transient scrotal hyperthermia and levonorgestrel enhance testosterone-induced spermatogenesis suppression in men through increased germ cell apoptosis.
BACKGROUND
In rodents and monkeys, a combination of hormonal and physical agents accelerates germ cell death.


OBJECTIVE
A "proof of concept" study was performed to investigate whether addition of heat exposure or a progestin to an androgen induces germ cell death and more complete and rapid spermatogenesis suppression.


METHODS
A randomized clinical trial was performed at academic medical centers.


METHODS
We treated four groups of healthy male volunteers (18 per group) for 18 wk: 1) testosterone undecanoate (TU) 1000 mg im (first dose), followed by 500 mg im every 6 wk; 2) submersion of scrota at 43 C in water for 30 min/d for 6 consecutive days; 3) TU plus heat; and 4) TU plus oral levonorgestrel (LNG) 250 microg/d.


METHODS
Semen parameters, testicular histology, and germ cell apoptosis were the main outcome measures.


RESULTS
Heat alone and TU plus heat suppressed sperm counts more than TU alone by wk 6. By wk 9, recovery began in the heat only group, whereas spermatogenesis remained suppressed in the TU plus heat group. Oral LNG plus TU suppressed spermatogenesis earlier and more severely than TU alone. At wk 2, significantly greater germ cell apoptosis occurred in heat and heat plus TU subjects, but not in subjects without heat treatment, compared with pretreatment subjects. By 9 wk, markedly smaller seminiferous tubule diameters and fewer spermatocytes and spermatids were noted in all 12 biopsies from men receiving TU, TU plus LNG, with most dramatic differences for the TU plus heat group, whereas no differences from pretreatment biopsies were observed in men who received heat treatment only.


CONCLUSIONS
Heat causes a rapid and transient suppression of spermatogenesis. TU plus heat resulted in low-sperm output that was maintained by continuous treatment with TU. Addition of an oral progestin accelerated spermatogenesis suppression by TU alone. Increased germ cell apoptosis contributed to suppression of spermatogenesis.
Wang
Christina
C
Department of Medicine, Harbor-University of California, Los Angeles, Torrance, California 90509, USA. wang@labiomed.org
Cui
Yu-Gui
YG
Wang
Xing-Hai
XH
Jia
Yue
Y
Sinha Hikim
Amiya
A
Lue
Yan-He
YH
Tong
Jian-Son
JS
Qian
Li-Xin
LX
Sha
Jia-Hao
JH
Zhou
Zuo-Min
ZM
Hull
Laura
L
Leung
Andrew
A
Swerdloff
Ronald S
RS
D000328:Adult; D000988:Antispermatogenic Agents / Q000097:blood / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D053713:Azoospermia / Q000473:pathology; D002452:Cell Count; D005334:Fever / Q000503:physiopathology*; D005786:Gene Expression Regulation / Q000502:physiology; D005854:Germ Cells / Q000187:drug effects* / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D007150:Immunohistochemistry; D016912:Levonorgestrel / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009845:Oligospermia / Q000473:pathology; D012611:Scrotum / Q000502:physiology*; D013076:Sperm Count; D013091:Spermatogenesis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000473:pathology; D013739:Testosterone / Q000097:blood / Q000494:pharmacology*; D016707:Tissue Fixation
D000988:Antispermatogenic Agents; D013739:Testosterone; D016912:Levonorgestrel