Ovarian steroid secretion and effects of testosterone in female Rana pipiens.

Abstract

Gravid leopard frogs (Rana pipiens) were injected with testosterone or oil, and half of each group received food while the other half did not. Among the fed frogs, those injected with oil gained twice as much weight as those injected with testosterone. Among the frogs that were not fed, testosterone injected animals lost almost three times as much weight as oil injected controls. Fed frogs had heavier spleens, fat bodies, livers, ovaries, and left gastrocnemius' than unfed frogs. In addition, in fed frogs fat bodies were 1.5 times heavier in oil injected than in androgen injected animals. These data suggest a higher metabolic rate, increased lipid utilization and/or decreased appetite in frogs that received exogenous testosterone. Not fed, androgen injected R. pipiens had much heavier oviducts than any other group. It is hypothesized that testosterone acted as a precursor for estradiol-17B in producing this effect. Rana pipiens follicles taken early in hibernation and late in hibernation showed much higher testosterone secretion than estradioll7B secretion in vitro. Frog pituitary homogenate (FPH) greatly enhanced the androgen secretion while not affecting estrogen secretion. It is hypothesized that high testosterone secretion during hibernation plays a specific, yet uncharacterized, role in successful egg production by Rana pipiens.