Calcitonin gene-related peptide injected ectopically alters gubernacular migration in the flutamide-treated rat with cryptorchidism

Abstract

Calcitonin gene-related peptide (CGRP) is proposed to be a neurotransmitter that is released from the genitofemoral nerve (GFN) to organize the migration of the gubernaculum. The hypothesis predicts that exogenous CGRP might alter gubernacular migration. In a pilot study prenatal administration of an antiandrogen, flutamide, produced rats with undescended testes that were treated from birth with injections of CGRP into the future scrotum. The exogenous CGRP rapidly extravasated throughout the groin, retarding growth of the vaginal processus (VP). In flutamide-treated rats, the definitive study aimed to show that gubernacular migration could be redirected upward by injecting CGRP into a position cranial to the developing gubernaculum. Injection of exogenous CGRP into the suprapubic region significantly altered caudal growth of the VP, with 77.3% of testes undescended compared with 30% undescended in control rats (P < 0.01). It was concluded that exogenous CGRP injected cranial to the developing gubernaculum prevented its caudal growth in the animals treated with flutamide. CGRP injection directly into the scrotum of a larger animal than the neonatal rat could determine whether CGRP can stimulate gubernacular migration and cure cryptochidism.