Prolactin inhibits both thyroid hormone-induced morphogenesis and cell death in cultured amphibian larval tissues

Tata, Jamshed R.; Kawahara, Akira; Baker, Betty S.

doi:10.1016/0012-1606(91)90447-b

Cited by 117 publications

(49 citation statements)

References 21 publications

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“…PRL has been considered a ''juvenile hormone'', opposing the actions of the THs and, thereby, delaying the time set for metamorphosis (Forsyth and Wallis 2002). This is based on in vivo (Dodd and Dodd 1976) and in vitro (Derby and Etkin 1968;Tata et al 1991;Takada and Kasai 2003) studies with mammalian PRL. However, this is in contrast with data showing that endogenous PRL plasma levels are low at pre-and prometamorphic stages, rising at the metamorphic climax (Clemons and Nicoll 1977;Yamamoto and Kikuyama 1982).…”

Section: Discussionmentioning

confidence: 99%

Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut

et al. 2005

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Fish larval development, not least the spectacular process of flatfish metamorphosis, appears to be under complex endocrine control, many aspects of which are still not fully elucidated. In order to obtain data on the functional development of two major endocrine glands, the pituitary and the thyroid, during flatfish metamorphosis, histology, immunohistochemistry and in situ hybridization techniques were applied on larvae of the Atlantic halibut (Hippoglossus hippoglossus), a large, marine flatfish species, from hatching through metamorphosis. The material was obtained from a commercial hatchery. Larval age is defined as day-degrees (D°=accumulated daily temperature from hatching). Sporadic thyroid follicles are first detected in larvae at 142 D°(27 days post-hatch), prior to the completion of yolk sack absorption. Both the number and activity of the follicles increase markedly after yolk sack absorption and continue to do so during subsequent development. The larval triiodothyronine (T 3 ) and thyroxine (T 4 ) content increases, subsequent to yolk absorption, and coincides with the proliferation of thyroid follicles. A second increase of both T 3 and T 4 occurs around the start of metamorphosis and the T 3 content further increases at the metamorphic climax. Overall, the T 3 content is lower than T 4 . The pituitary gland can first be distinguished as a separate organ at the yolk sack stage. During subsequent development, the gland becomes more elongated and differentiates into neurohypophysis (NH), pars distalis (PD) and pars intermedia (PI). The first sporadic endocrine pituitary cells are observed at the yolk sack stage, somatotrophs (growth hormone producing cells) and somatolactotrophs (somatolactin producing cells) are first observed at 121 D°( 23 days post-hatch), and lactotrophs (prolactin producing cells) at 134 D°(25 days post-hatch). Scarce thyrotrophs are evident after detection of the first thyroid follicles (142 D°), but coincident with a phase in which follicle number and activity increase (260 D°). The somatotrophs are clustered in the medium ventral region of the PD, lactotrophs in the anterior part of the PD and somatolactotrophs are scattered in the mid and posterior region of the pituitary. At around 600 D°, coinciding with the start of metamorphosis, somatolactotrophs are restricted to the interdigitating tissue of the NH. During larval development, the pituitary endocrine cells become more numerous. The present data on thyroid development support the notion that thyroid hormones may play a significant role in Atlantic halibut metamorphosis. The time of appearance and the subsequent proliferation of pituitary somatotrophs, lactotrophs, somatolactotrophs and thyrotrophs indicate at which stages of larval development and metamorphosis these endocrine cells may start to play active regulatory roles.

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Section: Discussionmentioning

confidence: 99%

Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut

et al. 2005

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“…Tail regression is induced in natural metamorphosis by high levels of TH, the active form of which is tri-iodothyronine (T 3 ; Leloup and Buscaglia, 1977). Tail regression can be induced experimentally precociously in vivo or in vitro on tail explants by treatment with exogenous T 3 (Tata et al, 1991). Furthermore, natural metamorphosis is correlated with a drop in expression of the T 3 -inactivating type III deiodinase (D3) in the tail at the end of metamorphosis (Huang et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

et al. 2005

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The climax of amphibian metamorphosis is marked by thyroid hormone-dependent tadpole tail resorption, implicating apoptosis of multiple cell types, including epidermal cells, fibroblasts, nerve cells, and muscles. The molecular cascades leading to and coordinating the death of different cell types are not fully elucidated. It is known that the mitochondrial pathway, and in particular the Bax and XR11 genes, regulates the balance between apoptosis and survival in muscle. However, the down-stream factors modulated by changes in mitochondrial permeability have not been studied in a functional context. To investigate further the mitochondrial-dependent pathway, we analyzed the regulation and the role of caspase 9 in Xenopus tadpoles. We report that caspase 9 mRNA is expressed in the tail before metamorphosis and increases before and during climax. Similarly, at the protein level, the production of active forms of caspase 9 increases in muscle tissue as metamorphosis progresses. To assess the functional role of caspase 9, we designed a dominant-negative protein. Overexpression of this dominant-negative abrogates both Bax-induced cell death in vitro and muscle apoptosis in vivo during natural metamorphosis. These findings consolidate a model of metamorphic muscle death that directly implicates the mitochondrial pathway and the apoptosome. Developmental Dynamics 233:76 -87, 2005.

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“…Producing feeding frogs with tails by inhibition of TH production at metamorphosis, Elinson et al (1999) indicated that these tails lose their fast muscle preferentially, showing that more than one cell death program is involved in primary myofiber resorption. Limb muscles, which do not appear until the middle of metamorphosis, are both induced by TH (Tata et al, 1991) and are characterized by a classic scheme of myogenesis, including myoblast fusion (Muntz, 1975;Dhanarajan and Atkinson, 1981;Fig. 3).…”

Section: Cell Death and Secondary Myogenesismentioning

confidence: 99%

Xenopusmuscle development: From primary to secondary myogenesis

Chanoine

Hardy

2002

Developmental Dynamics

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Xenopus myogenesis is characterized by specific features, different from those of mammalian and avian systems both at the cellular level and in gene expression patterns. During early embryogenesis, after the initial molecular signals inducing mesoderm, the myogenic determination factors XMyoD and XMyf-5 are activated in presomitic mesoderm in response to mesoderm-inducing factors. After these first inductions of the myogenic program, forming muscles in Xenopus can have different destinies, some of these resulting in cell death before adulthood. In particular, it is quite characteristic of this species that, during metamorphosis, the primary myotomal myofibers completely die and are progressively replaced by secondary "adult" multinucleated myofibers. This feature offers the unique opportunity to totally separate the molecular analysis of these two distinct types of myogenesis. The aim of this review is to summarize our knowledge on the cellular and molecular events as well as the epigenetic regulations involved in the construction of Xenopus muscles during development. Developmental Dynamics 226:12-23, 2003.

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Prolactin inhibits both thyroid hormone-induced morphogenesis and cell death in cultured amphibian larval tissues

Cited by 117 publications

References 21 publications

Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut

Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

Xenopusmuscle development: From primary to secondary myogenesis

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