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ENDOCRINE REGULATIONS



Volume 35 / No. 4 / 2001

 


DELTA-6 DESATURASE ACTIVITY AND GENE EXPRESSION, TISSUE FATTY ACID PROFILE AND GLUCOSE TURNOVER RATE IN HEREDITARY HYPERTRIGLYCERIDEMIC RATS

E. Demcakova, E. Sebokova, J. Ukropec, D. Gasperikova, I. Klimes

Diabetes & Nutrition Research, Institute of Experimental Endocrinology Slovak Academy of Science, Vlαrska 3, 833 06 Bratislava, Slovak Republic
E-mail: ueeniwar@savba.sk

Objective. We have shown previously that the impaired insulin action in hereditary hypertriglyceridemic (hHTg) rat is accompanied by a specific fatty acid (FA) profile in the insulin target tissues, possibly due to a desaturation defect. Thus, the aim of this study was to measure the enzymatic activity and gene expression of delta-6 desaturase in liver of hHTg rats and the tissue FA composition in relation to insulin action.
Methods. Glucose, triglycerides and insulin in plasma were measured using commercially available enzymatic sets. The hepatic delta-6 desaturase activity in hHTg rats was determined radiometrically in a microsomal fraction using the 1-14C-linoleic acid as substrate. delta-6 Desaturase gene expression was measured by the Northern blot technique using a specific cDNA probe. Tissue FA profile was determined by gas chromatography in the total lipid fraction extracted to chloroform. The glucose turnover rate was measured in conscious freely moving animals with the aid of euglycemic hyperinsulinic clamp method.
Results. Tissue triglycerides showed a high accumulation in skeletal muscle of hHTg rats. In the liver of these animals, a defect in delta-6 desaturase enzymatic activity was found, while the gene expression for delta-6 desaturase was not changed. Such decreased delta-6 desaturase activity in the liver was linked to a decrease of delta-6 desaturase index as calculated from the liver FA composition. Also the concentration of arachidonic acid (a final metabolite in the biosynthesis of polyunsaturated fatty acids of the n-6 series) was significantly decreased in hHTg rat liver. These changes in FA metabolism were accompanied by a decreased glucose infusion rate (a measure of in vivo insulin action) required to maintain euglycemia at hyperinsulinemia in hHTg rats, and correlated with the hepatic delta-6 desaturase activity.
Conclusions.
1. hHTg rats showed a reduced activity of the delta-6 desaturase in liver without any changes in gene expression for this enzyme; 2. such impairment is accompanied by a lower delta-6 desaturase index (18:2n-6/18:3n-6) found in the liver of these animals and by specific FA profiles in the tissues, particularly regarding the amount of long-chain PUFAs and 18:2n-6 metabolites; and (4) these alterations seem to be related to the impaired insulin action of hHTg rats.
Key words: hHTg rat – delta-6 desaturase (DS) activity – DS gene expression – Tissue fatty acid spectrum – Insulin action

ENDOCRINE REGULATIONS, Vol. 35, 179–186, 2001

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SINGLE DOSE OF MORPHINE INFLUENCES PLASMA CORTICOSTERONE AND GENE EXPRESSION OF MAIN NMDA RECEPTOR SUBUNIT IN THE ADRENAL GLAND BUT NOT IN THE HIPPOCAMPUS

Zdenko Pirnik, Marek Schwendt, Daniela Jezova

Institute of Experimental Endocrinology, Slovak Academy of Sciences, 833 06 Bratislava, Slovakia
E-mail: ueenpirn@savba.sk

Objective. This study was aimed to evaluate the effects of morphine on hypothalamo-pituitary-adrenocortical (HPA) axis, namely proopiomelanocortin (POMC) mRNA and plasma corticosterone, in relation to its influence on glutamate receptor gene expression in central and peripheral sites related to HPA axis regulation. As previous data on morphine action were obtained mainly in male rats, these experiments were performed in females to see potential gender differences.
Methods. Adult female Sprague-Dawley rats were injected with a single dose of morphine (10 mg/kg s.c.) or vehicle. Blood and tissues were sampled 4 h and 24 h following the treatment. In situ hybridization was used to measure POMC mRNA concentrations, reverse transcription-polymerase chain reaction to quantify mRNA coding for N-methyl-D-aspartic acid (NMDA) receptor subunit 1 and radioimmunoassay to measure plasma corticosterone.
Results. Single dose of morphine was followed by a decrease in gene expression of glutamate receptor subunit NMDAR1 in the adrenal gland. Concentrations of mRNAs coding for NMDAR1 in the hippocampus and for POMC in the anterior pituitary remained unaffected. However, plasma corticosterone levels, which were measured at 4 and 24 h after the treatment with morphine, showed a disturbed daily variation in corticosterone release. The efficacy of morphine was confirmed by Straub tail response, one of the classical effect of this drug, in mice.
Conclusions. Present data obtained in females allow to suggest that morphine exerts some of its effects on HPA axis by POMC unrelated mechanisms seemingly in a gender specific manner. Decrease in glutamate receptor gene expression in adrenals induced by a single dose of morphine may result in a modulation of adrenal function in response to subsequent exposure to opioids and contribute to some alterations occurring during opioid drug abuse.
Key words: Morphine – Gene expression – POMC – NMDA receptor – Corticosterone – Adrenal gland

