The catabolism of lipoprotein(a), Lp(a), remains unclear. Very recently we observed that estrogen, a hormone known to increase low-density lipoprotein (LDL) receptor activity, reduced serum Lp(a) levels in a man with familial hypercholesterolemia (FH) (JAMA 267: 2328, 1992). In the present study, we attempted to further evaluate this Lp(a)-lowering action of estrogen in men without FH. Seven men, aged 61-84yr, treated with estrogen for prostatic cancer were the subjects and seven men who underwent surgical treatment without estrogen therapy served as controls. Fasting blood was collected before and 1-3 months after estrogen therapy, and serum Lp(a) levels and lipoprotein profiles were determined. Estrogen treatment caused significant changes in serum lipoproteins, i.e., decreases in LDL-cholesterol, and increases in high-density lipoprotein (HDL)-cholesterol. Serum triglyceride levels tended to increase. Serum apo A-1 underwent a two-fold increase, while apo B did not change. Serum Lp(a) levels ranged from 8 to 62mg/dl. After estrogen treatment serum Lp(a) was reduced markedly, with a mean reduction of 81% (71-95%). Serum lipids, lipoproteins and Lp(a) did not change significantly in the controls. The results demonstrated a regulating effect of estrogen on serum Lp(a) levels, and the findings further suggested that Lp(a) is removed via LDL receptors. However, previous studies have shown that maneuvers causing a decrease in LDL-cholesterol do not always cause a reduction in serum Lp(a). Thus, our findings suggested the possible presence of a receptor which is estrogen-inducible and different from the LDL receptor.
Effects of n-butyrate on nuclear thyroid hormone receptors and on thyroid hormone-responsive nuclear protein were investigated by means of a perfusion system in rat liver. Treatment with 5mM n-butyrate resulted in an increase (150%) in the maximal binding capacity of 3, 5, 3'-L-triiodothyronine (T3) nuclear receptors without altering the affinity of receptor for T3. However, further perfusion for 4h decreased the number of the receptors to the control level. n-Butyrate increased the amount of acetylated histone H4. The ability of nuclear T3 receptors to bind to core histones was diminished by acetylation of the core histones. Thyroid hormone-responsive nuclear protein (n protein) was increased by T3. The induction of the n protein by T3 was augmented by n-butyrate. These results suggested that n-butyrate modulates thyroid hormone-responsive gene expression in rat liver via the increased number of nuclear receptors or changes in the chromatin constitution.
To examine the effect of unilateral adrenalectomy on compensatory growth and steroidogenesis in the remaining adrenal gland, we determined the tissue concentrations of protein, DNA and corticosterone in the remaining adrenal gland and the circulating corticosterone and ACTH concentrations at 1, 3, 5, 7 and 14 days after unilateral adrenalectomy in male rats. The remaining adrenal weight and total protein content increased steadily over the 14 days after the operation, while the plasma ACTH increased transiently on the 1st day. The adrenal total DNA level was not significantly changed after unilateral adrenalectomy, whereas the protein/DNA ratio was significantly increased by the 14th day. These findings suggest that compensatory growth is not induced by an increase in ACTH and that hypertrophy may occur rather than hyperplasia in the remaining gland. The serum corticosterone levels and corticosterone concentration in the remaining gland were significantly increased by the 3rd day, when the plasma ACTH levels returned to normal. The aldosterone/corticosterone ratio in the remaining gland did not change during the experiment. These results indicate that steroidogenesis stimulating factors other than ACTH may be present and stimulate rather the early stages than the late stages of steroidogenesis under conditions of unilateral adrenalectomy.
The effect of intravenous infusion of acetate, propionate and butyrate (0, 3, 10, 30μmol kg-1 min-1 over 40min) on the secretion of growth hormone (GH), insulin and glucagon in response to growth hormone-releasing factor (GRF) injection (0.25μg/kg, 10min after the onset of acid infusion) was determined in six sheep. The intravenous injection of GRF caused a marked increase in plasma GH at every dose of each acid. The GH response to GRF was unaffected by an intravenous infusion of acetate. The basal plasma levels of insulin, glucagon and glucose were unchanged by acetate infusion. The infusion of propionate markedly suppressed the GH response to GRF in a dose-dependent manner. Propionate produced increases in plasma insulin, glucagon and glucose concentrations. Butyrate infusion also caused a significant attenuation of GRF-induced GH secretion. Butyrate infusion stimulated the secretion of both insulin and glucagon and caused hyperglycemia. After cessation of the infusion of propionate or butyrate plasma GH tended to increase again. Plasma somatostatin concentrations, which were measured only for the highest dose of butyrate, were unchanged during acid infusion, but increased on discontinuing the infusion. It is concluded that propionate and butyrate suppress GH secretion, while stimulating the secretion of insulin and glucagon in sheep.
