Hypothalamic-Pituitary Axis and Peripheral Tissue Responses to TRH Stimulation and Liothyronine Suppression Tests in Normal Subjects Evaluated by Current Methods

Dare, Gustavo Leopoldo Rodrigues; Castro, Margaret de; Maciel, Léa Maria Zanini

doi:10.1089/thy.2007.0237

Cited by 7 publications

(3 citation statements)

References 30 publications

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“…Black horizontal lines represent the mean value; bars denote standard error of the mean ( SEM ), and P ‐values were calculated using a Mann‐Whitney U test. The Grey box defines the reference range for prolactin peak in accordance with published literature; RR 421‐1829 mU/L, minimum to maximum …”

Section: Resultsmentioning

confidence: 99%

A novel IGSF1 mutation in a large Irish kindred highlights the need for familial screening in the IGSF1 deficiency syndrome

Roche

McGowan

Koulouri

et al. 2018

Clinical Endocrinology

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SummaryObjectiveLoss‐of‐function mutations in IGSF1 result in X‐linked central congenital hypothyroidism (CeCH), occurring in isolation or associated with additional pituitary hormone deficits. Intrafamilial penetrance is highly variable and a minority of heterozygous females are also affected. We identified and characterized a novel IGSF1 mutation and investigated its associated phenotypes in a large Irish kindred.Design, Patients and MeasurementsA novel hemizygous IGSF1 mutation was identified by direct sequencing in two brothers with CeCH, and its functional consequences were characterized in vitro. Genotype‐phenotype correlations were investigated in the wider kindred.ResultsThe mutant IGSF1 protein (c.2318T > C, p.L773P) exhibited decreased plasma membrane expression in vitro due to impaired trafficking from the endoplasmic reticulum. Ten hemizygous males and 11 heterozygous females exhibited characteristic endocrine deficits. Ireland operates a TSH‐based CH screening programme, which does not detect CeCH; therefore, genetic ascertainment preceded biochemical diagnosis of moderate CH in five of seven boys as well as their 75‐year‐old grandfather. Clinical features potentially attributable to hypothyroidism were variable; normal free T3 (FT3) and low/low normal reverse T3 (rT3) concentrations suggested that preferential deiodination of FT4 to FT3 may help maintain tissue euthyroidism in some individuals. However, neonatal jaundice, delayed speech or growth, and obesity were observed in seven subjects in whom diagnosis was delayed.ConclusionsAs observed with other IGSF1 mutations, p.L773P results in variably penetrant IGSF1 deficiency syndrome. Our observations emphasize the need for multi‐generation genetic ascertainment in affected families, especially where TSH‐based CH screening programmes may fail to detect CeCH at birth.

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Section: Resultsmentioning

confidence: 99%

A novel IGSF1 mutation in a large Irish kindred highlights the need for familial screening in the IGSF1 deficiency syndrome

Roche

McGowan

Koulouri

et al. 2018

Clinical Endocrinology

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“…Insulin was measured by radioimmunoassay using a commercial kit (DPC-MEDLAB, São Paulo, Brazil) and corticosterone was evaluated according to the method described by Elias et al (10). Thyroid hormones were measured following the method described by Dare et al (8).…”

Section: Methodsmentioning

confidence: 99%

Effect of short-term cold exposure on skeletal muscle protein breakdown in rats

Manfredi

Zanon

Garófalo

et al. 2013

Journal of Applied Physiology

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Although it is well established that carbohydrate and lipid metabolism are profoundly altered by cold stress, the effects of short-term cold exposure on protein metabolism in skeletal muscle are still poorly understood. Because cold acclimation requires that an organism adjust its metabolic flux, and muscle amino acids may be an important energy source for heat production, we hypothesize that muscle proteolysis is increased and protein synthesis is decreased under such a stress condition. Herein, cold exposure for 24 h decreased rates of protein synthesis and increased overall proteolysis in both soleus and extensor digitorum longus (EDL) muscles, but it did not affect muscle weight. An increase in proteolysis was accompanied by hyperactivity of the ubiquitin-proteasome system (UPS) in both soleus and EDL, and Ca(2+)-dependent proteolysis in EDL. Furthermore, muscles of rats exposed to cold showed increased mRNA and protein levels of atrogin-1 and muscle RING finger enzyme-1 (MuRF1). Additionally, cold stress reduced phosphorylation of Akt and Forkhead box class O1 (FoxO1), a well-known effect that increases FoxO translocation to the nucleus and leads to activation of proteolysis. Plasma insulin levels were lower, whereas catecholamines, corticosterone, and thyroid hormones were higher in cold-exposed rats compared with control rats. The present data provide the first direct evidence that short-term cold exposure for 24 h decreases rates of protein synthesis and increases the UPS and Ca(2+)-dependent proteolytic processes, and increases expression of atrogin-1 and MuRF1 in skeletal muscles of young rats. The activation of atrophy induced by acute cold stress seems to be mediated at least in part through the inactivation of Akt/FoxO signaling and activation of AMP-activated protein kinase.

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“…The efficacy of serotonin-releasing agents for the treatment of psychopathology is also modulated by 5HTTLPR as assessed by changes in peripheral prolactin levels. While an array of neuroendocrine systems, including the stress (Sobrinho, 2003), reproductive (Egli, Leeners, & Kruger, 2010), thyroid (Dare, de Castro, & Maciel, 2008) and immune axes (Grattan & Kokay, 2008), modulate prolactin release, the increase in peripheral prolactin upon administration of serotonin-releasing agents is a valid surrogate measure of serotonin release because serotonin acts to disinhibit prolactin release from dopaminergic control (Fitzgerald & Dinan, 2008) and induces the release of prolactin from the pituitary gland (Matsushita et al, 1983). Individuals with the s-variant allele show diminished prolactin response to clomipramine (Whale, Quested, Laver, Harrison, & Cowen, 2000) and fenfluramine (Reist, Mazzanti, Vu, Tran, & Goldman, 2001) administration.…”

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confidence: 99%

Estradiol and progesterone modify the effects of the serotonin reuptake transporter polymorphism on serotonergic responsivity to citalopram.

Michopoulos

Berga

Wilson

2011

Experimental and Clinical Psychopharmacology

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Individual vulnerability to psychopathologies is linked to a number of genetic polymorphisms including the serotonin transporter (5HTT) promoter polymorphic region (5HTTLPR). A single copy of the short variant (s-variant) allele of 5HTTLPR confers increased susceptibility to anxiety disorders and depression and decreased efficacy of serotonin-releasing agents in pharmacotherapy compared to the homozygous long 5HTTLPR variant (l/l). The data suggesting that the 5HTTLPR polymorphism modulates the efficacy of serotonin-releasing agents in pharmacotherapy is inconsistent. Other factors such as age, gender, and hormonal status could interact with 5HTTLPR genotype to affect individual physiological and behavioral responses to serotonin reuptake inhibitors such as citalopram. Indeed, estradiol and progesterone, the primary female steroid hormones, exert an array of effects on the serotonergic system, including 5HTT expression. The present study used ovariectomized female rhesus monkeys to determine the interaction between the 5HTTLPR polymorphism and the effects of mid-follicular levels of estradiol and luteal levels of progesterone on serotonergic responsivity to acute citalopram administration. The increase in serum prolactin, a surrogate measure of serotonin activity, following citalopram administration was significantly larger in l/l females than in s-variant females over the course of two hours during concurrent estradiol and progesterone hormone replacement only. These data suggest that ovarian function and the 5HTTLPR polymorphism interact to gate serotonergic reactivity in females, suggesting that clinicians should be aware of the ovarian status and 5HTTLPR genotype of women when considering serotonergic pharmacotherapy in women.

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Hypothalamic-Pituitary Axis and Peripheral Tissue Responses to TRH Stimulation and Liothyronine Suppression Tests in Normal Subjects Evaluated by Current Methods

Cited by 7 publications

References 30 publications

A novel IGSF1 mutation in a large Irish kindred highlights the need for familial screening in the IGSF1 deficiency syndrome

A novel IGSF1 mutation in a large Irish kindred highlights the need for familial screening in the IGSF1 deficiency syndrome

Effect of short-term cold exposure on skeletal muscle protein breakdown in rats

Estradiol and progesterone modify the effects of the serotonin reuptake transporter polymorphism on serotonergic responsivity to citalopram.

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