ENDOCRINE REGULATIONS, Vol. 35, 187–193, 2001

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GENE EXPRESSION OF CATECHOLAMINE SYNTHESIZING ENZYMES IN A5 CELL GROUP AND MODULATION OF TYROSINE HYDROXYLASE mRNA BY IMMOBILIZATION STRESS

Lucia Micutkova , Alexander Kiss, Maxim Filipenko, Natasha Rychkova, Olga Krizanova , Miklos Palkovits, Richard Kvetnansky

Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlαrska 3, 833 06 Bratislava, Slovak Republic;
Institute of Bioorganic Chemistry, Russian Academy of Sciences, Novosibirsk, Russia and
Laboratory of Neuromorphology, Semmelweis University, Budapest, Hungary
E-mail: ueenmicu@savba.sk

Objective. The A5 group of noradrenergic neurons plays a key role in autonomic mechanisms like cardiovascular regulation, nociception and respiration. The aim of this work was to detect the gene expression of catecholamine synthesizing enzymes in A5 brain nuclei.
Methods. The gene expression of. tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine N-methyl-transferase (PNMT) in A5 brain nuclei was estimated. We also investigated various time intervals after the end of the single two-hour immobilization, as well as the effect of short-term repeated immobilization (120 min daily for 7 days) on tyrosine hydroxylase gene expression, the rate-limiting enzymes in catecholamines biosynthesis, in the A5 cell group. For all experiments, reverse transcription with subsequent polymerase chain reaction (RT-PCR) was used.
Results. As expected, we detected a clear signal for TH and DBH mRNA but no signal for PNMT mRNA. Both, single and repeated immobilization stress exposure increased significantly the gene expression of TH in A5 area. Maximal elevation in TH mRNA levels occurred after single immobilization for two hours and subsequent decapitation 24 hours later.
Conclusions. In this study we detected for the first time the presence of DBH mRNA in micro dissected A5 cell group. We also showed how the gene expression of tyrosine hydroxylase changed with the function of time after the single immobilization exposure. Thus, TH mRNA in A5 cell group is modulated by immobilization stress in a time-dependent manner.
Key words: tyrosine hydroxylase – A5 cell group – immobilization stress – gene expression

ENDOCRINE REGULATIONS, Vol. 35, 195–200, 2001

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SERUM INSULIN-LIKE GROWTH FACTOR I, BONE MINERAL DENSITY AND BIOCHEMICAL MARKERS OF BONE METABOLISM IN CHILDREN WITH IDIOPATHIC OSTEOPOROSIS

Danuta Chlebna-Sokol, Agnieszka Rusinska

Department of Paediatric Propedeutics, Institute of Paediatry, Medical University of Lodz, 91-738 Lodz, Poland

