Comparative Parasitology 67(2) 2000 - Peru State College

232 COMPARATIVE PARASITOLOGY, 67(2), JULY 2000
Table 1. Activity of iNOS (in nmoles/mg of protein/min) in T. spiralis-infected (I+NaCl) and infected +
methylprednisolone-treated mouse muscles (I+D).
Days
postinfection
(d.p.i.)
Controls
7
14
21
34
42
49
70
90
Activity (±SEM)
0.14 ± 0.01 (8)
0.08 ± 0.007 (2)
(P < 0.05)
0.15 ± 0.007 (4)
0.52 ± 0.1 (5)
(P < 0.01)
0. 1 1 ± 0.003 (6)
0.07 ± 0.003 (5)
(P < 0.05)
0.07 ± 0.003 (6)
(P < 0.05)
0.40 ± 0.063 (6)
(P < 0.01)
0.04 ± 0.003 (3)
(P < 0.05)
I + NaCl*
% of control
57
107
371
79
50
50
285
29
I + D|
Activity (±SEM)
0.11 ± 0.003 (3)
0.20 ± 0.026 (4)
0.11 ± 0.053 (5)
0.16 ± 0.003 (3)
(P < 0.05)
0.14 ± 0.056 (11)
0.06 ± 0.003 (5)
0.07 ± 0.003 (6)
(P < 0.05)
0.37 ± 0.254 (6)
0.04 ± 0.001 (3)
% of control
* The statistically significant differences in column I+NaCl when the values of activity in infected mice were compared with
normal mice. The number in parentheses is the number of measurements.
t The comparison of the results from infected and infected and treated by glucocorticoid methylprednisolone mice was carried
out using a Mann-Whitney test. The number in parentheses is the number of measurements.
infected and treated, between 7 and 70 days p.i.,
are presented in Table 1.
The investigations of iNOS activity in muscles
of mice infected with T. spiralis larvae
showed a 2-stage increase in enzyme activity
during the course of trichinellosis. An initial
peak of activity was seen at 21 days p.i., and a
second rise in activity occurred at 70 days pi
(285% of the activity in the control group). Statistically
the changes in activity during the stages
of trichinellosis mentioned above varied significantly
from controls (P < 0.01 or P < 0.05).
The investigation of muscle enzyme activity
was carried out on mice infected with T. spiralis
and treated simultaneously with glucocorticoid
methylprednisolone (I+D) at the same intervals
as those for the group of infected and untreated
animals. The I+D group mice had higher enzyme
activity than those of the I+NaCl group
on day 7 p.i. (182% of the control values) and
at 70 days p.i. (up to 336% of the control value)
with a statistically significant result compared
with the control group (P < 0.01). At 90 days
p.i. enzyme activity fell in a manner similar to
that seen in T. spiralis-infected and untreated
animals. Therefore, it may be assumed that
methylprednisolone exerted a normalizing influence
on iNOS activity only in the initial stage
of the muscular phase, i.e., at day 21 p.i.
Copyright © 2011, The Helminthological Society of Washington
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100
145
127
56
64
336
The comparison of changes in iNOS activity
in 2 infections, 1 caused by nonencysting T.
pseudospiralis larvae and the other by encysting
T. spiralis larvae, as presented in Figure 1, revealed
a totally different dynamic for iNOS
changes in muscles of infected mice. A statistically
significant difference existed between the
activity of the enzyme examined in mice infected
with the T. spiralis and T. pseudospiralis invasion
during all phases of trichinellosis (P <
0.01). In general, unlike T. spiralis, infection
with T. pseudospiralis was characterized by an
absence of iNOS stimulation during the first
weeks, while considerable stimulation (up to approximately
280% of the control) lasted
throughout and continued up to the end of the
muscle phase (from 42 to 70 days p.i.).
Discussion
The biochemical defense mechanisms for killing
T. spiralis larvae by eosinophils are mediated
by peroxidase (POX), with inclusion of the
process in which both neutrophils and eosinophils
produce hypochlorous acid, which is toxic
to the larvae of the parasite (Buys et al., 1981).
The quantitative results of research on the activity
of the inducible NOS isoform (iNOS) presented
in this paper clearly indicate that this enzyme,
supplying NO lethal to many parasites, is
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