Minoru Kanda (1), Koji Eto (2), Nobuaki Tanabe (1), Atsushi Sugiyama
(2), Keitaro Hashimoto (2,*) and Akira Ueno (1)
(1) Department of Urology and (2) Department of Pharmacology, Yamanashi
Medical University, Tamaho-cho 1100, Nakakoma-gun, Yamanashi 409-38, Japan
(*) To whom correspondence should be addressed.
Abstract: This study was conducted to evaluate effects of the
aldose reductase inhibitor ONO-2235 on the contractile response to acetylcholine
of the urinary bladder dome of streptozotocin-induced diabetes mellitus
(DM) rats and simultaneously observe the changes in the function and number
of muscarinic receptors and the sorbitol content of the bladder. The contractile
response to acetylcholine increased 51% in the DM rat bladder dome compared
to the normal rats; however, this was attenuated to a 10% increase by administration
of 100 mg/kg ONO-2235 for 2 weeks. Treatment with ONO-2235 significantly
decreased the specific [3H]quinuclidinyl benzilate binding in DM rats. However
there was no significant dose-dependency among the ONO-2235-treated groups.
The sorbitol levels of the sciatic nerve and the bladder were higher in
the DM rats compared to the control rats; ONO-2235 decreased the level,
although it did not completely reverse them to the control level. These
results suggest that an aldose reductase inhibitor attenuates the increase
of the muscarinic receptor number and normalizes the enhanced contractile
response to acetylcholine caused by hyperglycemia and diuresis, probably
through suppression of the polyol-pathway in the DM rat bladder dome.
Keywords: Diabetes mellitus, Bladder dome (rat), Aldose reductase inhibitor,
Polyol pathway, Muscarinic receptor