Objective. To determine whether the serum concentration of insulin-like growth factor I (IGF-I) correlates with the occurrence of idiopathic osteoporosis in children, and whether serum levels of IGF-I correlate with selected bone metabolism markers in patients with osteoporosis.
Methods. The study comprised 24 patients aged 7-18 years, including 12 with idiopathic osteoporosis and 12 control children. Bone mineralisation disorders were diagnosed on the basis of complex clinical, densitometric and biochemical evaluation. In all children serum concentration of IGF-I was estimated by radioimmunoassay and the third fraction of IGF binding proteins (IGFBP3) by immunoradiometry.. In children with osteoporosis the indices of bone metabolism were also assessed, e.g. serum levels of osteocalcin and activity of bone isoenzyme of alkaline phosphatase (bone formation markers) and urine concentration of pyridinoline and deoxypyridinoline and collagen type I crosslinked C-telopeptyde (resorption markers).
Results.
It was found that in children with osteoporosis IGF-I concentration was significantly lower than in the control group (mean values were 583 and 850 ng/ml, respectively; P<0.05). These differences were independent on biological age of the studied children and were present in all adolescence stages. Concentrations of IGFBP3 did not differ significantly between groups (3593 vs. 3955 ng/ml), while that of IFG-I correlated positively with total and spinal bone mineral density (R=0.85 and R=0.80, respectively; P<0.00001). In children with osteoporosis there was also a significant relationship between IGF-I concentration and elimination of pyridinoline and deoxypyridinoline with urine (R=0.64 and R=0.65, respectively; P<0.05). There was no significant correlation between the concentration of IGF-I and IGFBP3 and other studied bone metabolism markers.
Conclusions. The conducted study revealed that lower IFG-I concentrations correlate with higher bone resorption markers values and decreased mineralisation. These results suggest the importance of insulin-like growth factor in the ethiopathogenesis of idiopathic osteoporosis, which needs to be confirmed in further studies.
Key words.
Idiopathic osteoporosis – Children – Insulin-like growth factor I – Bone metabolism markers

ENDOCRINE REGULATIONS, Vol. 35, 201–208, 2001

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DEGENERATION AND RESTORATION OF SPERMATOGENESIS IN RELATION TO THE CHANGES IN LEYDIG CELL POPULATION FOLLOWING ETHANE DIMETHANESULFONATE TREATMENT IN ADULT RATS

Mariana Bakalska, N. Atanassova, P. Angelova, I. Koeva, B. Nikolov, M. Davidoff

Institute of Experimental Morphology and Anthropology, Bulgarian Academy of Sciences, Sofia, Bulgaria;
Higher Medical Institute, Department of Histology and Embryology, Plovdiv, Bulgaria
Institute of Anatomy, University of Hamburg, Hamburg, Germany
E-mail: mbakalska@dir.bg

Objective. To investigate degeneration and restoration patterns of spermatogenesis in relation to the changes in Leydig cells (LCs) after treatment with ethane dimethanesulfonate (EDS).
Materials and methods. Adult Wistar male rats were treated with EDS at a dose 75 mg/kg body weight and the testes were sampled at 7, 14, 21, 35 and 49 days after treatment for histological and ultrastructural studies.
Results. During the first two weeks after treatment stage dependent loss of germ cells was found within seminiferous tubules that led to a profound disturbance of spermatogenesis. The restoration of seminiferous epithelium followed also in stage specific manner and in relation to development of a new LC population (third week). The development of new LCs after EDS treatment repeats the normal dynamics of postnatal LC development within a similar time range.
Conclusion. EDS treatment of rats causes a temporary germ cell degeneration in the testis. The kinetics of disappearance of germ cells and their regeneration broadly follows the changes in LC population.
Key words: Spermatogenesis - Germ cells - Leydig cells – Testis – Rats – Ethane dimethanesulfonate

ENDOCRINE REGULATIONS, Vol. 35, 209–215, 2001

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CIRCADIAN SERUM LEVELS OF DEHYDROEPIANDROSTERONE SULPHATE IN POSTMENOPAUSAL ASTHMATIC WOMEN BEFORE AND AFTER LONG-TERM HORMONE REPLACEMENT

B. Kos-Kudla, Z. Ostrowska, B. Marek, N. Ciesielska-Kopacz, M. Kudla, D. Kajdaniuk, L. Siemidska, J. Strzelczyk

Department of Pathophysiology and Endocrinology,
Department of Clinical Biochemistry,
Clinic of Internal and Allergic Diseases,
III Clinic of Obstetrics and Gynaecology. Silesian Medical University, Katowice, Poland
E-mail: beatakos@ka.onet.pl

Objective. To assess mean 24-h serum concentrations of dehydroepianrosterone (DHEAS) in postmenopausal women with asthma before and after hormone replacement therapy (HRT).
Methods. Studies were performed in 55 asthmatic and 20 healthy postmenopausal women aged 48-60 before HRT and after 6 months of transdermal 17b-estradiol (E2) and medroxyprogesterone acetate treatment (cyclical method). Serum DHEAS concentrations were assessed with the use of RIA method.
Results. In the group of postmenopausal asthmatic women treated with glucocorticoids the mean 24 h DHEAS serum levels were lower than in a similar group not treated with glucocorticoids and a control group of healthy postmenopausal women. However, in both groups of asthmatic women (e.g. glucocorticoid treated and untreated) a significant increase of mean daily DHEAS levels after 6 months of HRT was observed. The hormone concentrations did not change in control group.
Conclusions. Postmenopausal asthmatic women show diminished circadian dehydroepiandrosterone sulphate serum concentrations irrespective whether they were treated with glucocorticoids or not. However, after 6 months of hormonal replacement therapy in these groups increased levels of DHEA were found.
Key words: Dehydroepiandrosterone sulphate - Bronchial asthma - Hormone replacement therapy

