Alterations in urinary bladder M2-muscarinic receptor protein and mRNA in 2-week streptozotocin-induced diabetic rats

The M-2 receptor (M-2-mAChR) is quantitatively the dominant muscarinic subtype in animal bladders. The alterations in its protein quantity and biosynthesis during diabetic cystopathy were investigated. Three-month-old male Wistar rats were divided into two groups: (1) 2-week-old diabetics; and (2) normoglycemic control rats. Diabetes was induced by single intravenous injection of 60 mg/kg streptozotocin. The amount of M-2 receptor protein in the rat bladder body tissue was measured by Western immunoblotting using monoclonal antibodies. For determination of Mp muscarinic receptor mRNA in the bladder tissue, the method of Northern blotting was employed. The results of the Western immunoblotting showed that the amount of M-2-mAChR protein in the diabetic bladder was significantly increased by 40.0 +/- 6.2% when compared with the control bladder (P < 0.05, n = 8). The Northern blotting demonstrated a 69.3 +/- 8.5% increase of the M-2-mAChR mRNA in the diabetic bladder (P < 0.05, n = 8). The findings of the present study demonstrated an upregulation of M-2-mAChR biosynthesis in the diabetic urinary bladder. This phenomenon could lead to increased reactivity to acetylcholine and thus results in detrusor instability. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.