Hyperplasia of the parathyroids and the pituitary in rats with experimental leydigiomas and inhibitory effect of several steroids.

Bilateral orchidectomy performed on 10- to 15-day-old Wistar rats, immediately followed by the homograft of one testis into the splenopancreatic epiploon, resulted 6 months later in leydigiomas at the site of the graft in 100% of the animals. After this latency period, the tumors continued to grow proportionately to time elapsed and were associated with both pituitary microadenomas of the aldehyde-fuchsin-, aldehyde-thionin-periodic acid-Schiff-, and periodic acid-Schiff-positive cells and diffuse hyperplasia of the parathyroids, affecting in particular the chief cells of the latter. After a 6- or 12-month leydigioma latency period, the rats were given a daily treatment by gavage for 45 days of one or two of the following steroids: Compound A, 17alpha-ethynyl, (5alpha)-androst-2-en, 17beta-ol (17 beta-acetate) (5 mg/kg when alone; 2.5 mg/kg when combined); Compound B, 17 alpha-ethynyl, (5 alpha)-androst-2-en, 17 beta-ol (17 beta-nicotinate) (always given in combined form at 2 mg/kg); Compound C, 16-oximinoestrone, 3-allyl ether (2 mg/kg when combined). The treatments caused, in various degrees, (a) involution of the leydigiomas until complete disappearance in up to 50% of the cases; (b) recovery of the characteristic morphological pattern of the pituitaries; and (c) cytolysis and interstitial fibrosis in the previously hyperplastic parathyroids.