Some Effects of Thyroxine and Antithyroid Compounds on Tadpoles and Their Relation to Hormonal Control of Growth

Steinmetz, C. H.

doi:10.1086/physzool.27.1.30152277

Cited by 32 publications

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“…Thiourea-treated tadpoles reach sizes not attained in normal development (13,16). The growth-promoting effect of prolactin in these animals is equally well documented (4)(5)(6)(7)(8).…”

Section: Discussionmentioning

confidence: 94%

Prolactin as a Goitrogenic Agent in Amphibia¹

Gona

1967

Endocrinology

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The nature of the inhibitory action of mammalian prolactin on the development of bullfrog tadpoles was investigated. Tadpoles injected ip with 20 jug of thyroxine (T 4 ) and 2 or 4 mg of ovine prolactin (NIH-P-S-7) underwent metamorphic changes in parallel with T 4 -injected controls. By contrast, tadpoles injected with 4 IU of bovine thyrotropic hormone (TSH) and either 4.0 or 0.4 mg of prolactin entered into developmental stasis after showing early signs of metamorphic climax, while TSH-injected controls completed the various metamorphic steps, including tail resorption. Histological examination of the thyroids of animals treated with both TSH and prolactin revealed an extremely high degree of hypertrophy and hyperplasia, with more pronounced depletion of the colloid than in TSH-injected controls. It is concluded that in these experiments prolactin acts at the level of the thyroid and that it has goitrogenic properties. (Endocrinology 8 1 : 748, 1967) P ROLACTIN appears to possess a great diversity of actions in different vertebrates aside from its well-known effects in mammals. For example, it elicits "waterdrive," or second metamorphosis, in the red eft stage of the common newt (1, 2). Another role concerns osmoregulation in fish (3). Excess growth in tadpoles carrying ectopic pituitary transplants was reported by Etkin and Lehrer (4), who postulated that this was the result of an increased rate of prolactin secretion by the ectopic pituitaries which are freed from the normally existing hypothalamic inhibition of prolactin release. Other investigations demonstrated that mammalian prolactin has a marked growth-promoting effect in tadpoles (5-8). Olivereau (9) reported a thyroid-stimulating effect of prolactin in eels and concluded that this hormone acts as a thyrotropin-releasing factor in these fish. More recently, it was found (10) that mammalian prolactin inhibits metamor-

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“…Thiourea-treated tadpoles reach sizes not attained in normal development (13,16). The growth-promoting effect of prolactin in these animals is equally well documented (4)(5)(6)(7)(8).…”

Section: Discussionmentioning

confidence: 94%

Prolactin as a Goitrogenic Agent in Amphibia¹

Gona

1967

Endocrinology

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“…Growth was determined by the measurement of live body weight. Steinmetz ( 1954) showed that live body weight of tadpoles is as adequate a measure of growth as dry weight. Tadpoles were weighed by first laying them on filter paper to remove surface water, and then placing them in a preweighed beaker of water.…”

Section: Methodsmentioning

confidence: 99%

Growth Inhibition in Crowded Tadpoles: Intraspecific and Interspecific Effects

Light¹

1967

Ecology

110

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Tadpoles are inhibited in growth when raised in water previously crowded by other larger tadpoles. The ‘alga—like’ cells described in earlier crowding studies were found in the fecal material and intestinal tracts of inhibited tadpoles. Results of 38 crowding experiments using 17 species of tadpoles show that the effects of the inhibitory cell are nonspecific. Water (with cell—laden fecal matter) from crowded tadpoles of one suborder can inhibit the growth of assay tadpoles of a different suborder. There is no decreasing level of inhibition with phylogenetic distance. Bufo woodhouse is the only one of 17 anuran species tested that seems immune to these inhibitory effects. Tests with Bufo woodhouse indicated the existence of a possible intraspecific growth—promoting substance. The substance may also inhibit some species, and not affect others. Metamorphosing tadpoles may release a nonspecific growth—stimulating substance (thyroxine?) into the water, which may alleviate the effect of inhibitory substances.

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“…In the larvae of R. temporaria, growth hormone is more effective than prolactin, but in the larvae of the toad, Bufo bufo, neither of the two hormones affects growth. Several an tithyroid agents stimulate growth in tadpoles [68,72,131,132]. Therefore, the growth-pro moting action of prolactin is believed to be the consequence of its antithyroid action.…”

Section: Endocrine Regulation O F Growthmentioning

confidence: 99%

Growth in Amphibians

Hota¹

1994

Gerontology

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The complex life history of many amphibians has been designed to take advantage of the resources of two completely different habitats. The aquatic free-living amphibian larva is different from the terrestrial adult regarding morphology, physiology and behavioural patterns. Therefore, in the lifetime of an individual amphibian, two discontinuous growth stanzas are exhibited. The sigmoid growth model fits well with both stanzas. The rapid growth of the larval amphibian can be described by the double exponential Gompertz equation, whereas the slow growth process of the transformed amphibian can be described by the von Bertalanffy growth model. The bulk of amphibian growth occurs in the terrestrial phase and is not independent of size, age, sex and environmental conditions. The endocrine regulation of growth in amphibians is unique in the sense that the mechanism of pituitary action is different in aquatic and terrestrial phases.

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Some Effects of Thyroxine and Antithyroid Compounds on Tadpoles and Their Relation to Hormonal Control of Growth

Cited by 32 publications

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Prolactin as a Goitrogenic Agent in Amphibia¹

Prolactin as a Goitrogenic Agent in Amphibia¹

Growth Inhibition in Crowded Tadpoles: Intraspecific and Interspecific Effects

Growth in Amphibians

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Some Effects of Thyroxine and Antithyroid Compounds on Tadpoles and Their Relation to Hormonal Control of Growth

Cited by 32 publications

References 0 publications

Prolactin as a Goitrogenic Agent in Amphibia1

Prolactin as a Goitrogenic Agent in Amphibia1

Growth Inhibition in Crowded Tadpoles: Intraspecific and Interspecific Effects

Growth in Amphibians

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Prolactin as a Goitrogenic Agent in Amphibia¹

Prolactin as a Goitrogenic Agent in Amphibia¹