{"title":"Tetrahydro-beta-carbolines elevate plasma prolactin in male rats.","authors":"N S Buckholtz, J G Ondo","doi":"10.3109/07435808009065974","DOIUrl":"https://doi.org/10.3109/07435808009065974","url":null,"abstract":"<p><p>The effects of systemic administration of three tetrahydro-beta-carbolines (TH beta C's) on plasma prolactin were determined in male rats. After intraperitoneal administration, 6-methoxy-TH beta C (6-MeO-TH beta C; 80 mg/kg) significantly elevated prolactin levels for 6 min. After intravenous administration via an indwelling jugular cannula, 6-MeO-TH beta C (20 mg/kg but not 2.0 mg/kg), TH beta C (20 mg/kg) and 6-OH-TH beta C (20 mg/kg) all produced a significant elevation in plasma prolactin for 30 min. with the latter compound effective for 60 min. Previous evidence indicated that the TH beta C's interact relatively selectively with the serotonergic neurotransmitter system to increase serotonergic function. Thus, the present data are consistent with previous studies which indicated that increased serotonergic activity resulted in enhanced prolactin secretion.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 4","pages":"221-30"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065974","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18479167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Epididymal androgen binding protein in protein-calorie malnourished rats.","authors":"D C Herbert, D J Tindall","doi":"10.3109/07435808009065959","DOIUrl":"https://doi.org/10.3109/07435808009065959","url":null,"abstract":"<p><p>Androgen binding protein (ABP) was measured at five-day intervals from 20 to 50 days of age in the epididymides of rats fed a low protein diet. The results were compared to findings made in age-matched controls fed a standard laboratory diet. ABP was consistently lower in the caputs of the malnourished rats throughout the entire study. Moreover, no significant changes were noted in caput ABP concentrations as these rats aged. In contrast, this protein was observed to increase during the course of the month-long experiment in those animals fed the standard laboratory diet. These findings indicate that dietary protein deficiency has a marked debilitative effect on Sertoli cell function.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 1","pages":"61-70"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065959","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17820174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of estrogen on luteinizing hormone releasing hormone in a hypothalamic synaptosomal fraction from the ovariectomized rat.","authors":"M Tytell, J H Clark, E J Peck","doi":"10.3109/07435808009065957","DOIUrl":"https://doi.org/10.3109/07435808009065957","url":null,"abstract":"<p><p>Previous investigations have shown that hypothalamic luteinizing hormone releasing hormone (LHRH) is localized within a subcellular fraction eqivalent or similar to the synaptosome or nerve ending particle. In the present study, the ovariectomized adult rat was employed to investigate the effects of estrogen on the distribution of LHRH among various subcellular fractions of the hypothalamus. In addition, the liberation of LHRH from a synaptosomal fraction by repeated freeze-thaw cycles was examined before and after in vivo estrogen treatment. Following a single injection of 5 micrograms of estradiol benzoate (EB), the LHRH concentration of the synaptosomal fraction rose as much as 100% in 27 h. Increasing the dose of EB to 50 micrograms shortened the latency of the rise and prolonged its duration, but did not alter its magnitude compared to the lower dose. Furthermore, the LHRH in that synaptosomal fraction was significantly more resistant to solubilization by repetitive freezing and thawing than the LHRH in a synaptosomal fraction from rats which had not received EB. These observations led us to conclude that estrogens can alter the physical properties of the hypothalamic LHRH-containing particles or the storage form of the peptide within those particles so that it is less easily released. This phenomenon may represent one aspect of the regulatory effects of estrogens on hypothalamic LHRH secretion.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 1","pages":"27-44"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065957","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18037684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Elevation of serum prolactin acutely after administration of p-chloroamphetamine in rats.","authors":"R W Fuller, H D Snoddy, J A Clemens","doi":"10.1080/07435808009065961","DOIUrl":"https://doi.org/10.1080/07435808009065961","url":null,"abstract":"<p><p>p-Chloroamphetamine hydrochloride (0.5-10 mg/kg, i.p.) caused a rapid (within 30 minutes), dose-related increase in serum prolactin concentration in male rats. The effect was antagonized by pretreatment with p-chlorophenylalanine, an inhibitor of serotonin synethesis, or by metergoline, a serotonin receptor antagonist. The acute elevation of serum prolactin may have been mediated by the release of serotonin by p-chloroamphetamine.