LACK OF ASSOCIATION OF PROGESTIN-INDUCED CYSTIC ENDOMETRIAL HYPERPLASIA WITH GH GENE-EXPRESSION IN THE CANINE UTERUS

Growth hormone (GH) is produced in progestin-induced hyperplastic duct ular mammary epithelia in dogs. Progestins also induce the development of cystic endometrial hyperplasia (CEH) in this species. The study re ported here investigated whether GH gene expression could also be demo nstrated in progestin-induced hyperplastic epithelium in the canine ut erus. Eight beagle bitches were treated with 10 mg medroxyprogesterone acetate (MPA) kg(-1) body mass s.c. at intervals of 3 weeks, for a to tal of five times in four dogs (group I) and for a total of 13 times i n the other four dogs (group II). Blood samples were collected twice d uring each 3 week period for measurement of plasma concentrations of G H, insulin-like growth factor I (IGF-I) and IGF-II. At the end of the series of injections uterine tissue was obtained by ovario-hysterectom y. Histological examination confirmed that CEH was present in all uter i after MPA treatment; the changes in the dogs of group I were less ma rked than those in group II. Immunohistochemical examination of the ut erine tissues showed that immunoreactive(i) GH was present in a number of uteri with CEH. iGH was usually located in the cytoplasm of glandu lar epithelial cells. However, reverse transcriptase PCR using GH-spec ific primers failed to demonstrate mRNA encoding GH in the uterine tis sue of all dogs. It is concluded that local production of GH is not in volved in progestin-induced hyperplasia of uterine epithelial cells in dogs.