Prolactin Receptor Expression in Rat Spermatogenic Cells

Abstract

To identify target cells of prolactin (PRL) in the male gonad, the expression of prolactin receptor (PRL-R) mRNA in adult rat testes was investigated by in situ hybridization using a digoxigenin-labeled cRNA probe. We also investigated PRL binding to testicular cells in vitro. Signals for PRL-R mRNA were detected not only in interstitial cells but also in spermatogenic cells. Although the reaction was positive in all phases of spermatogonia and spermatocytes, it disappeared in early round spermatids. No signals were detected in elongated spermatids or spermatozoa. The signal intensity varied among each phase of spermatogenic cells. PRL-R mRNA was expressed in all stages of the cycle of the seminiferous epithelium. PRL-R were detected on the surface of Leydig cells, Sertoli cells, all phases of spermatogonia and spermatocytes, elongated spermatids, and spermatozoa. Ovine PRL. did not bind to round spermatids. In Leydig cells, pachytene spermatocytes, and spermatozoa, PRL-R were observed in relatively large numbers. There were fewer receptors in other phases of spermatogenic cells. These results indicate that PRL-R mRNA expression is almost consistent with PRL binding sites except for elongated spermatids and spermatozoa, and suggest that PRL may have direct effects on spermatogenic cells.

Cabergoline treatment rapidly improves gonadal function in hyperprolactinemic males: a comparison with bromocriptine

“…The positive effect of CAB treatment on gonadal and sexual function in hyperprolactinemic males is closely correlated to the effect played by PRL not only on sexual steroid secretion but also on spermatogenesis. In fact, it has been recently demonstrated that PRL receptors are present in all stages of the cycle of the seminiferous epithelium, the surface of Leydig and Sertoli cells, all phases of spermatogonia and spermatocytes in male rats (23), suggesting that PRL plays a pivotal role in the development of spermatogenesis. In addition, several older studies on animals demonstrated that normal serum PRL levels are required for a normal testicular function and growth of accessory sex organs, since PRL acts synergistically with LH and testosterone (24,25) and it regulates the levels of the testosterone precursors for conversion under the in¯uence of LH (25).…”

Prolactin Induces Protamine 2 mRNA Expression in Rat Testis.

“…We previously reported that PRL-R mRNA was localized in type A and B spermatogonia and all spermatocyte stages [12]. Therefore, the PRM 2 mRNA expression pattern overlaps with that of PRL-R mRNA in spermatocytes.…”

“…The method for sense and antisense digoxigenin-labeled cRNA probe preparation has been described previously [12]. Deparaffinized sections (5 µm thickness) were treated with 4% paraformaldehyde/0.1 M phosphate buffer, 0.1 M glycine/0.2 M Tris-HCl (pH 7.6), and 8 µg/ml proteinase K/50 mM Tris-HCl (pH 7.5)/ 2 mM CaCl2, for 10 min.…”

“…After the cloning of the PRL receptor (PRL-R) cDNA in rat ovary and liver [9], the localization of PRL-R gene expression in rat testis was determined. PRL-R gene is expressed in Leydig cells and also in spermatogenic and/or Sertoli cells [10][11][12]. PRL increased the down-regulation of FSH receptors in Sertoli cells induced by FSH itself [13], and steroidogenic factor I modulated the promoter region of the PRL-R gene in Leydig cells [14].…”

Molecular Cloning and Expression of Suppressor of Potassium Transport Defect 3 (SKD3) in Rat Testis.

“…The method for sense and anti-sense cRNA probe preparation has been described previously [12]. An isolated rat SKD3 cDNA fragment in the plasmid Bluescript was used for preparing the cRNA probe.…”