摘要:

Effect of L-thyroxine and carbimazole on brain biogenic amines and amino acids content and circulating levels of thyroid hormones has been investigated in rats. L-thyroxine treatment caused marked elevation of 5-HT, histamine and glutamate along with the decline in the level of GABA whereas administration of carbimazole had a contrary effect on rat hypothalamus. Further, L-thyroxine administration also raised histamine as well as glutamate content and decreased GABA level in thalamic region of the rat brain but carbimazole treatment reduced 5-HT and glutamate content in this area of the rat brain. Similarly, cortical content of 5-HT and histamine also increased following L-thyroxine administration whereas carbimazole treatment lowered 5-HT, histamine and glutamate levels. Simultaneously, there was a considerable rise in the circulating levels of T3and T4in L-thyroxine-treated rats and a marked reduction in their levels in carbimazole-treated rats. There is a positive correlation between these amines and the thyroid hormone level. Thus, the results suggest that L-thyroxine and carbimazole administration cause marked alteration in biogenic amines and amino acids in rat brain, which may have an important role in the functioning of thyroid gland.

ISSN:0743-5800    

DOI:10.3109/07435809309033016

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The daily administration of 25µg of melatonin for 10 weeks resulted in an increase in the percentage of Type II cells in the Harderian glands of male Syrian hamsters. Harderian glands of melatonin injected animals consisted of 65–70% Type II cells while control animals which were injected with saline had 40% Type II secretory cells. The daily administration of 3 mg of the glutamate receptor agonist N-methyl-D-aspartate (NMDA) prevented the effects of melatonin on cell differentiation but was without effect when administered to saline treated hamsters alone. Both the relative number of mitoses and the number of total cells, estimated by counting the nuclei, was not affected. Thus, a conversion from Type I to Type II cells seems possible. The effects of melatonin and NMDA administration were independent of the serum levels of testosterone, luteinizing hormone and thyroxine, hormones which have been implicated in Type II cell differentiation. However, prolactin levels, which were affected by melatonin and NMDA administration, might be involved in the differentiation of Harderian gland secretory cells.

ISSN:0743-5800    

DOI:10.3109/07435809309033017

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The Sp-isomer of 5,6-dichloro-1-β-D-ribofuranosylbenz-imidazole-3′,5′-cyclic monophosphorothioate (Sp-5,6-DCl-cBIMPS) at micromolar concentrations was a more potent stimulus for insulin release than 8-bromo-cyclic (c) AMP in isolated pancreatic islets of the rat. Sp-5,6-DCl-cBIMPS increased basal secretion, and potentiated glucose-stimulated insulin release to levels similar to those evoked by glucagon. A ten-fold higher concentration of 8-bromo-cAMP was required to mimic the potentiating effects of Sp-5,6-DCl-cBIMPS. Neither 8-para-chlorophenylthio-cGMP, 8-bromo-cGMP, nor dibutyryl-cGMP affected insulin release. Thus, Sp-5,6-DCl-cBIMPS is a potent and specific stimulus for cAMP-mediated insulin release.

ISSN:0743-5800    

DOI:10.3109/07435809309033018

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Thyroid dysfunction influences the levels of Von Willebrand factor (VWF:Ag). Plasma VWF:Ag levels in 35 hyperthyroid patients were significantly elevated, which had a positive correlation with both T3 (Triiodothyronine) and T4 (Thyroxine) levels. A follow-up study of seven hyperthyroid patients undergoing anti-thyroid therapy showed that the elevated VWF:Ag levels returned to normal range with the normalization of thyroid function. On the other hand, after administration of 160 mg/day of propranolol, a specific blocker of beta-adrenergic receptors, to five hyperthyroid patients for twenty-eight days, plasma VWF:Ag levels returned to normal range, while T3, T4 levels remained high without significant alteration. These results demonstrated that the elevation of plasma VWF:Ag by thyroid hormone is mediated through beta-adrenergic receptors, which may be useful to further understand the physiological and pathological roles of thyroid hormone in the regulation of VWF:Ag levels.

ISSN:0743-5800    

DOI:10.3109/07435809309033019

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

We developed rickets and osteomalacia in rats by means of a low phosphorus, normal calcium and normal vitamin D diet, causing severly inhibited mineralization. The concentrations of gammacarboxyglutamic acid (Gla) in 10% formic acid and 5M guanidine extracts were studied in normal and phosphate-deficient rat bone. Although the Gla concentration in the formic acid extract was constant for both groups, it decreased in the guanidine extract of the phosphate-deficient group. The Gla content of the guanidine extract reflected a lower concentration of Gla-containing proteins, one of which, matrix Gla protein (MGP), acts as a mineral deposition inhibitor. Thus, the production of MGP decreased in the impaired mineralization of bone. The quantification of Gla in formic acid and guanidine extract is useful in studying the Gla-containig proteins, osteocalcin and MGP.

