Thyrotropin (TSH) in the Rat Stalk-Median Eminence

Bakke, John L.; Lawrence, Nancy

doi:10.1159/000121561

Cited by 17 publications

(14 citation statements)

References 2 publications

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“…In man, a variety of stressful situations by each agent. ~~~~l hormone growth levels were not significantly (3,10,30) as well as direct inrusion or epinephrine (12) result i n a different in the two groups (1.3 * 0.2 to 2.1 + 1.0 ng/ml in normal rise in plasma glucagon concentration. However, unlike insulin subjects; 3.0 + 1.1 to 6.0 * 3.1 ng/ml in diabetics (mean + and growth hormone, where there is uniform agreement that the SEM)) but the peak growth hormone after arginine was adrenergic effects are mediated via activation of adrenergic cantly greater in the diabetic children than control subjects (34.3 * receptors which are inhibitory or stimulatory, the precise role of 7.2 versus 12.3 A 3.1); in both groups &-blockade suppressed the these receptors in modulating glucagon secretion remains uncergrowth hormone response, whereas P-blockade had no significant tain.…”

Section: Effect Of Adrenergic Blockade On Glucagon and Growth Hormonementioning

confidence: 95%

Endocrine Studies of the Untreated Progeny of Thyroidectomized Rats

et al. 1975

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ExtractExperiments were conducted to assess late and persistent endocrine changes in the progeny of rats born of and/or nursed by thyroidectomized ( T x ) dams. Forty-five female rats were radiothyroidectomized several weeks before mating with normal males, and compared with the progeny of 26 control females. In all, 248 progeny were studied when adult.T x dams had significantly reduced fertility (87% of controls), increased pup (11% versus 0) and maternal mortality (27% versus 0), and smaller litters (6.5 versus 11.8 pups/litter). It was shown that the offspring of thyroidectomized female rats had delayed eye opening (15.3 versus 14.3 days), smaller weaning (40.4 versus 54.4 g ) and adult body weights (230 versus 260 g), smaller pituitary glands (12.2 versus 14.0 mg), and enlarged thyroid glands (14.2 versus 12.4 mg). Ovarian and testicular weights were decreased (73.9 versus 83.7 mg and 3.2 versus 3.6 g, respectively). The serum thyroid stimulating hormone ( T S H ) concentrations were increased from 53.8 to 84.4 wU/ml in the males. The pituitary T S H contents were not significantly altered, and the serum T S H response to thyrotropin releasing hormone ( T R H ) was normal. These persistent effects differed from the late effects of both fetal and neonatal hypothyroidism and neonatal underfeeding. Cross-fostering experiments showed that the diminished weaning weights were the result of the pups being nursed by the hypothyroid dams. The increased nursing mortality and the pituitary and thyroidal changes were the result of prenatal influences produced by the hypothyroid dams, since being nursed by a normal foster dam did not prevent them. The persistently enlarged thyroid glands and the elevated serum T S H in the male offspring of thyroidectomized dams suggested a permanent alteration in the set point of pituitary-thyroid regulation as the consequence of maternal hypothyroidism. SpeculationIt is speculated that the intrauterine environment provided by the pregnant hypothyroid mother produces permanent alterations in endocrine regulatory mechanisms in the offspring. It is suggested that the transplacental transfer of fetal thyroxine (T,) to the hypothyroid mother places a burden on the fetal pituitary-thyroid axis that permanently alters its function in these progeny. W e have shown previously that during a critical perinatal period, T , excess or deficiency can permanently alter hypothalamo-pituitary regulatory function in the offspring.Whether or not maternal hypothyroidism can cause fetal or congenital hypothyroidism has been an enigma for many years. It has been stated that if a woman has given birth to two cretins she has an increased chance of producing a cretin in the next pregnancy (10). However, even severely hypothyroid mothers usually deliver normal infants (21), and most mothers of cretins are euthyroid throughout their pregnancy. For these reasons, it has been necessary to consider other explanations for the sporadic congenitally hypothyroid infant. Current theory proposes that genetic factors may p...

