Somatotropic and lactotropic receptors in transgenic mice expressing human or bovine growth hormone genes

The somatotropic and lactotropic receptors were studied in liver microsomal preparations from transgenic mice carrying the human growth hormone (hGH) or bovine growth hormone (bGH) gene fused to mouse metallothionein-I (MT) or phosphoenolpyruvate carboxykinase promoter/regulator (PEPCK). Specificity studies indicated that, similarly to normal mice, liver microsomes from the transgenic animals possess a mixed population of somatotropic and lactotropic binding sites. In transgenic animals of both sexes, the binding capacity of somatotropic receptors was significantly increased without corresponding changes in affinity. Expression of the MT-hGH hybrid gene was associated with the induction of somatotropic receptors which was approximately twice as great as that measured in animals expressing the MT-bGH hybrid gene. The binding capacity of lactotropic receptors in liver microsomes (quantitated, by the use, of labelled ovine prolactin) was increased 2–3 fold in transgenic females and approximately 10-fold in transgenic males as compared to the respective normal controls. We conclude that lifelong excess of GH up-regulates hepatic GH and prolactin receptors, and that lactogenic activity of GH is not essential for induction of prolactin receptors in the liver of transgenic mice.     

Sensitivity changes to inotropic agents in rabbit atria after chronic experimental diabetes

The effect of experimental diabetes on the sensitivity of isolated left atrial strips to inotropic agents was investigated in rabbits made diabetic with alloxan. After 4 weeks of diabetes no change in sensitivity was detected in response to isoproterenol or ouabain. In contrast, 15 weeks of diabetes induced a decreased sensitivity to beta-adrenergic stimulation, exhibited as a shift to the right in concentration-response curves obtained in response to isoproterenol and noradrenaline. In addition, after 15 weeks of diabetes the inotropic response to ouabain was depressed, and a small decrease in sensitivity was detected in response to forskolin. In contrast, no significant changes in the concentration-response curves obtained from alpha-adrenergic stimulation by phenylephrine or calcium chloride were detected. Unlike the streptozotocin diabetic rat, which exhibits low serum thyroid hormone levels, no changes in serum thyroid hormones were detected in the alloxan diabetic rabbit. It is suggested that the increased inotropic sensitivity to alpha-adrenergic agonists observed in the diabetic rat, but not in the rabbit, may be due to low serum thyroid hormone levels. In contrast, the deleterious effects of diabetes on beta-adrenergic and ouabain sensitivity occur independently of changes in serum thyroid hormones.     

Calcitonin antibodies in experimental diabetes mellitus

Antibodies to calcitonin appear in blood of rats with experimental alloxan diabetes. This phenomenon is observed only under high blood sugar. At the stage of latent diabetes, i.e. during alloxan administration to the body and low blood sugar no antibodies to calcitonin are detected. It is possible that appearance of autoantibodies to calcitonin is one of pathogenetic factors of hyperglycemia development in rats with alloxan diabetes.     

Demonstration by immunofluorescence of somatotropic cells and prolactin cells in the monkeys Erythrocebus patas, Cercopithecus aethiops and Papio hamadryas]

Using antibodies against human STH and ovine prolactine, it is possible to identify somatotropic and prolactin cells in the pituitary anterior lobe of three species of monkeys: Erythrocebus patas, Cercopithecus aethiops and Papio hamadryas. The somatotropic cells are numerous in both adult and infant male or female monkeys, especially in the lateral lobes of the pituitary gland. The prolactin cells can be distinguished in all pituitaries studied, regardless age or sex; indeed there are more numerous in adult females. The immunofluorescent technique reveals a more great number of cells of somatotropic and prolactin type than the classical tetrachrome technique.     

Regulation of hormone secretion in primary cell cultures of human somatotropinomas]

The effects of somatostatin and thyroliberin (thyrotropin-releasing hormone; TRH) on growth hormone (GH) and prolactin (PRL) secretion were studied in short-term (0.5-3h) or long-term (21-24h) incubations using monolayer cell cultures of somatotropin obtained from surgical material of patients with acromegaly. High sensitivity of both GH and PRL release to inhibitory action of somatostatin (10(-11) M) was established. We could not reveal the unambiguous influence of TRH on somatotropic function in the in vivo and in vitro conditions, as compared to the action of this tripeptide on PRL secretion. The results obtained permit us to propose that cell cultures of pituitary adenomata represent adequate and convenient models for studying the pathogenesis of tumor processes in the pituitary gland and for the development of new procedures of pharmacotherapy.     

