Showing papers in "European Journal of Endocrinology in 1972"

Radioimmunoassay of oestrone and oestradiol in human and bovine peripheral plasma

Abstract: Researchers in Sweden developed and assessed radioimmunoassays of estrone and estradiol in human and bovine peripheral plasma. An antibody against estradiol-17-beta-succinyl-bovine-serum-albumin was employed. Without any previous treatment the antibody was diluted in .1% phosphate buffer to 1:150000. Estrone and estradiol fractions were separated with Sephadex LH-20 chromatography. In both women and cows highly accurate and precise measurements of estrone and 17-beta-estradiol were obtained. In the pregnant cow estrone levels could be measured with a rapid technique which omitted the chromatographic step. In the pregnant cow the predominant free estrogen in the peripheral plasma was estrone. In the 34 normal menstrual cycles observed in women a well defined midcycle estrogen peak always occurred; the luteal phase was less pronounced.(Authors modified)

Radioimmunoassay of oestrone and oestradiol in human plasma

Abstract: A radioimmunoassay for determining estrone and estradiol after lipophilic gel filtration on microcolumns is described and evaluated in terms of theoretical and practical errors. The chromatographic separation on Sephadex LH-20 was facilitated with dyes; eluates were collected directly into counting vials for estimating recovery. Antiserums were purified sheep serum or rabbit serum against estradiol-1 7-hemisuccinate-bovine serum albumin. Unbound estrogens were removed with dextran-charcoaly Theoretical errors for each term in the computation of results were estimated: overall errors could range from 5.7% to 20% in female plasma and from 7.1% to 35% in male plasma. Standard curves varied considerably (coefficient of variation 16%) over several months. Precision (coefficient of variation) ranged from 13% to 27% in serial determination of pooled plasma. The sensitivity was limited to 10 pg/ml by theoretical error. The concentration of estradiol in healthy women was 69 pg/ml on Days 1-10 of the menstrual cycle 126 on Days 11-20 and 99 on Days 21-30. Corresponding values for estrone were 119 156 and 156 pg/ml. The innovations of this method were use of estradiol with a higher specific activity to reduce c ounting time use of gelatin in the antiserum dilution buffer and incubation of antiserum overnight at low temperature all procedures which increase sensitivity. If incubation is shortened and column chromatography omitted a rapid assay for total estrogens results.

Effect of adrenergic blocking agents on insulin response to glucose infusion in man