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 2","pages":"77-85"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07435808009065961","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17506774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Activation of bovine renal cortex membrane adenylyl cyclase by low concentrations of parathyroid hormone.","authors":"E B Heath, J E Zull","doi":"10.1080/07435808009065962","DOIUrl":"https://doi.org/10.1080/07435808009065962","url":null,"abstract":"<p><p>Under conditions designed to reduce non-specific adsorption of parathyroid hormone (PTH), the sensitivity of the renal membrane adenylyl cyclase to PTH was significantly enhanced. Stimulation of the enzyme could be observed at hormone concentrations as low as 2 x 10-11M. In addition, kinetic analysis of hormone activation revealed that under conditions where non-specific adsorption is great, downward concavity of Eadie-Hofstee plots is observed, whereas when such adsorption is reduced these plots become upwardly concave. These results suggest that in the absence of non-specific adsorption, PTH activation of kidney membrane adenylyl cyclase can occur at hormone concentrations approaching physiological. In addition, at low hormone concentrations PTH activation is probably more complex than previously recognized.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 2","pages":"87-98"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07435808009065962","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18417761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of endogenous TSH on the in vitro responsiveness and binding of TSH in rat thyroid tissue.","authors":"S D Holmes, J B Field","doi":"10.3109/07435808009065973","DOIUrl":"https://doi.org/10.3109/07435808009065973","url":null,"abstract":"<p><p>These studies examined the effect of deficient endogenous TSH (hypophysectomy) on in vitro TSH responsiveness and binding in rat thyroid tissue. The results showed that thyroid from hypophysectomized rats were hyper-responsive to stimulation of cyclic AMP by TSH while PGE1 stimulation of cyclic AMP was similar in hypophysectomized rats compared to controls. When iodide organification was measured, the TSH and dibutyryl cyclic AMP stimulation in hypophysectomized rats was equivalent to the response of control animals. Binding studies demonstrated there was an increased number of TSH receptors in the thyroid from hypophysectomized rats compared to the control group. The affinity constant was unchanged. The results demonstrate that endogenous TSH appears to inversely regulate the responsiveness and number of TSH receptors in thyroid tissue. The effect of an i.v. injection of TSH on the levels of cyclic AMP and binding characteristics of TSH was also examined. Although cyclic AMP levels were significantly increased after a 10 min in vitro incubation of the lobes from TSH-injected rats as an indication of persistently bound TSH, the number of TSH binding sites was the same in the saline the TSH-injected animals.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 4","pages":"205-19"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065973","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17322234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"CAMP-dissociation kinetics in hormone-dependent and -independent rat mammary tumor cytosols.","authors":"F Y Tang, K Skerrett, D Heiman, N Ballatori","doi":"10.3109/07435808009065977","DOIUrl":"https://doi.org/10.3109/07435808009065977","url":null,"abstract":"<p><p>Cytosols from 7, 12-dimethylbenz (alpha) anthracene-induced rat mammary tumors which exhibit different hormone-responsiveness were compared with respect to their cAMP-dissociation kinetics. At 22 degree C, pH 4.5, 1 micrometer cAMP, hormone-dependent mammary tumors exhibited monophasic dissociation rates with a rate constant of k-1 = 0.06 min-1. In contrast, hormone-independent mammary tumors exhibited biphasic dissociation curves with rate constants of k-1 = 0.47 and k-2 = 0.06 min-1. The binding of cAMP was completely reversible; radio-labeled ligand was completely dissociated by 1mM nonradioactive cAMP; the binding protein could be reassociated to