Quantitative changes in Cu, Zn-superoxide dismutase and catalase isolated from the liver of alloxan diabetic rats

The contents of Cu, Zn-superoxide dismutase and catalase isolated and purified from the rat liver at the terminal stages of alloxan diabetes were decreased by 40% and 15%, respectively, as compared to the control. It can be concluded that the decrease in superoxide dismutase and catalase activity in experimental alloxan diabetes is mainly connected with the decline in the content of these proteins at the terminal stages of the disease, this, probably, being the result of DNA degradation and RNA transport disturbances under the effect of oxygen active forms.     

Immunofluorescent identification of somatotropic and prolactin cells in the anterior lobe of the hypophysis (pars distalis) of the monkey,Macacus irus

Summary Using antibodies against human growth hormone and ovine prolactine, it is possible to identify somatotropic and prolactin cells in the anterior lobe of the hypophysis (pars distalis) of the monkey, Macacus irus. These cells are present in both adult and infant male and female monkeys. The density of the somatotropic cells is greater at the periphery of the anterior lobe. Prolactin cells are of two types: one type is dispersed throughout the pars distalis and consists of small and large cells, the other type forms clusters of large cells.We wish to express our thanks to Mrs. M. Raccurt (CNRS) for her highly skilled technical assistance     

Histology of the pituitary gland of the grey mullet, Mugil cephalus L.

The present communication deals with a histological study of the pituitary gland of the teleost fish Mugil cephalus , found in the estuarine waters of Cochin area. Six different cell types were identified in the pituitary gland on the basis of their grouping, distribution and staining properties. The prolactin and the TSH cells (thyroid stimulating hormone producing cells or thyrotrops) were identified in the rostral pars distalis and the ACTH cells (adrenocorticotropic hormone producing cells or corticotrops) in the interphase between the neurohypophysis and the rostral pars distalis. The STH cells (somatotropic hormone producing cells or somatotrops) and the gonadotropic cells were distinguished in the proximal pars distalis and the MSH cells (melanin stimulating hormone producing cells or melanotrops) in the pars intermedia.     

Differential effects of placental lactogen,growth hormone and prolactin on rat liver ornithine decarboxylase activity in the perinatal period

Ovine placental lactogen, (oPL), ovine growth hormone, (oGH), and ovine prolactin, (oPRL) are present in high concentrations in the fetal circulation late in gestation. To determine if these hormones stimulate the activity of ornithine decarboxylase (ODC), an enzyme widely implicated in the control of cellular growth, rat fetuses were injected $\text{in utero}$ with 100 μg of oPL, oGH, oPRL, rat growth hormone (rGH) or rat prolactin (rPRL) and ODC activity in the livers, hearts, and brains of the fetuses was measured 2, 4, and 6 hours after injection. OPL stimulated fetal liver ODC activity by 282 ± 45% (mean ± SEM) as compared to litter mates injected with buffer alone but oGH, oPRL, rGH and rPRL had no effect on fetal liver ODC activity. However, in neonatal rats 24–48 hours old all five hormones significantly increased liver ODC activity. ODC activities in the hearts and brains of the fetuses and neonates were unaffected by any of the five hormones. In other experiments 50 μg of oPL significantly stimulated fetal liver ODC activity while 250 μg of oGH were without effect. However 25 μg of oGH significantly stimulated liver ODC activity in rat pups 1–2 days after birth. These results suggest that oPL, by its stimulation of ODC activity, has somatotropic effects in the fetus and that rat liver ODC activity becomes responsive to growth hormone and prolactin in the perinatal period.     

Developmental expression of growth hormone and prolactin genes in the bovine pituitary

Cell-free translation was used to initially characterize the major mRNA species present in the bovine anterior pituitary as a function of development. The only detectable change in translation products, which occurred during the transition from fetus to adult, was a reversal in the relative ratio of pituitary growth hormone and prolactin. Subsequent hybridization analysis with cloned growth hormone and prolactin cDNA probes indicated that growth hormone mRNA comprised over 40% of the total fetal mRNA and was 50- to 100-fold higher than prolactin mRNA. The steady state levels of growth hormone mRNA remained relatively constant throughout gestation. In contrast, prolactin mRNA levels, which were low early in gestation, increased during development to become the principal mRNA in the adult pituitary. Since growth hormone and prolactin are synthesized and secreted by specialized cells (somatotrophs and mammotrophs, respectively) immunochemical staining was used to determine whether the changes in the mRNA levels for these two hormones were a reflection of specific cell proliferation. For growth hormone, there was a close correlation between the number of somatotrophs and the relative levels of growth hormone mRNA. In contrast, the increase in prolactin mRNA exceeded the increase in the number of mammotrophs. Thus, the cellular concentration of growth hormone mRNA remains relatively constant during development, while the cellular concentration of prolactin mRNA increases by more than an order of magnitude.     