ENDOCRINE REGULATIONS, Vol. 35, 217–222, 2001

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ESTROUS CYCLE-DEPENDENT CHANGES IN STEROID SECRETION BY PIG OVARIAN CELLS EXPOSED IN VITRO TO POLYCHLORINATED BIPHENYL (PCB 153)

Anna K. Wojtowicz, Erik Ropstad, Ewa L. Gregoraszczuk

Laboratory of Physiology and Toxicology of Reproduction, Department of Animal Physiology, Institute of Zoology, Jagiellonian University, Ingardena 6, 30-060 Krakσw, Poland.
Department of Reproduction and Forensic Medicine, Norwegian School of Veterinary Science, Oslo, Norway.
E-mail: greg@zuk.iz.uj.edu.pl

Objective. To characterize PCB 153 action on the ovary, the direct effect of PCB153 was investigated in vitro using a co-culture of pig granulosa and theca cells collected during different stages of follicular development.
Methods. The cells were cultured in the absence or presence of 5, 10, 50 or 100 ng/ml of PCB 153. Media were changed after 48, 96 and 144 h and frozen until further estradiol (E2), progesterone (P4) and testosterone (T) analysis.
Results. 48 hrs exposure of follicular cells collected from small-size follicles to all the investigated doses of PCB 153 caused statistically significant decrease in progesterone (P4) secretion and at doses of 50 ng and 100 ng/ml in testosterone (T) secretion. No effect on estradiol (E2) secretion was observed. After 96h and 144h exposure to PCB an increase in P4 secretion with concomitant drastic decrease in T secretion and a tendency to decrease in E2 secretion was observed. Similarly as in the case of small follicles, the action of PCB on steroid secretion by cells collected from medium follicles depended on time of exposure. The increase in T secretion and no influence on P4 and E2 secretion was observed after 2 days of exposure to PCB. Antiestrogenic action of PCB was noted after 4 and 6 days of exposure to PCB. In large, preovulatory follicles 2 days exposure to PCB had no effect on steroids secretion while longer exposition to this congener caused statistically significant antiestrogenic action.
Conclusion. The presented paper suggests various actions of PCB 153 as an endocrine disrupter on estradiol, progesterone and testosterone secretion from ovarian cells in vitro which were dependent on both exposure length and stage of the follicular development.
Key words: PCB 153 – Ovarian follicles – Estradiol – Progesterone – Testosterone - Steroid secretion – Estrous cycle

ENDOCRINE REGULATIONS, Vol. 35, 223–228, 2001

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MINIREVIEW: MICRODIALYSIS OF THE BLOOD OUTFLOWING FROM THE BRAIN

Anna Goraca

Department of Experimental and Clinical Physiology, Institute of Physiology and Biochemistry, Medical University of Lodz. 92-215 Lodz, Poland

In past several years the in vivo blood microdialysis technique has been widely used for a variety of pharmacological and physiological applications to study, monitor and analyze endogenous substances, such as neurohormones, and exogenous substances such as therapeutic drugs and their metabolites. The technique is being desctribed in detail and discussed, in which microdialysis probes were implanted into the jugular vein, blood was flowing freely around the dialysis membrane. The probe was perfused at a very low flow rate (~ 1-2 ΅L/min)with the solution resembling closely the composition of body fluid. In this laboratory (Department of Experimental and Clinical Physiology, Institute of Physiology and Biochemistry, Medical University of Lodz) the technique of in vivo blood minidialysis was worked out in small laboratory animals (rat, guinea-pig, hamster) and used to demonstrate that neurohypophysial hormones can be released into the blood outflowing from the region of the sella turcica and blood dialysate from the femoral vein.
Key words: Microdialysis – Cavernous sinus – Brain blood – Small animals – Minireview

ENDOCRINE REGULATIONS, Vol. 35, 229–236, 2001

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AUTHOR AND SUBJECT INDEX

ENDOCRINE REGULATIONS, Vol. 35, 237–240, 2001

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