title: Micturition-suppressing region in the periaqueductal gray of the mesencephalon of the cat.
abstract: 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.
authors.affiliation: Department of Urology, Asahikawa Medical College, Midorigaoka higashi 2-1-1-1, Asahikawa, Japan. anuma@asahikawa-med.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Numata
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iwata
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Iuchi
authors.forename: Narumi
authors.initials: N
authors.lastname: Taniguchi
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kita
authors.forename: Naoki
authors.initials: N
authors.lastname: Wada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kato
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kakizaki
mesh_terms: 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
chemical_list: D018756:GABA Antagonists; D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline