The effect of CIS hydroxyproline on ventral prostatic growth in rats

Changes in prostatic collagen were measured in Sprague-Dawley rats to gain further insight into the relationship between this stromal component and androgen mediated prostatic growth. Regulation of prostatic collagen by other endocrine factors was also studied. Collagen content per prostate was estimated by determination of tissue levels of hydroxyproline. The 1st experiment examined changes in the content of hydroxyproline in the prostate during pre- and post-pubertal growth with the use of rats between 21 and 80 days of age. As the animals grew, their prostatic weights and hydroxyproline contents increased in a parallel fashion (correlation coefficient R = 0.977, p less than 0.01). In the 2nd experiment, rats were castrated for a period up to 28 days. The hydroxyproline content in the prostate did not change significantly by castration despite a marked decrease in prostatic weights. Results of the 3rd experiment indicated that castration-hypophysectomy or castration-hypophysectomy plus estrogen treatment did not significantly change the content of prostatic hydroxyproline from that in the untreated intact animals. The 4th experiment studied the effect of the collagen synthesis inhibitor, cis-4-hydroxyproline, on prostatic growth. Subcutaneous injection of cis-4-hydroxyproline to castrated testosterone treated rats caused a significantly slower increase in total ventral prostatic weights and contents of protein, DNA and hydroxyproline than those of saline treated controls. This inhibition in prostatic growth is unlikely to be related to any antiandrogenic effect of cis hydroxyproline as the protein/DNA ratio in the prostate was the same for both saline and cis-4-hydroxyproline treated groups. Electron microscopic studies revealed that cis-4-hydroxyproline treatment resulted in a derangement of the basement membrane in the ventral prostate. The above results suggest that collagen plays an important role in limiting prostatic growth since inhibition of collagen synthesis by cis-4-hydroxyproline retarded the testosterone induced increase in prostatic weight, DNA, protein and hydroxyproline content in the prostate of rats.