Attenuating Role of Vitamin C on Sperm Toxicity Induced by Monosodium Glutamate in Albino Rats
The toxicity of monosodium glutamate has been on the increase due to increased patronage of fast foods; with its attendant effects. There have also been attempts to attenuate these effects. Hence, the attenuating role of vitamin C on sperm toxicity induced by monosodium glutamate was accessed on the weight of testes and epididymes, epididymal count, motility, viability, semen pH and sperm head abnormality in albino rat as a model. The male rats were divided into five groups of six rats each. The rats were administered with MSG and vitamin C treatments for 65 days. Vitamin C attenuated the MSG induced toxicity on weight of testes and epididymes, sperm motility, count and sperm head abnormality. Vitamin C can actually attenuate the effect of MSG induced toxicity in rats as a model.
Received: March 14, 2013;
Accepted: April 02, 2013;
Published: July 10, 2013
Monosodium Glutamate (MSG), a sodium salt of glutamic acid is one of the main
flavor enhancer used in various food products associated with food in Chinese
restaurants. The flavor enhancer comes in common names such as Vedan, Sasa,
Ajinomoto, Miwan and Weichaun, among others (Geha et
MSG gives a feeling of special taste (Leung and Foster,
1996). It stimulates taste, enhances and improves appetite (Eweka,
2007). In large amount it may cause chest pain sensation, facial pressure,
headaches, burning sensation, excessive fluid retention and sweating (Xiong
et al., 2009), resulting in a condition called Chinese restaurant
Most Nigerians use MSG to remove stains from fabrics (Kondoh
and Torii, 2008). Reports indicated that MSG is toxic to human and experimental
animals (Eweka, 2007). Harmful or toxic effects of MSG
have been reported in experimental animals and man (Hayes,
1982; Eweka, 2007).
According to Igwebuike et al. (2011), the oral
administration of MSG results in lower serum testosterone levels and reduction
in the caudal epididymis sperm reserves of male rats. MSG causes testicular
hemorrhage, degeneration and alteration of sperm population and morphology (Oforofuo
et al., 1997; Das and Ghosh, 2010), hence
could lead to infertility. MSG can severely destroy testicular tissues and affect
spermatogenesis also causing a decrease in their testicular weight and testicular
diameter, reduction in germinal epithelium height, decrease in sperm count and
increase in abnormalities of sperm morphology (Das and Ghosh,
2010; Nosseir et al., 2012).
Vitamin C is needed for many physiological functions (Halliwell,
2001). According to Nayanatara et al. (2008)
vitamin C is a natural antioxidant that prevents the increased production of
free radicals induced by oxidative damage to lipids and lipoproteins in various
cellular compartment and tissues. The protective role of vitamin C against oxidative
stress and morphological changes has been reported by Karawya
and El-Nahas (2006) and El-Sokkary and Awadalla (2011).
Also its protection to testicular tissues indicated by increased testicular
weight, increases organ weight, reduces sperm abnormalities and significantly
increases sperm count in rats (Fernandes et al., 2011;
Al-Amoudi, 2012). Restoration of germinal epithelium
and partial protection to the genetic material has also been shown by Karawya
and El-Nahas (2006). Nashwa and Venes (2008) also
showed the protective effects of vitamin C on the genotoxicity induced by deltamethrin.
In view of above finding, this study set out to ascertain whether vitamin C
could attenuate the sperm toxicity induced by MSG in albino rats as model; using
short-term in vivo assays.
MATERIALS AND METHODS
Chemicals: Emvit-C tablets from Emzor pharmaceutical industries limited,
Lagos, Nigeria was used as source of vitamin C. Vedan, a concentrated brand
of monosodium glutamate (about 99.9% pure MSG) was procured from Marian market,
Calabar, Nigeria. Other chemicals used in the course of the study were of certified
Animals: Thirty healthy and sexually mature male albino rats of 12 weeks
old were used in this study. The rats were obtained from the Experimental Animal
Unit of Department of Genetics and Biotechnology, University of Calabar, Calabar.
The rats were housed in conventional wire mesh cages under standard laboratory
conditions. They were allowed free access to water and pellet feed throughout
the period of the experiment. Generally, the study was conducted in accordance
with the recommendation from the declarations of Helsinki on guiding principles
in care and use of animals.
Experimental design and procedure: The thirty male rats were randomly
divided into five groups of six rats each. The animals were acclimatized for
one week before the commencement of the study. The treatment lasted for 65 days
and the protocol is shown on Table 1. The rats were sacrificed
under chloroform anaesthesia 24 hours after the last treatment. The epididymes
and testes were dissected out and weighed using Scout Pro SPU 601 electronic
weighing balance. The epididymes were processed for epididymal sperm motility,
viability, count and sperm head abnormality.
Semen pH and sperm motility: Immediately after dissection, a puncture
was made in the epididymis with a sterile pin. The semen smeared on the pin
was rubbed on a pH paper of range 4.0-10.0. The colour change corresponds to
the pH and was read from the paper. Two drops of sperm suspension was put on
a microscope slide and cover slip was placed. The number of progressively motile
cells was divided by the total number of spermatozoa counted under x40 lenses
was expressed as a percentage.
