J. Seligman et al., EFFECTS OF CASTRATION ON THIOL STATUS IN RAT SPERMATOZOA AND EPIDIDYMAL FLUID, Molecular reproduction and development, 47(3), 1997, pp. 295-301
Mammalian spermatozoa gain their fertilizing ability as they mature in
the epididymis, a process which is accompanied by oxidation of sperm
protein thiols. Since sperm maturation is dependent upon normal androg
enic support to the epididymis, the present work was designed to study
the effects of castration on thiol status. Spermatozoa and epididymal
fluid were isolated from the epididymides of male rats 5 days after c
astration or after 11 daily injections of the antiandrogen, cyproteron
e acetate. Spermatozoa and epididymal fluid were labeled with the fluo
rescent thiol labeling agent monobromobimane. Intact spermatozoa were
evaluated by fluorescence microscopy, protein thiols were analyzed by
electrophoresis, and fertilizing ability was examined after inseminati
on of sperm suspension into the uterine horns of immature superovulate
d female rats. We found that both treatments resulted in an increase i
n cauda sperm thiols as shown by increased fluorescence in the intact
spermatozoa. Protamines and nonbasic proteins were found to have incre
ased levels of reactive thiols. The protein profiles of epididymal flu
id from castrated vats were different from those of the controls, and
the fluorescence patterns corresponded to the protein profiles; Our re
sults indicate that testosterone withdrawal leads to inhibition of spe
rm thiol oxidation. (C) 1997 Wiley-Liss, Inc.