The effect of prolactin on the Dunning R3327H rat prostatic adenocarcinoma.

The Dunning R3327 rat prostatic adenocarcinoma contains specific binding sites for iodo-oPRL (ovine prolactin) in the membrane fraction (100,000 X g pellet). These are normally present at a low level, but immunization with oPRL produces a dramatic increase in tumor binding in either sex (females bear an implant of testosterone propionate pellet). Under these experimental conditions, the ventral prostate of rats bearing the tumors have no detectable PRL receptors. 5 alpha-Reductase activity, on the other hand, is lower in the tumors than in the normal prostates. Immunization also decreased somewhat the rate of growth of the tumors.