Changes of Bladder M 1,3Muscarinic Receptor Expression in Rats Fed with Short‐Term/Long‐Term High‐Fat Diets

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Objectives To investigate the effect of high‐fat diet (HFD) on bladderM1,3muscarinic receptor expression and contractile function in the rat. Methods Eight‐week‐old male rats were divided into two groups including one withHFDfor 8 weeks (short‐term) and the other for 24 weeks (long‐term). Each group was compared to age‐matched rats fed with normal chow as controls. The body weight, food intake amount and blood biochemistry were monitored. Bladder muscle contractile responses to acetylcholine (0.1–10 μM), bethanechol (10 μM) andKCl(50 mM) were studied in an organ bath set‐up. BladderM1andM3muscarinic receptor protein expressions were measured byWestern blotting analysis. Results Increase in body weight as well as blood triglyceride, cholesterol and sugar levels compared to controls were noted in both 8‐ and 24‐weekHFDrats. Eating appetite change with increased food and water intakes was noted in theHFDrats. Significantly decreased bladder contractile responses to acetylcholine and bethanechol were shown in bothHFDgroups. On the other hand, decreased bladder contractile response toKClwas demonstrated in the 24‐week group but not the 8‐week group. The expressions of bladderM1andM3muscarinic receptor proteins were significantly and progressively decreased byHFDfeeding from 8 to 24 weeks. Conclusions High‐fat diet induces obesity and polyphagia in rats. Short‐term and long‐termHFDfeeding decrease rat bladderM1andM3receptor expressions as well as contractile responses to the agonistic stimulation. In addition, bladder muscle dysfunction develops after long‐termHFDfeeding.