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At least 649 records · Page 36Linked to original sources
PubMed1994

Neurotrophins in the developing and adult primate adenohypophysis: a new pituitary hormone system?

Expression of neurotrophins and of the low-affinity neurotrophin receptor p75 was examined immunocytochemically in pituitary glands of twelve developing and adult macaques, ranging in age from fetal day 100 through age 5 years. Neurotrophins were identified by labeling with a rabbit polyclonal antiserum raised against purified mouse nerve growth factor, which recognizes brain-derived neurotropic factor and neurotrophin-3 as well. During pituitary morphogenesis, neurotrophins were present in epithelial cells distributed throughout all divisions of the anterior pituitary (pars distalis, pars intermedia, and pars tuberalis). Near term and in the adult, neurotrophin-immunoreactive cells were fewer in number and their distribution was limited to the pars distalis and pars tuberalis. A monoclonal antibody against the human neurotrophin receptor p75 heavily labeled mesenchymal boundary structures and blood vessels in the developing gland, and several populations of glial-like cells with a presumed paracrine function (folliculostellate cells in the pars distalis, and pituicytes and tanycytes in the neural lobe and infundibulum, respectively) as well as axons innervating the portal vasculature in postnatal specimens. These complementary patterns of neurotrophin and receptor expression suggest a possible inductive role for neurotrophins in pituitary morphogenesis and in the establishment of hypothalamic neural and hormonal control of pituitary function. In the adult anterior pituitary, examined using double-label immunocytochemistry for neurotrophins and conventional anterior-pituitary hormones, neurotrophins did not colocalize with human prolactin, human adrenocorticotropic hormone, recombinant human growth hormone, or the beta subunits of human luteinizing hormone, human follicle-stimulating hormone, or human thyrotropin. Neurotrophin-containing cells therefore appear to be a distinct population, suggesting novel paracrine or endocrine functions for this family of neuropeptides.

Aging↗
PubMed2002

Adipokinin, a proopiomelanocortin-derived lipid-mobilizing anterior pituitary hormone.

Hormonal control of lipid metabolism during prolonged fasting is unclear. The involvement of the classical, lipid-mobilizing hormone from the anterior pituitary, i.e., beta-lipotropin (beta-LPH), is suspect. It and adrenocorticotropin (ACTH) are formed concurrently in the pituitary during the processing of the prohormone, proopiomelanocortin (POMC), and are secreted together. During prolonged fasting the control of metabolism requires minimal participation by ACTH and maximal lipid-mobilizing activity which is inconsistent with the present concept of ACTH and beta-LPH secretion. Hypothetically, the needed control can be satisfied by the alteration of the accepted processing of POMC so as to form beta-LPH and a new lipid-mobilizing hormone which also has modest ACTH-like activity. It is proposed that this hormone be named 'adipokinin'. An analog of this proposed hormone appears to have been isolated previously from porcine pituitaries.

Adrenocorticotropic Hormone↗
PubMed1996

Ovariectomy-induced high turnover in cortical bone is dependent on pituitary hormone in rats.

The aim of this study is to examine the interrelationship of pituitary and ovarian hormone deficiency on the regulation of bone growth and bone formation rate. 48 female rats, at 3 months of age, were divided into age-matched intact control, hypophysectomized (HX), ovariectomized (OV), and HX + OV groups. Ten rats were killed at 3 months of age as baseline controls, and the rest of the animals were killed 5 weeks after surgery. Serum levels of osteocalcin and dynamic histomorphometry on the periosteal surface of the tibial shaft and fifth lumbar vertebrae were measured to evaluate systemic and local bone turnover. Tibial and fourth lumbar vertebral bone area, bone mineral content, and bone density were measured by dual-energy X-ray absorptiometry (DXA). Our results confirmed that OV increased and HX suppressed systemic and periosteal bone formation parameters in both bone sites, OV increased and HX suppressed the gain in bone size and bone mass. When OV rats were HX, the serum levels of osteocalcin and periosteal bone formation parameters of the tibial shaft and the fifth lumbar vertebrae were, however, depressed and did not differ from that of the HX alone. DXA results show that the effect of OV on bone size and bone mass is also abolished by HX. In conclusion, we have demonstrated that OV increases tibial and lumbar vertebral bone formation and bone growth and this effect is pituitary hormone dependent.