Abstract: Glucose induces the discharge of insulin from the \\g=b\\-cellprobably by acting on a specific cell membrane receptor. This then transmits the insulinogenic signal of glucose to the release mechanisms of the cell, probably via the adenyl cyclase-cyclic AMP system. Thus, in the \\g=b\\-cell,glucose acts not only as a substrate \\p=n-\\as in every other type of cell \\p=n-\\but also exerts a [00BB]hormone-like[00AB]action. In the present study, the relation of this hypothetic glucose receptor to the adrenergic receptor of the \\g=b\\-cellhas been investigated. In 16 healthy subjects, blockade of the \\g=b\\-adrenergicreceptors by iv infusion of propranolol resulted in significant inhibition of the initial as well as of late insulin responses to glucose infusion. This inhibition was partially reversed when aminophylline was administered together with propranolol. Blockade of the \\g=a\\-adrenergicreceptors with phentolamine had no significant effect on the glucose induced insulin release. These findings suggest that the glucose receptor of the \\g=b\\-cellis closely related to the \\g=b\\-adrenergicreceptor, propranolol being capable of interfering with the transmission of the insulinogenic signal of glucose. It cannot be excluded, however, that propranolol acts in an unspecific way, e. g., by stabilizing the cell membrane or by blocking adenyl cyclase, actions which by themselves may lead to the inhibition of insulin secretion. The precise mechanism by which glucose induces the release of insulin is a matter of debate. Most of the work in this field has been concentrated on the role of glucose metabolism in the /Ocell for insulin secretion (for a review, see Mayhew et al. 1969). Work from our laboratory has, however, pointed to Downloaded from Bioscientifica.com at 09/26/2018 09:40:25PM via free access the cybernetic nature of glucose induced insulin discharge, and we have sug¬ gested that glucose in this respect might act directly on specific receptors in the /Ocell membrane (Cerasi Sc Luft 1970). The nature of this receptor, how¬ ever, is as yet not known. Recent work has emphasized the significance of the adenyl cyclase cyclic AMP system in insulin secretion (Sussman et al. 1966; Lambert et al. 1967; Malaisse et al. 1967; Turtle et al. 1967; Cerasi Sc Luft 1969). We have sug¬ gested that the signal induced by the action of glucose on its receptor is transmitted to the insulin secretory mechanisms of the cell by adenyl cyclase. Since it is known that the adrenergic receptors are related to adenyl cyclase (Robison et al. 1967), and since some adrenergic agonists like adrenaline in¬ fluence insulin release (Coore Sc Rändle 1964; Porte 1967a, 1969; Cerasi et al. 1971), the question arises whether the glucose receptors and the adrenergic receptors of the /Ocell are related to each other or share common charac¬ teristics. In the present work, which is an extension of an earlier preliminary report (Cerasi et al. 1969), the effect of blocking the aand /Oadrenergic receptors on glucose induced insulin release has been studied. MATERIAL AND METHODS The subject material consisted of 16 healthy, non-obese volunteers, aged 25-45 years, who had normal intravenous glucose tolerance and normal insulin response to glucose infusion. The adrenergic blocking agents used were dl-propranolol chloride (Inderai®, ICI, Macclesfield, England) and phentolamine methansulphate (Regitine®, Ciba, Basle, Switzerland). Theophylline was given as Aminophylline® (ACO, Stockholm, Sweden). These drugs were diluted in 500 ml of saline and infused at the rates described below. The subjects reported at the laboratory early in the morning after an overnight fast. The tests were performed with the subjects in the recumbent position after a short period of rest. Teflon catheters were placed into a superficial brachial vein of both arms and kept patent with a slow infusion of saline. The glucose infusion test (GIT) was performed as described previously: 500 mg of glucose per kg body weight was injected rapidly and followed by a 60 min infusion of 20 mg of glucose per kg per min. Blood samples for the determination of glucose and insulin were drawn at 10 min intervals during the infusion, and at 20 min intervals during the following hour. In four subjects a second GIT with half the above amount of glucose was also performed: 250 mg of glucose per kg and 10 mg per kg per min. In the GIT-propranolol experiments, 30 min before the administration of glucose, 3 mg of propranolol was given intravenously during 5 min, and followed by the in¬ fusion of 0.08 mg per min for 85 min. Additional blood samples were drawn 30, 20 and 10 min before the GIT. In an additional experiment three subjects were given half the dose of propranolol (1.5 mg and 0.04 mg per min). In the GlT-propranolol-theophylline studies, Aminophylline was given in a dose of 200 mg (corresponding to 80 mg of theophylline) intravenously during 3 min, 30 Downloaded from Bioscientifica.com at 09/26/2018 09:40:25PM via free access min before the administration of propranolol, and followed by the infusion of 3.5 mg per min for 57 min. Additional blood samples were drawn at 60, 45, 30, 20 and 10 min before the start of the GIT. In the GlT-phentolamine experiments, Regitine was administered intravenously in a dose of 0.5 mg per min during 90 min, starting 30 min before the GIT. Additional blood samples were taken 30, 20 and 10 min before the GIT. Blood glucose was determined enzymatically (Kabi, Stockholm, Sweden), and plasma insulin by the double antibody technique of Hales & Rändle (1963). The insulin response to glucose infusion was evaluated by simulating the experi¬ mentally obtained blood glucose and plasma insulin curves with the aid of an analogue computer model (Cerasi 1967). Four logarithmic parameters, characterizing different aspects of the glucose insulin interrelationship, were used: k¡4, relating the initial insulin response to the magnitude of the rise in blood glucose; k¡2, correlating the later peak level of insulin to the prevailing blood glucose concentration; b, giving the slope of the later rise in plasma insulin; and kg, a measure of the efficiency by which endo¬ genous insulin lowers the blood glucose concentration.

Experimental studies on the endocrine regulations during the periovulatory phase of the human menstrual cycle

Abstract: PIP: In order to simulate some parts of the progesterone and estrogen patterns of the normal menstrual cycle in a normal women, im injections of progesterone and estradiol benzoate were used in 7 amenorrheic, castrated, postmenopausal, or eugonadal women who were receiving 60 mcg of ethinyl estradiol orally per day. Both progesterone and estradiol benzoate were found to produce a positive feedback on the hypothalamic cycle center as measured by the plasma LH surge. Subsequent LH peaks could be induced by either hormone after an estradiol-induced peak, but neither hormone could induce an LH peak after the first progesterone-induced peak. Progesterone-induced LH peaks were always immediate and short-lived with the duration of the LH release appearing to be inversely related to the dose. Estradiol-induced LH peaks did not appear until at least 24 hours after the injection. Only progesterone induced a significant increase in plasma FSH levels. It is inferred from these experiments and the steroid pattern of the normal mentrual cycle that 17-beta-estradiol is the initial triggering stimulus in the cycle leading to an LH surge. This in turn results in an increase in plasma progesterone which regulates the amount of LH release in the second part of the biphasic midcycle peak, which is a possible periovulatory mechanism for mono-ovulation in the human female.

