Transient testicular warming enhances the suppressive effect of testosterone on spermatogenesis in adult cynomolgus monkeys (Macaca fascicularis).
BACKGROUND
The context of the study was to examine whether combined testosterone (T) and heat (H) treatment have additive or synergistic effects on suppression of spermatogenesis.


OBJECTIVE
The objective of the study was to determine whether T+H induces a greater suppression of spermatogenesis than either treatment alone in monkeys.


METHODS
The study was a randomized, placebo-controlled study.


METHODS
The study was conducted at a primate center in China.


METHODS
The study population was comprised of 32 adult cynomolgus monkeys.


METHODS
Groups of eight adult monkeys were treated for 12 wk with: 1) two empty implants (C); 2) two T implants (T); 3) daily testicular heat exposure (43 C for 30 min) for 2 consecutive days (H); or 4) two T implants plus testicular heat exposure (T+H). Treatment was followed by an 8-wk recovery period.


METHODS
Measures included sperm counts and germ cell apoptosis.


RESULTS
Serum T levels were elevated in both the T and T+H groups during treatment but not in the C or H group. Sperm counts were transiently suppressed after heat to 16.4% of baseline at 4 wk and then returned to pretreatment levels. Sperm counts were suppressed slowly after T treatment to nadir of 6.4% of pretreatment levels at 12 wk. T+H rapidly suppressed sperm output as early as 4 wk to 3.9% of pretreatment levels that was maintained throughout treatment. The decreased sperm counts were due to increased germ cell apoptosis in all treatment groups. Sperm counts recovered to the pretreatment levels in all groups by 8 wk after treatment.


CONCLUSIONS
This proof-of-concept study demonstrates that transient testicular warming enhances and hastens the effect of T implant on the suppression of spermatogenesis in monkeys.
Lue
Yanhe
Y
Division of Endocrinology and Metabolism, Harbor-University of California, Los Angeles Medical Center, Box 446, 1000 West Carson Street, Torrance, CA 90509, USA.
Wang
Christina
C
Liu
Yi-Xun
YX
Hikim
Amiya P Sinha
AP
Zhang
Xue-Sen
XS
Ng
Chiu-Ming
CM
Hu
Zhao-Yuan
ZY
Li
Yin-Chuan
YC
Leung
Andrew
A
Swerdloff
Ronald S
RS
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001706:Biopsy / Q000662:veterinary; D005854:Germ Cells / Q000502:physiology; D006651:Histocytochemistry / Q000662:veterinary; D006979:Hyperthermia, Induced / Q000662:veterinary*; D020287:In Situ Nick-End Labeling; D008252:Macaca fascicularis / Q000502:physiology*; D008297:Male; D011897:Random Allocation; D013076:Sperm Count / Q000662:veterinary; D013091:Spermatogenesis / Q000187:drug effects* / Q000502:physiology; D013737:Testis / Q000187:drug effects* / Q000502:physiology*; D013739:Testosterone / Q000008:administration & dosage* / Q000097:blood
D013739:Testosterone