Immunolocalization and in situ hybridization analysis of steroidogenic enzymes demonstrated the localization of steroidogenesis in the adrenal cortex and its disorders. The findings obtained provided new insights into adrenocortical hormonal metabolism, especially through establishing endocrine-pathological correlation.
Recent advances in ET research on the cardiovascular and endocrine systems were reviewed. Considering the potent vasculotropic actions, strategically advantageous localization, and recent findings with the specific receptor antagonist, ET is Table 2. Effects of dehydration for 2 days on hematocrit, serum osmolarity, plasma levels of it-VP, plasma and neurohypophyseal levels of it-ET-1, density of NSG, and density of it-ET-1 in NSG potentially involved in the regulation of hemodynamic homeostasis and in the pathogenesis of essential and secondary hypertension. The mitogenic action on the vascular smooth muscle cells suggests its more chronic effect on the vascular structure. In addition to the hypertensinogenic aspects, the role of ET in maintaining blood pressure in a hypotensive condition should not be overlooked. The development of specific antagonists which block the action of locally operating ET in vivo will be a powerful tool in elucidating the pathophysiological significance of ET and will provide a new therapeutic approach for hypertension. The roles of ET in the endocrine system are also fascinating. Accumulating evidence supports the notion that ET modulates the secretion of pituitary and adrenal hormones. The mode of action is likely to be paracrine/autocrine rather than endocrine, although a possible role of circulating ET cannot be ruled out. The pathophysiological role of ET in the endocrine tissues remains to be clarified. The diversity of the action of ET on the blood pressure and endocrine functions provides further evidence of the complexity of the homeostatic mechanisms, leaving us an intriguing subject for future study.
The signal transduction system acts either monodirectionally (synergistically) or bidirectionally (antagonistically) in different tissues. We activated the signal transduction system in BeWo human choriocarcinoma cells and studied the effects on human chorionic gonadotropin (hCG) secretion, cell proliferation, and DNA synthesis. Protein phosphorylation in the cytosolic fraction was also studied by two-dimensional polyacrylamide gel electrophoresis. When phorbol 12-myristate 13-acetate (PMA) was added to cultures, hCG secretion was increased dose-dependently, but cell proliferation and 3H-thymidine uptake were not affected. When only cholera toxin was added, hCG secretion was also stimulated dose-dependently, but when both PMA and cholera toxin were added there was a synergistic potentiation of hCG production. In contrast, Ca ionophore A23187 had almost no effect on hCG secretion. Two-dimensional gel electrophoresis and autoradiography showed that phosphorylation of a 33kd acidic protein was produced by cholera toxin, while phosphorylation of a 45kd acidic protein and dephosphorylation of a 14kd acidic protein were caused by the phorbol ester. These proteins may be specific substrates of protein kinase A and protein kinase C, respectively, in BeWo cells.
Thyroid hormone plays an important role in growth hormone (GH) synthesis and secretion. To study the relationship between thyroid function and urinary GH secretion in the hyperthyroid and hypothyroid states, we measured thyroid hormones, simultaneously with serum and urinary GH levels, in 54 patients with thyroid diseases. GH-releasing hormone (GRH) test was performed in 18 patients in order to evaluate serum and urinary GH responses to GRH in hyper- and hypothyroid states. Serum thyroid hormone levels were strongly correlated with the urinary GH levels in the patients, and the correlation was greater than that between serum thyroid hormone and serum GH levels. Urinary GH levels were significantly higher in the hyperthyroid patients than in the euthyroid and hypothyroid patients, although serum GH levels were not significantly different among these three groups. Serum GH response to GRH was significantly decreased in hyperthyroid patients as compared to euthyroid patients. However, urinary GH levels after GRH administration were not decreased in the hyperthyroid patients. These results suggest that hyperthyroid states increase GH in urine and may accelerate the urinary clearance of GH.
A chimeric gene comprising murine whey acidic protein (mWAP) and human growth hormone (hGH) was used to produce transgenic rats that express hGH and secrete it into the blood. Two lines of transgenic rats carrying the mWAP/hGH construct were established: Line 1 was characterized by relatively high levels of serum hGH, and Line 2 had relatively low levels. The secretory profiles of rat GH (rGH) as well as hGH, the transgene product, were obtained in transgenic males and females of Line 2; both hGH and rGH serum levels were flattened with no episodic fluctuations, and the overall mean concentration of rGH was significantly lower than in normal littermates. Although the animals of Line 1 showed an accelerated increase in growth rate, those of Line 2 did not. Nevertheless, the onset of puberty in females, as assessed by vaginal opening and occurrence of first ovulation, advanced by 7-8 days in both Lines of animals. Accordingly, the body weight at puberty of Line 2 transgenic females was much lower than that of normal littermates, indicating that continuous hGH expression could induce precocious puberty without enhancing the growth rate.
