Action of Mammalian Sex Hormones in the Lizard,Sceloporus occidentalis

Abstract

With the discovery of an increasing number of estrogens and androgens in mammals, and an increasingly diverse series of physiological activities in which they are involved, it has become of great interest to examine the action of such substances in lower vertebrates. In adult frogs, injection of estrogens prevents atrophy of the oviduct after ovariotomy, 1 and high doses (1,000 rat units) stimulate growth of the oviduct in rormal animals. 2 In normal toads, however, dosages of estrone as high as 10,000 international units have little or no demonstrable action. 3 , 4 A surprising result is ovulation in Xenopus laevis in response to progesterone, testosterone, and allied compounds, but not to estrogenic substances, such as estrone, estriol, and estradiol. 5 , 6 In young alligators estrone stimulates the ovary and oviduct; testosterone also stimulates the oviduct. 7 , 8 In lizards testosterone induces secretory activity in “sexual segments” of urinary tubules, and an increase in the size of the oviduct. 9 Estrone, however, produces a marked reduction in testicular size in lizards, but stimulates the epididymis and Wolffian duct. 10 , 11

In this report the results of administration of theelin and testosterone propionate (Oreton)∗ to adult Fence Lizards Sceloporus occiden-talis, of both sexes are outlined. Dosages of each hormone used were either .4 cc (.08 mg theelin, 4.0 mg testosterone) given over a period of 5 days, or .5 cc (.10 mg theelin, 5.0 mg testosterone) given over a period of 2 weeks. The difference in effect between the two modes of treatment was only slight, a more pronounced effect being found in each case in the .5 cc group.