Modulation by desmopressin of neuronal activity in brainstem micturition center.
OBJECTIVE
To examine the effect of desmopressin (DDAVP) on bladder contraction and on the neurons that fire in relation to spontaneous bladder contraction (bladder-related neurons) in and around Barrington's nucleus, the micturition center. DDAVP is used for the treatment of nocturnal enuresis because of its antidiuretic action, but the mechanism of this action has not been proved.


METHODS
Urethane-anesthetized Sprague-Dawley male rats (n = 20) were used. DDAVP was infused intravenously or as an intracerebroventricular infusion into the lateral ventricle.


RESULTS
We encountered three types of bladder-related neurons: those that fired before the start of the contraction (type E1), those that fired synchronous with the bladder contraction (type E2), and those that fired during bladder relaxation (type I). Intravenous infusion caused inhibition in three of five type E1 neurons, excitation in two of five type E2 neurons, and excitation (one neuron) and inhibition (one neuron) of four type I neurons. With intracerebroventricular infusion into the lateral ventricle, two of four type E1 neurons were inhibited, and one of seven type E2 neurons and three of four type I neurons were excited. Bladder contraction was suppressed in 4 of 12 rats by intravenous infusion and in 2 of 8 rats by intracerebroventricular infusion into the lateral ventricle. In all cases, when the bladder contraction was suppressed, an electroencephalogram of larger amplitude and slower frequency appeared.


CONCLUSIONS
DDAVP seems to regulate bladder activity by affecting bladder-related neurons in the micturition center.
Iwasaki
Hiroshi
H
Department of Physiology, Fukushima Medical University School of Medicine, Fukushima, Japan.
Koyama
Yoshimasa
Y
Tanaka
Yoshiyuki
Y
Kawauchi
Akihiro
A
Jodo
Eiich
E
Kayama
Yukihiko
Y
Miki
Tsuneharu
T
D000818:Animals; D001933:Brain Stem / Q000187:drug effects*; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D012076:Renal Agents / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D001743:Urinary Bladder / Q000294:innervation*; D014554:Urination / Q000502:physiology
D012076:Renal Agents; D003894:Deamino Arginine Vasopressin