Hypothalamic decapeptide, gonadotropin-releasing hormone (GnRH) has been found to stimulate human chorionic gonadotropin (hCG) secretion by trophoblast cells in vitro. To determine the biological effect of GnRH on the release of hCG in vivo, we studied the effect of the administration of GnRH on the serum levels of human chorionic gonadotropin (hCG) during pregnancy. Serum hCG levels were measured before and 15, 30, and 60min after the intravenous administration of 100μg of GnRH to 22 volunteers with normal pregnancy. Nine of the 12 (75%) women responded to GnRH in the first trimester, while only 1 of the 5 women (20%) responded to GnRH in the second trimester. None of the 5 women tested in the third trimester showed a significant response of hCG to the injection of GnRH. The average increase in hCG during the first, second and third trimester was 160.7±13.5%, 111.0±7.4% and 95.0±2.3%, respectively (mean±SEM). Whereas the pregnant courses of all the cases were uneventful and normal, other abnormal pregnancies were also investigated with informed consents. Three patients with missed abortions also showed a significant response of hCG to GnRH (increase: 136.7±8.5%) when GnRH was administered before curettage of the uterine cavity. However, 4 patients with unruptured ectopic pregnancies did not respond to GnRH stimulation. These findings indicate that GnRH can stimulate the release of hCG by the placenta in vivo, consistent with the previous in vitro study, while the responsiveness depends on gestational age and the implantation site.
Effects of reserpine treatment, not associated with pituitary irradiation, on the pituitary-adrenocortical axis in a total of 37 untreated patients with Cushing's disease were evaluated. With short-term treatment (2mg daily for 2 weeks, n=36), basal excretion of urinary 17-OHCS significantly decreased from 11.2±5.2mg/day/m2 (body surface area) (mean ±SD) to 9.6±4.4mg/day/m2 (P<0.01), and metyrapone-induced incremental responses of urinary 17-OHCS decreased from 58.4±41.4mg/3 days/m2 to 45.9±29.8 mg/3 days/m2 (P<0.05). Long-term treatment (1.7±0.3mg/day for a mean of 15.8±19.9 weeks) induced a marked reduction in plasma cortisol, and 24-h urinary 17-OHCS and/or free cortisol in 4 of 8 patients examined. Long-term reserpine administration caused normal suppression of plasma cortisol (or 11-OHCS) in 3 of 9 patients with 1mg, and in all of 5 patients with an 8mg overnight dexamethasone suppression test. Plasma ACTH response to CRH was evidently decreased in one patient evaluated one month after the initiation of reserpine. The circadian rhythm of plasma cortisol was normal in one patient when the basal glucocorticoid level became normal with reserpine treatment. The present findings suggest that reserpine itself contributes in a causal fashion to the effectiveness of our regimen, reserpine and pituitary irradiation, for some Cushing's disease patients in whom it is effective.
To evaluate the diagnostic value of subject-based reference values in thyroid function tests, we compared intra-individual and inter-individual variation. Five specimens were collected over a period of 2 weeks from each of 47 normal subjects, 29 women and 18 men, aged 20-47 yrs. T4, FT4, T3, and FT3 were assayed by RIA, and TSH by a sensitive immunoradiometric assay. One-way ANOVA for each test was statistically significant for a main subject effect, indicating that the subjects differed in their personal mean values for the thyroid function tests (T4, P<0.01; FT4, P<0.05; T3, P<0.01; FT3, P<0.05; TSH, P<0.01). The ratio value (intra- over inter-individual variation) was T4, 0.41; FT4, 0.60; T3, 0.53; FT3, 0.63; TSH 0.36. The data indicate that conventional reference values are insensitive when compared to subject-based reference intervals in assessing the thyroid status of a given subject. Reactivity of the thyroid to the stimulation of endogenous TSH was assessed by the ratio ΔFT3/ΔTSH in TRH stimulation tests. A positive correlation between basal FT3 and ΔFT3/ΔTSH (r=0.566, P<0.05) indicates that the thyroid with higher reactivity to TSH secretes more daily thyroid hormone. Negative correlation between basal TSH and ΔFT3/ΔTSH (r=-0.536, P<0.05) means that a subject with lower reactivity of the thyroid needs a higher basal TSH level to compensate. The thyroid reactivity to TSH may be an important determinant for the individuality of the pituitary-thyroid axis.