Effect of lithium on thyroid function in man.

Abstract: Thyroid function was assessed in a prospective survey of 13 manicdepressive patients before and after 3 months on lithium carbonate and in a further 12 patients who had received lithium for 20 months. There was a significant increase in thyroid size as measured by quantitative scintiscanning in 8 patients in the first group. One male in the second group had a goitre. There was a rise in plasma TSH in the first group and a significant fall in saliva to plasma iodide. It is suggested that pathogenesis of lithium induced goitre is related to a disturbance in the iodide concentrating mechanism. Thyroid status should be evaluated in patients who are suitable for lithium therapy. Lithium salts were noted to have a calming effect on manic patients more than 20 years ago (Cade 1949). Lithium carbonate is now being increasingly used in the treatment of mania and in the prophylaxis against recurrent manicdepressive disorders (Davis Sc Fann 1971). The development of soft, diffuse, enlarged thyroids in 12 of 330 patients receiving lithium has been previously recorded (Schou et al. 1968). Pieve Sc Platman (1968) reported the presence of goitre in 6 out of 19 patients on lithium and goitre and hypothyroidism has been described in a woman as a result of lithium therapy (Shopsin 1970). However, in the only prospective study of goitre incidence during lithium treatment in which thyroid scanning was used no thyroid enlargement was found (Cooper Se Simpson 1969). An increased 1311 uptake and depression of the protein bound iodine (PBI), free thyroxine and plasma inorganic iodide have been noted in patients reLeverndale Hospital, Glasgow, S.W.3. Downloaded from Bioscientifica.com at 11/29/2018 05:56:24AM via free access ceiving lithium (Schou et al. 1968; Sedvall et al. 1968, 1969; Shopsin 1970). In animals, however, a decrease in 131I uptake has been shown (Sedvall et al. 1969; Hullin 8c Johnson 1970), and the PBI was not lowered. The available evidence suggests that lithium is goitrogenic but there is in¬ sufficient baseline data on patients before and after treatment. Also, there is disagreement about the abnormalities in iodine metabolism produced by lithium (Davis Sc Fann 1971). The present study was undertaken to study these questions further. PATIENTS AND METHODS Two groups of manic-depressive patients were studied. The first group (A) comprised 13 patients (8 males and 5 females, mean age 48). The second group (B) consisted of 12 patients (4 males and 8 females, mean age 45). All patients had been diag¬ nosed by one of us (E. H. B.) and judged to be suitable for lithium therapy. Three patients in group A had a family history of goitre but had no thyroid enlargement themselves. Psychiatric symptoms in group A patients were contained before starting lithium carbonate (Priadel®) by tranquilisers or antidepressants1). These were used singly or in combination depending on the clinical indications. Group A was studied before starting lithium and when 3 months on lithium, thus acting as their own controls. At the time of the first assessement 8 patients were receiving chlorpro¬ mazine, three imipramine, one imipramine and chlorpromazine and one haloperidol and chlorpromazine. Following stabilisation with lithium therapy, 5 patients required no additional therapy at the time of the 3 month study. The others required reduced doses of their original psychotropic therapy (4 chlopromazine, 3 imipramine and 1 chlorpromazine and haloperidol). Group patients were studied once, while on lithium for a mean of 20 months. One patient was taking amitriptyline in addition to lithium, but the remainder were not receiving any other medication. Patients in group A had psychiatric clinical status evaluated and serum lithium estimated every week for one month and then fortnightly for two months. Patients in group were similarily reviewed at 2 month intervals. Both groups were examined for signs of thyroid disease. Serum lithium was measured by atomic absorption spectrophotometry and maintained between 0.5 and 1.5 meq./l for the duration of treatment in all patients. The laboratory assessment of group A patients consisted of measurement of PBl27I, T3 resin uptake (Abbott) and serum thyroxine (Abbott). Stable iodine studies were performed as previously described (Alexander et al. 1962). Thyroid size was evaluated by estimation of the area on an A-P scintiscan and multiplying this by a factor (Myhill et al. 1965) which related to previous work (from thyroidectomy and phantom specimens) which showed that a change in thyroid mass could be estimated by this technique to within 20 Vo (Wood Se Horton, personal communication). Thyroid antibodies (precipitin, tanned red cell and microsomal) were estimated on all patients as was serum cholesterol. Thyroid simulating hormone (TSH) was estimated by Professor R. Hall (Hall et al. 1971). Group patients had the same tests as group A with the exception of the stable iodine studies and thyroid scan. The iodide concentrating mechanism was studied in saliva and saliva/plasma (S/P) !) Chlorpromazine, haloperidol and imipramine. Downloaded from Bioscientifica.com at 11/29/2018 05:56:24AM via free access ratios for iodide were obtained from both groups of patients. This was done as previously described (Lazarus et al. 1971). The actual S/P ratios were plotted against flow rate and the equation of the resulting inverse curve was evaluated for four flow rates (0.05, 0.1, 0.5 and 1.0 ml/min) for each patient. All curves plotted showed statistically significant correlations between S/P and 1/flow rate. The statistical tests used were the Student's paired i-test and Wilcoxon significance of rank differences (one tailed) (Documenta Geigy 1971).

