PURPOSE: Mast cell activation and stress have been
suggested as factors in the pathogenesis of interstitial
cystitis, a painful disorder of the bladder that is
diagnosed more frequently in women and characterized by
increased urgency and frequency with absent infection.
Intravesical sodium hyaluronate has been used to treat
interstitial cystitis due to its possible replenishment of
bladder glycosami-noglycans. We investigated the effect of
sodium hyaluronate on the activation of bladder mast cell
and release of proinflammatory mediators in the urine
induced by acute immobilization stress in rats.
MATERIALS AND METHODS: Using anesthesia a catheter was
inserted in the bladder of 170 gm. female Sprague-Dawley
rats. After emptying post-void residual urine a solution of
normal saline, 0.08% or 0.4% sodium hyaluronate was
introduced for 30 minutes. Each rat was allowed to recover
from anesthesia and stressed for 30 minutes by confining it
in a clear acrylic plastic immobilizer, while urine was
continuously collected. Urinary histamine, rat mast cell
protease-I and interleukin (IL)-6 were then determined. At
the end of the experiments each rat was sacrificed by CO2
asphyxiation, and the bladder was removed and fixed with 4%
paraformaldehyde. Frozen sections were stained with
acidified toluidine blue, and the mast cell number and
degree of activation were determined by granule extrusion
and reduced cellular staining.
RESULTS: Mean bladder mast cell activation plus or minus
standard deviation in 6 control rats was 30.4% +/- 3.7% but
it increased to 76.2% +/- 6.1% in 6 stressed animals (p =
0.0001). Intravesical administration of 0.4% sodium
hyaluronate for 30 minutes in 6 rats before stress reduced
mean bladder mast cell activation by 69.7% to 23.1% +/- 6.1%
compared with stressed controls (p = 0.0003). However,
compared to itself before stress there was no significant
difference, indicating complete inhibition in 6 rats.
Intravesical 0.08% sodium hyaluronate had a weaker
inhibitory effect in 6 rats, decreasing mean degranulation
by 22.5% to 59.1% +/- 7.6% (p = 0.02). In 6 rats stress
increased the total mean amount of urinary rat mast cell
protease-I by 271% from 0.14 +/- 0.09 to 0.52 +/- 0.17 ng.
(p = 0.008). Pretreatment with 0.4% sodium hyaluronate
reduced mean rat mast cell protease-I 80.8% compared with
stressed controls (p = 0.008) and prevented any increase in
response to stress in the same group of 8 rats with a mean
pre-stress and post-stress level of 0.09 +/- 0.04 and 0.1
+/- 0.04 ng., respectively (p = 0.8). Acute stress increased
mean urinary histamine in 6 rats 40.2% from 137.3 +/- 29.7
before to 193.7 +/- 7.6 ng./ml. after stress (p = 0.004).
Pretreatment with 0.4% sodium hyaluronate reduced mean
histamine 7.1% compared with stressed controls but
completely prevented any increase in the same group of 8
rats, in which it was 174.5 +/- 23.1 before and remained
179.4 +/- 9.9 ng./ml. after stress (p = 0.75). Acute stress
in 7 rats also increased the mean amount of IL-6 released in
the urine by 31.5% from 775.9 +/- 69.2 to 1,021.1 +/- 93.3
pg./ml. (p = 0.007). Pretreat-ment with 0.4% sodium
hyaluronate in 9 rats reduced mean IL-6 17% compared with
stressed controls but again prevented any increase from
baseline, since the value was 898.6 +/- 299.3 before and
824.4 +/- 196.4 pg./ml. after stress (p = 0.03).
CONCLUSIONS: Immobilization stress induces bladder mast
cell activation and the secretion of proinflammatory
mediators, which are inhibited by sodium hyaluronate.
Intravesical sodium hyaluronate may be a useful therapeutic
option for interstitial cystitis, especially in patients
with bladder mastocytosis who have symptom exacerbation with
stress.
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