying excessive extracellular adenosine (ADO) accumulation in the bladder lamina propria (LP) of mice with type 2 diabetes (T2D) induced by a high‐fat, high‐sucrose diet (HFHSD), conceivably leading to bladder underactivity.
Methods
Performing automated, non‐invasive, continuous monitoring in metabolic cages, we evaluated 24‐h water intake and urine output of male C57Bl/6 nondiabetic (ND) and HFHSD‐T2D mice. Using a detrusor‐free bladder model and HPLC with fluorescence detection, we assessed availability of ATP, ADP, AMP, and ADO as well as the degradation of 1 N 6 ‐etheno‐ATP (eATP, 2 µM) in extraluminal solutions (ELS) interfacing with the LP of both nondistended and distended bladders from ND and HFHSD‐T2D mice. We also investigated the effect of ENT1 inhibition on transurothelial eADO transport and quantified AMPKα expression, its phosphorylation status, and ENT1 protein levels in ND and T2D bladder mucosa using the Jess Protein Western nano‐immunoassay. Glass's ∆ and Hedges' g effect size indicators were used to compare non‐diabetic and HFHSD‐T2D groups.
Results
In the HFHSD‐T2D mice, the number of voids per 24 h was significantly decreased (Glass's ∆ 3.694) whereas urine volume per void was significantly increased (Glass's ∆ 1.554) in comparison with ND mice. Purines were released in ELS/LP of ND and diabetic bladders. T2D bladders exhibited a marked reduction in ATP (Glass's ∆ 12.772) and a substantial elevation in ADO levels within the ELS of distended preparations (Glass's ∆ 4.472). Hydrolysis of eATP to eADP, eAMP, and eADO was accelerated in the T2D ELS/LP. AMPKα2 expression and T172 phosphorylation were notably diminished in T2D bladder mucosa (Glass's ∆ = 2.453 and 2.572, respectively). Pharmacological inhibition of ENT1 reduced the transport of eADO from the lumen to the ELS. ENT1 protein levels were significantly lower in T2D bladder mucosa (Glass's ∆ = 12.824).
Conclusions
Excessive accumulation of the inhibitory purine ADO in the LP of T2D bladders is driven by two convergent mechanisms: (1) accelerated degradation of ATP possibly linked to AMPK dysregulation, and (2) impaired cellular uptake of ADO due to diminished ENT1 expression. Together, these disruptions contribute to elevated extracellular ADO levels, which likely inhibit detrusor muscle contractility and promote the development of an underactive bladder.