Topic
Hypophysectomy
About: Hypophysectomy is a research topic. Over the lifetime, 3425 publications have been published within this topic receiving 78467 citations.
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TL;DR: The main regulation of the thyroid gland involves a positive control by pituitary TSH, which is generated in these cells from plasma T4 (1, 2) as discussed by the authors.
Abstract: I. Introduction IN classical physiology, the main regulation of the thyroid gland involves a positive control by pituitary TSH. The pituitary thyrotrophs that synthesize and secrete TSH are submitted to tonic stimulation by the hypothalamic TRH and to negative feedback by T3, which is generated in these cells from plasma T4 (1, 2). The predominant role of TSH in thyroid regulation is exemplified by physiological experiments and pathological situations. Hypophysectomy, or treatment with thyroid hormones that reduces plasma TSH levels without interfering with other pituitary functions, almost abolishes thyroid function and greatly reduces the weight and cell mass of the gland. Conversely, chronic inhibition of the synthesis of thyroid hormones, and thus of their secretion, which greatly enhances TSH plasma levels, enhances thyroid growth and iodine metabolism upstream from the inhibited step. In pathology, hyperthyrotropinemia caused by pituitary adenomas induces hyperthyroidism and goiter. Hypopituitarism ...
616 citations
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TL;DR: The molecular structure of GH was not revealed until the beginning of the 1970s when the total amino acid sequence was determined and it was found that GH increased the nose-tail length in hypo...
Abstract: I. Introduction AT THE beginning of this century Aschner (1) demonstrated a relationship between a factor in the pituitary and body growth. In subsequent experiments Evans and Long (2) produced supranormal growth in intact rats with administration of bovine pituitary extracts. In the 1940s a highly purified protein was isolated from bovine pituitaries (3, 4) that produced somatic growth when administered to hypophysectomized or normal rats. This protein exhibited no or small effects on the gonads and the thyroid gland and was called GH or somatotropin. The molecular structure of GH was not revealed until the beginning of the 1970s when the total amino acid sequence of GH was determined (5, 6). As early as 1923 Dott and Fraser (7) observed a decrease in epiphyseal cartilage width in cats and dogs after hypophysectomy. Dott (8) also found that treatment with extracts from the anterior pituitary lobe partially reversed this effect. Freud and co-workers (9) found that GH increased the nose-tail length in hypo...
580 citations
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TL;DR: The activity of phenylethanolamine N- methyltransferase, the enzyme that catalyzes the N-methylation of noradrenaline to form adrenaline, falls following hypophysectomy, and can be restored by injections of adrenocorticotropic hormone (ACTH) or of dexamethasone, a potent synthetic glucOCorticoid.
536 citations
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531 citations
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TL;DR: A cDNA encoding the growth hormone (GH) receptor was cloned from rat liver and expression in liver, kidney, heart and muscle was developmentally regulated, being low at birth and rising to adult levels in 5 weeks.
477 citations