Does the sensory nucleus of the genitofemoral nerve have a role in testicular descent?

Background/Purpose: A role for the genitofemoral nerve (GFN) and its neurot ransmitter, CORP, in testicular descent has been well established, The exac t mechanism, however, by which circulating androgens act on the GFN is not yet known. The authors studied the sensory nucleus of the GFN (L1-L2 dorsal root ganglia [DRG]) to determine whether it is sexually dimorphic and able to be influenced by intrauterine antiandrogen treatment. Methods: Sprague-Dawley rats were injected daily with 100 mg/kg/d of the an tiandrogen flutamide on day 16 to 19 of pregnancy. Control animals were tre ated with vehicle only. At the age of 2 to 3 days the newborn rats underwen t unilateral dissection of the GFN. The proximal end was labelled with fluo rescent dye, diamidinophenyl indole. The rats were killed 48 hours later, a nd the relevant ganglia (L1,L2) were removed. Cryostat frozen serial sectio ns were cut, and retrogradely labelled fluorescent cells were counted under an epifluorescence microscope. In 32 animals, the cells were double fluore scent labelled with antibody to CORP and FITC. Results: Of 75 rats evaluated, the mean number of the DAPI-positive, retrog radely labelled cells in the control groups was 266 +/- 55 in the male, and 230 +/- 67 in the female as opposed to 186 +/- 45 and 161 +/- 35 in the fl utamide-treated male and female groups, respectively. In 32 animals the DRG sections were double labelled for CORP. The number of CORP plus DAPI-posit ive cells were as follows: control males, 60 +/- 12; control females, 50 +/ - 9; flutamide males, 36 +/- 8; flutamide females, 40 +/- 10. Conclusions: These findings show a sexual dimorphism in the number of GFN c ell bodies in the DRG. Flutamide decreases the number of GFN cell bodies in the DRG of both males and females. Our results are consistent with a role for circulating androgens acting on the sensory nucleus of the GFN (DRG) in stead of the motor nucleus as previously thought. The release of CORP from the nerve endings may occur via the sensory branch of the GFN.