Effects of testosterone on oviduct growth in the northern leopard frog (rana pipiens).

Abstract

Testosterone has been shown to cause oviduct hypertrophy in some amphibians. To understand the role of testosterone, ovariectomized and immature frogs were injected with estradiol and testosterone and compared to oil-treated animals. Since testosterone can be converted to estradiol, dihydrotestosterone (DHT), which cannot be converted, was also used. Animals treated with testosterone or estradiol plus testosterone had the largest oviducts, whereas oviducts from mature animals were slightly smaller in groups treated with estradiol alone. DHT had no effect in mature animals, and only a very slight effect in immature animals. These results suggest that oviduct growth in testosterone-treated animals was due to the aromatization of testosterone to estradiol. To test this hypothesis oviduct tissue was incubated with testosterone. The medium showed high estradiol levels, supporting the presence of aromatization in the oviduct. Protein and total polysaccharide content of oviducts were examined across groups with little significant difference. Hexose content of the total polysaccharides was not different between groups. Total plasma proteins from groups injected with estrogen plus androgen were smaller than those injected with estrogen alone. This suggests that androgen effects on plasma proteins are not due to conversion to estradiol.