Luteinizing hormone-releasing hormone (LHRH) in rat prostate: characterization of LHRH peptide, messenger ribonucleic acid expression, and molecular processing of LHRH in intact and castrated male rats.

Continuous administration of LHRH agonist suppresses the pituitary-gonadal axis, achieving chemical castration. Thus, LHRH agonist has been used as an alternative (to surgical castration) for the treatment of steroid-dependent prostate cancer. However, recent reports have demonstrated that LHRH agonist had a direct inhibiting effect on prostate cancer cell proliferation and that cancerous prostate tissue contained a LHRH-like peptide. In this paper we are reporting for the first time that the normal rat ventral prostate contained immunoactive and bioactive LHRH as well as its precursor molecule, pro-LHRH. Our investigation showed that the LHRH concentration in prostate increased 2 weeks after castration from 1.68 +/- 0.09 to 3 +/- 0.2 pg/mg tissue (P < 0.001). At the same time, the concentration of pro-LHRH decreased from 149 +/- 6.5 to 68 +/- 6.8 pg/mg tissue (P < 0.001). Furthermore, intact rat prostate expressed LHRH mRNA, which increased 13-fold 2 weeks after castration. In summary, the prostate of intact Sprague-Dawley rats has the capacity to produce the LHRH precursor and process it to the mature decapeptide, and this production/processing increases significantly after castration.