EFFECTS OF EXOGENOUS ESTROGEN AND TESTOSTERONE ON REPRODUCTIVE STRUCTURES AND SPERMATOGENESIS IN THE...
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EFFECTS OF EXOGENOUS ESTROGEN AND TESTOSTERONE ON REPRODUCTIVE STRUCTURES AND SPERMATOGENESIS IN THE MALE RAT Ryan Olney 1, Anna Ballard 2, Cyndi Goberdhan
EFFECTS OF EXOGENOUS ESTROGEN AND TESTOSTERONE ON REPRODUCTIVE
STRUCTURES AND SPERMATOGENESIS IN THE MALE RAT Ryan Olney 1, Anna
Ballard 2, Cyndi Goberdhan 2, Ben Cooper 2, Debora Christensen
(Mentor). Dept of Biology 1, Dept of BCMB 2, College of Arts &
Sciences Results Methods Introduction Results (continued)
Discussion Testosterone and estrogen are both important to the
development and maintenance of male reproductive organs. Leydig
cells produce testosterone, which causes development of secondary
sex characteristics. Testosterone stimulates spermatogenesis by
binding to the Sertoli cells that line the straight tubuli recti of
the seminiferous tubules. Estrogen receptors are found in the
seminiferous tubules. Estrogen is essential for normal
spermatogenesis; however, elevated levels of estrogen can cause
reproductive dysfunction in males. Bromodeoxyuridine (Brd-U) is
used to visualize proliferating cells because of its ability to
incorporate into newly synthesized DNA. Hypothalamus Sertoli Cells
FSH LHInhibin Testosterone Anterior Pituitary GnRH Estradiol
Inhibitory Stimulatory Leydig Cells O CH 3 OH HO CH 3 OH Aromatase
TestosteroneEstradiol 12 reproductively mature male Sprague-Dawley
rats were given one of three hormonal implants: empty (control,
contained no hormone), estrogen (0.040mg), or testosterone
(0.036mg) Implants were implanted into the subcutaneous tissue
between the shoulder blades and remained in place for 3 weeks. 2
hours prior to sacrifice, rats were injected with Brd-U (1ml/100g).
Rat testes were excised, lengths and weights recorded, and tissues
fixed in formalin for immunohistochemistry. Testes were embedded in
paraffin, sectioned (7.5m), and stained with H&E and Brd-U.
Study Objective Investigate how exogenous estrogen and testosterone
affect maintenance of reproductive organs in the adult male rat
Investigate how estrogen and testosterone affect spermatogenesis in
the adult male rat. Males with testosterone implants had gonads
that were 50% lighter than controls. Estrogen-implanted male gonads
were 75% lighter than controls. Elevated testosterone or estradiol
decreased body size. Brd-U staining showed evidence of mitotic
division, and hence spermatogenesis, in all groups. There was an
overall reduction in spermatogenesis in hormone-treated rats when
compared with controls. Both elevated estrogen and testosterone
depressed normal spermatogenesis. Results indicate that rats might
be more sensitive to estradiol than testosterone or that the
testosterone:estrogen ratio may be more important than levels of
either hormone individually. Rat #Implant Tx Weight 1 (g) Weight 2
(g) Gonad Weight (g) Length Gonad (mm) 6Empty4124344.202822.5
16Empty4004033.881123 8Estradiol3843300.661515
12Estradiol276.12821.258821 20Estradiol3133081.16817
1Testosterone305.53422.571219 13Testosterone283.83311.76120.5
19Testosterone298.43111.86418.5 Table 1. Gonads were significantly
lighter in males that received estradiol implants (p=0.0015) when
compared to controles. Males that received testosterone had lighter
testes as well, but this difference was not significant (p=0.07).
Figure 2. Average body weights before and after treatment with
empty, estradiol, and testosterone implants. Rats with both steroid
hormones were an average of 15% lighter than those receiving no
additional hormone but not different from their pretreatment
weights 3 weeks earlier. Acknowledgements Original experimental
design, construction of hormonal implants, all rat surgeries, and
testicular measurements were performed by Ryan Olney, Anna Ballard,
and Cyndi Goberdhan. Liz Stucker for provided the rats. Thanks to
Dr. Christensen for her dedication, mentoring, and support
throughout the entire experiment. Figure 3. Histological sections
of mature male Sprague-Dawley rat testis stained with Brd-U
revealed that there an increase in spermatogenesis in the control
males (far left) when compared to those receiving estrogen (middle)
and testosterone (far right). Rats with additional steroid hormones
had a visually-distinguished decreased seminiferous tubule size.
Estradiol treated testis showed predominance of tubules with round
spermatids and decreased cell height, whereas empty showed
elongating spermatids that were more abundant throughout the
tissue. Magnification x100. Figure 1. From left to right: Silastic
implants. Ryan Olney performing rat surgery with Dr. Christensen.
Rotary microtome used for sectioning tissues.