Electronic Library of Scientific Literature


ENDOCRINE REGULATIONS



Volume 30 / No. 1 / 1996


Regulation of Gene Expression and Activity of Malic Enzyme in Liver of Hereditary Hypertriglyceridemic (hHTG) Insulin Resistant Rat: Effect of Dietary Sucrose and Marine Fish Oil

E. Sebokova, I. Klimes, J. Knopp, D. Gasperikova, P. Bohov, P. Langer, M.T. Clandinin

Diabetes and Nutrition Research Group, Institute of Experimental Endocrinology, Slovak Academy of Sciences, SK-83306 Bratislava, Slovak Republic and
Nutrition & Metabolism Research Group, University of Alberta, Edmonton, Canada

The effect of increased dietary intake of n-3 polyunsaturated fatty acids (PUFA) on hepatic malic enzyme (EC 1.1.1.40) gene expression and activity was investigated in either hereditary fixed or dietary induced hypertriglyceridemia after euglycemic hyperinsulinemic (6.4 mU/kg/min) clamp. The hereditary hypertriglyceridemic rats (hHTG) were fed for 2 weeks basal (B) or high (63 cal %) sucrose (HS) diet, with or without fish oil (FO, 30 wt % n-3 PUFA). The results were compared with the data obtained in control (C) animals subjected to identical protocol. In hHTG rats, increased gene expression [hHTG: 1.7 ± 0.1 vs. C: 0.5 ± 0.05 arbitrary units (AU), P<0.02] for malic enzyme (ME) was not accompanied by increased activity of this enzyme in liver [hHTG: 1.1 ± 0.1 vs. C: 3.1 ± 0.4 nkat/mg, P<0.001]. HS feeding raised the activity [HS-hHTG: 4.2 ± 0.3 nkat/mg, P<0.001; HS-C: 7.5 ± 0.9 nkat/mg, P<0.001] and mRNA levels [HS-hHTG: 10.4 ± 0.3 AU, P<0.001; HS-C: 7.7 ± 0.3 AU, P<0.001] in liver of both hHTG and control rats. The supplementation of HS diet with FO led to striking suppression of activity by 63 % [2.8 ± 0.5 nkat/mg, P<0.001] and gene expression [2.9 ± 0.2 AU, P<0.001] for ME in liver of control rats. Such inhibitory effect was not as pronounced in hHTG rats and reached about 50 % in the ME activity [HS+FO: 2.0 ± 0.06 nkat/mg vs. HS:4.2 ± 0.3 nkat/mg, P<0.001] or 30 % decrease in ME mRNA levels [HS+FO: 7.5 ± 0.8 Au vs. HS:10.4 ± 0.3 AU, P<0.001]. Thus, hHTG rats have markedly elevated levels of mRNA for malic enzyme in liver accompanied by decreased enzymatic activity. Dietary manipulations leading to alteration of hypertriglyceridemia (HS diet, omega-3 PUFA) influenced both the activity of malic enzyme and its transcription in the liver.

Key words: Lipogenesis – Malic Enzyme – Liver – Hereditary Hypertriglyceridemic Rat – Sucrose Diet – Fish Oil
pp. 5-12

Arginine-Vasopressin Influences the Mitogen Induced Development of T and B Effector Cells

A. Germer, V. Enzmann, K. Drossler

University of Leipzig, Department of Biology, Institute of Zoology, Talstraίe 33, D-04103 Leipzig, Germany
University of Leipzig, Department of Medicine, Institute of Ophthalmology, Liebigstraίe 22 b, D-04103 Leipzig, Germany

Using a solid phase enzyme-linked immunospot assay (ELISPOT) for enumerating antibody and interleukin secreting cells it could be demonstrated that arginine-vasopressin (AVP) inhibits the activation process of in vitro cultivated murine spleen lymphocytes. Lipopolysaccharide stimulated B cells could be influenced by high AVP concentrations (10[-5] M), while ConA induced Th1 cells respond also to a lower AVP level (10[-8] M) and such response by the IL-4 secreting Th2 cells may be demonstrated only after the activation with suboptimal doses of Con A. These observations suggest that AVP is not only able to suppress immunological reactions by stimulating proopiomelanocortin processing and secretion of adrenocorticotropic hormone, but also by a direct binding to lymphocytes and, moreover, that the susceptibility in monitoring this signal among the murine lymphocyte subpopulations is different.