Effect of constant light and androgen-sterilization on the amine turnover of the tubero-infundibular dopamine neurons: blockade of cyclic activity and induction of a persistent high dopamine turnover in the median eminence

Abstract: The dopamine (DA) turnover in the median eminence and in the neostriatum in the rat has been studied during the normal ovarian cycle, in rats exposed to constant light and in androgen-sterilized rats treated with the tyrosine hydroxylase inhibitor \\g=a\\-methyl-tyrosine-methylester. The rate of depletion of DA provides an estimation of the turnover and this can be evaluated semi-quantitatively by means of the highly sensitive and specific histochemical fluorescence method of Falck and Hillarp for the demonstration of catecholamines (CA). The results reveal cyclic turnover changes in the tubero-infundibular DA neurons during the ovarian cycle but not in the neostriatal DA neurons. The turnover is decreased during pro-oestrus and early oestrus. In the persistent oestrous rats, whether induced by constant light or by neonatal steroid treatment, no cyclic changes in DA turnover in the median eminence occurred. The turnover remained at a constant high level in these rats, similar to that found in dioestrus of normal cycling rats. The high oestrogen secretion in persistent oestrous rats was probably responsible for the high DA turnover, since in these rats castration caused a marked This paper was presented in part at the NPR Work Session on »Monoamines and Neuroendocrinology«, May 1968, in Boston, and at the Third International Endo¬ crinology Meeting, July 1968, in Mexico City. Downloaded from Bioscientifica.com at 11/27/2018 12:49:54PM via free access reduction in the DA turnover. Testosterone and oestrogen caused a dosedependent increase in DA turnover in the median eminence in androgensterilized castrated rats. The DA neurons of the androgen-sterilized castrated rats were found to be somewhat less sensitive to treatment with oestrogen than those of normal castrated rats. The present results support the view that the tubero-infundibular DA neurons participate in the inhibition of the cyclic release of LHRF and FSHRF from the median eminence and that the inhibitory feed-back action of oestrogen and testosterone is partly mediated via an increase in DA turnover and release in the median eminence, resulting in inhibition of LHRF and-FSHRF release. In previous papers (Fuxe et al. 1967, 19696) it has been reported that the activity of the tubero-infundibular DA neurons is markedly increased during pregnancy, lactation and pseudo-pregnancy, i.e. conditions in which there is a low FSH and LH secretion and blockade of ovulation. Furthermore, it has been briefly reported (Fuxe et al. 1967) that the tubero-infundibular DA neurons undergo cyclic activity changes during the oestrous cycle with low activity during pro-oestrus and early oestrus, suggesting that at the time of LHRF release the activity of the system is low. Subsequently, a detailed study revealed a decrease in DA activity in the median eminence already in early pro-oestrus before the critical period. The release of LH in the afternoon of pro-oestrus was indicated in the same group of rats as a fall in pituitary LH content (Ahrén et al. 1971). All these findings suggest that the tubero-infundibular DA neurons may be involved in the control of gonadotrophin secretion from the anterior pituitary. In view of the turnover changes observed it was postulated that the DA neurons in the median eminence act partly by inhibiting LHRF secretion from the median eminence. In order to study this hypothesis, other conditions involving blockade of ovulation have been studied, i. e. the persistent oestrous syndrome induced by constant light or by androgen-sterilization. Furthermore, castration and treatment with sex hormones have been performed in androgen-sterilized rats. MATERIAL AND METHODS