The effect of propylthiouracyl-induced low thyroid function on secretion response and action of insulin in sheep

Achmadi, Joelal; Terashima, Yoshiaki

doi:10.1016/0739-7240(94)00017-u

Cited by 17 publications

(7 citation statements)

References 23 publications

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“…62,63 PTU has been used in people to treat hyperthyroidism 62 and also has been used in a variety of species, including rats, mice, hamsters, gerbils, sheep, and cattle, to produce hypothyroidism experimentally. [64][65][66][67][68][69][70][71] The degree of thyroid inhibition in those species is dose related and reversible. The dosage of PTU used in this study was selected after a pilot study showed that this dosage produced hypothyroidism after 5 weeks of administration, whereas 2 mg/kg/d did not (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Thyroid-Stimulating Hormone in Adult Euthyroid and Hypothyroid Horses

Breuhaus

2002

J Vet Int Med

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The purpose of this study was to validate a thyroid-stimulating hormone (TSH) assay in a model of equine hypothyroidism. Thyrotropin-releasing hormone (TRH) stimulation tests were performed in 12 healthy adult mares and geldings, aged 4 to greater than 20 years. before and during administration of the antithyroid drug propylthiouracil (PTU) for 6 weeks. Serum concentrations of equine TSH, total and free thyroxine (T4), and total and free triiodothyronine (T3) were measured. Before PTU administration, mean +/- standard deviation baseline concentrations of TSH were 0.40 +/- 0.29 ng/mL. TSH increased in response to TRH, reaching a peak concentration of 0.78 +/- 0.28 ng/mL at 45 minutes. Total and free T4 increased from 12.9 +/- 5.6 nmol/L and 12.2 +/- 3.5 pmol/L to 36.8 +/- 11.4 nmol/L and 23.1 +/- 5.9 pmol/L, respectively, peaking at 4-6 hours. Total and free T3 increased from 0.99 +/- 0.51 nmol/L and 2.07 +/- 1.14 pmol/L to 2.23 +/- 0.60 nmol/l and 5.78 +/- 1.94 pmol/L, respectively, peaking at 2-4 hours. Weekly measurements of baseline TSH and thyroid hormones during PTU administration showed that total and free T, concentrations fell abruptly and remained low throughout PTU administration. Total and free T4 concentrations did not decrease dramatically until weeks 5 and 4 of PTU administration, respectively. A steady increase in TSH concentration occurred throughout PTU administration, with TSH becoming markedly increased by weeks 5 and 6 (1.46 +/- 0.94 ng/mL at 6 weeks). During weeks 5 and 6 of PTU administration, TSH response to TRH was exaggerated, and thyroid hormone response was blunted. Results of this study show that measurement of equine TSH in conjunction with thyroid hormone measurement differentiated normal and hypothyroid horses in this model of equine hypothyroidism.

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Section: Discussionmentioning

confidence: 99%

Thyroid-Stimulating Hormone in Adult Euthyroid and Hypothyroid Horses

Breuhaus

2002

J Vet Int Med

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“…According to Achmadi and Terashima (1995), the reduction in serum concentration of T 3 can decrease the secretion of insulin in sheep. The reduced concentrations of thyroid hormones, in association with a low concentration of insulin during lactation, promote the mammary gland's preferential utilization of the substrates (Gueorguiev, 1999).…”

Section: Discussionmentioning

confidence: 99%

Serum concentration of thyroid hormones in crioula lanada serrana ewes in gestation and lactation

Colodel

Martins

et al. 2010

Arch. zootec.