Key words: Arginine-vasopressin – Interleukin-2 – Interleukin-4 – Antibody Production – ELISPOT – Murine Spleen Lymphocytes
pp. 13-17

Circadian Variations of Norepinephrine and Melatonin in Extremely Obese Men and Women

Z. Ostrowska, B. Buntner, K. Zwirska-Korczala, E. Swietochowska, Z. Spyra

1st Department of Pathophysiology and Clinical Biochemistry, Silesian Academy of Medicine, 41-800 Zabrze, Poland

The relationship between 24 h variations of norepinephrine (NE), melatonin (MEL) and the values of body mass index (BMI) and waist-to-hip circumference ratio (WHR) was evaluated. The circadian rhythm of NE and MEL was examined in 26 extremely obese patients (14 men and 12 women) and 24 healthy volunteers (13 men and 11 women) with normal body weight. In extremely obese men and women it showed following similar characteristics. In 9/14 obese men (64.3 %) and 8/12 obese women (66.7 %) mean 24 h NE levels were significantly higher than those in controls, while only moderate elevation of mean 24 h NE values was found in the remaining patients. Mean 24 h MEL concentrations were markedly higher in all obese patients studied. Moreover, the disturbances of MEL secretion in the form of acrophase shift and the suppression of its 24 h rhythmicity were observed in patients with markedly higher NE levels. Mean 24 h NE concentrations correlated positively with mesor values of MEL and also with body mass and fat distribution as measured by BMI and WHR, respectively. In contrast, no significant correlation was found between the values of BMI index, WHR ratio and MEL.

Key words: Obesity – Norepinephrine – Melatonin – Circadian Rhythms
pp. 19-27

Inhibition of Cold Stimulated Thyrotropin Release in Rats by Neurotropic Drugs: Specific or Unspecific Effect?

P. Langer, Cs. Ruzsas, O. Foldes, B. Mess

Institute of Experimental Endocrinology, Slovak Academy of Sciences, 833 06 Bratislava, Slovakia
Department of Anatomy, University Medical School, 7643 Pecs, Hungary

Male Wistar Olac rats were kept in stainless steel cages at 24 ± 1 °C. Three days before the experiment they were transferred into another room and kept 3 days at 30 °C. On the day of experiment, groups of 14–16 animals each were injected i.p. with 10 mg/kg morphine hydrochloride (MO), 1.5 mg pimozid (PI), 10 mg/kg cyproheptadine (CY) or with the combinations of MO+PI and MO+CY in the doses indicated above. Exactly after 30 min each animal was transferred to individual plexiglass cage and then a half of each group (consisting of 7–8 animals) was transferred to the cold room (4 °C), while the other half was kept at 30 °C. Precisely after 60 min the animals were quickly decapitated, the trunk blood was collected and thyrotropin (TSH) was estimated in serum using specific rat TSH radioimmunoassay kit supplied by National Pituitary Agency, Bethesda, Md.
It was found that the level of TSH significantly decreased (P < 0.01) in PI injected group even at 30 °C as compared with all other groups. The same was found at 4 °C. In addition, at 4 °C the groups injected with CY, PI+MO and CY+MO showed the TSH level significantly decreased (P < 0.01) as compared with “cold control” and even with the group injected MO only. Since the animals injected with PI and CY irrespectively of MO were deeply sleeping and showed decreased body temperature and blood pressure, it was suggested that the effect of these and possibly some other drugs using for the study of the central regulation of cold stimulated TSH release may be at least partly, if not completely, unspecific.

Key words: Cold stress – TSH – Morphine – Pimozid – Cyproheptadine – Rats – Unspecific effect
pp. 29-32

Association of Body Mass and Body Fat Distribution with Serum Melatonin Levels in Obese Women either Non-Operated or After Jejunoileostomy

Z. Ostrowska, K. Zwirska-Korczala, B. Buntner, M. Pardela, M. Drozdz

I. Department of Pathophysiology and Clinical Biochemistry and II. Department of General and Vascular Surgery, Silesian Academy of Medicine, 41-800 Zabrze, Poland

