[The actual existence of a single pituitary hormone. II. Variations in the extent of oxytocin and vasopressin activities of the pituitary of rats on growth and reproduction].
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GH, PRL, LH, FSH and TSH were measured in serum and in cerebrospinal fluid (CSF) in 16 patients with chromophobe adenomas, in 8 with acromegaly and in 18 subjects with neurological diseases without endocrine troubles. Elevated mean GH and PRL levels in serum and in CSF were found in patients with chromophobe adenomas and with acromegaly. No constant correlation was observed between serum and CSF values. The highest hormonal levels in CSF were usually observed in adenomas with suprasellar extension, but this finding was inconstant. The determination of hormonal levels in CSF does not seem to supply any reliable information about the characteristics of pituitary tumors.
The mRNA expression of pituitary prolactin (prl), growth hormone (gh), somatolactin (sl), proopiomelanocortin (pomc), and gonadotropins (gthI and gthII) was quantified by real-time PCR, in sea bass, Dicentrarchus labrax, adapted for 1 month to seawater (SW) or freshwater (FW). In addition, IGF-I (igfI) mRNA expression in liver and branchial Na+/K+ -ATPase activity were determined. L17 ribosomal protein (rpL17) and elongation factor 1alpha (ef1alpha) were validated as reference genes in real-time PCR in the experimental context. The real-time PCR assays were validated for the different hormone genes considered. Expression of pituitary pomc, gthI, gthII, gh, and liver igfI was not significantly different between FW and SW fish. Pituitary prlwas 4.5-foldhigher in FWthan in SW, whereas pituitary sl was 1.8-fold higher in SW- compared with FW-adapted fish. Gill Na+/K+ -ATPase specific activity was 2.3-fold higher in FW sea bass compared with SW fish. Plasma cortisol levels were 6.5-fold lower in SW- than in FW-adapted specimens. The results are discussed in relation to the osmoregulatory strategy of this euryhaline SW species, which displays features that do not fit present models based on salmonids and FWeuryhaline teleosts.
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Mammary tumors of line TPDMT-4, established in DDD mice, were characterized by growth during pregnancy and regression after parturition; this resulted in higher growth peaks in subsequent pregnancies in breeders and no growth in virgins. The effect of hypophysectomy on tumor growth in mice given 17beta-estradiol (E) and progesterone (P) or deoxycorticosterone acetate (DCA) was investigated. Growth of cancers occurred in E+P- and E+DCA-treated virgins, but not in cholesterol-treated virgins. Tumors did not grow to palpable sizes in cholesterol-, E+P-, and E+DCA-treated hypophysectomized virgins; this indicated that pituitary hormones were essential for tumor growth. Impalpable cholesterol-treated, 5 of 10 E+P-treated, and 3 of 6 E+DCA-treated hypophysectomized animals. The neoplasms showed ductal and tubular structures that were lined by a single layer of well-differentiated buoidal epithelium, which suggested that the tumor line might be derived from ductal cells.
As an experiment to elucidate the canine luteal function maintenance system, a PGF2alpha-analogue, fenprostalene (PGF-F), was administered 24 and 54 days after ovulation to induce luteal regression, and the responses of luteinizing hormone (LH) and prolactin (PRL), which are considered to support the canine corpus luteum, were investigated. The plasma progesterone (P(4)) level was rapidly decreased, by which the plasma PRL level was increased, but no change was observed in the plasma LH level. The decrease in the plasma P(4) level after PGF-F administration may have induced positive feedback to the superior system, and stimulated secretion of the pituitary hormones. These findings suggested that the canine corpus luteum is maintained by PRL, not by LH.
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Alkylphenols such as 4-nonylphenol (NP) are one of the wide variety of environmental chemicals reported to have estrogenic effects in both in vitro and in vivo studies. Induction of eggshell zona radiata proteins (Zrp) and vitellogenin (Vtg) mRNA and protein synthesis in the liver are widely used biomarkers for xenoestrogen exposure in fish. However, little work has been done to characterize the molecular effects of xenoestrogens on other potential target organs such as the pituitary. To evaluate pituitary effects and develop new potential biomarkers for xenoestrogens, the influences of NP and 17beta-estradiol (E2) on the mRNA levels of pituitary gonadotropic hormone (GTH) beta subunits [leutinizing hormone beta (LH beta or GTH II beta) and follicle stimulating hormone beta (FSH beta or GTH I beta)], prolactin (PRL), growth hormone (GH) and the pituitary specific transcription factor (Pit-1) were investigated in individual male and female juvenile Atlantic salmon (Salmo salar), 3 days after a single intraperitoneal (i.p.) injection. In one experiment, fish were injected with NP (125 mg/kg body weight (BW)) or E2 (5 mg/kg BW) and a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method was used to analyze LH beta and FSH beta mRNA levels. In the second experiment, fish were injected with three doses of NP (10, 50, 125 mg/kg BW) or a single dose of E2 (5 mg/kg BW) and Northern blot analysis was used to quantify LH beta, FSH beta, PRL, GH and Pit-1 mRNAs. Both NP (50 and 125 mg/kg BW) and E2 significantly induced LH beta mRNA levels (P<0.01), but only in females. The highest dose of NP (125 mg/kg BW) significantly induced Pit-1 mRNA in males (P<0.01). NP did not have significant effects on any of the other pituitary transcripts. NP induced LH beta mRNA synthesis in females by up to 6-fold and the changes appeared to correlate with the increases in hepatic Vtg and Zrp mRNA levels. The results show that LH beta mRNA assay in female juvenile salmonids may be used as a marker for pituitary effects of xenoestrogens. The data also suggest that NP may have the potential to perturb the regulation of LH beta gene expression by mimicking E2.