Absorptiometry, Photon↗
PubMed2000

Combined pituitary hormone deficiency in german shepherd dogs with dwarfism.

In German shepherd dogs pituitary dwarfism is known as an autosomal recessive inherited abnormality. To investigate whether the function of cells other than the somatotropes may also be impaired in this disease, the secretory capacity of the pituitary anterior lobe (AL) cells was studied by a combined pituitary AL stimulation test with four releasing hormones (4RH test) in four male and four female German shepherd dwarfs. In addition, the morphology of the pituitary was investigated by computed tomography. The physical features of the eight German shepherd dwarfs were primarily characterized by growth retardation and stagnant development of the hair coat. The results of the 4RH test confirmed the presence of hyposomatotropism. The basal plasma TSH and prolactin concentrations were also low and did not change upon stimulation. Basal plasma concentrations of LH were relatively low and responded only slightly to suprapituitary stimulation. With respect to the plasma FSH levels there was a clear gender difference. In the males plasma FSH concentrations remained below the detection limit throughout the 4RH test, whereas in the females the basal plasma FSH levels were slightly lower and there was only a small increase following suprapituitary stimulation, compared with the values in age-matched controls. In contrast, basal and stimulated plasma ACTH concentrations did not differ between the dwarfs and the controls. Computed tomography of the pituitary fossa revealed a normal sized pituitary with cysts in five dogs, an enlarged pituitary with cysts in two dogs, and a small pituitary gland without cysts in the remaining dog. The results of this study demonstrate that German shepherd dwarfs have a combined deficiency of GH, TSH, and prolactin together with impaired release of gonadotropins, whereas ACTH secretion is preserved. The combined pituitary hormone deficiency is associated with cyst formation and pituitary hypoplasia.

Adrenocorticotropic Hormone↗
PubMed1987

Effect of hypophysectomy, adrenalectomy, pituitary hormone secretion and gastric acid secretion on neurotensin induced gastric protection against stress gastric lesions.

In previous studies we have established that intracisternal (i.c.) but not peripheral (intravenous) administration of neurotensin (NT), a brain and gastrointestinal tridecapeptide, totally prevents the development of gastric lesions produced by cold-restraint stress (CRS) with food-deprived rats. In this investigation, removal of the pituitary and adrenal gland, anterior pituitary hormone secretion and gastric acid secretion were evaluated independently as potential intermediates for NT's protective effect. NT (30 micrograms) produced a significant reduction of gastric lesions incidence and severity in intact and sham-operated controls. Adrenalectomy, but not hypophysectomy totally blocked the protective effect of i.c. NT. In addition, replacement therapy with s.c. prednisone (1 mg/kg) for 5 days following adrenalectomy did not restore the protective activity of central (i.c.) NT in adrenalectomized rats. A significant reduction of serum levels of TSH, PRL and GH following i.c. NT (30 micrograms) was observed after 2h of CRS. The gastrosecretory studies revealed that i.c. NT (30 micrograms) did not affect gastric acid secretion in pylorus ligated rats. However, blockade of peripheral (gut) cholinergic (muscarinic) receptors with i.p. atropine methylbromide (1 mg/kg) significantly raised gastric pH and reduced gastric acid concentration and output. In conclusion, the results of this study indicate that the acute protective effect of brain NT appears to be mediated, at least in part, by the sympathoadrenomedullary axis, and not by the pituitary gland or substances derived from the pituitary or by inhibition of gastric acid secretion.

Adrenalectomy↗
PubMed1981

[Effect of pituitary hormones on phosphodiesterase and adenyl cyclase activity of brain tissue in vitro].

