Abstract
Endocrine disrupting effects have become a major issue in the field of
environmental toxicology. Due to the testicular toxicity reported for
acrylamide and confirmed in our study, and the double jeopardy with its
well-documented carcinogenicity following leaching out from overcooked
starchy foods, the current study was extended to address the possible
protective effects of two nutraceuticals.
The present study was designed to assess the possible reproductive
toxicity of acrylamide in adult male Swiss albino rats. Also, the work
was extended to investigate the potential protective effects of two
nutraceuticals namely; thymoquinone (TQ) and capsaicin against
acrylamide-induced reproductive toxicity.
Sixty male albino rats were allotted into six groups. Group 1: Rats
received free tap water and served as control group. Group 2: Rats
received acrylamide in a daily dose and served as the model. Group 3:
Rats were administered TQ twice weekly. Group 4: Rats were administered
capsaicin once daily. Group 5: Rats challenged with acrylamide were
administered TQ twice weekly. Group 6: Rats challenged with acrylamide
were administered capsaicin once daily.
A murine model of acrylamide testicular toxicity was reproduced and was
characterized biochemically, morphologically and histologically.
Acrylamide increased oxidative stress, expression of testicular
NF-κB/p65, in addition down regulated the expression of occludin that
may further account for its testicular toxicity. Both nutraceuticals; TQ
and capsaicin have proven more or less efficacy in ameliorating all the
toxic insults exerted by acrylamide in the current reproductive toxicity
model.
Key words: Testicular failure; Thymoquinone; Capsaicin; Acrylamide;
NF-ΚB/P65; Occludin.
Abbreviations
Thymoquinone (TQ); nuclear factor kappa B (NF-κB/p65); luteinizing
hormone (LH); follicle stimulating hormone (FSH); lactate dehydrogenase
isoenzyme-X (LDH-X); reduced glutathione (GSH); superoxide dismutase
(SOD); thiobarbituric acid reactive substances (TBARS); catalase (CAT);
malondialdehyde (MDA).
Introduction
Acrylamide is a versatile organic compound that finds its way into many
products in our everyday life. Acrylamide has been found to occur in
many cooked starchy foods and is of concern as a possible carcinogen.
Acrylamide was accidentally discovered in foods in April 2002 by
scientists in Sweden when they found the chemical in
starchy foods, such as
potato chips,
French fries,
and bread that had been heated above120°
(Tareke, Rydberg, Karlsson, Eriksson, &
Törnqvist, 2002). Apart from its possible carcinogenic effects,
acrylamide has shown reproductive toxicity in rats
(Parzefall, 2008) and(Abdel-Fattah, Matsumoto, &
Watanabe, 2000). However, the precise mechanism(s) are not fully
explored.
Nutraceutical, a
portmanteau of the
words “nutrition” and
“pharmaceutical”,
is a food or food product that reportedly provides health and medical
benefits, including the prevention and treatment of
diseases
(Yadav, PATIL, & Gupta, 2013). Such
products may range from isolated nutrients,
dietary
supplements and specific diets to genetically engineered foods,
herbal products,
and processed foods such as cereals, soups, and beverages
(Parvez, Malik, Ah Kang, & Kim, 2006).
They provide health and medical benefits that delay, prevent and treat
chronic inflammatory diseases due to the presence of the phytochemicals.
Their beneficial effects reside for the most part on their
anti-oxidative role that can reduce the level of ROS and free radicals,
beside its powerful anti-inflammatory actions
(Pyun, Kim, Han, Hong, & Lee, 2014).
Thymoquinone (TQ) is a
phytochemical
nutraceutical found in the plantNigella
sativa. It has
antioxidant effects,
and has been shown to protect against heart, liver and kidney damage in
animal studies, as well as having possible anti-cancer effects
(B Aggarwal et al., 2011). It also has
analgesic
(Abdel-Fattah et al., 2000) (and
anticonvulsant
effects in animal models (Hosseinzadeh &
Parvardeh, 2004).
Capsaicin is the main capsaicinoid in chili peppers. Capsaicin is
currently used in topical
ointments, as well as a
high-dose dermal
patch, to relieve the pain of
peripheral neuropathy
such as post-herpetic
neuralgia caused by
shingles
(Chhabra, Aseri, Goyal, & Sankhla,
2012). Many pharmacological studies have used capsaicin as a tool to
activate many physiological systems, with an emphasis on pain research,
but also including functions such as the cardiovascular system, the
respiratory system, and the urinary tract
(O’Neill et al., 2012).
Taken together, the current study has been conducted to address the
possible protective effects of two nutraceuticals, well known for their
potential anti-oxidant and anti-inflammatory effects namely; TQ and
capsaicin in acrylamide-challenged male rats.
The main objectives of the current study; to identify the possible
mechanisms whereby acrylamide may induce damage in testicular and
edpididymal tissues following the toxic insult with the xenobiotic. In
addition, address the potential chemopreventive effects of the test
compounds under investigation, and the possible underlying mechanism(s)
with special emphasis on occludin as a tight junction protein crucial
for the integrity of the basement membrane of the blood testes barrier,
and nuclear factor kappa B (NF-κB/P65) as a marker of inflammation that
would ultimately signal an adverse change to spermatogenesis after toxic
insult.