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Section: Effect Of Adrenergic Blockade On Glucagon and Growth Hormonementioning

confidence: 95%

Endocrine Studies of the Untreated Progeny of Thyroidectomized Rats

et al. 1975

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“…Pituitary hormones such as ACTH [12,17], alpha-MSH [2], growth hormone [17], prolactin [8], and luteinizing hormone (LH) [7], have also been reported to be present in the CNS. The anterior pituitary peptide, thyroidstimulating hormone (TSH), has been shown to be present in the rat median eminence at levels independent of circu lating TSH levels [1], Later the findings of extrapituitary TSH in the hypothalamus were attributed to contamination from retrograde blood flow from the anterior pituitary [16]. More recently, however, we have reported that a material extractable from selected areas of the rat and monkey brain not only cross-reacts in the TSH radioimmunoassay [15] but does not disappear from many areas of the rat brain long af ter removal of the pituitary.…”

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confidence: 99%

TSH in the Rat and Monkey Brain

et al. 1982

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Characterization of the molecular, immunological and biological properties of a thyrotropin-stimulating hormone (TSH)-like peptide in rodent brain tissue showed similarities to its pituitary counterpart. The distribution of immunoreactivity in rodent brain was determined by radioimmunoassay in both intact and hypophysectomized animals. Easily detectable but smaller quantities of immunoassayable TSH were present in formalin fixed, acetone-stored brains from Macaca mullata. No change in the level of this TSH-like peptide was observed in most rat brain parts, although the hypothalamus did show a significant drop in hormone level after removal of the pituitary. Extracts of brain containing TSH-like material restored thyroid histology to normal when administered to hypophysectomized rats. Tissue cultured neural cells from both intact and hypophysectomized rats released a TSH-like material into the medium over a 30-day time period. Sodium /-thyroxine suppressed TSH release from pituitary monolayers but did not alter TSH release from brain derived cells that were similarly cultured. Surgical thyroidectomy resulted in a striking rise in serum TSH concentrations with no alteration in the content of brain TSH.

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“…Hypothalamic tissue contains IR-TSH-like material which is biologically [2,3], immunologically [7,8,13,16], and phvsicochemically [7,8,13,22] similar to pituitary TSH. In vitro, I R-TSH is released from hypothalamic tissue by depolarizing concentrations of potassium or veratridine by a calcium-dependent mechanism [7,8].…”

Section: Discussionmentioning

confidence: 99%

“…However, subsequent studies from several labo ratories have shown that hypothalamic IR-TSH is not sim ply a reflection of plasma or pituitary IR-TSH concentra tions [2, 8, 13, 16. 22 (ME) of hypophysectomized rats [2,8,13], while neither hypothyroidism nor hyperthyroidism results in parallel changes in the concentrations of IR-TSH in the pituitary and hypothalamus [8]. More importantly, hypothalamic tis sue from 21-day hypophysectomized rats, maintained in tis sue culture for 30 days, spontaneously releases IR-TSH into the culture medium (13].…”

mentioning

confidence: 99%

Subcellular Localization of Immunoreactive Thyroid-Stimulating Hormone in the Rat Hypothalamus

DeVito¹,

Spearman²,

Connors³

et al. 1986

Neuroendocrinology

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Hypothalamic tissue contains TSH-like material which is biologically, immunologically, and physicochemically similar to pituitary TSH. Immunoreactive thyroid-stimulating hormone (IR-TSH) is released from hypothalamic tissue in vitro by depolarizing concentrations of potassium or veratridine by a calcium-dependent mechanism. In the present study, we investigated the subcellular localization of IR-TSH using equilibrium density centrifugation. Tissue homogenates from intact, hypophysectomized or thyroidectomized rats were centrifuged at 150 g at 4°C for 10 min and the supernatants were layered onto continuous sucrose gradients (1.00–1.27 g/ml) and centrifuged at 100,000 g (max) for 16 h. IR-TSH in pituitary supernatants from intact and thyroidectomized rats showed high equilibrium density peaks with a modal density around 1.2 g/ml. Fractionation of the supernatant from ventral or dorsal hypothalamic homogenates resulted in abimodal distribution of IR-TSH. In supernatants from both tissues, IR-TSH containing particles were found at the top of the gradient in a low equilibrium density peak between 1.0 and 1.08 g/ml. In addition, IR-TSH containing particles were found in ventral and dorsal hypothalamic supernatants with modal densities at 1.16 and 1.25, respectively. These high density IR-TSH particles were present in tissue taken from hypophysectomized rats, and were not appreciably affected by thyroidectomy. Homogenization of the tissue in a hypo-osmotic medium disrupted the high density IR-TSH particles resulting in a single low density peak at the top of the gradient. These data suggest that hypothalamic IR-TSH is stored in membrane bound particles which have densities similar to that of secretory granules.

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Thyrotropin (TSH) in the Rat Stalk-Median Eminence

Cited by 17 publications

References 2 publications

Endocrine Studies of the Untreated Progeny of Thyroidectomized Rats

Endocrine Studies of the Untreated Progeny of Thyroidectomized Rats

TSH in the Rat and Monkey Brain

Subcellular Localization of Immunoreactive Thyroid-Stimulating Hormone in the Rat Hypothalamus

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