The thyroid hormones A thesis concerning their action

Hulbert, A. J.

doi:10.1016/0022-5193(78)90181-9

Cited by 78 publications

(18 citation statements)

References 73 publications

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“…One possibility is that thyroid hormones regulate events at a sub-cellular level in a similar manner in a variety of tissues to give rise to the apparent diversity of thyroid regulatory functions. Such an hypothesis is not unreasonable and has been proposed by several authors ) Stevens 1973, Barrington 1978, Etkin 1978, Hulbert 1978. However, other explanations may be equally appropriate.…”

Section: Discussionmentioning

confidence: 87%

Environmental physiology of the teleostean thyroid gland: a review

Leatherland

1982

Environ Biol Fish

140

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SynopsisRecent studies of thyroid hormone function are reviewed as they relate to the environmental physiology of teleost fish. In addition, reports dealing with the apparent interdependence of thyroid gland function with that of other endocrine glands are discussed with emphasis on the interrelated endocrine response associated with changing physiological status of teleosts.Seasonal changes in thyroid gland activity are described in several species. Although seasonal alterations in apparent thyroid status are concomitant with changes in ambient temperature, photoperiod and/or gonadal status, their biological significance is not fully understood and direct relationships are for the most part, not proven. Similarly, most reports of thyroid involvement in gonadal development or maturation are based on indirect evidence of the relationship. The exception to this is a study in immature or hypophysectomized goldfish in which thyroxine (T4) was shown to promote ovarian development and maturation, possibly acting collateralistically or synergistically with gonadotropin. Even in this study it is not clear whether the Td effect is a direct action on the ovarian tissue or an indirect action via the regulation of metabolites necessary for gonad metabolism. Integumentary silvering and retinal porphyropsin formation in salmonids are stimulated by administration of T4 or thyroid extracts. Administration of T4 or triiodothyronine (T3) enhances skeletal and somatic growth in some teleostean species, although the effect on somatic growth is most pronounced when these hormones act synergistically with somatotropin (STH) or androgens. The growth-promoting effects of T4 and T3 may be linked to their apparent involvement in lipid, carbohydrate, protein and vitamin metabolism. Alterations in apparent thyroid activity concomitant with changes in ambient temperature have been reported (for example correlated with seasonal ambient thermal changes), although there are marked contradictions in data presented by different investigators. Reported temperature-related effects on thyroid function are probably secondary responses of thyroid metabolism to altered temperatures. Evidence of a direct rate of thyroid hormones in the regulation of migration (and associated behavioural modifications), salmonid smoltification, oxygen consumption, and osmotic or ionic regulation although highly suggestive in a number of areas is inconclusive and requires further critical experimental evaluation.The pituitary control (by thyrotropin) of thyroid secretion of T4 is convincingly shown in several teleosts, and Receivrd 26.6.1980 Accepted 6.12.1980 0 Dr W. Junk Publishers, The Hague. Printed in The Netherlands. 0378.1909/82/0071-0083 $03.4083 evidence of an inhibitory hypothalamic control of thyrotrop activity is highly suggestive in some species. A thyrotropic effect of somatotropin preparations is well established in several teleostean species; the effect does not appear to be related to contamination of the somatotropin preparations with thyrotropin, and ma...

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Section: Discussionmentioning

confidence: 87%

Environmental physiology of the teleostean thyroid gland: a review

Leatherland

1982

Environ Biol Fish

140

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“…S. heathi may require a normal T 4 to stimulate sufficient thermogenesis during torpor to prevent body temperature from falling below a critical level that would necessitate arousal. The proposed hypothesis may also explain why the bat do not drop their body temperature much below 20-24ºC during winter dormancy (Hulbert, 1978). Ground squirrel, which have low T 4 during most of their hibernation periods, can let their body temperature drop to 0ºC (Lyman & Chatfield, 1955).…”

Section: Discussionmentioning

confidence: 91%

Changes in the thyroid gland during the reproductive cycle of the male vespertilionid bat, Scotophilus heathi

Krishna

Singh

1998

Rev. Bras. Biol.