ISSN:0743-5800    

DOI:10.3109/07435809309033020

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Our laboratory has previously reported the isolation of a 48.5 kDa membrane protein fromXanthomonas maltophilia(ATCC 13637) which immunologically cross-reacts with theβ-subunit of human chorionic gonadotropin (hCG) in both polyclonal and monoclonal radioimmunoassays (RIA) (1). The protein showed no reaction in RIAs for human LH, TSH, or the free alpha subunit of hCG. We have now improved the protein purification procedure and have obtained adequate bacterial protein to characterize the pure protein (designated xCG) in RIAs and also to obtain amino acid composition and partial sequence. We present these data and compare homology to hCG. An RIA for the bacterial protein has also been developed.

ISSN:0743-5800    

DOI:10.3109/07435809309033021

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

An acute treatment with rat growth hormone (1µg/g) to intact female rats produced immediate changes in muscle and bone protein synthesis as well as in muscle protein breakdown, while glucose and glutamate-piruvate transaminase plasma levels were not altered. These effects, apparently, are not mediated by systemic insulin-like growth factor I. Also a long-term treatment with somatotropin (0.1µg/g/d) for 22 days was performed, in which protein synthesis rates in muscle, liver and bone remained unchanged. However, the growth hormone long-term treatment induced a decrease in muscle proteolytic activity and an increase in tibia weight. In this context, this experiment describes, apparently for the first time, the systemic effect of growth hormone in entire female rats.Data suggest that a single dose of rat growth hormone produces immediate changes in tissue protein metabolism, through a direct effect of growth hormone. These effects were not observed after the long-term growth hormone treatment, although these animals showed an increased in tibia proportions.

ISSN:0743-5800    

DOI:10.3109/07435809309033022

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The effect of ethanol (EtOH) on LH and FSH releasein vitrohas been studied in order to determine whether the effect of alcohol observedin vivocould be mediated by a direct action at the level of the anterior pituitary. Pituitary glands were incubated for 4 hours in TC-199 medium with or with 100 mM ethanol. Basal gonadotrophin release was examined as well as secretion stimulated by luteinizing hormone releasing hormone (LHRH) in the presence or absence of cycloheximide. The total amount of LH and FSH released during the incubation period was calculated. Ethanol did not significantly alter basal gonadotrophin release or LHRH-stimulated FSH release. However, LH secretion induced by LHRH was decreased by EtOH when compared to the LHRH-stimulated group. Cycloheximide decreased the LHRH-stimulated release of LH and FSH but this effect was not altered by EtOH. The results show that EtOH alters the release but not the synthesis of gonadotrophins by a direct effect on the anterior pituitary gland.

ISSN:0743-5800    

DOI:10.3109/07435809309033023

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

FSHin vitrostimulates increased oxygen uptake by isolated follicular granulosa cells from immature rats treated with diethylstilbestrol (DES) when substrates are present (glucose, glutamate, pyruvate or fumerate) or are completely absent. However, when glucose is the only substate or when any single substrate is omitted from the buffer, FSH has no effect. FSHin vitroalso increases the uptake of glucose and the formation of14CO2from [1–614C]-glucose.Granulosa cells from diabetic immature rats treated with DES did not show increased oxygen uptake within vitroFSH. Diabetic cells had similar receptor binding of FSH to that of control non-diabetic cells. The addition of both insulin and FSHin vitroto buffer with diabetic granulosa cells gave increased oxygen uptake over that of control cells from diabetic rats. The insulin stimulation of oxygen uptake by FSH in cells from diabetic rats was not duplicated by either epidermal growth factor (EGF) or insulin-like growth factor I (IGF-1).Follicle counts of ovaries from diabetic and control immature rats treated with DES showed increased atresia in the diabetic ovaries after only 44 hr. of diabetes. Follicle counts of ovaries from adult diabetic rats showed increased atresia in 24 hours after induction of diabetes at proestrus. Follicle counts of pseudopregnant rats showed increased atresia by 3 days after diabetes was induced. We conclude that diabetes prevents normal follicle growth stimulated either by exogenous DES or by endogenous hormones secreted during proestrus.

ISSN:0743-5800    

DOI:10.3109/07435809309033024

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Hypothyroidism frequently presents with muscle complaints. No consistent histopathology nor electrophysiology explains these symptoms and signs. As well, no previous study shows specific changes in components of the nerve-muscle synapse nor excitation-contraction coupling in adult muscles, but changes are seen in hormone-treated embryonic myoblasts. In this study, adult male Holtzman rats underwent thyroidectomy and their age-matched euthyroid controls were simultaneously subjected to sham operation. Thirty days post-operative, animals were sacrificed for anterior tibialis muscles harvest. Muscle dihydropyridine type calcium channel (isradipine) and acetylcholine receptor ($aL-bungarotoxin) binding were measured and compared between experimental treatment groups. There were no significant differences in either the affinity or density of isradipine binding. However, hypothyroid muscles showed a nearly 50% reduction in acetylcholine receptor density when compared to control muscles. Thyroidectomy is associated with specific effects on components of neuromuscular transmission in adult fast twitch muscle.

ISSN:0743-5800    

DOI:10.3109/07435809309033025

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor