Faculty Opinions recommendation of Critical role of the hypothalamic-pituitary-thyroid axis in bone.

AbstractThyroid hormone (TH) regulation is important for development, energy homeostasis, heart function, and bone formation. To control the effects of TH in target organs, the hypothalamus-pituitary-thyroid (HPT) axis and the tissue-specific availability of TH are highly regulated by negative feedback. To exert a central feedback, TH must enter the brain via specific transport mechanisms and cross the blood-brain barrier. Here, tanycytes, which are located in the ventral walls of the 3rd ventricle in the mediobasal hypothalamus (MBH), function as gatekeepers. Tanycytes are able to transport, sense, and modify the release of hormones of the HPT axis and are involved in feedback regulation. In this review, we focus on the relevance of tanycytes in thyrotropin-releasing hormone (TRH) release and review available genetic tools to investigate the physiological functions of these cells.

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The Hypothalamic-Pituitary Thyroid Axis : Studies on the Regulatory Role of Thyrotropin Releasing Hormone (TRH)

Folia Endocrinologica Japonica ◽

10.1507/endocrine1927.52.9_908 ◽

1976 ◽

Vol 52 (9) ◽

pp. 908-925

Author(s):

Yoshifumi HIROOKA

Keyword(s):

Thyrotropin Releasing Hormone ◽

Regulatory Role ◽

Releasing Hormone ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

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Dominant Role of Thyrotropin-releasing Hormone in the Hypothalamic-Pituitary-Thyroid Axis

Journal of Biological Chemistry ◽

10.1074/jbc.m511530200 ◽

2005 ◽

Vol 281 (8) ◽

pp. 5000-5007 ◽

Cited By ~ 67

Author(s):

Amisra A. Nikrodhanond ◽

Tania M. Ortiga-Carvalho ◽

Nobuyuki Shibusawa ◽

Koshi Hashimoto ◽

Xiao Hui Liao ◽

...

Keyword(s):

Dominant Role ◽

Thyrotropin Releasing Hormone ◽

Releasing Hormone ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

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The role of leptin in the regulation of TSH secretion in the fed state: in vivo and in vitro studies

Journal of Endocrinology ◽

10.1677/joe.0.1740121 ◽

2002 ◽

Vol 174 (1) ◽

pp. 121-125 ◽

Cited By ~ 78

Author(s):

TM Ortiga-Carvalho ◽

KJ Oliveira ◽

BA Soares ◽

CC Pazos-Moura

Keyword(s):

Fold Increase ◽

Adult Rats ◽

Fed State ◽

Rat Pituitary ◽

Pituitary Thyroid Axis ◽

Tsh Secretion ◽

Thyroid Axis

Leptin has been shown to stimulate the hypothalamus-pituitary-thyroid axis in fasting rodents; however, its role in thyroid axis regulation under physiological conditions is still under investigation. Here it was investigated in freely fed rats whether leptin modulates thyrotroph function in vivo and whether leptin has direct pituitary effects on TSH release. Since leptin is produced in the pituitary, the possibility was also investigated that leptin may be a local regulator of TSH release. TSH was measured by specific RIA. Freely fed adult rats 2 h after being injected with a single s.c. injection of 8 microg leptin/100 g body weight showed a 2-fold increase in serum TSH (P<0.05). Hemi-pituitary explants incubated with 10(-9) and 10(-7) M leptin for 2 h showed a reduced TSH release of 40 and 50% respectively (P<0.05). Conversely, incubation of hemi-pituitary explants with antiserum against leptin, aiming to block the action of locally produced leptin, resulted in higher TSH release (45%, P<0.05). In conclusion, also in the fed state, leptin has an acute stimulatory effect on TSH release in vivo, acting probably at the hypothalamus. However, the direct pituitary effect of leptin is inhibitory and data also provide evidence that in the rat pituitary leptin may act as an autocrine/paracrine inhibitor of TSH release.

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Studies on the Physiological Role of Hypothalamic TRH on the Negative Feedback Mechanism of the Pituitary-Thyroid Axis

Folia Endocrinologica Japonica ◽

10.1507/endocrine1927.55.6_776 ◽

1979 ◽

Vol 55 (6) ◽

pp. 776-786

Author(s):

Masatomo MORI ◽

Kihachi OHSHIMA ◽

Sakae MARUTA ◽

Hitoshi FUKUDA ◽

Yohnosuke SHIMOMURA ◽

...

Keyword(s):

Negative Feedback ◽

Physiological Role ◽

Feedback Mechanism ◽

Negative Feedback Mechanism ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

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Role of the Orexin System on the Hypothalamus-Pituitary-Thyroid Axis

Frontiers in Neural Circuits ◽

10.3389/fncir.2016.00066 ◽

2016 ◽

Vol 10 ◽

Cited By ~ 17

Author(s):

Antonietta Messina ◽

Carolina De Fusco ◽

Vincenzo Monda ◽

Maria Esposito ◽

Fiorenzo Moscatelli ◽

...

Keyword(s):

Pituitary Thyroid Axis ◽

Thyroid Axis

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Biological aspects of social phobia

Acta Neuropsychiatrica ◽

10.1017/s0924270800036978 ◽

1996 ◽

Vol 8 (4) ◽

pp. 87-89

Author(s):

I.M. van Vliet

Keyword(s):

Panic Disorder ◽

Social Phobia ◽

Metabolic Activity ◽

General Anxiety ◽

Pituitary Thyroid Axis ◽

Thyroid Axis ◽

Challenge Tests ◽

Biological Aspects ◽

Pituitary Adrenal Axis

SummaryIn contrast to the research in panic disorder, not much neurobiological studies have been conducted in social phobia. In challenge-tests using lactate or pentagastrin general anxiety and anxiety symptoms were induced in social phobies, although not as frequent is in panic disorder patients, but no specific social phobic anxiety was induced. The role of neurotransmitters such as serotonin, dopamine and noradrenalin is, as yet, unclear. There are no indications for abnormal hypothalamic-pituitary-adrenal-axis activity or abnormal hypothalamic-pituitary-thyroid-axis activity in social phobia. To the present, preliminary findings in neuroimaging studies show no differences between patients and controls, except a possibly diminished and reversible metabolic activity.

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