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The aim of present study was to compare the changes in thyroid gland with the reproductive cycle of S. heathi. Thyroid showed marked seasonal variation in weight, quantity of colloid and follicular epithelial height, suggesting the thyroid gland to be inactive during quiescence and winter dormancy and active during the time of recrudescence and breeding similarly to the testicular cycle. Plasma thyroxin (T 4 ) concentration showed a significant seasonal change with high concentration during breeding and post-breeding and low concentration during quiescence. However, the T 4 concentration increased from breeding to post-breeding phase, when the testes weight was declining. It is suggested that in S. heathi the positive correlation between thyroid and testicular cycles occurs only during the phases of the reproductive cycle when the body weight and testicular activity are also closely correlated.Key words: Thyroid, thyroxin, testes, bat, body weight, reproduction. RESUMO Mudanças na glândula tireóide durante o ciclo reprodutivo masculino em um morcego vespertilionídeo Scotophilus heathiO objetivo do presente estudo foi comparar as mudanças na glândula tireóide com o ciclo reprodutivo de S. heathi. A tireóide mostrou variação sazonal marcada em peso, quantidade de colóide e altura do epitélio folicular, sugerindo que esta glândula está inativa durante a quiescência e o torpor de inverno e ativa durante o tempo de recrudescência e acasalamento, similarmente ao ciclo testicular. A concentração de tiroxina (T 4 ) do plasma mostrou significantes mudanças sazonais com alta concentração durante o acasalamento e pós-acasalamento e baixa concentração durante a quiescência. Entretanto, a concentração plasmática de T 4 aumentou da fase reprodutiva à pós-reprodutiva, quando o peso dos testículos estava se reduzindo. Sugere-se que, em S. heathi, a estreita correlação entre os ciclos testicular e tireóideo durante algumas fases do ciclo reprodutivo esteja relacionada à sensibilidade aumentada no período reprodutivo e à atividade metabólica.

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“…Membrane composition may influence many aspects of mitochondrial function, including enzyme activity, coupling of respiration, and susceptibility to oxidative damage (Hulbert, 1978;McMurchie et al, 1984). We analyzed lipid composition of membranes in mitochondria from MCD and SILIPHOS livers.…”

Section: Effects Of MCD Diet-induced Nash On Lipids Composition Of Hementioning

confidence: 99%

A Silybin-Phospholipid Complex Prevents Mitochondrial Dysfunction in a Rodent Model of Nonalcoholic Steatohepatitis

Serviddio

Bellanti

Giudetti

et al. 2009

J Pharmacol Exp Ther

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Mitochondrial dysfunction and oxidative stress are determinant events in the pathogenesis of nonalcoholic steatohepatitis. Silybin has shown antioxidant, anti-inflammatory, and antifibrotic effects in chronic liver disease. We aimed to study the effect of the silybin-phospholipid complex (SILIPHOS) on liver redox balance and mitochondrial function in a dietary model of nonalcoholic steatohepatitis. To accomplish this, glutathione oxidation, mitochondrial oxygen uptake, proton leak, ATP homeostasis, and H 2 O 2 production rate were evaluated in isolated liver mitochondria from rats fed a methionine-and cholinedeficient (MCD) diet and the MCD diet plus SILIPHOS for 7 and 14 weeks. Oxidative proteins, hydroxynonenal (HNE)-and malondialdehyde (MDA)-protein adducts, and mitochondrial membrane lipid composition were also measured. Treatment with SILIPHOS limited glutathione depletion and mitochondrial H 2 O 2 production. Moreover, SILIPHOS preserved mitochondrial bioenergetics and prevented mitochondrial proton leak and ATP reduction. Finally, SILIPHOS limited the formation of HNE-and MDA-protein adducts. In conclusion, SILIPHOS is effective in preventing severe oxidative stress and preserving hepatic mitochondrial bioenergetics in nonalcoholic steatohepatitis induced by the MCD diet. The modifications of mitochondrial membrane fatty acid composition induced by the MCD diet are partially prevented by SILIPHOS, conferring anti-inflammatory and antifibrotic effects. The increased vulnerability of lipid membranes to oxidative damage is limited by SILIPHOS through preserved mitochondrial function.

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The thyroid hormones A thesis concerning their action

Cited by 78 publications

References 73 publications

Environmental physiology of the teleostean thyroid gland: a review

Environmental physiology of the teleostean thyroid gland: a review

Changes in the thyroid gland during the reproductive cycle of the male vespertilionid bat, Scotophilus heathi

A Silybin-Phospholipid Complex Prevents Mitochondrial Dysfunction in a Rodent Model of Nonalcoholic Steatohepatitis

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