Abstract:
Clothianidin (CTD) is one of the latest members
of the synthetic organic insecticides, the neonicotinoids.
In the present study, it was aimed to investigate if
daily oral administration of CTD at low doses for
90 days has any deleterious effects on reproductive
functions of developing male rats. Animals were randomly
divided into four groups of six rats each, assigned
as control rats, or rats treated with 2 (CTD-2), 8 (CTD-8)
or 32 (CTD-32) mg CTD/kg body weight by oral gavage.
The significant decreases of the absolute weights
of right cauda epididymis and seminal vesicles, and
body weight were detected in the animals exposed to
CTD administration at 32 mg/kgBW/day. Epididymal
sperm concentration decreased significantly in CTD-32
group and the abnormal sperm rates increased in CTD-
8 and CTD-32 groups when compared to control group.
The testosterone level was significantly decreased in
CTD-32 group when compared to control group. The
administration of all CTD doses resulted in a significant
decrease in the level of GSH. The number of TUNELpositive
cells significantly increased in the germinal
epithelium of testis of rats exposed to CTD at
32 mg/kgBW/day. In groups CTD-8 and CTD-32,
only docosapentaenoic, arachidonic, palmitic and palmitoleic
acids were significantly elevated when compared
to control. The ratios of 20:4/18:2 and 18:1n−9/
18:0 were decreased when rats exposed to CTD. Sperm
DNA fragmentation was observed in CTD-32 group,
but not CTD-2 and CTD-8. It is concluded that low
doses of CTD exposure during critical stages of sexual maturation had moderate detrimental effects on reproductive
organ system and more severe effects are likely
to be observed at higher dose levels. In addition, the
reproductive system may be more sensitive to exposure
of CTD even earlier in development (prenatal and early
postnatal), and therefore it could be expected that more
severe effects could also be observed at the NOAEL
dose levels, if dosing had occurred in utero or early
postnatal.
