Influence of 5-hydroxytryptamine and the effect of a new serotonin receptor antagonist (sarpogrelate) on detrusor smooth muscle of streptozotocin-induced diabetes mellitus in the rat.
BACKGROUND
We evaluated the changes in the response of detrusor muscle to 5-hydroxytryptamine (5-HT; serotonin) and its receptor mechanisms in pathologic bladder of diabetes mellitus rats.


METHODS
Eight-week-old male Wistar rats were given an intraperitoneal injection of streptozotocin (STZ, 60 mg/kg) in order to induce diabetes mellitus (4 weeks' duration). The bladder strips (10 x 2 mm) were subjected to a tension of 1.0 g in organ baths for the measurements of isotonic contractile responses to 5-HT or relaxation responses to 5-HT antagonists.


RESULTS
Bladder strips from STZ-diabetic rats responded to 5-HT with greater contractions than did those of control rats, given vehicle alone. However, bladder strip weights gradually increased in the STZ-diabetic rats as compared with control rats and when the contractile response to 5-HT was expressed as a percentage of the response to 10(-1) mol/L KCl there was no statistically significant difference between the groups. In both control and diabetic rats, the 5-HT3 selective antagonist did not markedly inhibit the contractile response to 5-HT. In contrast, the 5-HT2A selective antagonist inhibited the contractile response to 5-HT in a dose-dependent manner.


CONCLUSIONS
These results suggest that the increased contractile response to 5-HT in diabetic rats' bladder is related to smooth muscle hypertrophy and/or hyperplasia and indicate that this effect is mediated by activation of 5-HT2A receptors.
Kodama
M
M
Department of Urology, Nihon University School of Medicine, Surugadai Nihon University Hospital, Tokyo, Japan.
Takimoto
Y
Y
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013386:Succinates / Q000494:pharmacology*; D001743:Urinary Bladder / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D001745:Urinary Bladder Diseases / Q000188:drug therapy* / Q000209:etiology
D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013386:Succinates; C064294:sarpogrelate; D012701:Serotonin