Partial urethral obstruction: ATF3 and p-c-Jun are involved in the growth of the detrusor muscle and its motor innervation.
OBJECTIVE
Infravesical obstruction leads to growth of urinary bladder smooth-muscle cells. The ganglion cells innervating the bladder muscle also increase in size. Stretch of detrusor muscle cells rapidly activates c-Jun NH₂-terminal kinase (JNK), which phosphorylates the transcription factor c-Jun, and stimulates the synthesis of the cotranscription factor ATF3. The aim of the study was to determine whether ATF3 and p-c-Jun were involved in growth of bladder smooth-muscle and ganglion cells.


METHODS
The urethra was partially obstructed in female rats. After 3 days or 10 weeks bladders were weighed, fixated and cut for immunohistochemistry to demonstrate ATF3 and p-c-Jun. Ganglia were processed separately. Unoperated and sham-operated rats were used as controls.


RESULTS
There was no ATF3 or p-c-Jun in control detrusor muscle. After 3 days of obstruction bladder weight had nearly doubled. Almost all nuclei in the detrusor showed immunofluorescence for ATF3 and p-c-Jun. After 10 weeks bladder weight had increased 10-fold. Almost all detrusor nuclei still showed p-c-Jun, but few had ATF3 activity. In control ganglia there was no ATF3 and only faint nuclear p-c-Jun activity. After 3 days of obstruction the ganglion cells had increased in size and many nuclei showed intense immunofluorescence for ATF3 and p-c-Jun. After 10 weeks the ganglion cell size had increased further. There was no ATF3 activity and no more p-c-Jun than in control ganglia.


CONCLUSIONS
ATF3 and p-c-Jun seem to be involved in the growth of the detrusor muscle and its motor innervation following infravesical outlet obstruction.
Xu
Abai
A
Department of Urology, Skane University Hospital, Malmo, Sweden.
Frederiksen
Hans
H
Kanje
Martin
M
Uvelius
Bengt
B
D051700:Activating Transcription Factor 3 / Q000378:metabolism*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005260:Female; D005724:Ganglia / Q000378:metabolism / Q000473:pathology; D007150:Immunohistochemistry; D009046:Motor Neurons / Q000378:metabolism / Q000473:pathology; D009130:Muscle, Smooth / Q000294:innervation / Q000378:metabolism / Q000473:pathology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014524:Urethral Obstruction / Q000378:metabolism* / Q000473:pathology*; D001743:Urinary Bladder / Q000294:innervation* / Q000378:metabolism* / Q000473:pathology
D051700:Activating Transcription Factor 3; C497108:Atf3 protein, rat; D016755:Proto-Oncogene Proteins c-jun