HUMAN CHORIONIC-GONADOTROPIN BUT NOT THE CALCITONIN-GENE-RELATED PEPTIDE INDUCES POSTNATAL TESTICULAR DESCENT IN MICE

The androgen-regulated paracrine factor, calcitonin gene-related pepti de (CGRP), has been proposed as a possible mediator of testicular desc ent. This peptide has been found to increase rhythmic contractions of gubernaculae and is known to be released by the genitofemoral nerve. W e have investigated the ability of CGRP to induce premature testicular descent. CGRP was administered alone, or in combination with human ch orionic gonadotropin (hCG) to C57BL/6 male mice postnatally. The exten t of testicular descent at 18 days postpartum was then ascertained. Th e potential relationship between testicular weight and descent was als o examined. Our results show that testes of mice treated with either h CG alone, or in combination with 500 ng CGRP, were at a significantly lower position than those of controls by 16% and 17%, respectively. In contrast, mice treated with 500 ng of CGRP alone had testes at a high er position when compared to those of controls, by 19%. In mice treate d with 50 ng of CGRP alone or in combination with hCG, testes were at a position similar to those in controls. Furthermore, testicular desce nt was analyzed in relation to testicular weight, and we found that si gnificantly smaller testes per gram of body weight than those of contr ols were at a significantly lower position compared to those of contro ls. Our data demonstrate that CGRP had no effect on postnatal testicul ar descent and that there is no relationship between postnatal descent and testicular weight.