Sperm viability: The sperm viability test was determined using Eosin-Nigrosin
one-step staining technique (Bjorndahl et al.,
2003). A portion of the sperm suspension was mixed with equal volume of
Eosin-Nigrosin stain and five air-dried smears were prepared on glass slides
for each sample.
|| Protocol for treatment of experimental animals
The slides were examined for percentage viability. Normal live sperm cells
excluded the stain and appeared whitish, whereas dead sperm cells took up stain
and appeared pinkish. Percentage viability was calculated based on the number
of live sperm cells out of the total number of sperm cells observed.
Sperm count: The epididymal sperm samples were obtained by macerating
known weights of cauda epididymes in physiological saline in the ratio of 1:10
weight by volume. After vigorous pipetting to release the sperm cells. The suspension
was filtered using an 80 μm stainless mesh. Epididymal sperm count was
obtained by cytometry using the improved Neubauer cytometer and was expressed
as million mL-1 of suspension (Ekaluo et al.,
Sperm head abnormality test: A portion of the sperm suspension was mixed
with 1% eosin Y solution (10:1) for 30 min and air-dried smears were prepared
on glass slides for the sperm head abnormality test. The slides were examined
for percentage sperm head abnormalities in every 200 spermatozoa observed on
each slide and five air-dried smears were prepared on glass slides for each
sample. The percentage of sperm head abnormality was calculated according to
Ekaluo et al. (2009).
Statistical analysis: Data from weight of testes and epididymes, epididymal
semen pH, motility, viability, count and sperm head abnormality were subjected
to the Analyses of Variance (ANOVA) test while differences in means were separated
using least significant difference (LSD) test.
Weight of testes and epididymes: The weight of the testes and epididymes
of the rats were significantly (p<0.05) reduced in the MSG treatment groups
(MSG, MSG+vitamin C and 2MSG+vitamin C) when compared with 1.24 and 0.46 g,
respectively for the testes and epididymes in the control group. The values
of the control group were also comparable to that of the vitamin C group and
not significantly different (p>0.05). Vitamin C attenuated the effect of
MSG toxicity on weight of testes and epididymes of the rats as shown in Table
2. The attenuating effect of vitamin C on the epididymes was in a dose-dependent
manner as follows: MSG (0.34)<2MSG+vitamin C (0.38)<MSG+vitamin C (0.42)<
control (0.46)<vitamin C (0.48).
|| Effect of vitamin C on sperm parameters of rats with MSG-induced
|Values across the table with similar superscripts are not
significantly different at 5% based on ANOVA, MSG: MSG at 2 mg kg-1
BW, 2MSG: MSG at 4 mg kg-1 BW, Vitamin C: Vitamin C at 100 mg
Semen pH and sperm viability: The semen pH and sperm viability was not
significantly (p>0.05) affected by MSG and vitamin C treatments shown in
Sperm motility: The sperm motility was significantly (p<0.05) reduced
in the MSG treatment groups (MSG, MSG+vitamin C and 2MSG+vitamin C) when compared
with the control (66.16 %) and vitamin C (79.25 %) groups. The attenuating effect
of vitamin C on MSG induced toxicity was also seen on the motility of the sperm
cells was also in a dose-dependent manner as follows: MSG (55.35%)<2MSG+vitamin
C (60.55%)<MSG+vitamin C (63.25%).
Sperm count: The sperm count was significantly (p<0.05) reduced in
the MSG treatment groups (MSG, MSG+vitamin C and 2MSG+vitamin C) when compared
with 7.63x106 mL-1 in the control group. Vitamin C showed
attenuating effect on MSG induced toxicity on sperm count by increasing the
sperm count from 5.69 to 6.86 x106 mL-1 as follows: MSG<2MSG+vitamin
C<MSG+ vitamin C<control; as shown in Table 2.
Sperm head abnormality: The sperm head abnormality was also attenuated
by vitamin C with significant (p<0.05) reduction from 5.54% in MSG to 3.75%
in MSG+vitamin C; compared with 3.60% in the control group.
The rats in MSG treatment groups (MSG, MSG+vitamin C and 2MSG+vitamin C) showed
significant (p<0.05) reduction in weight of the testes and epididymes, sperm
count and motility; as well as increase in sperm head abnormalities agree with
(Oforofuo et al., 1997; Das
and Ghosh, 2010; Igwebuike et al., 2011);
Nosseir et al., 2012). Vitamin C attenuated
the effect of MSG toxicity on weight of testes and epididymes of the rats by
increasing their weights over that of the group treated with MSG only. This
increases in weight of the testes and epididymes agree with the reports of (Fernandes
et al., 2011; Al-Amoudi, 2012); which can
be attributed to protective role of vitamin C against oxidative stress and morphological
changes (Karawya and El-Nahas, 2006; Nayanatara
et al., 2008; El-Sokkary and Awadalla, 2011).
The attenuating effect of vitamin C on MSG induced toxicity on sperm count and
motility as well as sperm head abnormality could also be attributed to the protective
role of vitamin C which agrees with earlier reports of (Karawya
and El-Nahas, 2006; Nashwa and Venes, 2008; Nayanatara
et al., 2008; El-Sokkary and Awadalla, 2011;
This study shows that vitamin C administered orally at 100 mg kg-1
BW actually attenuate the effect of MSG (2 and 4 mg kg-1 BW) induced
toxicity on weight of testes and epididymes, sperm motility, sperm count and
sperm head abnormality in rats as a model in dose-dependent manner.
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