Effects of short and long exposure to the diabetic state induced by an injection of streptozotocin to young female rats on glucagon- and catecholamine-sensitive adenylate cyclase activity and adrenergic receptors of hepatic membranes have been studied. The short period of exposure to the diabetic state exhibited an increase in the sensitivity of the enzyme to isoproterenol without changes in the affinity and the number of β-adrenergic receptors. The increased response of adenylate cyclase activity to isoproterenol was accompanied with a greater GTP-induced lowering of the affinity to the β-adrenergic agonist in diabetic membranes than in the controls. The chronic diabetic state produced a decrease in the adenylate cyclase activity to hormonal or non-hormonal stimuli with a fall in the number of α-and β-adrenergic receptors. These results suggest that the observed effects of the diabetic state on hormonally sensitive adenylate cyclase activities and their receptor binding sites of the hepatic membranes would vary depending on the duration and/or severity of the diabetic state experimentally induced.

View full abstract

We present here a 13-year-old male with hypopituitarism which accompanied an insidious and gradual progress of ACTH deficiency. ACTH deficiency finally led to an overt crisis of adrenal insufficiency at the age of 12 years and 7 months. This patient is unique because the insidious and gradual progress has been proved by not only the laboratory results but also the clinical course for over 13 years. The cause of panhypopituitarism including ACTH deficiency is thought to have existed before or at the delivery because of the stalk transection seen on the magnetic resonance image (MRI). At the crisis, his laboratory results suggested that he had secondary adrenal insufficiency, whereas he showed normal adrenal function proved by the insulin tolerance test (ITT) at the age of 4 years. Abrupt crisis of secondary adrenal insufficiency developed at the age of 12 years, although he had been well until the crisis.

View full abstract

A patient with a rare combination of prolactinoma and aldosterone producing adrenal adenoma (APA) was reported in relation to studies concerning dopaminergic regulation of PRL and aldosterone secretion. The patient is a 38-year-old female with plasma PRL and aldosterone concentrations (PAC) of 563ng/ml and 54ng/dl, respectively. A bolus of 10mg of metoclopramide significantly increased plasma PRL in 6 normal subjects and in 4 patients with APA, whereas the responses were blunted in 7 patients with prolactinoma and in our patient. The response of aldosterone to metoclopramide was less than that of PRL, but similar in all studied subjects, indicating that the dopaminergic inhibition of aldosterone secretion is less than that of PRL in normal subjects and did not change in patients with APA or prolactinoma. Oral administration of 2.5mg of bromocriptine suppressed plasma PRL significantly in all the subjects studied, but did not produce any consistent changes in PAC. Discrepancies in the response of PRL and aldosterone to metoclopramide and to bromocriptine suggest a difference in the dopaminergic regulation of PRL and aldosterone secretion in both normal subjects and patients with prolactinoma and APA. It is unlikely that reduced dopaminergic inhibition is the basis for hypersecretion of PRL and aldosterone in our patient.

View full abstract

A case of a 29-year-old man with an ACTH-producing pituitary tumor disseminated into the subarachnoid space is described. After total adrenalectomy for Cushing's disease at the age of 15, Nelson's syndrome developed. Transsphenoidal adenomectomy at 17 and 21years of age, pituitary irradiation and medical therapies with sodium valproate, baclofen and bromocriptine failed to lower his plasma ACTH level. Multiple intracranial and intraspinal tumors associated with the symptoms of left hemiparesis developed. The removal of a tumor grown at the level of C1-3 was performed with successful palliation of his symptoms. Histologically, the tumor cells showed sinusoidal, papillary and diffuse patterns with a preponderance of the former over the latter two, although the papillary pattern predominated in the primary pituitary tumor. Immunohistochemical analysis demonstrated most cells to be positive for ACTH in the metastatic tumor as well as the primary adenoma. The clinical significance of his course is discussed with a review of 11reported cases with metastatic ACTH-producing pituitary tumors.

View full abstract

To assess the possible role of mineralocorticoids in the onset and maintenance of hypertension in adrenal regeneration hypertensive (ARH) rats, the change in plasma mineralocorticoids, with adrenal regeneration after enucleation in ARH rats was investigated and compared with those in unilaterally nephroadrenalectomized, 1% saline-fed (UNA) rats, sham-operated, 1% saline-fed (1% NaCl) rats and water-fed (water) rats. Plasma aldosterone was determined by RIA and the other mineralocorticoids were measured by HPLC. How plasma PRL, a marker of central dopaminergic activity, affected aldosterone secretion was determined by RIA. In ARH, plasma corticosterone (B), 18-OH-DOC and aldosterone levels 2 weeks after operation were as low as 20-30% of corresponding values, but the plasma DOC level was almost 100% of the corresponding value in the other groups. Four weeks after operation plasma B increased to a level comparable with that in the other groups and the plasma aldosterone level remained low. However, plasma DOC and 18-OH-DOC levels 4 weeks after operation were as high as 120-200% of corresponding values in the other groups. Six weeks after operation, the plasma aldosterone level returned to a value comparable with that in UNA and 1% NaCl and plasma DOC and 18-OH-DOC levels returned to corresponding values in the other groups. The plasma PRL level 4 weeks after operation was significantly lower in ARH than in the other groups. These results suggest that transient DOC and 18-OH-DOC increases observed in ARH may be important in the onset of hypertension, while other factors may be involved in its maintenance and that the transient central dopaminergic hyperactivity observed in ARH may be responsible for a delayed return from aldosterone deficiency.