Effects of seiwhale somatotropin (STH), its biologically active fragment 77--107, porcine corticotropin (ACTH) and seiwhale prolactin on phosphodiesterase and adenylate cyclase activity of glial cells and synaptosomes isolated from the rat brain cortex were investigated. As compared with control, ACTH increased phosphodiesterase activity of glial cells by 392%, of synaptosomes by 123%, while STH by 49 and 77%, respectively, somatotropin fragment by 455 and 74%, and prolactin by 30 and 37%, respectively. Adenylate cyclase activity was significantly changed only by ACTH and only in synaptosomes (a 50% decrease). STH, its fragment and prolactin virtually failed to alter adenylate cyclase activity. The data obtained indicate that some of pituitary hormones, primarily ACTH and STH, may play the role of neuromodulators in some brain structures by decreasing the cyclic AMP level, by activating phosphodiesterase (STH and ACTH) and inhibiting adenylate cyclase (ACTH in synaptosomes).

Adenylyl Cyclases↗
PubMed2000

Stiff-person like syndrome in a patient with multiple pituitary hormone deficiencies.

A patient with long-standing, occult pituitary insufficiency, who developed painful muscle stiffness and superimposed spasms, closely resembling stiff-person syndrome, was described. Complete resolution of neuromuscular symptoms with hormone replacement in this case, as well as in a previously reported one, led to the suggestion that a syndrome like stiff-person could represent a rare consequence of multiple pituitary hormone deficiencies.

Female↗
PubMed2002

Familial combined pituitary hormone deficiency caused by PROP-1 gene mutation. Growth patterns and MRI studies in untreated subjects.

BACKGROUND: Mutations of the prophet of PIT-1 (PROP-1), a paired-like homeodomain transcription factor which is responsible for early embryonic pituitary development, have recently been reported as a cause of combined pituitary hormone deficiency. METHODS: We describe the phenotype, long-term auxological data and MRI findings in two families with 4 affected members, all of whom have a mutation of the PROP-1 gene. GH, TSH, PRL, LH and FSH were completely deficient in all patients. RESULTS: ACTH deficiency was not diagnosed until the 3rd or 4th decades of life. Pituitary MRI showed an empty sella in 2 subjects, but unspecific tissue accumulation resembling a pituitary mass lesion in another patient. The affected boy from family II who was continuously treated with all the necessary hormones reached the familial target height. However, the 3 subjects in family I were only treated sporadically (GH treatment lasting from 1 to 3 years). CONCLUSION: Despite this insufficient therapy, final height was in the lower normal range. Longitudinal growth continued up to the age of 40 years in these subjects.

Adolescent↗
PubMed1980

Toluene-induced activation of certain hypothalamic and median eminence catecholamine nerve terminal systems of the male rat and its effects on anterior pituitary hormone secretion.

Subacute exposure to high concentrations (500--1000 ppm) of toluene vapour led to an increase of noradrenaline levels in the subependymal layer of the median eminence (SEL) and to an increase of noradrenaline turnover within the subependymal layer, the paraventricular hypothalamic nucleus and the anterior periventricular hypothalamic nucleus (PV I). Increased dopamine levels in the lateral palisade zone of the median eminence (LPZ) and increased catecholamine turnover within the medial palisade zone (MPZ) were also produced. Measurement of the anterior pituitary hormone secretion showed a significant increase of FSH and delayed increase of corticosterone secretion following toluene exposure.

Animals↗
PubMed1993

Multiple pituitary hormone deficiencies in a patient with spinocerebellar ataxia: magnetic resonance imaging and hormonal studies.

Degenerative spinocerebellar ataxia has a rare association with hypogonadotropic hypogonadism. In this report we present the results of the detailed endocrine evaluation and magnetic resonance imaging in one such patient. A 20-year-old male with progressive cerebellar ataxia, hypogonadism, and short stature was investigated. Basal testing revealed hypogonadotropic hypogonadism (LH < 5 mU/L, FSH < 5 mU/L, testosterone 2.5 nM/L). There was no rise in LH after stimulation with LHRH, peak LH level being < 5 mU/L. Insulin hypoglycemia testing was consistent with GH deficiency, with peak GH being 3.2 mU/L. On TRH stimulation, there was no significant rise in prolactin, though the TSH response was normal. Magnetic resonance imaging revealed cerebellar atrophy. The anterior pituitary was atrophic, with a height of 1.4 mm. The posterior pituitary and the pituitary stalk were normal in size and position. This patient with degenerative spinocerebellar ataxia had multiple pituitary hormone deficiencies. The results of our endocrine evaluation and MR imaging lead us to believe that these deficits may result from a lesion at the level of the pituitary gland.

