Superoxide Dismutase and Glutathione Peroxidase in Dogs with Leishmaniasis Following Antimoniate Therapy - Veterinary Science - page 72

MCHC Mean corpuscular hemoglobin concentration
MCV Mean corpuscular volume

RBCs Red blood cells

ROS Reactive oxygen species

Sb v Pentavalent antimony

SOD Superoxide dismutase

12.1 Introduction

Reactive oxygen species (ROS) contribute to the development and persistence of
anemia during canine visceral leishmaniasis (CanVL) through multiple mechanisms
(Weed and Reed 1966 ; Sen et al. 2001 ). The interaction between ROS and hemoglo-
bin (HGB) results in the denaturation and precipitation of protein with the production
of methemoglobin (Biswas et al. 1997 ), influencing the average lifespan of red blood
cells (RBCs) (Weiss 1982 ). The peroxidation of RBC membrane lipids induced by
ROS leads to the alteration of cell-membrane morphology and plasticity, promoting
premature erythrocatheresis (Biswas et al. 1997 ). Among blood enzymes with free-
radical scavenging activity, the erythrocyte form of superoxide dismutase (SOD)
and the erythrocyte and plasmatic forms of glutathione peroxidase (GSHPx) are of
particular interest (Guemouri et al. 1991 ). In our previous study, we detected a
significant increase in the mean value of erythrocyte SOD activity and a significant
reduction of RBCs and HGB in dogs with CanVL as compared with healthy dogs
(Britti et al. 2008 ). In that study, the mean value of GSHPx activity in dogs with
CanVL was decreased as compared with that of healthy dogs, even though this
difference was not significant. The aim of this study was to evaluate the effect of
Sb v treatment on erythrocyte SOD and blood GSHPx activities in dogs with CanVL
and to determine the potential associations between these enzyme activities and
RBCs, HGB, and others indices of anemia before and after treatment.

12.2 Materials and Methods

Twelve dogs (7 males) of several breeds, average age 5.2 2.0 years, with

spontaneous CanVL as detected by serological (IFAT) and parasitological (lymph
node cytology) methods, and with negative serological test results for ehrlichiosis
and babesiosis, were enrolled in the study. Data were obtained at the time of
diagnosis of CanVL ( T 0 ) and after 60 days of therapy ( T 60 ) with 75 mg/kg of
N -methylglucamine antimoniate, SC q12h equivalent to 21.38 mg/kg of Sb v .
Twenty-five clinically healthy dogs (10 males) of several breeds, average age
4.1 2.5, with no diseases as judged by the methods listed above, were used as

controls (CTRL). From each of the 37 dogs, a 6.0-mL blood sample was drawn by