Authors:P. Van As, K. Janssens, K. Pals, B. De Groef, O. M. Onagbesan, V. Bruggeman, V. M. Darras, C. Denef and E. Decuypere
growth hormone-releasing factor (hpGRF) and thyrotropin-releasing hormone (TRH). Neuroendocrinology 39, 314-320.
Comparative stimulation of growth hormone secretion in anaesthetized chickens by human pancreatic growth hormone
Authors:P. Van As, C. Careghi, V. Bruggeman, O. M. Onagbesan, S. Van der Geyten, V. M. Darras and E. Decuypere
Harvey, S. and Baidwan, J. S. (1989): Thyrotropin-releasing hormone (TRH)-induced growth hormone secretion in fowl: binding of TRH to pituitary membranes. J. Mol. Endocrinol. 3 , 23-32.
Thyrotropin-releasing hormone (TRH
Authors:Á. Klein, Margit Kulcsár, Virág Krízsik, R. Mátics, P. Rudas, J. Török and Gy. Huszenicza
The basic patterns of thyroid hormones [thyroxine (T4) and 3,3',5-triiodothyronine (T3)] and the T4 and T3 responses induced by thyrotropin releasing hormone (TRH) are reported in captive female barn owls (Tyto alba) during the non-breeding period. The main findings of the study, conducted on a total of 10 owls, are as follow: (1) The thyroid gland of barn owl can be stimulated by the classical TRH stimulation test. (2) T3 response was much more pronounced both under cold (around 10°C) and warm (around 20°C) conditions, whereas T4 response ranged so widely that we could not point out any significant change in it. (3) Basal T3 plasma level was significantly (p = 0.036) higher in birds exposed to cold temperature, and they responded to TRH treatment with a lower plasma T3 elevation than the birds kept in a warm chamber. This pattern, however, cannot be explained by increased food intake, but is in agreement with the fact that enhanced T3 level may account for higher avUCP mRNA expression, which results in higher heat production on the cell level. From the results it is concluded that altering T3 plasma level plays a significant role in cold-induced thermoregulation.
Authors:Éva Ivanics, P. Rudas, G. Sályi and R. Glávits
In a goose flock consisting of 2300 birds of 6 months of age severe goitre was diagnosed. To the best of our knowledge this is the first report of naturally occurring goitre in geese, which is not related to the feeding of rapeseed meal. The major pathological findings included retarded growth and plumage development, significantly (300%) increased relative thyroid weight, fat accumulation in the mesenteric and abdominal region, and lipid infiltration of liver and kidney cells. Subsequent hormone analysis showed undetectable thyroxine (T4) levels and a dramatic drop in triiodothyronine (T3) plasma levels of the diseased geese. Thy- roidal histology displayed the typical signs of struma parenchymatosa. In order to get more information about the possible causes of the goitre, 10 geese from the affected farm were transferred into the laboratories of the Central Veterinary Institute. The geese were allotted into two groups. Group I received iodine supplementation for 55 days, while the other group served as sick control (Group S). Iodine treatment caused a dramatic improvement in the birds clinical condition except in plumage growth in Group I, while the clinical and main pathological signs of goitre remained unchanged or worsened in the untreated Group S. Contrary to this, the serum levels of thyroid hormones and responsiveness to thyrotropin releasing hormone (TRH) improved not only in Group I but also in Group S. Almost euthyroid biochemical parameters were found after 55 days of iodine treatment in Group I and, surprisingly, a considerable improvement (especially in serum T3 levels) occurred also in Group S. These findings confirm the diagnosis of goitre but also call attention to the fact that iodine deficiency was not the only factor eliciting the disorder. The underlying possible goitrogenic substance could not be traced down.