Undescended testis is accompanied by calcitonin gene related peptide accumulation within the sensory nucleus of the genitofemoral nerve in trans-scrotal rats

Purpose: Recent data suggest that calcitonin gene related peptide (CGRP) re leased from the sensory branch of the genitofemoral nerve may regulate test icular descent. We studied the number of CGRP immunoreactive cells in the s ensory nucleus of the genitofemoral nerve (L1 to L2 dorsal root ganglia) in cryptorchid trans-scrotal rats. Four-week-old trans-scrotal rats with unilateral undescended testis underwe nt bilateral genitofemoral nerve dissection and retrograde nerve labeling w ith the fluorescent dye 4,6-diamidino-2-phenylindole (DAPI). Animals were s acrificed 48 hours later and the L1 to L2 dorsal root ganglia were removed. Serial sections were obtained and double fluorescent labeled with antibody to CORP. Retrograde labeled and CORP immunoreactive cells were counted usi ng an epi-fluorescent microscope. In the 6 male trans-scrotal rats evaluated we noted a mean plus or minus st andard deviation of 1,272 +/- 98 retrograde labeled dorsal root ganglion ce lls ipsilateral to a fully descended testicle, including 98 +/- 34 that wer e also CGRP immunoreactive. On the side of the undescended testis there was a mean of 1,600 +/- 304 DAPI positive cells and 160 +/- 51 CGRP immunoreac tive, DAPI labeled cells. The difference was significant (p <0.02). This study shows that in trans-scrotal rats the sensory nucleus of the geni tofemoral nerve contains more CGRP immunoreactive cells ipsilateral to an u ndescended testis than on the contralateral side, highlighting the signific ance of CORP supply through the sensory branch of the genitofemoral nerve f or testicular descent.