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Autosomal recessive deficiency of combined pituitary hormones (except ACTH) in a consanguineous Brazilian kindred.

Familial hypopituitarism represents a clinically and genetically heterogeneous disorder. In a subset of these families, defects in Pit-I, a transcription factor essential for proper pituitary development have been identified as underlying molecular cause. These patients present extreme short stature, GH, PRL and TSH deficiency but intact ACTH, LH and FSH secretion. The pituitary is usually hypoplastic. In this report we describe a consanguineous family (the parents are first cousins) with thirteen siblings. Of the ten living siblings, four (two males and two females) have panhypopituitarism with severe growth failure. They had evidence of growth hormone, prolactin and gonadotropin deficiencies and developed central hypothyroidism late in life. ACTH secretion was normal. Bone age was retarded and dual-photon bone densitometry indicated severe osteoporosis. Combined provocative tests for pituitary hormones indicated blunted responses for GH, LH, FSH and a modest rise in serum PRL and TSH. A clonidine-test failed to induce pituitary GH response. A corticotropin-releasing factor (CRF) provocative test was conducted after 6 months without the use of prednisone with a normal ACTH response after CRF in the affected sibling. Plasma IGF-I and IGF-BP3 were below normal levels. Serum E2 (females) and serum testosterone (males) levels were very low. MRI evaluation of the pituitary indicated pituitary aplasia in all subjects. The phenotype described in this kindred is different from families reported with Pit-1 mutations. However, it resembles previously published kindreds with similar clinical and biochemical findings. The relative preservation of ACTH suggests a genetic defect early in pituitary gland development.

Adolescent↗

Prolonged effects of tumor necrosis factor-alpha on anterior pituitary hormone release.

We examined the chronic (72 h) effects of 30 ng/ml recombinant murine tumor necrosis factor (TNF)-alpha on release of immunoreactive growth hormone (GH), prolactin (PRL), thyrotropin (TSH), and TSH glycosylation, as assessed by lectin binding, in cultured rat anterior pituitary cells. In cultured cells from adult female rats, TNF-alpha significantly suppressed basal and GH-releasing hormone (GRH)-stimulated GH release. TNF-alpha also suppressed basal PRL release and completely abolished the PRL response to TRH (0.1-10 nM). Whereas TNF-alpha reduced basal TSH release, it significantly enhanced the maximal TSH response to TRH. TNF-alpha did not affect the concanavalin A and lentil lectin binding of TSH accumulated in the medium during the 4-day culture, but significantly decreased the lentil lectin binding of TSH released in response to acute TRH stimulation. TNF-alpha significantly enhanced the inhibitory effect of somatostatin on stimulated PRL release, but not on GH or TSH release. Compared to cell cultures from adult female rats, in anterior pituitary cell cultures from 12-day-old rats the effects of prolonged exposure to TNF-alpha on hormone release were diminished or absent. Pituitary hormone release was unaffected by acute (3 h) exposure to TNF-alpha. These results demonstrate a direct effect of TNF-alpha on anterior pituitary hormone release, which is cell-type specific and age dependent.

Animals↗

Application of the peroxidase-antiperoxidase procedure to the localization of pituitary hormones and calcitonin in various domestic animals and human beings.

Specific cell populations in the pituitary glands of the rat, cat, pig, and human being were positive for thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). When reacted with prediluted rabbit anti-human TSH, LH, and FSH, antisera were not positive for the demonstration of these hormones in the horse, cow, or dog. Immunocytochemical staining was obtained in the horse, cow, and dog by the use of a primary antiserum against a specific beta-subunit of bovine TSH. The immunocytochemical staining of TSH, LH, FSH, adrenocorticotropic hormone, growth hormone, prolactin, and calcitonin was examined by the peroxidase-antiperoxidase method, using standard commercially available kits. All species examined had a strong positive reaction in specific pituitary cell populations for adrenocorticotropic hormone, growth hormone, and prolactin. Sections of normal thyroid gland tissue had positive staining of C cells containing calcitonin at the dilution of 1:100 of the primary antibody in the rat, horse, cow, dog, cat, pig, and human being.

Adrenocorticotropic Hormone↗

Plasma pituitary hormone responses to the synthetic enkephalin analog (FK 33-824) in normal subjects and patients with pituitary diseases.

D-Ala, Mephe, Met, enkephalin (Sandoz FK 33-824) is a stable long acting analog of methionine-enkephalin. FK 33-824 (0.5 or 1.0 mg), elicited plasma GH and PRL responses in normal subjects. In 23 patients with pituitary dwarfism, the response of plasma GH was markedly impaired, while PRL responded to a variable degree. In patients with acromegaly, there was little or no increase in GH and PRL after FK 33-824. Plasma GH increased to a variable degree after FK 33-824 in patients with hyperprolactinemia, with little change in plasma PRL. FK 33-824 decreased plasma cortisol in normal subjects and patients with pituitary disease. These results show that patients with acromegaly and hyperprolactinemia due to pituitary adenomas and patients with pituitary dwarfism do not respond well to FK 33-824, presumably because of hypothalamic or pituitary derangement.

