The concentrations of collagen-associated amino acids are higher in GnRH agonist-treated uterine myomas

To test the hypothesis that the effects of estrogen reduction on uterine leiomyoma regression are mediated through changes in cell density or the extracellular matrix. Uterine myomas were obtained from 20 women who had received randomly either the GnRH agonist leuprolide acetate depot for 3 months or placebo. The biochemical and morphologic characteristics studied included: total protein, DNA, and amino acid concentrations; histologic appearance; collagen content; and nuclear density. The absolute and relative concentrations of hydroxylysine, hydroxyproline, glycine, and proline were significantly greater (P < .05) in uterine myomas from patients pretreated with a GnRH agonist compared with placebo-treated controls. The GnRH agonist was also associated with trends toward increased mean total protein, DNA, and nuclear density, but the differences did not reach statistical significance. The concentrations of the amino acids contained in collagen were significantly greater in uterine myomas from patients treated with the GnRH agonist compared to myomas from placebo-treated controls. In addition, our observations suggest that the reduction in uterine myoma volume associated with GnRH agonist therapy is associated with alterations in the extracellular matrix.