A male with pseudohypoparathyroidism presented with several hormonal abnormalities. He was clinically euthyroid with no palpable goiter, His serum T4, total T3, T3 Sephadex retention, and 131I uptake were normal. However, elevated basal TSH levels and exaggerated TSH responses to TRH which normalized during the administration of thyroid extract suggested reduced thyroidal reserve. Despite these finding the 131I uptake increased after exogeneous TSH, and the T3 level rose after TRH. Basal testosterone levels and response to hCG were normal however, gonadotropins were elevated and there was an exaggerated response after LRH treatment. Both LH and FSH levels were suppressed by testosterone propionate. The patient demonstrated intermittent basal hyperprolactinemia and impaired PRL responsiveness after metolopramide, chlorpromazine, and insulin administration. There was, however, an intact response to TRH. Basal PRL, TSH, and LH levels decreased after the administration of L-dopa and bromocriptine. Although the precise mechanism underlying these finding is unknown, the elevated basal levels of TSH, LH, and FSH and the exaggerated responses to their respective releasing hormones suggest the presence of partial degree of end-organ resistance to these pituitary trophic hormones. Together with the resistance to PTH, this may imply a common defect, presumably at a postreceptor level. However, hyporesponsiveness of PRL to metoclopramide and chlorpromazine and normal responsiveness to TRH suggest that an abnormality of dopamine tone also exists in pseudohypoparathyroidism.
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UNLABELLED: A 6-year old girl was examined having two years previously presented a transient Cushing's syndrome, followed by recurrent hyponatremia, attributed to inappropriate ADH secretion (SIADH). The brain MRI showed no abnormalities on repeated examinations, except for a suggestion of empty sella syndrome. During the past two years she also presented recurrent episodes of a prolonged febrile illness of unknown origin. All investigations related to infectious, autoimmune neoplastic diseases, histiocytosis-X or neurosarcoidosis were negative and the fever was characterized as central. The patient also presented episodes of tonic-clonic seizures, myoclonias and behavioral problems (alternating states of irritability, sleepiness and apathy, optic and hearing illusions and phobias) with or without hyponatremia. Her cerebrospinal fluid (CSF) examination was not indicative of encephalitis and the encephalogram (EEG) showed only slowing of background activity. At the age of 4.75 years she, started to have recurrent episodes of hypopnoea/apnoea with severe desaturation and hypercapnia, occasionally requiring intubation and ventilation. She also developed unilateral miosis corneal ulceration and bilateral ptosis (oculo-sympathetic paresis). Repeat brain MRI and CT scans of the mediastinum excluded organic causes of apnoeas and of oculo-sympathetic paresis, such as neuroblastoma or lymphoma. Furthermore, on a 24 hour electrocardiogram recording, using power spectral analysis, significantly reduced heart rate variability was observed, by comparison with age-specific normal ranges. Thus the apnoeas, ptosis, miosis and temperature instability were attributed to autonomic dysfunction. During the same period, the patient presented significant growth retardation and growth hormone (GH) deficiency was confirmed during two provocative tests (peak GH levels: 3.1 and 2.9 ng/ml (normal>10). Moreover, thyrotropin (TSH) deficiency and persistent hyperprolactinemia were detected. She was started on hGH and thyroxine. She was also put on fluid restriction and increased sodium intake for her SIADH. She was advised to use O2 administration by mask in case of apnoeas. The child died at age 6 6/12 years as a result of apnoea during sleep. IN CONCLUSION: Multiple pituitary hormonal abnormalities, together with symptoms of autonomic neuropathy (apnoeas, ptosis, miosis, tachycardia, temperature instability) and encephalopathy (seizures, myoclonias and behavioral problems) developed in a 4-year old girl. The suggested diagnoses were: 1. Neurometabolic disorder, 2. Mitochondrial disorder, 3. Post infectious autoimmune process.
Bromocriptine was used for Parkinson's disease in 15 patients for 20 weeks. Immunoreactive plasma lutrophin (LH), follitrophin (FSH), prolactin, and somatotrophin (GH, growth hormone) concentrations were analysed before and during the treatment. Plasma prolactin levels were very markedly reduced during treatment. Plasma lutrophin levels were increased significantly in female patients, but not in male patients. No changes were noticed in follitrophin levels, but plasma somatotrophin levels were reduced during treatment. No correlations were found between the degree of clinical response and changes in plasma gonadotrophin and somatotrophin. This suggests that the effects of bromocriptine on extrapyramidal and neuroendocrine dopaminergic neurones are unrelated. We suggest careful and frequent controls of neuroendocrine secretion patterns in patients with Parkinson's disease who are treated with high doses of dopamine receptor stimulators, since the response of some pituitary hormones to bromocriptine are very marked.