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SUMMARYThe effects of gestation and lactation on the dynamics of the thyroid hormones, triiodothyronine (T 3 ) and thyroxine (T 4 ) were evaluated in Crioula Lanada Serrana ewes from the plateau region in Santa Catarina -Brazil. To evaluate the effects of gestation, twenty four ewes were randomly divided into groups I and II. Group I was composed of 12 pregnant ewes and the control group (II) was composed of 12 non-pregnant ewes. The effects of lactation were evaluated in the same ewes of group I after parturition (LE) and in the control group (NL). Blood samples were taken in the first, second and third periods of gestation, at parturition, and at 30, 60 and 90 days of lactation. T 3 and T 4 concentrations were determined by radioimmunoassay (RIA). Pregnant ewes showed lower serum concentrations of T 3 and T 4 than those of non-pregnant ewes. At parturition, there was no significant difference in T 3 concentrations between groups I and II (p>0.05). During lactation, serum T 3 concentrations were lower (p≤0.05) in LE than in NL ewes. Serum T 3 concentrations were greater (p≤0.05) at lambing than during the lactation periods. Serum T 4 concentrations in LE at parturition did not differ (p>0.05) from those of NL ewes. During lactation, T 4 concentrations of LE were lower (p≤0.05) than those of the NL ewes. The results of this study have shown that gestation causes a variation in the T 3 and T 4 serum concentrations, and that lactation results in a decrease of serum concentrations of T 3 and T 4 in Crioula Lanada Serrana ewes. RESUMOOs efeitos da gestação e lactação sobre a dinâmica dos hormônios tireoidianos triiodotironina (T 3 ) e tiroxina (T 4 ) foram avaliados em ovelhas Crioula Lanada Serrana na região do Planalto Serrano Catarinense. Para avaliar os efeitos da gestação, foram utilizadas vinte e quatro ovelhas distribuídas aleatoriamente em dois grupos. O grupo I foi formado por 12 ovelhas gestantes e o grupo controle por 12 ovelhas não gestantes (grupo II). Os efeitos da lactação foram avaliados nas mesmas ovelhas do grupo I após a parição (LE) e no grupo controle (NL). Foram colhidas amostras sanguíneas no primeiro, segundo e terceiro terço da gestação, ao parto e aos 30, 60 e 90 dias de lactação. As concentrações de T 3 e T 4 foram determinadas por radioimunoensaio (RIA). As ovelhas gestantes apresentaram concentrações séricas de T 3 e T 4 inferiores àquelas não gestantes. Ao parto não houve diferença significativa nas concentrações de T 3 entre os grupos I e II (p>0,05). Durante a lactação as concentrações Archivos de zootecnia vol. 59, núm. 228, p. 510

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“…T 3 concentrations are higher in spring and early summer and lowest in late summer and early autumn (Rhind & McMillen, 1995;Rhind et al 1998Rhind et al , 2000. A reduction in T 3 concentrations in ruminants can induce an increase in insulin secretion and a reduction in the rate of degradation (Achmadi & Terashima, 1995). This may increase insulin concentrations in the hepatic-portal vein, into which the insulin is secreted (Harmon, 1992), without necessarily altering concentrations in the peripheral circulation where portal blood is significantly diluted.…”

Section: Are There Indirect Hormonal Effects On the Brain?mentioning

confidence: 99%

Seasonality of food intake in ruminants: recent developments in understanding

Rhind¹,

Archer²,

Adam³

2002

NRR

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Domestic ruminants are used to exploit many vegetation resources that would otherwise be unproductive. For maximal effectiveness, there is a need to understand underlying mechanisms controlling animal performance, including seasonal variations in appetite and food intake. Potentially useful experimental approaches, recent findings and aspects for future study are discussed. Seasonal variation in intake is expressed through changes in the pattern of meals (duration, frequency, inter-meal interval and ingestion rate). These changes are signalled through alterations in both structure and function of the gastrointestinal tract and physiological signals. Studies suggest that multiple, interactive signals are involved, including hormones such as cholecystokinin, insulin, leptin and triiodothyronine. However, baseline concentrations in the peripheral circulation are not appropriate measurements of some of these hormones since there can be seasonal differences in postprandial profiles or changes in rate of dilution in the bloodstream or in the rate of degradation in the liver. Interactions between these circulating signals, liver function and neural signals to the brain need clarification. Systemic nutritional signals also act directly in the brain where they are integrated with seasonal photoperiod (melatonin) signalling within the hypothalamus. Melatonin target sites critical to appetite regulation have still to be identified, but leptin receptors and downstream neuropeptides have been localised within the ovine hypothalamus. These orexigenic and anorexigenic 'compensatory' pathways are sensitive to imposed changes in nutritional status but, with the exception perhaps of cocaine-and amphetamine-regulated transcript, do not appear to drive seasonal 'anticipatory' changes in intake. Mechanisms underlying seasonal changes in hypothalamic sensitivity to nutritional feedback clearly deserve further study.

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The effect of propylthiouracyl-induced low thyroid function on secretion response and action of insulin in sheep

Cited by 17 publications

References 23 publications

Thyroid-Stimulating Hormone in Adult Euthyroid and Hypothyroid Horses

Thyroid-Stimulating Hormone in Adult Euthyroid and Hypothyroid Horses

Serum concentration of thyroid hormones in crioula lanada serrana ewes in gestation and lactation

Seasonality of food intake in ruminants: recent developments in understanding

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