Ultrastructural localization of prolactin,growth hormone and luteinizing hormone by immunocytochemical techniques in the bovine pituitary

Summary The technique of ultrastructural immunocytochemistry involving the unlabeled antibody and the soluble peroxidase-antiperoxidase complex was used to identify and describe the prolactin (P) cells, somatotropic (STH) cells and luteinizing hormone (LH) cells in the bovine anterior pituitary gland. This method was used to localize the three hormones at the electron microscopic level. Staining of varying intensity was found on the secretory granules and on the small granules and vesicles within the Golgi complex. No stain was found in nuclei, on mitochondria or in the endoplasmic reticulum.     

Influence of experimental diabetes on the kinetic behaviour of renal cortex hexose monophosphate dehydrogenases

1. Short term (1-2 hr) and long-term (2 days) effects of experimental alloxan induced diabetes on the kinetics of the renal hexose monophosphate shunt dehydrogenases are reported. 2. Alloxan diabetes for 2 days significantly increased kidney weight (16%) adding about 80 mg/day per g of kidney. No significant changes were found in renal growth 1-2 hr after alloxan injection. 3. Under these experimental conditions, the activities of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase significantly increased (103 and 33% respectively) at all substrate concentrations, without affecting the KmS of either enzyme. 4. There was no effect of alloxan on the activity of these enzymes at 1-2 hr. Saturation curves show that all enzymes exhibited a M-M kinetic without evidence of sigmoidicity. 5. The results suggest that increased renal hexose monophosphate dehydrogenases activities are due to increased concentrations of the rate limiting proteins. 6. The relationship between these changes and renal hypertrophy is also discussed.     

Ovine placental lactogen stimulation of ornithine decarboxylase activity in brain and liver of neonatal rats

Ovine placental lactogen (oPL), growth hormone (oGH), prolactin (oPRL) and human placental lactogen (hPL) were administered intracisternally (ic) or intraperitoneally (ip) to 17 day old rats and brain and liver ODC activities determined four hours later. When given ic, oPL, oGH and oPRL caused significant increases in brain ODC activity, while hPL had no significant effect. After ip administration, oPL and oGH also caused a significant increase in brain as well as liver ODC activity but oPRL and hPL were without significant effect. The stimulation of polyamine metabolism by oPL together with earlier reports of its potent somatotropic effects and its high concentration in the fetus supports the hypothesis that oPL may be important in the regulation of fetal growth.     

The effect of a somatostatin analogue (SMS 201-995, Sandostatin) on the concentration of phosphoribosyl pyrophosphate and the activity of the pentose phosphate pathway in the early renal hypertrophy of experimental diabetes in the rat

The effect of a long-acting somatostatin analogue on the acute renal hypertrophy following induction of experimental diabetes in the rat has been studied. The kidney weight increase occurring at 2 and 7 days after alloxan injection was significantly lower in the diabetic group receiving somatostatin. Similarly, the previously reported increase in glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) found in the kidney at 2 and 7 days of diabetes was less marked in the group receiving SMS 201-995. The fall in renal phosphoribosyl pyrophosphate associated with early diabetic renal hypertrophy (7) was also lessened by administration of SMS 201-995. No effects of the drug were found in the normal rat on the same regimen of treatment. These observations indicate involvement of glucagon and/or growth hormone in the initiation of kidney growth in diabetes.     

Streptozotocin and alloxan produce alterations in rat brain monoamines independently of pancreatic beta cells destruction.

In recent years the effect of experimental diabetes mellitus on brain neurochemistry has been under an intensive investigation. In most of these studies diabetes was produced by a peripheral administration of streptozotocin or alloxan. In line with previous reports, a week after such an application of alloxan (200 mg/kg s.c.) we found the concentration of serotonin, dopamine and norepinephrine to be increased in the brain of a diabetic rat. Accumulation of these monoamines, produced by inhibition of monoamine oxydase with pargyline (100 mg/kg i.p.) decreased in animals made diabetic by alloxan or streptozotocin (100 mg/kg i.p.) suggesting a decrease in deamination rate. Surprisingly, however, one week after an intracerebroventricular administration of non-diabetogenic doses of streptozotocin (5-20 mg/kg) or alloxan (20 mg/kg), changes in brain monoamines were similar to those observed in diabetic animals. This observation apparently suggests that the CNS effect of streptozotocin or alloxan is not necessarily related to a diabetogenic, beta-cytotoxic action of these substances.     