its original binding level after dextran-coated charcoal adsorption. The mammary cytosols exhibited specific binding for cAMP which could be displaced partially by cGMP but not by ATP, ADP, AMP, or adenosine. Receptor inactivation during the course of incubation was negligible. Both mammary tissue cytosols exhibited similar association rates at 22 degree C, pH 4.5, 1 micrometer cAMP (k+1 = 5-7 x 10(5)M-1 min-1). These data indicate that mammary tissues exhibit 2 cAMP dissociation rates. Hormone-dependent mammary tumors exhibit a dissociation constant of a high affinity binding site (k-1/k+1 = 0.07 micrometer) whereas hormone-independent mammary tumors exhibit dissociation constants of one high affinity (k-1/k+1 = 0.07 micrometer) and a second low affinity site (k-1/k+1 = 0.05 micrometer).</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 4","pages":"253-67"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065977","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17322235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Depression of leucine and isoproterenol induced insulin secretions in the spontaneously diabetic New Zealand white rabbit.","authors":"R L Taylor, H H Conaway, S I Roth","doi":"10.1080/07435808009065966","DOIUrl":"https://doi.org/10.1080/07435808009065966","url":null,"abstract":"<p><p>Rabbits were studied from a closed colony of NZW rabbits which exhibits a 19% occurrance of spontaneous diabetes mellitus. Six overtly diabetic rabbits and eight rabbits with normal glucose disposal were tested with intravenous glucose challenge (500 mg/kg), L-leucine administration (125 mg/kg), and 30 minute infusions with isoproterenol (10 microgram/kg/min.). These agents were shown to be ineffective insulin secretogogues in the overtly diabetic group when compared to the highly significant IRI response observed in colony rabbits with normal glucose disposal. The data indicate that the defect in IRI secretion observed in the spontaneously diabetic NZW rabbits is not confined to stimulation by glucose, but represents an abnormal IRI release mechanism which appears to lack secretogogue specificity.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 2","pages":"121-36"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07435808009065966","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18045994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced hepatic chromatin protein methylation induced by triiodothyronine treatment of the rat.","authors":"J Short, L Kibert","doi":"10.1080/07435808009065965","DOIUrl":"https://doi.org/10.1080/07435808009065965","url":null,"abstract":"<p><p>A pharmacological dose of 3,3',5-triiodo-L-thryonine (200 microgram/100g) that induce marked DNA replication in rat liver cells, also is shown to cause a significant increase in the methylation of chromatin proteins in these cells. This increase in the methylation apppears to correlate with the increase in DNA replication. Specificity of this phenomenon is suggested by its absence in kidney and spleen of the hormone-treated animals, two tissues that also fails to respond proliferatively to the iodothyronine.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 2","pages":"113-9"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/07435808009065965","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18418800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Measurement of urinary production rates of melatonin as an index of human pineal function.","authors":"A J Fellenberg, G Phillipou, R F Seamark","doi":"10.3109/07435808009065970","DOIUrl":"https://doi.org/10.3109/07435808009065970","url":null,"abstract":"<p><p>The urinary production rate of melatonin has been estimated for two male subjects at approximately 30 micrograms per 24 h by measurement of the specific incorporation of deuterium label into 6-hydroxy melatonin sulphate following administration of deuterium-labelled melatonin as an isotopic tracer. No pharmacological effect due to the tracer was apparent on endogenous melatonin secretion and the production rates calculated were unaffected by either dosage or time of administration. It is, therefore, concluded that the use of deuterium-labelled melatonin coupled with quantitative gas chromatography-mass spectrometry offers a practical procedure for providing a clinically useful index of melatonin production in man.</p>","PeriodicalId":75821,"journal":{"name":"Endocrine research communications","volume":"7 3","pages":"167-75"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/07435808009065970","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18429085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}