GABAergic contribution to rat bladder hyperactivity after middle cerebral artery occlusion.
To evaluate the influences of gamma-aminobutyric acid (GABA) mechanisms on bladder hyperactivity after left middle cerebral artery occlusion, cystometric recordings were obtained from unanesthetized female rats. Intracerebroventricular administration of both muscimol (GABA(A) receptor agonist; 0.1-10 nmol) and baclofen (GABA(B) receptor agonist; 0.1-3 nmol) produced dose-dependent inhibitions of micturition with increases in bladder capacity (BC). The effects of high doses (1-10 nmol) were similar in sham-operated (SO) and cerebral-infarcted (CI) rats. However, lower doses of muscimol (0.1 or 0.3 nmol) and baclofen (0.1 nmol) reduced BC in CI rats. After bicuculline (GABA(A) receptor antagonist; 1 or 3 nmol) administration, BC in both SO and CI rats first decreased and subsequently increased. An increase in urethral pressure was observed after administration of bicuculline (3 nmol) but not with either muscimol or baclofen. Infarct volumes in muscimol-, bicuculline-, or baclofen-treated rats were not significantly different from those of vehicle-treated rats. These results suggest that GABAergic mechanisms inhibit the micturition reflex at the supraspinal level but that this can change as a result of CI.
Kanie
S
S
Department of Urology, Kanazawa University School of Medicine, Kanazawa University, Ishikawa 920-8641, Japan.
Yokoyama
O
O
Komatsu
K
K
Kodama
K
K
Yotsuyanagi
S
S
Niikura
S
S
Nagasaka
Y
Y
Miyamoto
K I
KI
Namiki
M
M
D000818:Animals; D001418:Baclofen / Q000008:administration & dosage / Q000494:pharmacology*; D001640:Bicuculline / Q000008:administration & dosage / Q000494:pharmacology; D002544:Cerebral Infarction / Q000503:physiopathology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D058785:GABA-A Receptor Agonists; D058786:GABA-B Receptor Agonists; D007276:Injections, Intraventricular; D020768:Middle Cerebral Artery / Q000502:physiology*; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000503:physiopathology; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D014554:Urination / Q000187:drug effects / Q000502:physiology
D058785:GABA-A Receptor Agonists; D058786:GABA-B Receptor Agonists; D009118:Muscimol; D001418:Baclofen; D001640:Bicuculline