The cynomolgus monkey prostate under physiological and hypogonadal conditions: an ultrasonographic study.
OBJECTIVE
Although the prostate of the cynomolgus monkey has been shown to be a particularly suitable model for the human, in vivo data on this organ are hardly available. We therefore applied transrectal ultrasonography to the investigation of the physiology and pathophysiology of monkey prostate under normogonadotropic and hypogonadal conditions in vivo.


METHODS
Five intact and 7 long-term castrated monkeys were analysed repeatedly for assessment of the feasibility and variability of the method. In addition, cross-sectional evaluation was performed on 30 intact monkeys of various ages and on 7 long-term castrated monkeys. Finally, the vehicle (n = 5) controlled effects of androgen deprivation treatment with the GnRH antagonist cetrorelix (n = 4) for 25 days followed by semicastration at day 16 and full castration on day 25 were examined and prostate size was followed thereafter.


RESULTS
The monkey prostate shows an ellipsoid shape and ultrasonic appearance similar to the human prostate. Variability in 5 intact monkeys (mean +/- SE = 4.67 +/- 0.55 ml.) and 7 long-term castrated monkeys (0.88 +/- 0.08 ml.) was 8.5% and 5.6% respectively. In intact animals a linear correlation between age and prostate size/animal surface area was found (p = 0.0001). Prostate size in castrated animals was reduced (p < 0.001) compared to intact animals. In the experimental study, GnRH antagonist led to a significant reduction of prostate volume and testosterone levels compared to the vehicle group, while semicastration had no influence. Following removal of the second testis a further decrease of prostate volume was seen (p < 0.0001). When compared, castration and GnRH antagonist treatment induced a similar decrease of prostate volume over time.


CONCLUSIONS
Transrectal ultrasonography provides a feasible and reproducible approach for determination of prostate size in cynomolgus monkeys. Castration and GnRH antagonist treatment are equally effective in reducing prostate size.
Kamischke
A
A
Institute of Reproductive Medicine of the University, Münster, Germany.
Behre
H M
HM
Weinbauer
G F
GF
Nieschlag
E
E
D000818:Animals; D002369:Castration; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D007006:Hypogonadism / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008252:Macaca fascicularis; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D014463:Ultrasonography
D006727:Hormone Antagonists; D007987:Gonadotropin-Releasing Hormone; C062876:cetrorelix