Acromegaly↗

Effects of the H2 receptor antagonist ranitidine on anterior pituitary hormone secretion in man.

The effect of an i.v. bolus of the H2-receptor antagonist ranitidine 50, 100, 200 and 300 mg on serum levels of prolactin, TSH, GH, LH, FSH and cortisol was studied in 12 normal males. Ranitidine 200 and 300 mg significantly stimulated prolactin release without affecting any of the other hormones. Ranitidine 300 mg caused a rise in prolactin comparable to that observed following cimetidine 200 mg. The results show that ranitidine releases prolactin in man, but only when a large intravenous injection is given.

Adult↗

Differential activation of pituitary hormone genes by human Lhx3 isoforms with distinct DNA binding properties.

Lhx3 is a LIM homeodomain transcription factor essential for pituitary development and motor neuron specification in mice. We identified two isoforms of human Lhx3, hLhx3a and hLhx3b, which differ in their ability to trans-activate pituitary gene targets. These factors are identical within the LIM domains and the homeodomain, but differ in their amino-terminal sequences preceding the LIM motifs. Both isoforms are localized to the nucleus and are expressed in the adult human pituitary, but gene activation studies demonstrate characteristic functional differences. Human Lhx3a trans-activated the alpha-glycoprotein subunit promoter and a reporter construct containing a high-affinity Lhx3 binding site more effectively than the hLhx3b isoform. In addition, hLhx3a synergized with the pituitary POU domain factor, Pit-1, to strongly induce transcription of the TSHbeta-subunit gene, while hLhx3b did not. We demonstrate that the differences in gene activation properties between hLhx3a and hLhx3b correlate with their DNA binding to sites within these genes. The short hLhx3b-specific amino-terminal domain inhibits DNA binding and gene activation functions of the molecule. These data suggest that isoforms of Lhx3 may play distinct roles during development of the mammalian pituitary gland and other neuroendocrine systems.

Amino Acid Sequence↗

The effect of electric convulsion therapy on the circulating concentrations of pituitary hormones, cortisol and cyclic adenosine monophosphate.

In order to evaluate the effect of electroconvulsive therapy on the human pituitary-adrenal function, serial plasma samples were assayed for FSH, LH, TSH, HGH, ACTH, cortisol and cyclic AMP before and after nine shocks in five subjects. A prominent finding was the rapid stimulation of the ACTH-cortisol production in all subjects, while no consistent changes in FSH, LH, TSH, HGH or cyclic AMP were found.

Adrenocorticotropic Hormone↗

Pituitary hormone gene expression and secretion in human growth hormone-releasing hormone transgenic mice: focus on lactotroph function.

The human GH-releasing hormone (hGHRH) transgenic mouse has a hyperplastic anterior pituitary gland that eventually develops into an adenoma. We showed previously that the number of lactotrophs in the male hGHRH transgenic mouse is increased 2-fold, yet there is no concomitant increase in plasma levels of PRL. To further elucidate underlying changes in lactotroph function in the hGHRH transgenic mouse, the objectives of this study were to 1) examine the relative differences in PRL gene expression in transgenic mice and their siblings, 2) quantify PRL secretion at the level of the individual cell, 3) determine whether tyrosine hydroxylase gene expression and/or activity are altered in the hypothalamus of transgenic mice, and 4) assess dopamine receptor gene expression and functional sensitivity in lactotrophs of transgenic mice. Total PRL messenger RNA (mRNA) levels were increased nearly 5-fold in the hGHRH transgenic mouse, whereas the concentrations of PRL mRNA (PRL mRNA per microg total RNA) were unchanged. In contrast, total PRL contents were unchanged, whereas the concentrations of PRL (micrograms of PRL per mg total protein) were decreased 3-fold. Hypothalamic tyrosine hydroxylase steady state mRNA levels were not altered in the hGHRH transgenic mice, but hypothalamic tyrosine hydroxylase activity was increased 2-fold in transgenic mice. Dopamine D2 receptor mRNA concentrations in the anterior pituitary were increased 2.5-fold in hGHRH transgenic mice, and total pituitary D2 receptor mRNA levels were increased nearly 10-fold. Furthermore, the basal secretory capacity of lactotrophs from transgenic mice was increased significantly at the level of the single cell, and dopamine inhibited the secretion of PRL to a greater extent in hGHRH transgenic mice. Thus, although the total number of lactotrophs is increased 2-fold in hGHRH transgenic mice, the present data are consistent with the hypothesis that increased hypothalamic dopamine synthesis and release coupled with an increase in D2 dopamine receptor gene expression and functional sensitivity in the pituitary result in normal plasma levels of PRL.

Animals↗