The presence of hypopituitarism and invisible pituitary stalk on a magnetic resonance image (MRI) is commonly attributed to birth trauma. Two patients with severe hypopituitarism and invisible pituitary stalk are presented. One was born by breech delivery, the other by Cesarean section. The presence of a micropenis since early infancy in these two patients suggested that their hypopituitarism might have begun during early fetal life thus effecting penile growth during the second and third triministers of gestation. These findings raise the possibility that the association of hypopituitarism and invisible pituitary stalk may have multiple etiologies including hormonal abnormalities during early fetal life.
The pituitary function of patients with Rathke's cleft cyst before and after surgery was investigated to clarify the significance of surgery and operative indications. The authors have treated 19 patients with Rathke's cleft cyst. There were panhypopituitarism in 2 patients (11%), amenorrhea and/or galactorrhea in 3 (16%), diabetes insipidus in 4 (21%), and visual disturbance in 9 (47%). All the patients underwent systematic endocrinological examination and were found to have various degrees of pituitary dysfunction. Panhypopituitarism was endocrinologically confirmed in 2 patients. Hyperprolactinemia was observed in 4. These patients underwent aspiration of the cyst contents and biopsy of the cyst wall. Postoperative follow-up endocrinologic evaluation performed more than 3 months after surgery showed improvement in pituitary function in 9 out of 13 patients (69%). Amenorrhea and/or galactorrhea recovered or improved in 100% of patients and visual disturbance improved in 89%. However, diabetes insipidus and panhypopituitarism did not improve postoperatively, in any patient. The results of the present study indicate that the incidence of pituitary dysfunction in patients with Rathke's cleft cyst is higher than suspected and in most cases surgical intervention improves pituitary function and the clinical status of the patient. Therefore, surgical treatment is recommended even when the patient has only mild symptoms or signs, including pituitary dysfunction, to prevent irreversible panhypopituitarism.
We investigated the serum concentration of IGF-II in patients with thyroid diseases (25 with untreated Graves' patients, 30 with hypothyroidism, 23 with thyroid adenoma) and in 72 healthy adults as normal controls, by a sensitive radioimmunoassay of serum IGF-II. Thyroid hormones are known to increase IGF-I production in the liver through the enhancement of GH secretion. In case of IGF-II, however, knowledge has been rather limited. The mean ±SD concentration in healthy subjects was 556 ±94μg/L with neither sex nor age dependence. In untreated Graves' patients, serum IGF-II levels (675 ±129μg/L) were significantly (P<0.01) higher than in normal controls, and significantly lower in patients with hypothyroidism (460±106μg/L; P<0.01). Thyroid hormones revealed positive correlation with the IGF-II concentration.
To evaluate a possible physiological role of Interleukin-2 (IL-2) in the control of Luteinizing hormone (LH), Follicle stimulating hormone (FSH) and Prolactin (PRL) release, conscious, ovariectomized (OVX) rats were given injections of IL-2 into the third ventricle. The third ventricular injection of IL-2 induced a significant decrease in plasma LH levels when compared to values in control animals (P<0.05). Plasma LH concentrations were significantly decreased within 5min after the injection of IL-2 and remained decreased for 1h. In contrast, injections of IL-2 had no effect on plasma FSH or PRL levels. To evaluate a possible direct action of IL-2 on LH, FSH and PRL release from the anterior pituitary gland, the cytokine was incubated with dispersed anterior pituitary cells for 4 h. IL-2 in the dose range between 10-1 and 10-3 unit stimulated the release of LH and FSH into the culture medium (P<0.05, P<0.025 vs. control, respectively). The release of PRL from incubated anterior pituitary cells was not affected at any dose of IL-2 tested. These results indicate that IL-2 possibly plays an inhibitory role in the control of gonadotropin secretion, via hypothalamic action, although it acts directly to stimulate the release of the gonadotropins at the level of the anterior pituitary gland.
