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The
effects of low-level exposure of heptachlor on sperm characteristics,
spermatogenesis and serum testosterone levels in male Sprague-Dawley
rats
Ms. Yasmin Rasyid, *Professor Ramli bin Abdullah, Associate Professor
Mustafa Ali Mohd Department of Pharmacology, Faculty of Medicine,
* Institute of Biological Sciences, University Malaya, Kuala Lumpur,
Malaysia
The effects of oral administration of heptachlor at a fixed dosage
of 0.5 mg/kg/day on epididymal sperm characteristics, spermatogenesis
and serum testosterone levels were examined. The drug was administered
to juvenile male rats over a period of 60 days and the effect was
assessed at the end of the dosing period. The study found that sperm
motility decreased as shown by the significant differences (P<0.001)
between the treated group and the negative control group. The numbers
of motile sperm cells in the treated group were significantly reduced
(P<0.001) with a highly significant increase in the numbers of medium
(P<0.001) and slow (P<0.001) cells. However, the total number of sperm
cells and number of static sperm cells between the heptachlor-exposed
and control group did not show much variance. This indicates that
heptachlor does not reduce the production of sperm cells or destroy
sperm cells per se but affects the fertility of male rats by decreasing
the sperm cells' viability (e.g., reduced sperm motility, reduced
progressive movement of sperm cells, etc.).
Histopathological investigation showed that heptachlor-treated male
rats showed varying degrees of tubule abnormality in the testes, ranging
from completely normal tubules with full spermatogenesis to severely
abnormal tubules lined with only Sertoli cells. The overall severity
of tubule damage was evident by the ultrastructural studies that demonstrated
disorganization of tubular elements with increased intercellular space.
A significant decrease in the diameter of seminiferous tubules, with
variable degrees of maturation arrest in different stages of spermatogenesis,
was also noted. Heptachlor treated rats also exhibited significant
decrease in serum levels of testosterone (a general reduction of 50%,
P< 0.001) which correlates with the decrease in viability of epididymal
sperm cells and the severity in seminiferous tubular abnormality.
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