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SUMMARY
The use of the resting plasma cortisol level, the diurnal plasma cortisol rhythm and plasma cortisol response to a maximal adrenocorticotrophic hormone (ACTH) infusion or insulin-induced hypoglycaemia as indirect tests of hypothalamo—pituitary—adrenocortical function was examined in a group of 27 patients with pituitary disease. While the first three tests provided similar information about hypothalamo—pituitary—adrenocortical function, the plasma cortisol response to insulin-induced hypoglycaemia did not provide further clinically useful information. Difficulties in interpretation of dynamic tests of hypothalamo—pituitary—adrenocortical function are discussed.
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The distribution of specifically stained corticotrophic cells has been studied in the pituitary glands of 11 dogs with pituitary-dependent hyperadrenocorticism. The results suggest that the disease is not a single entity, and that some cases are caused by primary abnormality of the pituitary gland whereas others appear to be the result of dysfunction of the hypothalamus or central nervous system.
The patterns correspond closely to those demonstrated in the human pituitary gland in Cushing's disease, and confirm that the canine disease is a useful model for the study of the pathogenesis of the variants of the condition.
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, Ahima & Antwi 2008 ). In addition, leptin modulates the activity of several neuroendocrine axes, including the hypothalamus–pituitary–thyroid (HPT) axis. Similar to leptin, thyroid hormones (THs) are essential for the maintenance of basal metabolism and
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It is generally believed that the activity of the sebaceous glands depends to a large extent on the gonads. The pituitary also appears to be involved in the physiology of these glands (Ebling, Ebling & Skinner, 1969; Nikkari & Valavaara, 1969; Thody & Shuster, 1970). The relationship between the pituitary and the sebaceous glands may be exerted via growth hormone and prolactin for Ebling et al. (1969) have shown that these pituitary hormones facilitate the effect of testosterone on sebum secretion. This present study was carried out to see whether the pituitary influence on sebum secretion is also mediated through the thyroid and adrenal glands.
The rate of sebum secretion was measured (Archibald & Shuster, 1969) in 12- to 15-week-old rats which had received one of the following treatments: castration, castration and adrenalectomy, castration and thyroidectomy, castration and hypophysectomy, or no treatment (intact controls). Castration was carried out when the
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A complete inventory of pituitary trophic responses depends on precise estimates of mitotic activity and apoptotic events, and accurate characterization and quantification of pituitary cell subtypes irrespective of previous and current physiological demand. For a discrete structure that has been so extensively studied, it is disappointing but perhaps not surprising that none of these measures is available and therefore that the relative contributions to changes in the proportions of pituitary cellular subpopulations of trophic activity, differentiation of pluripotent cells and variations in the secretory profiles of apparently committed cells remain almost impossible to determine. To fully appreciate the extent of this dilemma, it should be remembered that conservative estimates of the proportion of corticotrophs in the rat anterior pituitary under basal conditions vary over twofold and that it is still not clear whether the apparent threefold increase in mammotrophs during pregnancy is the result of maturation of uncommitted cells, transdifferentiation of other cells such as somatotrophs, cell division, or a mixture of all three. Equally, while it has been known for some time that adrenalectomy results in a transient increase in anterior pituitary mitotic activity and appropriately timed supraphysiological glucocorticoid replacement with a wave of apoptosis, the precise identity of the cells involved in both of these responses is open to question. Thus, although many of the physiological stimuli associated with apparent changes in the proportions of pituitary cellular subpopulations are known, the precise mechanism of the changes and the consequences of the same remain obscure. This review summarizes the limited literature on pituitary trophic activity and asks what, if anything, analysis of pituitary trophic activity using current technology can tell us.
Department of Clinical and Experimental Endocrinology, University of Göttingen, 37075 Göttingen, Germany
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Department of Clinical and Experimental Endocrinology, University of Göttingen, 37075 Göttingen, Germany
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Department of Clinical and Experimental Endocrinology, University of Göttingen, 37075 Göttingen, Germany
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Department of Clinical and Experimental Endocrinology, University of Göttingen, 37075 Göttingen, Germany
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pituitary luteinizing hormone (LH) secretion and diminishing or ceasing hot flushes. Thus, the negative feedback action of E2 or substances with estrogenic activity on LH secretion can be used as an indirect measure of the potency to ameliorate hot flush
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Introduction Pituitary tumor-transforming gene 1 ( PTTG1 ) is an oncogene that is overexpressed in pituitary tumors and other neoplasms ( Zhang et al. 1999 , Yu & Melmed 2001 , 2004 ). Human PTTG1 is identified as securin, a
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function of the hypothalamus–pituitary–thyroid axis (HPT) is no exception ( Figs 1 and 2 ). Since the end of the 19th century, European physicians and surgeons associated neck swelling (thyroid enlargement, goiter), with iodine deficiency, cretinism, and
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ABSTRACT
Specific hybridization of polyadenylated RNA, extracted from rat, rabbit and human pituitary glands with a 638 bp rabbit GH receptor (rGHR) cRNA was demonstrated by Northern analysis. In-situ hybridization of tissue sections with the probe demonstrated the localization of rGHR mRNA throughout the rat pituitary gland and its presence in the anterior lobe of the rabbit pituitary. Growth hormone binding sites on pituitary membranes were not, however, demonstrated by radioligand binding studies. Thus, although the GH receptor gene is expressed in pituitary tissue, functional GH receptors may not be inserted into pituitary plasma membranes.