Immunoreactive corticotropin-releasing factor-binding protein (CRF-BP) concentrations in human plasma were determined by means of radioimmunoassay for human CRF-BP. CRF-BP antiserum to the C-terminal fragment of human CRF-BP (298-322) was produced, and CRF-BP (298-322) was used as the tracer and the standard. Large amounts of human CRF did not affect measurement of plasma CRF-BP with this radioimmunoassay. The basal plasma CRF-BP concentration in normal subjects was 4.19± 0.57nmol/L (mean±SD). The CRF-BP concentration was low in patients with Cushing's syndrome, except those with preclinical Cushing's syndrome, and high in patients with Addison's disease, hypopituitarism and isolated ACTH deficiency. After surgery, the plasma CRF-BP concentration in patients with Cushing's syndrome rose, peaked, and then decreased to the control level. In patients with Addison's disease, the high plasma CRF-BP concentration decreased to the control level after hydrocortisone replacement, the same as plasma ACTH concentration. These findings suggest that the immunoreactive CRF-BP concentration in human plasma was decreased by glucocorticoids, at least under chronic conditions.
To gain a better understanding of the existence of an ultra-short feedback mechanism controlling LHRH secretion in the medial preoptic area (MPO), we examined the effects of microinjections of LHRH or the LHRH antagonist [D-pGlu1, D-Phe2, D-Try3, 6] into the MPO on pulsatile secretion of LH in ovariectomized rats and on the surge of LH secretion in proestrous rats. Neither the injection of 10ng LHRH nor 100ng its antagonist into the MPO had any effect on pulse frequency or the mean LH concentration in ovariectomized rats. The injection of 100ng LHRH antagonist or 10ng LHRH delayed or advanced, respectively, the LH surge in proestrous rats. Taking these results together with our previous report, the present study indicates that 1) endogenous LHRH in the MPO is involved in the ultra-short feedback regulation of LHRH release and 2) the ultra-short positive feedback mechanism in the MPO acts at the time of the proestrous LH surge but not under a hormonal milieu as in ovariectomized rats.
In the present studies, the long term effects of IFNα on thyroid function and thyroid autoantibodies were evaluated in 42 patients with chronic viral hepatitis type C treated with IFNα for at least 4 months. Before IFN treatment, 41 patients tested were all euthyroid. Five (12%) out of 24 patients tested had positive tests for thyroid autoantibodies. MCHA/TPOAb was detected in all 5 and TGHA/TGAb in 3 out of these 5 patients. Six to 10×106 units (U) of recombinant or natural IFNα were given intramuscularly daily for the first 2 to 4 weeks, followed by 3 to 10×106 U thrice weekly for the subsequent 14 to 22 weeks. Thyroid dysfunction and/or rises in titers of thyroid autoantibodies were observed in 6 patients during IFNα treatment; clinically overt thyroid dysfunctions, destructive thyroiditis and thyrotoxicosis of unidentified etiology, developed in 2 patients 4 to 5 months after start of IFN treatment, subclinical hypothyroidism with a slight increase in serum TSH concentrations but no serum thyroid hormone alternations was observed in 2 patients, and increases in titers of thyroid autoantibodies without thyroid dysfunction were found in 2 patients. Thus, IFNα exacerbated thyroid autoimmunity exclusively in all patients with positive tests for thyroid autoantibodies prior to treatment, but did not induce thyroid autoimmunity in thyroid autoantibody-negative patients. These data suggest that the prolonged IFNα therapy can lead to exacerbation of thyroid autoimmunity in susceptible (thyroid autoantibody-positive) patients.
In this study the efficacy of flutamide, an antiandrogen which does not have a steroid structure, or progestational and estrogenic activities, on hirsutism and hormone levels in polycystic ovary syndrome (PCOS) and idiopathic hirsutism (IH) was investigated. Ten patients with PCOS and nine patients with IH between 19 and 36 years of age were selected for the study. They were given a 500mg daily dose of flutamide and were followed up for clinical and hormonal effects at the second, sixth, eighth and twelfth months of the treatment. The severity of hirsutism was assessed according to the Ferriman-Gallwey's score. There was a slight decrease to below the pre-treatment level in serum LH at the end of the eighth month (P<0.05) and there was also a persistent decrease in progesterone (P) after the second month of the treatment (P<0.05). No other significant change was observed in ovarian or adrenal androgens. Clinical examinations revealed that after six months of the therapy the dose of flutamide had caused a significant alleviation of hirsutism and this continued during the following months.