Adult↗
PubMedDate not supplied

The simultaneous isolation of the human pituitary hormones. II. The luteinizing hormone.

The main purpose of the work is the isolation of luteinizing hormone (LH) from frozen human pituitaries. The procedure for the processing of the glands included the steps described by P. Roos [22] for the preparation of the follicle stimulating hormone (FSH) slightly modified and adapted to our conditions. After thawing, the pituitaries were homogenized in 0.03 N Naphosphate buffer, pH 5.7. The protein bulk containing growth hormone (GH) was separated by precipitation with saturated ammonium sulfate (v/v). The supernatant containing gonadotrophins, obtained by centrifugation, was fractionated by chromatography on DEAE cellulose, the first peak being further fractionated by column gel-filtration on Sephadex G-100 after a previous concentration by dialysis against polyvinylpyrolidone 10%. The first peak obtained by this last fractionation was considered for the time being, as pure LH. The extraction and fractionation steps were followed by disc polyacrylamide gel electrophoresis and by radioimmunoassay measurement of the LH concentration. Studies concerning the homogeneity and the biological activity of our LH preparation by comparison to the LH preparations recommended by WHO, are in progress in our laboratory.

Chromatography, DEAE-Cellulose↗
PubMed1991

Effects of exogenous monoiodotyrosine on the serum levels of anterior pituitary hormones.

Monoiodotyrosine is a tyrosine hydroxylase inhibitor. Ingestion of one gram monoiodotyrosine caused a 10,000-fold increase of serum monoiodotyrosine from basal levels of 0.69 +/- 0.20 nmol/l to a peak of 10.6 +/- 1.7 mumol/l in women and 7.1 +/- 2.3 mumol/l in men 30 min later, and the t1/2 was 45 min. Monoiodotyrosine stimulated PRL to a peak of 170 +/- 51 micrograms/l in women and 90 +/- 6 micrograms/l in men 30 min after the monoiodotyrosine peak, or 60 min after the ingestion. Other anterior pituitary hormones were unchanged. Dopamine infusion or L-dopa pretreatment attenuated the monoiodotyrosine effect. TRH exaggerated the PRL peak, and chlorpromazine did not increase but prolonged the hyperprolactinemia. These results suggest that dopamine synthesis inhibition may be the mechanism of PRL stimulation.

Adult↗
PubMed1994

Effects of ritanserin, a novel serotonin-S2 receptor antagonist, on the secretion of pituitary hormones in normal humans.

The availability of a new potent and selective serotonin-S2 antagonist, ritanserin (RIT), encouraged us to further investigate the effect of serotonin on the basal secretion of anterior pituitary hormones in normal humans. Administered in a single 30-mg dose to group 1 consisting of 10 normal women, RIT failed to affect the baseline LH, FSH, GH or TSH levels. In group 2 consisting of 20 normal subjects (ten males and ten females), the same dose of RIT decreased in parallel both ACTH and cortisol levels but only at 180 min. Group 3 consisting of 8 normal men was studied on three separate occasions seven days apart: each subject received graded doses of 10 mg, 20 mg and 30 mg RIT. The mean baseline PRL concentration at 180 min as well as the net integrated area under the hormone curve (nAUC) decreased only after the highest dose, while the baseline cortisol concentrations at 180 min as well as the corresponding nAUC values displayed a clear dose-dependent response. The findings indicated the serotonin-S2 receptors to be only partially involved in the basal secretion of ACTH in normal humans.

Adolescent↗