Changes in Thyroid Hormone Concentrations and Total Contents through Ontogeny in Three Anuran Species: Evidence for Daily Cycles

Gancedo, B.; Alonso-Gómez, A.L.; Pedro, Nuria de; Delgado, M.J.; Alonso‐Bedate, M.

doi:10.1006/gcen.1997.6922

Cited by 30 publications

(11 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the majority of limb motorneuron generation occurs after the thyroid gland becomes functional, which is around NF stage 46, as determined by its ability to incorporate radioactive iodine (data not shown). A recent study (29) that used published counts of all spinal motorneurons in young tadpoles (30), published counts of limb motorneurons during metamorphosis (9,10), and published measurements of TH levels (31)(32)(33), came to the same conclusion that TH likely regulates the generation of spinal cord cells in tadpoles. However, the fact that RALDH-2 cells are present in small numbers in brachial and lumbar spinal cord even during embryogenesis (data not shown) also suggests that TH may not be required for their generation.…”

Section: Inhibiting Th Function Perturbs the Development Of The Spinamentioning

confidence: 87%

Thyroid hormone controls the development of connections between the spinal cord and limbs during Xenopus laevis metamorphosis

Marsh-Armstrong

Cai

Brown

2003

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

During premetamorphic stages, Xenopus laevis tadpoles expressing either a dominant-negative thyroid hormone (TH) receptor or a type-III iodothyronine deiodinase transgene in the nervous system have reduced TH-induced proliferation in the spinal cord and produce fewer hindlimb-innervating motorneurons. During prometamorphic stages, innervation of the hindlimbs is reduced, and few functional neuromuscular connections are formed. By metamorphic climax, limb movement is impaired, ranging from uncoordinated leg swimming to complete quadriplegia. This phenotype is due to transgene action in the tadpole spinal cord. The requirement of TH for neurogenesis during premetamorphosis is the earliest TH-regulated process reported to date in the sequence of metamorphic changes in anurans. The muscle formed during limb growth was previously shown to be a direct target of TH control. Here, we show that the same is true of the development of spinal cord cells that innervate the limbs. D uring amphibian metamorphosis, thyroid hormone (TH) controls remodeling of the nervous system (1). TH removes neural circuits that are larval-specific, for example, the spinal cord Rohon-Beard cells (2). TH also promotes the development of cells that participate in frog-specific circuits such as within the olfactory (3), visual (4-7), and auditory (8) systems. In the retina TH acts, in part, by regulating the proliferation of neural progenitors. This action of TH appears to be cell-autonomous, because progenitor cells found in the dorsal retina, but not those found in the ventral retina, are protected from TH action by the precise expression of type-III iodothyronine deiodinase (D3), an enzyme that inactivates TH (7).The spinal cord of anurans is remodeled during metamorphosis. The most dramatic change is the development of neural circuits within the brachial and lumbar spinal cord that control the movement of arms and legs, respectively. The spinal cord cell type that has been most studied during metamorphosis is the limb motorneuron, which is the only spinal cord cell that directly innervates limbs. Limb motorneuron number reach a peak as the limb bud emerges at the beginning of premetamorphosis and then decreases dramatically soon after the limb is innervated (9, 10). To date, it has been unclear whether any change observed in limb motorneurons is due to the action of TH within spinal cord cells. Alternatively, changes in limb motorneurons and other spinal cord cells might be a consequence of the growth and development of limbs, which is a known TH-dependent process.In the current study, we show that inhibiting TH action in the spinal cord by means of neural-specific transgenes leads to a defect in TH-induced neurogenesis, and a decreased generation of lumbar motorneurons that innervate the hindlimb. This defect in neurogenesis is followed by a reduction in hindlimb innervation and a deficiency in functional connections between nerve and muscle within the hindlimb. In terms of hindlimb movement, the phenotypes in these transgenic animals range ...

show abstract

Section: Inhibiting Th Function Perturbs the Development Of The Spinamentioning

confidence: 87%

Thyroid hormone controls the development of connections between the spinal cord and limbs during Xenopus laevis metamorphosis

