Influence of glutamatergic projections to the rostral pontine reticular formation on micturition in rats.
OBJECTIVE
We examined the effect of injecting glutamate or a glutamate receptor antagonist into the rostral pontine reticular formation (RPRF) on the micturition reflex in anesthetized rats and conscious rats.


METHODS
Forty-eight female rats were divided into an isovolumetric cystometry group and a continuous cystometry group. Under urethane anesthesia or while conscious, physiological saline, glutamate, or MK-801 (a glutamate receptor antagonist) was injected into the RPRF, and then the changes of bladder activity were examined.


RESULTS
There was no significant change of bladder activity after injection of physiological saline. In anesthetized rats, the injection of either glutamate or MK-801 into the RPRF transiently inhibited bladder contractions. There was a complete recovery of bladder activity 10-20 min after glutamate or MK-801 injection and there were no significant changes of cystometry parameters after the recovery of bladder contractions. In conscious rats, injection of glutamate into the RPRF prolonged the interval between bladder contractions and decreased the baseline bladder pressure. On the other hand, injection of MK-801 into the RPRF caused numerous small bladder contractions, some of which were accompanied by a leakage of a small amount of fluid from around the urethral catheter.


CONCLUSIONS
RPRF neurons receive glutamatergic projections, possibly from the forebrain, and the RPRF inhibits the micturition reflex pathway. RPRF neurons are also regulated by inhibitory interneurons, which receive glutamatergic projections as well. Therefore, the RPRF plays an important role in the regulation of urine storage.
Naka
Hidekatsu
H
Division of Urology, Department of Organ-oriented Medicine, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
Nishijima
Saori
S
Kadekawa
Katsumi
K
Sugaya
Kimio
K
Saito
Seiichi
S
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012154:Reticular Formation / Q000187:drug effects / Q000502:physiology*; D001743:Urinary Bladder / Q000502:physiology; D014554:Urination / Q000187:drug effects / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D016291:Dizocilpine Maleate