To clarify the role of estrogen on male pituitary function, the effects of different doses of transdermal E2 on pituitary secretion were evaluated in a man with aromatase deficiency. The study protocol was divided into the following three phases: no E2 treatment (phase 1); 25 microg transdermal E2 twice weekly for 9 months (phase 2);12.5 microg transdermal E2 twice weekly for 9 months (phase 3). Pituitary function was studied in detail during each phase of the study protocol by measuring hormone levels in basal conditions and after dynamic testing (GnRH, insulin tolerance test, GHRH plus arginine, TRH, and corticotropin-releasing factor; tests). Basal and GnRH-stimulated gonadotropin levels resulted inversely related to E2 serum levels, according to the dosage of estrogen administered. Basal and stimulated GH, PRL, and TSH serum levels did not change during the protocol study. The secretory pituitary reserve of GH was clearly impaired. Basal and stimulated ACTH and cortisol serum levels were not modified by estrogen administration. This study demonstrated that in the human male E2 is required at pituitary level for normal functioning of gonadotropin feedback both in basal and stimulated conditions. In this patient GH deficiency seems to be an adult-onset event since he reached a tall stature. However, the finding of a severe impairment in GH response to potent provocative stimuli together with the insensitivity of GH/IGF-I axis to circulating estrogens strongly suggest a possible involvement of estrogens on both the development and maturation of the somatotrophic axis. Finally, the congenital lack of estrogen activity seems to be associated with a slightly impaired secretion of PRL and TSH, suggesting a possible role of estrogens on the pituitary secretion of these hormones in the human male.
Placental peptides, such as human chorionic gonadotropin (hCG) and human placental lactogen (hPL), which have marked homologies to pituitary peptides, were described in the early part of this century. Recently, the presence in placenta of additional peptides previously demonstrated as occurring in other tissues, such as brain and pituitary, has been reported. Their presence in placenta has been attributed to similar embryological origin of the tissues which share these peptides, although this has by no means been proven. Placental concentrations of these recently described peptides are several orders of magnitude lower than described for their original sites of production. In many instances, definitive characterization of structural identity with their extraplacental counterparts has not been performed, but has been based on indirect evidence obtained by immunoassay or immunocytochemistry. Evidence of placental synthesis has been obtained for hCG, hPL, and pro-opiomelanocortin (the precursor molecule for adrenocorticotropic hormone (ACTH), B-lipotropin (B-LPH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin, and other thus far uncharacterized peptides). Possible functions for the recently described peptides might include actions on the maternal or fetal systems or local (paracrine) actins affecting other placental constituents, although to date no definitive physiological roles have been demonstrated.
Interferons (IFNs) are now in use worldwide for the treatment of chronic viral hepatitis. Unfortunately, various side effects of IFNs have been reported. Because cytokines, which include IFNs, can affect endocrine function, endocrinological abnormalities are sometimes observed in patients treated with IFNs. We examined the effects of IFN-beta on peripheral levels of pituitary and adrenal hormones and cytokines. Six million international units of IFN-beta dissolved in glucose solution was injected for 30 min. As a control study, glucose solution without IFN-beta was injected. Pituitary hormones (ACTH, GH, TSH, prolactin (PRL), LH, FSH, and arginine-vasopressin (AVP)), cortisol, and cytokines such as interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF), and interleukin-1 receptor antagonist (IL-1ra) were measured before and after IFN-beta injection. The study was carried out on 14 patients with chronic hepatitis type C who were under treatment with IFN-beta. All studies were performed when the patients were afebrile. None of the patients had any endocrine or autoimmune diseases. Plasma ACTH levels increased significantly at 60-120 min after IFN-beta injection compared with the levels before IFN-beta injection and in the control study using glucose injection. Plasma cortisol levels increased after IFN-beta injection, in parallel with plasma ACTH elevation. Serum GH levels increased significantly at 120 min after IFN-beta injection. All the increased hormones including ACTH, cortisol, and GH, were decreased at the end of the study-180 min after IFN-beta injection. Serum levels of TSH, PRL, LH, FSH, and AVP were not changed significantly by IFN-beta injection. Plasma IL-1 and TNF levels did not change after IFN-beta injection, while IL-6 and IL-1ra were elevated significantly. The increases in IL-6 and IL-1ra were gradual, reaching their peak levels at 180 min after IFN-beta injection. However there were no correlations between the hormones measured in this study and the levels of IL-6 or IL-1ra. It would seem that IFN-beta has direct or indirect stimulatory effects for ACTH and GH without mediation of the cytokines. These in vivo results are important for investigating the relationship between endocrine and cytokine systems in humans.