Marsh-Armstrong

Cai

Brown

2003

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Cao et al (2012) also reported no significant changes in circulating total T 4 in mice at 22 months compared to 6 months of age but did observe decreases in free T 3 (Cao et al, 2012). In addition, circadian rhythms are increasingly disrupted in humans during ageing (Campos Costa et al, 2013;Froy, 2011), notably affecting TSH secretion levels (Bitman et al, 1994;Gancedo et al, 1997;Morris et al, 2012). Furthermore, the binding capacity of TRs also decreases in the cortex and cerebellum of 24 month-old rats (De Nayer et al, 1991).…”

Section: Roles Of Th In the Ageing Brainmentioning

confidence: 97%

Comparative approaches to understanding thyroid hormone regulation of neurogenesis

Gothié

Demeneix

Remaud

2017

Molecular and Cellular Endocrinology

View full text Add to dashboard Cite

Thyroid hormone (TH) signalling, an evolutionary conserved pathway, is crucial for brain function and cognition throughout life, from early development to ageing. In humans, TH deficiency during pregnancy alters offspring brain development, increasing the risk of cognitive disorders. How TH regulates neurogenesis and subsequent behaviour and cognitive functions remains a major research challenge. Cellular and molecular mechanisms underlying TH signalling on proliferation, survival, determination, migration, differentiation and maturation have been studied in mammalian animal models for over a century. However, recent data show that THs also influence embryonic and adult neurogenesis throughout vertebrates (from mammals to teleosts). These latest observations raise the question of how TH availability is controlled during neurogenesis and particularly in specific neural stem cell populations. This review deals with the role of TH in regulating neurogenesis in the developing and the adult brain across different vertebrate species. Such evo-devo approaches can shed new light on (i) the evolution of the nervous system and (ii) the evolutionary control of neurogenesis by TH across animal phyla. We also discuss the role of thyroid disruptors on brain development in an evolutionary context.

show abstract

“…Then 300 mL of distilled and deionized water were added to each tube, and samples were homogenized with an electric mechanical homogenizer (Ultra Turrax, IKA-Labortechnik). Whole-body determinations were necessary in this and the next experiment, due to the small size of bufonid tadpoles (Weber et al 1994;Gancedo et al 1997;Ultsch et al 1999). Tubes were then centrifuged at 7,000 g for 20 min.…”

Section: Experiments 1: Effect Of Salinity On Development and Physiologymentioning

confidence: 99%

Developmental Alterations and Osmoregulatory Physiology of a Larval Anuran under Osmotic Stress

Gómez-Mestre

Tejedo²,

Ramayo³

et al. 2004

Physiological and Biochemical Zoology

View full text Add to dashboard Cite

Water salinity represents an environmental stress for many species. Amphibians are particularly sensitive because they are generally poor osmoregulators, and most species are completely absent from brackish and saline environments. We experimentally examined the effect of different salinity levels on larvae of the toad Bufo calamita L., a species that occupies freshwater ponds but can also breed in brackish ponds. Two independent experiments are reported here. In both experiments, tadpoles under saline conditions (ranging between 85 and 200 mOsm) showed a slower developmental rate, metamorphosing between 4 and 9 d later than the controls. Bufo calamita tadpoles reared in brackish water increased their osmolality and solute concentration (mainly sodium and chloride), decreased their levels of glucose, and decreased the total protein content, all measured from whole-animal extracts. Although most larval anurans are strictly ammoniotelic until the completion of metamorphosis, a few species exposed to dehydrating environments have evolved the ability to use urea as an osmolyte during the larval phase. The data presented here reveal that although B. calamita seems to be yet another exception to the rule of larval strict ammoniotelism, the tadpoles are not able to use urea as an osmolyte and rely on sodium-chloride balance instead. Preliminary immunoassays of thyroid hormone content suggest a possible decrease in hormone levels induced in water salinity conditions that correlate with a decreased developmental rate.

show abstract

Changes in Thyroid Hormone Concentrations and Total Contents through Ontogeny in Three Anuran Species: Evidence for Daily Cycles

Cited by 30 publications

References 30 publications

Thyroid hormone controls the development of connections between the spinal cord and limbs during Xenopus laevis metamorphosis

Thyroid hormone controls the development of connections between the spinal cord and limbs during Xenopus laevis metamorphosis

Comparative approaches to understanding thyroid hormone regulation of neurogenesis

Developmental Alterations and Osmoregulatory Physiology of a Larval Anuran under Osmotic Stress

Contact Info

Product

Resources

About