Thyroxine-binding globulin (TBG) is a major thyroid hormone transport protein in human serum. Its complete deficiency (TBG-CD) is one of inherited TBG abnormalities that transmit on X-chromosome. We previously reported a nucleotide deletion at codon 352 of the TBG gene (TBG-CDJ) in Japanese families with TBG-CD. To determine the prevalence of this mutation in Japanese with TBG-CD, 23 affected subjects (19 males and 4 females) belonging to unrelated families living in 4 major islands of Japan were analyzed with regard to the mutation at codon 352. Their genomic DNAs were amplified by the polymerase chain reaction with allele specific primers. Nineteen male and four female subjects were shown to have the mutation as hemizygotes and heterozygotes, respectively. It is concluded that TBG-CDJ may be a common cause of TBG-CD in Japanese and might have appeared in the ancestors of the Japanese after the human race divergence.
The effectiveness and safety of MCI-028, a synthetic human corticotropin-releasing hormone (hCRH), as a diagnostic drug were examined in 65 healthy male and 24 healthy female adult volunteers. Mean maximum concentrations of plasma ACTH and cortisol after intraveneous administration of 100 μg of MCI-028 were 3.0 and 2.0 times their basal concentrations, respectively, and there were no significant age or sex differences in the responses. Good reproducibility was observed in the responses in 59 male subjects who received a second administration after 1 to 2 weeks. Although slight adverse reactions such as mild and transient hot flushing were observed, these were not serious.
A dose of 1.5μg/kg of MCI-028, human corticotropin-releasing hormone (hCRH), was administered intravenously to 38 children with non-endocrine short stature with normal function in the hypothalamo-pituitary-adrenocortical axis and to 71 children with a disorder in the same axis. Blood levels of adrenocorticotropic hormone (ACTH) and cortisol were determined to evaluate the axis. The 95% confidence limits of peak responses of ACTH and cortisol in non-endocrine short stature were between 17.2 and 135.3pg/ml, and between 13.1 and 35.6μg/dl, respectively, and were used as standards for children. When compared with these standards, the hormonal responses in children with various disorders in the hypothalamo-pituitary-adrenocortical axis were as follows: in two children with Cushing's syndrome caused by adrenal tumor, ACTH values were decreased and were not responsive to hCRH, while cortisol values, though within the normal limit, were not responsive; in children with primary adrenal insufficiency or congenital adrenal hyperplasia, cortisol values were decreased and not responsive, whereas ACTH values tended to be increased and ACTH response high except for 21α-hydroxylase deficiency of congenital adrenal hyperplasia. In two cases of pituitary dwarfism complicated with ACTH deficiency, both ACTH and cortisol values were decreased and poorly responsive; and in children who were receiving glucocorticoid, both ACTH and cortisol values tended to be decreased and to respond poorly to hCRH. As for side effects, hot flushing was observed among 8.0% of the subjects after administration of hCRH. But this symptom was not severe and no other side effects of clinical importance were observed. In conclusion, this study demonstrated that the hCRH test was also safe and useful in evaluating hypothalamo-pituitary-adrenocortical function in children.
The pharmacokinetics, responses of plasma ACTH and cortisol, urinary excretion of steroid hormones, and safety of MCI-028, a synthetic human corticotropin-releasing hormone (hCRH), were examined in eight healthy adult male volunteers after intravenous administration of 33, 100 and 200μg of the drug. The disappearance of MCI-028 from plasma could be fitted to a biexponential decay curve, the plasma half-lives (T1/2) were 0.12 to 0.15h for α phase, and 0.57 to 0.67h for β phase. Plasma ACTH and cortisol concentrations and the urinary excretion of steroid hormones (particularly free cortisol) increased significantly in relation to the MCI-028 dose administrated. Although hot flushing and an increase in the heart rate were observed at higher doses, they were mild and transient. It is also considered that the urinary excretion of free cortisol after the administration of MCI-028 can be an index reflecting the functioning of this system.
