Differential expression of vascular endothelial growth factor, and angiopoietin 1 and 2 in functionally divergent experimental rabbit models of bladder hypertrophy.
OBJECTIVE
Partial bladder outlet obstruction or ovariectomy with subsequent estrogen replenishment induces bladder hypertrophy in rabbits and yet the functional outcomes of these procedures differ. We investigated whether these models might be distinguished by differential expression of the genes controlling angiogenesis.


METHODS
Groups of male rabbits underwent sham surgery or partial bladder outlet obstruction for 1 or 2 weeks. Groups of females underwent sham surgery, ovariectomy or ovariectomy plus estrogen for 1 or 2 weeks. Bladders from each group were weighed and assayed for the contractile response, smooth muscle content and vascular density. Mucosa and muscle layers were separated and RNA from the fractions was assayed by quantitative real-time polymerase chain reaction to measure the relative expression of vascular endothelial growth factor, and angiopoietin 1 and 2 mRNA.


RESULTS
Male bladders with partial outlet obstruction had attributes that typified hypertrophy with a loss of contractile function. Vascular endothelial growth factor expression was up-regulated in the mucosa and muscle layers but the effect was most pronounced in mucosa. Angiopoietin 1 expression was significantly up-regulated in muscle. Female bladders with ovariectomy plus estrogen had attributes that typified bladder hypertrophy with increased contractile function. Vascular endothelial growth factor expression was up-regulated early in mucosa but more highly and consistently increased in muscle. Angiopoietin 1 and 2 expression was not significantly affected.


CONCLUSIONS
Although these models have similar outcomes with regard to bladder hypertrophy, they have opposite functional outcomes that coincide with compartmental differences in the expression of genes involved in the regulation of angiogenesis. The disparity in gene expression might explain the difference in the functional outcomes.
Walker
Adam
A
Division of Urology, Albany Medical College, Albany, New York, USA.
Tanner
Matthew J
MJ
Husson
Paul
P
Schuler
Catherine
C
Kogan
Barry A
BA
Buttyan
Ralph
R
Levin
Robert M
RM
D042683:Angiopoietin-1 / Q000096:biosynthesis* / Q000235:genetics; D042702:Angiopoietin-2 / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005786:Gene Expression Regulation; D006984:Hypertrophy / Q000235:genetics / Q000378:metabolism; D008297:Male; D009389:Neovascularization, Pathologic / Q000235:genetics; D011817:Rabbits; D001743:Urinary Bladder / Q000378:metabolism* / Q000473:pathology*; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D042461:Vascular Endothelial Growth Factor A