FERTILIZATION-PROMOTING PEPTIDE IN REPRODUCTIVE TISSUES AND SEMEN OF THE MALE MARMOSET (CALLITHRIX-JACCHUS)

Fertilization-promoting peptide (FPP) is present in the prostate gland and semen of some mammals, and has been shown to enhance the fertiliz ing ability of both epididymal mouse and ejaculated human spermatozoa. The novel peptide may prove of importance for the treatment of some c ases of male infertility, and a suitable animal model would be useful to test this hypothesis. To this end, we examined reproductive tissues and semen of the male marmoset for the presence of FPP. Peptides were extracted from seminal plasma, testes, prostate, and bulbourethral gl ands of intact and castrated male marmosets. The peptides were identif ied by ion-exchange chromatography followed by radioimmunoassay, The m ean concentration of FPP immunoreactivity in semen from intact males w as 58.7 nM (SE +/- 9.9 nM, n = 10), and anion-exchange chromatography revealed FPP as the only immunoreactive peptide present. Analysis of t is sues revealed that FPP in semen was likely to be derived from the p rostate gland, which contained this peptide as the major source of imm unoreactivity (10.86 pmol/gland; SE +/- 4.39 pmol/gland, n = 4). Only low concentrations of FPP were detectable in the bulbourethral glands, and the peptide was undetectable in the testis. Surprisingly, FPP was readily detectable in the seminal plasma from one castrated marmoset and was present in the prostate gland from 3 castrates at levels which did not differ significantly from those in intact animals (5.47 pmol/ gland, SE +/- 1.64 pmol/gland, n = 3). Plasma testosterone measurement s indicated that residual circulatory androgens remained after castrat ion, which may be consistent both with the maintenance of mating behav ior and the presence of prostatic FPP, We conclude that FPP is present within the prostate gland and seminal plasma of the marmoset at conce ntrations consistent with a role in male fertility in this species. (C ) 1997 Wiley-Liss, Inc.