To assess the diagnostic usefulness of a synthetic human corticotropin-releasing hormone (CRH) formulation (Code No. MCI-028), we administered 100μg of the peptide intravenously to 183 patients with hypothalamo-pituitary-adrenocortical (HPA) disorders, and obtained the following findings. Among the 183 patients, data from 125 patients were suitable for analyzing the effects of the test. In patients with Cushing's disease, high plasma adrenocorticotropic hormone (ACTH) and cortisol levels increased further in response to MCI-028, while in patients with adrenal Cushing's syndrome, low ACTH and high cortisol values remained unchanged. In patients with pituitary-type hypopituitarism or isolated ACTH deficiency, low ACTH and cortisol levels responded poorly or insignificantly to MCI-028, whereas those with hypothalamic hypopituitarism showed delayed and considerable degree of responses of plasma ACTH and little increase in plasma cortisol levels. In Addison's disease, high plasma ACTH increased further in response to MCI-028, but low cortisol levels did not change. In patients with Cushing's syndrome soon after successful surgical treatment, plasma ACTH responsiveness was low or different depending on the clinical course of the patient. Patients treated with high doses of glucocorticoids for non-endocrine diseases tended to show impaired ACTH and cortisol responsiveness to MCI-028. Side effects, including the transient flushing which was observed most frequently in this study, did not cause any clinical problems.
Twenty three male Wistar rats were divided into five groups and were immunized with five overlapping synthetic peptides (Group I (n=5), peptide 12-30; Group II (n=5), 24-44; Group III (n=4), 308-328; Group IV (n=5), 324-344; and Group V (n=4), 339-364) of human thyrotropin receptor (TSHR), which had been conjugated with rabbit serum albumin. Sera obtained 34 days after the first immunization were investigated for their ability to displace 125I-TSH binding to thyrotropin receptor (thyrotropin binding inhibitor immunoglobulins (TBII)). In addition, biological activity, namely thyroid stimulating (TSAb) or blocking (TSBAb) activities in them were tested with cultured porcine thyroid cells. TBII activities in Group I, II, III, IV, and V rats were 12.6±4.1% (range 9.2-17.2%), 16.3±4.0% (range 11.7-22.0%), 16.7±4.9% (range 13.2-20.1%), 14.5±5.7% (range 8.1-19.0%), and 13.8±6.3% (range 8.1-14.3%), respectively, which were not significantly different from control rat sera (12.3±6.7%, range 1.2-20.1%). TSAb activities in Group I, II, III, IV, and V rats were 608±675% (range 275-1813%), 234±26% (range 209-265%), 313±175% (range 187-568%), 190±63% (range 145-301%), and 134±24% (range 107-158%), respectively. TSAb activities in Group I, II, III, and IV rats were significantly higher than those from control rat sera (P<0.01) while those of Group V were not significantly different from control rat sera. None of the rats in each group exhibited TSBAb activity. Measurement of serum T3 and T4 in each group of rats has shown a significant positive correlation between serum T3 and TSAb activity (r=0.55, P<0.05). These results are consistent with the hypothesis that the major binding site of immunoglobulins with TSAb activity is located in residues 12-30. Localization of TSBAb binding site(s) was not clear from our present investigation.
The patient was a 26-year-old man with Cushing's disease who underwent transsphenoidal microscopic surgery for a pituitary microadenoma. His postoperative course was uneventful, but he died suddenly five years after the operation. At autopsy, a ruptured dissecting aneurysm with marked atherosclerosis was observed in the aorta. In the pituitary, a small focus of adrenocorticotropic hormone (ACTH) producing adenoma, possibly residual adenoma, was detected and Crooke's degeneration was observed in the non-tumorous pituitary gland. But immunohistochemical patterns of pituitary hormones in the non-tumorous pituitary gland were normal and the adrenal cortex was unremarkable. In the hypothalamus, corticotropin-releasing hormone immunoreactivity was not detected and arginine vasopression was sporadically positive. Considering these findings, this patient may have developed subclinical hypercortisolism due to the residual adenoma at the time of autopsy, despite clinical remission. Cushing's syndrome is considered to be a risk factor dissecting aneurysm, and in this case the metabolic changes in Cushing's disease may have influenced the development of the dissecting aneurysm. Periodic cardiovascular re-evaluations should therefore be performed when there is clinical remission of Cushing's syndrome.
Adrenal cysts are rare; most lack endocrinologic activity and do not produce clinical symptoms. The present case is the first to be reported with both an adrenal cyst and a functioning adenoma present ipsilaterally. This 39-year-old male with hypertension was diagnosed as having primary aldosteronism as reflected by hypokalemia and an excess plasma aldosterone concentration (PAC). However, examination by computed tomography revealed a grossly enlarged left adrenal gland with a cyst-like lesion. The right adrenal appeared normal. At surgery, an adenoma and a cyst were found to coexist in the left adrenal cortex. The cyst fluid contained three times the amount of aldosterone present in plasma, less than in previous reports, and was considered to lack endocrinologic activity. Following a left adrenectomy, the patient's blood pressure, serum potassium concentration, and PAC all normalized without the need for medical treatment.