الفهرس 
TESTOSTERONE
Testosterone and metabolismOnly 14 pages are availabe for public view
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Abstract
18.7% of Egyptian male adults were reported to be obese in 2010. In
the Middle East and the Arab Gulf countries , if both overweight and
obese males are considered , the percentage increases dramatically to
reach 69-77% of all males.
40% of obese non diabetic men demonstrate a reduced level of serum
free testosterone and obesity is often also associated with a low level of
total testosterone as well as low sex hormone binding globulin.
Obesity can be associated with a state of hypothalamic
hypogonadismwhich is also manifested by a lower sperm count and
poorer sperm quality suggesting thus an important negative effect of
obesity on germ cells and spermatogenesis .
Vitamin D is currently being investigated as both a preventive and a
curative supplement that can modulate many disease processes beyond
its classical role in bone health and calcium homoestasis.
.
Emerging evidence suggests that vitamin D may be involved in many
non-skeletal health outcomes such as muscle and immune function,
cardiovascular disease, type II diabetes, cancer development , mood
regulation and central and peripheral nervous system functions, skin and
hair health state , bronchial asthma and many others . Several research
papers advocate a possible role for vitamin D in modulation of
reproductive processes in women and men.
The aim of the current study was to evaluate the effect of vitamin D
supplementation on free testosterone levels in rats fed a high fat diet.
This aim was achieved through studying 60 male albino rats over a
period of 16 weeks. After obtaining the approval from the ethics
committee, the rats aged between 5-6 weeks were divided into four
groups and kept under standard conditions in the animal house of Kasr
Al Aini Faculty of Medicine,
group I rats were fed a standard rat chow, group II rats were fed the
standard rat chow and receiving daily oral supplementation of vitamin
D3 in the dose of 12ug/kg, group III rats were fed a high fat diet
containing 20% of animal fat, group IV rats were fed a high fat diet and
received vitamin D3 orally in the dose of 12ug/kg daily for 16 weeks
which is the duration of the study.
The animals were weighed weekly and their weights recorded and the
dose adjusted to reflect any change in weight.
At the end of the 16 weeks, the animals were weighed and their nasoanal length and abdominal circumference were measured. Body mass
index was calculated by dividing Weight in kgs by naso anal length in
m2. Blood samples were taken from the inner canthus of the eye using
capillary tubes for later measurement of serum free testosterone levels as
well as 25(OH)2D3 using Enzyme linked immunosorbent technique.
The animals were then sacrificed by decapitation and abdominal incision
was immediately done for separation of testes . The two testes were
taken and washed by saline (0.9%), dried by filter paper and weighed .
Visceral fat was separated , washed in saline, dried by filter paper and
weighed
One testicle was then placed in formalin for later histopathology
sections while the other was kept in saline to be later homogenized in
proper buffer for the analysis of testicular tissue levels of testosterone
and 25 (OH) D3.
Testicular tissue sections were performed with a thickness of 5um and
stained by hematoxylin and Eosin after proper preparation to be later
examined.
The results of our study show that vitamin D supplementation in groups
II and IV resulted in stabilization of body weight between weeks 12 and
16 and a significant reduction of the final body weight of group II
compared to I and group IV compared to III. Vitamin D
supplementation abolished any significant difference in weight between
group IV and group I. Similar results were obtained when comparing
visceral fat weight and body mass index between different groups
suggesting an important effect of the vitamin D in the dose and duration
used in controlling body weight gain.
Looking at the levels of 25 (OH)2 D3 achieved, it could be seen that a
high fat diet in group III resulted in a significant reduction in serum
levels of 25(OH)2D3 while giving vitamin D in a dose adjusted to body
weight in group IV restored that level to almost control levels. The dose
used also raised serum levels of vitamin D in group II though not to a
significant level when compared to group I.
However, tissue levels of 25 (OH)2 D3 showed a slightly different
picture in group III where testicular tissue level was slightly more than
the control level in spite of a reduction in serum levels suggesting that in
obesity, vitamin D can also be stored in other tissues with a high lipid
content including the testicles.
Levels of serum free testosterone did not differ significantly between
groups I , II and III animals in spite of the significant difference in body
weight between these groups.
Looking at tissue sections of group II animals, it can be seen that though
vitamin D supplementation did not result in a significant increase in
serum testosterone, it did result in an increase in the density of
seminiferous tubules suggesting a positive effect on the germinal
epithelium and spermatogensis.
Serum free testosterone results of group III suggest that a high fat diet
might not result in a reduction of the serum free testosterone in spite of
its negative effect on other aspects of testicular functions.
Examination of the tissue sections of group III showed a disturbed
architecture, vascular congestion and hypertrophy of vascular wall,
reduction of density of germinal cell layers especially in the zones
around the blood vessels as well as vacuolation .
Serum levels of free testosterone increased significantly in group IV
when compared to group III and tissue sections showed reduction of
vascular congestion and an improved architecture of seminiferous
tubules.