Diabetogenic action of alloxan in short-term termination of the blood supply to the pancreas and spleen

It has been shown that the development of alloxan diabetes in rats and the appearance of diabetogenic factor in blood is caused by the direct alloxan action on pancreas and spleen--the organs supplying by blood through the spleen artery. The stopping of blood circulation in that artery preserves rat's organism from the development of general toxic effect of alloxan. The inactivation of alloxan as a diabetogenic agent has been shown after its 5-minute at 37 degrees C incubation with blood. It has been established that the half activity of intravenous injected alloxan disappears in rat's organism during 50 s. and does not depend on alloxan sensitivity of animals.     

异搏定对四氧嘧啶损害大鼠胰岛β细胞的保护作用

本工作用四氧嘧啶(尾静脉注射)造成大鼠实验性糖尿病模型。若预先由腹腔注射异搏定(40mg/kg)则可使大鼠血糖水平明显降低,不产生糖尿病,注射四氧嘧啶后48h,血糖浓度的平均值由22.93±1.37mmol/L下降到8.79±0.83mmol/L。口服葡萄糖耐量试验观察到,经过异搏定处理的糖尿病大鼠,在注射四氧嘧啶后的48h,其胰岛素分泌功能较未经异搏定处理的糖尿病大鼠有明显的恢复。组织学切片也显示,胰岛β细胞内胰岛素分泌颗粒的含量在异搏定处理组较单独四氧嘧啶处理组明显增多。上述结果表明,预先注射异搏定能减轻四氧嘧啶对胰岛β细胞造成的急性损伤。     

Regulation of enzymes of glucose metabolism and lipogenesis in diabetic rat liver by thyroid hormones

Experimental diabetes in rats is associated with a degree of hypothyroidism. Hepatic enzymes involved in carbohydrate and lipid metabolism were estimated in control (untreated), control +T3 treated, alloxan diabetic and alloxan diabetic + T3-treated rats. The key glycolytic enzymes, phosphofructokinase and pyruvate kinase, were decreased in activity in diabetes and unchanged by further treatment with T3. In contrast, certain enzymes involve in lipogenesis, ATP-citrate lyase 'malic' enzyme and 6-phosphogluconate dehydrogenase, which were decreased in activity in diabetes, were increased to, or above, control values when diabetic rats were treated with T3. It is suggested that T3 deficiency may play a role in the decrease in enzyme activities observed in experimental diabetes, in particular, some enzymes associated with lipogenesis and the provision of NADPH.     

Endocrine disorders in 66 suprasellar and pineal tumors of patients with prepubertal and pubertal ages.

Tumor oncotypes, initial symptoms and endocrine disturbances before and/or 1 month after surgery were studied in 66 patients with prepubertal and pubertal ages having suprasellar or pineal intracranial tumors. Neoplasms found in patients of prepubertal age were: 15 craniopharyngiomas (CRA), 24 neuroepithelial-cell-derived tumors (NEC), 5 germ cell tumors (GERM) and 4 other lesions (OTHER). In patients of pubertal age, there were 7 CRA, 7 pituitary tumors (PIT), 2 NEC, 1 GERM and 1 OTHER. Approximately 90% of patients had visual abnormalities as one of the initial signs and symptoms, while 59% had increased intracranial pressure. Short stature was observed in only 10% of patients. Before surgery, somatotropic function was found to be deficient (by 2 pharmacological tests) in 90-100% of patients with CRA, PIT or GERM and in 40% of patients with NEC. Overt hypothyroidism was found in 5-25% of CRA, NEC or GERM but in 40% of PIT. Abnormal TSH responses to TRH were observed in 64% of CRA and in 29% of NEC. Low basal serum cortisol was found in 21 or 6% of patients with CRA or NEC, but in 100 or 60% of patients with PIT or GERM, respectively. Diabetes insipidus was diagnosed in 13.6% of all patients. Surgery produced few additional disturbances in endocrine function, except for the incidence of diabetes insipidus which was doubled. Gonadotropic deficiency was found in most patients of pubertal age with CRA and PIT. They were readily differentiated by the high prolactin or growth hormone (GH) levels of the latter.(ABSTRACT TRUNCATED AT 250 WORDS)     

The determination of the cytodifferentiation of the adenohypophysis in embryonic development

This is a review of the literature and author's own data on determination of various cell types of adenohypophysis during embryonic development. Recent studies using techniques of organ culture and immunohistochemistry have established the time of determination of glandular cells of adenohypophysis. It has been shown in rat embryos that the direction of differentiation of all major cell types of adenohypophysis is programmed late during the development of the epithelial anlage of this organ. Similar data as concerns somatotropic and prolactin cells have been obtained on chick embryos. Chick embryos possess regional type of determination of prolactin and somatotropin-containing cells in the anlage in correspondence with their location in definitive adenohypophysis.