Comparison of the effects of oestrogen deficiency and old age on primary bladder afferent activity and voiding behaviour in the ageing female rat.
OBJECTIVE
To determine if a decrease in oestrogen (E) levels increases activity in bladder afferent nerves, by investigating the effects of E loss on afferent nerve activity in ovariectomized (OVX) rats, and making comparisons with findings in ageing female rats.


METHODS
Female Sprague-Dawley rats were divided into four groups: ageing; OVX+ E; OVX+ vehicle (V); and sham-operated (SHAM) + V. The E (250 µg/kg) or V (cottonseed oil) was injected s.c. once a week for 8 weeks. Frequency-volume recordings were performed with the rats in metabolic cages, and single Aδ- or C-fibre activities from the bladder were measured. After measurements, the blood serum was collected and the estradiol (E2) level was measured.


RESULTS
The C-fibre activity of OVX + V rats was significantly lower than in the other groups. Aδ-fibre activity was unchanged. Despite low E2 levels, ageing rats showed high afferent activity and voiding frequency.


CONCLUSIONS
Although a low E level may affect storage function, it is unlikely that it is the main cause of the high afferent activity and voiding frequency observed in the ageing female rat.
Aizawa
Naoki
N
Department of Urology, Faculty of Medicine, University of Antwerp, Antwerp, Belgium.
Iijima
Kazuyoshi
K
Rosenbaum
Jan S
JS
Downs
Thomas R
TR
Igawa
Yasuhiko
Y
Andersson
Karl-Erik
KE
Wyndaele
Jean-Jacques
JJ
D000344:Afferent Pathways; D000375:Aging / Q000502:physiology*; D000818:Animals; D004958:Estradiol / Q000097:blood*; D004967:Estrogens / Q000097:blood* / Q000172:deficiency; D005260:Female; D009413:Nerve Fibers, Myelinated; D036421:Nerve Fibers, Unmyelinated; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000294:innervation / Q000502:physiology; D014554:Urination / Q000502:physiology*
D004967:Estrogens; D004958:Estradiol