Micturition-suppressing region in the periaqueductal gray of the mesencephalon of the cat.
The periaqueductal gray (PAG) of the mesencephalon has been implicated to be involved in the control of micturition. We investigated the micturition-suppressing region in the PAG of the cat. Decerebrated 27 adult cats were used. A microelectrode was inserted stereotaxically into the PAG, and a region was searched where electrical stimulation suppressed isovolumetric bladder contractions. Simultaneous stimulation of the pontine micturition center (PMC) and micturition-suppressing region in the PAG was performed before and after an injection of bicuculline (GABA(A) blocker) into the PMC. The micturition-suppressing region was found at the dorsolateral margin of the rostral PAG. Bladder contractions were not provoked by simultaneous stimulation of the PMC and micturition-suppressing region in the PAG. However, after bicuculline injection into the PMC, partial bladder contractions were provoked by simultaneous stimulation of the PMC and the micturition-suppressing region in the PAG. These results suggest that the dorsolateral margin of the rostral PAG includes the micturition-suppressing region that seems to have neural connections with the PMC. GABA is assumed to be one of the neurotransmitters that are involved in the PMC inhibition from the micturition-suppressing region in the PAG.
Numata
Atsushi
A
Department of Urology, Asahikawa Medical College, Midorigaoka higashi 2-1-1-1, Asahikawa, Japan. anuma@asahikawa-med.ac.jp
Iwata
Tatsuya
T
Iuchi
Hiromichi
H
Taniguchi
Narumi
N
Kita
Masafumi
M
Wada
Naoki
N
Kato
Yuji
Y
Kakizaki
Hidehiro
H
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002415:Cats / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D010487:Periaqueductal Gray / Q000502:physiology*; D014554:Urination / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000187:drug effects / Q000502:physiology
D018756:GABA Antagonists; D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline