Peng, Tang Suk
(2016)
Effects of tualang honey on paraquat intoxication in rats.
Masters thesis, Universiti Sains Malaysia.
Abstract
Paraquat (PQ) is an herbicide widely used in the world and has been postulated to
exert its toxic effects via the production of various reactive oxygen species causing
subsequent oxidative damage at key cellular components. Tualang honey (TH) has
been reported to possess good antioxidant properties and may help ameliorate the
oxidative damages in case of PQ poisoning. Therefore, the main objectives of this
study were to evaluate the possible protective effect of TH in acute (study 1) and
subacute (study 2) PQ toxicities in rats. Male Sprague-Dawley rats aged eight weeks
old were used. In study 1, selected oral doses of PQ and TH were 225 mg/kg and 0.2
g/kg, respectively. The effects of single and multiple TH treatments on PQintoxicated
rats were then investigated: single TH treatment groups received TH at
0.5 (PQ + TH0.5h), 2 (PQ + TH2h) or 6 (PQ + TH6h) hours following PQ
administration; multiple TH treatment groups received TH at 0.5, 2 and 6 hours (PQ
+ THtrp) or further daily treatment for next six days (PQ + TH7d) following PQ
administration, respectively (n = 6 per group). The survival time of each rat was
recorded until day 28 before sacrifice. Although treatment with TH did not improve
the survival rate of PQ-intoxicated rats, the median survival time of rats which
received multiple TH treatments was significantly longer when compared to group
PQ + TH6h. Furthermore, TH treatment improved the histological outcome of PQintoxicated
rats particularly in the lungs, thus suggesting the potential role of honey
in delaying the toxic effects of PQ. In study 2, the protective effect of TH on PQinduced
oxidative stress in rats’ midbrain and lung regions were investigated (n= 15
per group). The rats were orally treated with distilled water (Groups N & PQ, 2
mL/kg/day), TH (Groups TH & PQ + TH, 1.0 g/kg/day) or ubiquinol (Group PQ +
QH, 0.2 g/kg/day) throughout the experimental period. Two weeks after the
respective treatments, the rats were administered with saline (Groups N & TH; 1
mL/kg/week, i.p) or PQ (10 mg/kg/week, i.p.; Groups PQ, PQ + TH and PQ + QH)
once a week for four consecutive weeks. The animals were then sacrificed a week
following the final injection of saline or PQ. Serum urea was significantly lower in
groups which received TH (TH and PQ + TH) or ubiquinol (PQ + QH). Serum
creatinine was markedly reduced in group PQ + TH as well, when compared to
controls (N and TH). Significantly lower levels of ALT were observed in groups TH
and PQ + TH when compared to group PQ. These findings suggest that TH treatment
may have some beneficial effects on the kidney and liver’s function. Following fourweekly
PQ-administration, the midbrain GPx activity was significantly reduced
when compared to healthy control (N). PQ-induced dopaminergic neuronal damage
was demonstrated by a significant reduction in the number of tyrosine hydroxylaseimmunopositive
neurons in the midbrain substantia nigra pars compacta while in the
lungs, marked reduction in the activities of SOD and GST were observed in group
PQ when compared to the control group. Treatment with TH ameliorates the toxic
effects seen in the midbrain and lungs with comparable effects to ubiquinol, the
control drug used in study 2. These findings suggest that pre-treatment with TH
showed some protective effects against subacute PQ toxicities. It is plausible that the
protective effects of TH are conferred by its antioxidant properties.
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