Estrogen has been shown to stimulate lactotroph proliferation and expression of the prolactin (PRL) gene. Recently it has been established that Pit-1, a pituitary-specific transcription factor, is required for lactotroph proliferation. Furthermore, in vitro studies showed that an increase in the PRL promoter activity caused by estrogen was dependent of the amount of cotransfected Pit-1-expressing plasmid. These findings led us to examine whether the induction of Pit-1 mRNA is required for the estrogen-increased PRL gene expression in the rat anterior pituitary in vivo. Short term estrogen treatment was achieved by means of a single intramuscular injection of estradiol dipropionate. DNA synthesis, the levels of PRL and Pit-1 messenger RNAs in the anterior pituitary were determined. Estradiol dipropionate resulted in a significant increase in DNA synthesis 24h after administration and in PRL mRNA after 48h. In contrast, the Pit-1 mRNA level was not altered. Since Pit-1 is expressed not only in lactotroph but also in somatotroph and thyrotroph, and the lactotroph cell population has been reported to be less than 10% in the pituitary, the change in the Pit-1 mRNA level in lactotrophs was not seen following only short term estrogen treatment. An increase in the lactotroph cell population was therefore achieved by chronic estrogen treatment (subcutaneous implantation of a silastic tube containing 17β-estradiol powder for 30 days). This treatment resulted in the marked proliferation of lactotrophs and a 3-fold increase in PRL mRNA. However, no alteration in Pit-1 mRNA was observed. These results suggest that the increase in Pit-1 mRNA is not required for the estrogen-induced lactotroph proliferation or PRL gene expression.
The effect of His-D-Trp-Ala-Trp-D-Phe-Lys-NH2(GHRP) on growth hormone (GH) release from cultured bovine anterior pituitary (AP) cells was studied in vitro with the interactive effects of GH-releasing factor (GRF: hpGRF (1-29)-NH2) and somatostatin (SRIF). The AP cells (5×104cells per well) were incubated with media, and the media were changed 3 days after plating. After 3.5 days in culture, cells were incubated for 2h with the peptides. GHRP stimulated GH release from cultured cells in a dose-related manner. At doses from 10-11to 10-7M GHRP, the amount of GH released was significantly greater than the controls (P<0.05 to P<0.001). The amounts of GH released at lower doses of GHRP (10-14to 10-12M) were not significantly different from the controls. GH concentrations after treatment with 10-11and 10-7M GHRP were 3.98±0.27 and 4.81±0.16ng/ml, respectively. In experiments performed similarly, the 10-7M GHRH, GHRP, and combined treatment with GHRP plus GHRH increased GH 126, 57, and 139%, respectively (P<0.001). The GH releasing effects of either GHRH alone or GHRP plus GHRH were significantly more potent than that of GHRP alone (P<0.001). The additive effect was not significant when compared with GHRH alone. GH release induced by either GHRH or GHRP was significantly inhibited by SRIF (P<0.01) compared with the untreated control. The inhibitory effect of SRIF in combined treatment with GHRP plus GHRH was significantly less than that of SRIF with GHRH or with GHRP (P<0.01). The present study suggests that GH-releasing peptide (GHRP) induced GH release in cattle via a direct action on anterior pituitary cells in vitro.
It is well known that cholera toxin (CT) stimulates ADP-ribosylation of Gs and also pertussis toxin (PT) does Gi. Each GTP-binding protein has its own action in the regulation of adenylate cyclase. A human non-functioning adrenocortical cancer tissue showed an unresponsiveness in adenylate cyclase to ACTH although ACTH and CT activated adenylate cyclase in a non-functioning adrenal adenoma tissue. CT ADP-ribosylated 40kDa protein of the plasma membrane of the cancer tissue while CT and PT could ADP-ribosylate 43kDa and 38kDa protein in the adenoma tissue, respectively. Immunoblotting analysis of the cancer tissue demonstrated that 40kDa protein was detected by anti-Gs antibody as well as by anti-Gi antibody. The present experiments demonstrated that CT could ADP-ribosylate Gs which has stimulatory action on adenylate cyclase and also Gi which inhibits adenylate cyclase. Thus it is suggested that CT can activate the ADP-ribosylation of Gs and also Gi in a human adrenocortical cancer tissue, partly resulting in abnormal regulation of adenylate cyclase which may be crossly related to ACTH-unresponsiveness.