significantly lower TSHβ mRNA in pair fed controls at t = 48 h. Discussion It is known that profound alterations occur in the central part of the hypothalamic-pituitary-thyroid (HPT)-axis during illness. We and other researchers
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A Boelen, J Kwakkel, W M Wiersinga, and E Fliers
Patricia C Lisboa, Ellen P S Conceição, Elaine de Oliveira, and Egberto G Moura
postnatal early overnutrition (EO) programs for thyroid dysfunction, which is characterized by low T 4 and T 3 serum levels, which may, in turn, be related to the changes in the leptin-signaling pathway in hypothalamic–pituitary–thyroid (HPT) axis
E M de Vries, H C van Beeren, M T Ackermans, A Kalsbeek, E Fliers, and A Boelen
Introduction Profound changes occur in the hypothalamus–pituitary–thyroid (HPT) axis during illness and starvation. The nonthyroidal illness syndrome (NTIS) is characterized by decreased serum tri-iodothyronine (T 3 ) and thyroxine (T 4
G. T. Taylor, M. Bardgett, S. Farr, S. Womack, D. Komitowski, and J. Weiss
ABSTRACT
A paradigm using chronic social stress and multiple measures of the reproductive system were used to assess changes with ageing in the dynamics of endogenous steroid interactions. The 22- to 24-month-old male rats lived for 8 weeks in one of four types of colony, in groups of the same sex or groups of mixed sex including familiar or unfamiliar old males. Measures of endocrinology (circulating steroid levels), behaviour (exploration and sociosexual responses), physiology (body and organ weights and epididymal sperm count) and histology (adrenal and ventral prostate glands) served as markers of activation of the hypothalamic-pituitary-adrenal (HPA) or hypothalamic-pituitary-testicular (HPT) axes. Old males living under stable conditions as familiar same-sex colonies served as the comparison group. Results indicated clear chronic activation of the HPA axis in the unfamiliar all-male colonies and of the HPT axis in the familiar males from mixed-sex colonies, whereas both steroidal axes were stimulated in colonies of unfamiliar males and females. Findings from aged males under chronic stress suggested that reproductive dysfunction may be limited to situations in which activation of the HPA axis occurs without concurrent stimulation of the HPT axis. Data on steroidal interactions from mixed-sex groups suggested that (1) chronic excitation of the HPA failed to suppress function in the reproductive system of the old males, (2) their stress responses were little affected by chronic HPT activation and (3) there was no evidence for stress-induced pathology, even in the vulnerable prostate gland. The conclusion is that increased risks for urogenital pathology with long-term exposure to stress is not an inevitable outcome for ageing male rats nor, perhaps, for other social species living under conditions in which multiple endocrine systems typically undergo simultaneous activation.
Journal of Endocrinology (1993) 137, 115–122
A Boelen, J Kwakkel, DC Thijssen-Timmer, A Alkemade, E Fliers, and WM Wiersinga
During illness, major changes in thyroid hormone metabolism and regulation occur; these are collectively known as non-thyroidal illness and are characterized by decreased serum triiodothyronine (T(3)) and thyroxine (T(4)) without an increase in serum TSH. Whether alterations in the central part of the hypothalamus-pituitary-thyroid (HPT) axis precede changes in peripheral thyroid hormone metabolism instead of vice versa, or occur simultaneously, is presently unknown. We therefore studied the time-course of changes in thyroid hormone metabolism in the HPT axis of mice during acute illness induced by bacterial endotoxin (lipopolysaccharide; LPS).LPS rapidly induced interleukin-1beta mRNA expression in the hypothalamus, pituitary, thyroid and liver. This was followed by almost simultaneous changes in the pituitary (decreased expression of thyroid receptor (TR)-beta2, TSHbeta and 5'-deiodinase (D1) mRNAs), the thyroid (decreased TSH receptor mRNA) and the liver (decreased TRbeta1 and D1 mRNA). In the hypothalamus, type 2 deiodinase mRNA expression was strongly increased whereas preproTRH mRNA expression did not change after LPS. Serum T(3) and T(4) fell only after 24 h.Our results suggested almost simultaneous involvement of the whole HPT axis in the downregulation of thyroid hormone metabolism during acute illness.
FP Prince
Leydig cell development in humans, although for years described as being biphasic, with fetal and adult phases of maturation, is better considered as a triphasic developmental phenomenon. The morphological literature is summarized in this commentary. Although the majority of studies are of a qualitative nature and many questions remain as to the relative and absolute numbers of cells involved in these developmental phases, this literature is more consistent with a triphasic developmental pattern. This view of Leydig cell development is in accord with the well-known triphasic history of testosterone production, i.e. peaks at 14-18 weeks of fetal life, 2-3 months after birth, and from puberty throughout adult life. It is also significant that the neonatal phase of testosterone production is dependent upon reactivation of the hypothalamic-pituitary-testicular axis (HPT). The current interest in the functional implications of the neonatal period will be better served by considering human Leydig cell development as triphasic.
Julia N C Toews, Geoffrey L Hammond, and Victor Viau
detail below. Early postnatal development (postnatal days 1–15): androgen imprinting and HPT axis maturation Interactions between the liver and several endocrine systems are already evident during the first 2 weeks of postnatal life in rats
Michael A Hahn, Julie McDonnell, and Deborah J Marsh
elongation ( Rozenblatt-Rozen et al . 2005 , Yart et al . 2005 ). To date, over 60 mutations have been reported, both in the germline of patients with Hyperparathyroidism–Jaw Tumour (HPT–JT) syndrome ( Carpten et al . 2002 , Marsh et al . 2007 ) and
Z Zhang, P H Bisschop, E Foppen, H C van Beeren, A Kalsbeek, A Boelen, and E Fliers
. n = 8−10 per group. * P < 0.05, ** P < 0.01. Effect of T 3 administration in the PVN on HPT axis Placement of T 3 Ps in the PVN did not change Trh mRNA in the PVN or VMH region, while decreasing pituitary Tshb mRNA expression
Arturo Hernandez and M Elena Martinez
physiological response of the hypothalamic-pituitary-thyroid (HPT) axis. They also exhibited a significant reduction in testis size ( Bakke et al . 1975 ). Similar mouse models of TH administration during neonatal life have also shown a decrease in testis
