Immunoreactive Arginine Vasopressin in the Testis: Immunocytochemical Localization and Testicular Content in Normal and in Experimental Cryptorchid Mouse1

The presence of arginine vasopressin (AVP)-like peptide(s) and AVP receptors has been previously demonstrated in the testis of several species. In this study we examined the immunocytochemical localization of AVP and of its associated neurophysin (NPII) within the mouse tesMouse testes were foundtis, and the testicular immunoreactive (IR)-AVP content in normal pubertal and adult mice and in unilaterally cryptorchid animals. Immunostaining was conducted on fresh frozen adult testicular sections and on cultured testicular cells using the avidin-biotin immunoperoxidase technique. Immunoreactivities for AVP and NPII were localized at the periphery of the seminiferous tubules. Staining for AVP and NPII was reduced in testes showing impaired spermatogenesis. AVP and NPII immunoreactivities were present in cultured Sertoli cells, but staining was undetectable in cultured Leydig cells. Negative controls were obtained by applying antiserum that had been preabsorbed with excess peptides in place of primary antiserum. Mouse testes were found to contain IR-AVP, which co-eluted with synthetic AVP on HPLC and diluted in parallel in a specific RIA for AVP. Levels of IR-AVP expressed as pg/mg wet-weight testis were significantly higher (p < 0.05) in pubertal (36.6 ± 1.5) than in adult animals (27.4 ± 1.5). Experimental unilateral cryptorchidism in adult animals resulted 2 wk later in a marked reduction (p < 0.01) in IR-AVP levels in the abdominal testis (18.1 ± 1.0 pg/mg testis) as compared to the contralateral scrotal testis (29.8 ± 1.1 pg/mg testis). The present study provides, for the first time, information on the probable site of production of IR-AVP in the mouse testis and indicates that the testicular IR-AVP content is influenced by the maturational and functional status of the testis. These results are consistent with a paracrine role for AVP-like peptide(s) in the regulation of testicular function.