View full abstract

The effect of vasoactive intestinal peptide (VIP) and PHI-27 on dopamine accumulation in cultured rat hypothalamic cells was investigated. VIP enhanced [³H] dopamine accumulation dose dependently. This effect was siffnificant at 10^-8-10^-5M VIP with a concomitant increase in intracellular cyclic AMP (cAMP), and reached its plateau level at 10^-6M VIP. VIP increased [³H] dopamine accumulation significantly within 15 min. PHI-27 and dibutyryl cAMP ((Bu)₂-cAMP) also enhanced [³H] dopamine accumulation. These results suggest that VIP enhances dopamine accumulation in hypothalamic cells by increasing intracellular cAMP.

View full abstract

Human beta thyroid hormone receptor (c-erb A beta protein) produced by an Escherichia coli expression system was purified by sequential column chromatography followed by electroelution from an electrophoresis gel and an antibody was prepared. The antibody recognized a 56kDa protein band in a partially purified rat hepatic nuclear thyroid hormone receptor fraction on Western blotting. Although multiple bands appeared on Western blotting of crude rat hepatic receptor preparations, a 56 kDa band was the most prominent and preadsorption of the antibody by purified c-erb A protein resulted in almost complete disappearance of the 56 kDa band, indicating that the 56 kDa band was formed by a specific antigen-antibody interaction. Furthermore, the 56kDa protein appeared to co-elute with 3, 5, 3'-triiodo-L-thyronine binding activity in hydroxylapatite, Sephacryl S-200, and DNA-cellulose column chromatography of rat hepatic nuclear receptor, and sequential column purification resulted in selective enrichment of the 56 kDa band. These results suggest that the 56 kDa protein may be the major component of the rat hepatic thyroid hormone receptor.

View full abstract

To examine whether immature rat Sertoli cells in culture secrete a factor (s) which stimulates testosterone production by mature mouse Leydig cells, Sertoli cell-enriched cultures were prepared from 3-week-old male rats with trypsin and collagenase.
Sertoli cells were plated at an initial density of 3-5×10⁶ cells/35mm well and cultured in 3ml serum free media supplemented with insulin (10μg/ml). Sertoli cell culture medium (SCCM) collected every 3rd day was added to Leydig cells (10⁶ cells in 1ml of MEM with 2% steroid-free FCS) prepared from 10-week-old mice by mechanical separation and incubated for 3h at 34°C. Secreted testosterone was determined by RIA. SCCM 15 times concentrated by Amicon YM10 membrane demonstrated a dose-dependent stimulation of testosterone production, whereas there was no effect on testosterone secretion when Leydig cells were maximally stimulated by LH. Leydig cell stimulating activity was retained by both a dialysis membrane with a pore size of 24 Å and an ultrafiltration membrane with a molecular weight cut-off of 10kDa. However, activity was reduced by heating at 60°C for 30min and almost lost after incubation with 0.1% trypsin for 1 h at 37°C. This activity was not retained by means of a Con A-Agarose column and was demonstrated only in break-through fractions. HPLC gel filtration of a 15 times concentrated SCCM preparation on a TSK gel G3000SW revealed Leydig cell-stimulating activity at approximately 13kDa. In conclusion, immature rat Sertoli cells in culture secrete a factor (s) which stimulates testosterone production from adult mouse Leydig cells. This factor (s) is a heat-sensitive protein with a molecular size around 13kDa.

View full abstract

In order to identify insulin receptors in the bovine adrenal cortex and medulla, we have studied ¹²⁵I-porcine insulin binding to the membrane preparations from the bovine adrenal cortex and medulla. ¹²⁵I-porcine insulin bound not only to the bovine adrenal cortex but to the medulla in time-, temperature-, and pH-dependent manners. The maximum levels of ¹²⁵I-porcine insulin binding in the two tissues were observed at 4°C for 24h of incubation, and its optimum pH ranged from 7.6 to 8.0. Under these conditions, at tracer concentration of porcine insulin (200pg/ml), 10.4% and 6.6% of ¹²⁵I-porcine insulin added to each reaction tube bound specifically to 10⁵×g-pellet fractions (microsomal membrane) from the cortical tissue (0.3mg of protein) and from the medullary tissue (2mg of protein), respectively. ¹²⁵I-porcine insulin binding was observed predominantly in the microsomal membrane from the bovine adrenal cortex, and in a 15, 000×g pellet fraction (synaptosomal membrane) from the bovine adrenal medulla. Scatchard analysis of binding data yielded curvilinear plots in each tissue. Analysis of curvilinear plots based on two sites model revealed similar affinity constant between the cortex and medulla. Receptor concentration of the cortex was several times higher than that of the medulla. In the two bovine adrenal tissues, human proinsulin and insulin-like growth factor I (IGF-I) had about 1/100 potency compared to porcine insulin in displacing ¹²⁵I-porcine insulin binding. Porcine glucagon added with concentration up to 10^-6M did not inhibit ¹²⁵I-porcine insulin binding to both the cortex and the medulla. These kinetic properties and specificity of insulin receptors in the two bovine adrenal tissues were similar to those of insulin receptors previously reported in mammalian target tissues.

View full abstract