Calcitonin gene-related peptide receptors in the gubernaculum of normal rat and 2 models of cryptorchidism.

We investigated calcitonin gene-related peptide binding in the gubernaculum from a normal rat, a TS rat (congenitally cryptorchid from unknown causes) and a flutamide rat (cryptorchid secondary to prenatal antiandrogen treatment). Gubernacular sections from 2-day-old male pups were incubated with 125iodine-calcitonin gene-related peptide with various concentrations of unlabeled calcitonin gene-related peptide. After exposure to x-ray film, developed film was quantified by computerized densitometry. The binding analysis showed that concentrations of calcitonin gene-related peptide receptors were 22.9 +/- 2.12, 13.5 +/- 1.70 and 30.3 +/- 2.63 (mean plus or minus standard error of mean, fmol./mg. polymer) for each rat, respectively, and there were significant differences between the normal and TS rats (p < 0.01), and the normal and flutamide rats (p < 0.05). However, there was no significant difference in the dissociation constant among the 3 models. This result shows that deficiency and excess of calcitonin gene-related peptide binding in the gubernaculum are associated with cryptorchidism. Calcitonin gene-related peptide released from the genitofemoral nerve may regulate its own receptor concentration to control gubernacular motility in vivo.