Calcitonin gene-related peptide stimulates mitosis in the tip of the rat gubernaculum in vitro and provides the chemotactic signals to control gubernacular migration during testicular descent.
OBJECTIVE
We investigated whether calcitonin gene-related peptide (CGRP) released from sensory genitofemoral nerve branches could stimulate rodent gubernacular growth and provide chemotactic signals for directing inguinoscrotal gubernaculum migration in vitro.


METHODS
Neonatal rat gubernacula containing a developing cremaster sac (n = 60) were removed at days 0, 2, 4, 6, 8, and 10 (n = 10 per age; n = 5 per experimental group) and placed in organ culture for 24 hours with or without added CGRP (720 nmol/L). The gubernacula were stained for bromodeoxyuridine (BrdU) immunohistochemistry. Cells were counted (3 x 100 cells) in the mesenchymal tip of the gubernaculum to find the percentage of BrdU uptake. A further group of neonatal rat gubernacula (n = 21 per group) were placed in organ culture on an agar platform with 5 agarose beads soaked in either PBS or 10(-6) mol/L CGRP placed approximately 0.8 to 1 mm on each side of the tip of the cremaster sac. After 72 hours, the position of the gubernaculum was compared with its starting position and any deviation measured.


RESULTS
Exogenous CGRP caused a significant increase in BrdU uptake in the tip of the gubernaculum in 0-day-old rats compared with control cultures. Two-way analysis of variance in the cellular proliferation pattern between gubernacula cultured +/- CGRP between 0 and 10 days showed a significant difference (P < .001). The cultures containing CGRP-impregnated beads caused significant (P < .01) deviation of the tip of the gubernaculum toward the beads, whereas the controls demonstrated no net movement of the tip.


CONCLUSIONS
These studies demonstrate that mitosis in the tip of the rat gubernaculum is significantly increased in response to CGRP in vitro. Also, CGRP may provide chemotactic signals to control inguinoscrotal gubernacular migration in the rat.
Yong
Eric X Z
EX
F Douglas Stephens Surgical Research Laboratory, Murdoch Children's Research Institute, Parkville, Victoria 3052, Australia.
Huynh
Jenny
J
Farmer
Pamela
P
Ong
Sim Y
SY
Sourial
Magdy
M
Donath
Susan
S
Ting
Alvin Y S
AY
Chow
Yan
Y
Hutson
John M
JM
D000818:Animals; D000831:Animals, Newborn; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002633:Chemotaxis; D004195:Disease Models, Animal; D008297:Male; D008938:Mitosis / Q000187:drug effects* / Q000502:physiology; D009924:Organ Culture Techniques; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012680:Sensitivity and Specificity; D013737:Testis / Q000187:drug effects* / Q000254:growth & development*
D015740:Calcitonin Gene-Related Peptide