The association of body mass index (BMI) and body fat distribution (as measured by waist-to-hip circumference ratio; WHR) with serum melatonin (MEL) levels determined at 02 and 14 h were examined in 22 non-operated obese women and 21 obese women who underwent jejunoileostomy for morbid obesity 2 to 6 years earlier as well as in 20 gender and age-matched healthy controls with normal body weight. All non-operated obese women either with moderate or morbid obesity had significantly higher MEL concentration at 14 h compared with controls, whereas the amount of MEL secreted at 02 h was elevated only in morbidly obese women. The mean differences between serum MEL levels at 14 h and 02 h (delta MEL) was reduced in morbidly obese women – it may be due to desynchronisation of its circadian rhythmicity. Among women who underwent jejunoileostomy for morbid obesity the values of MEL were normalized only in those with a noted body mass reduction and with BMI and WHR indexes less than 28 kg/m² and 0.83, respectively. MEL correlated positively with BMI and WHR indexes at 14 h in all subjects studied. Negative correlation was noted between the relative values of delta MEL and BMI in both non-operated and operated obese women with BMI indexes >31 kg/m².

Key words: Melatonin – Circadian Rhythm – Body Mass – Body Fat Distribution – Obese Women – Jejunoileostomy
pp. 33-40

Long Term Administration of Ascorbic Acid Does not Improve a Decreased Bone Weight and Mineral Content in Rats with Neonatally Induced Streptozotocin Diabetes

P.D. Broulik, P. Stolba

Third Department of Internal Medicine, Faculty of Medicine, Charles University, Prague and Research Institute of Endocrinology, Prague, Czech Republic

Adult female rats which were neonatally made diabetic with streptozotocin showed evidence of a pronounced decrease of dry weight, ash weight, calcium, phosphorus and ascorbic acid content in the femur, as compared with control rats. However, such diabetic rats receiving large doses of ascorbic acid (100 mg/kg/day) for 85 days did not show any improvement of the above measures in spite of normalization of bone ascorbic acid content. Thus, additional ascorbic acid given to diabetic rats with osteopenia restored bone ascorbic acid content but did not improve the bone loss resulting from chronic diabetes mellitus. Additional ascorbic acid given to intact rats did not show any additional effect on the increase of bone mass and mineral content.

Key words: Streptozotocin diabetes – Rats – Ascorbic Acid – Bone Density – Osteopenia
pp. 41-44

LHRH – Modulator of Progesterone and Estradiol Secretion by Theca and Granulosa Cells of Porcine Follicle in Mono- and Co-culture

S. Stoklosowa, E.L. Gregoraszczuk, L. Zabaglo

Laboratory of Animal Endocrinology and Tissue Culture, Department of Animal Physiology, Institute of Zoology, Jagiellonian University, Krakow, Poland

Progesterone (P4) and estradiol (E2) secretion by granulosa and theca cells cultured alone or in co-culture under the influence of LHRH was studied. Follicular cells were separated from the follicles of different size: small (1–3 mm), middle (4–6 mm) and large (7–10 mm). The cells were cultured in medium M199 containing 100 ng LH/ml for 30 h. LHRH in a dose of 10[–8] M was added to LH treated cultures after 24 h in culture. Then the cultures were incubated with this hormone during subsequent 6 h. LHRH significantly increased LH-stimulated E2 secretion by granulosa cells (GC) harvested from small and middle follicles, but not from large ones. LHRH had no effect on P4 secretion by granulosa cells alone from small and middle follicles, but it significantly decreased P4 secretion in cultures of granulosa cells harvested from large follicles. In cultures of theca layers (T) alone, decreased secretion of E2 was observed from small follicles only. LHRH had no effect on P4 secretion by theca cell from large follicles cultured alone. However, it markedly increased P4 secretion by T cells from middle follicles and decreased that by theca cells from small follicles. In co-culture of granulosa and theca cells resembling an in vivo follicle, the addition of LHRH to LH stimulated cells harvested from small and middle follicles caused an increase of E2 and decrease of P4 secretion. On the other hand, in co-cultures of cells from large preovulatory follicles, both E2 and P4 secretion was suppressed. It may be concluded that the diverse effects of LHRH (either inhibitory or stimulatory) depend on the degree of follicular maturation.

Key words: LHRH – Granulosa Cells – Theca Cells – Progesterone – Estradiol – Cell Culture
pp. 45-50

Vitamin A Deficiency Inhibits the Mitogenic Effect of Proteins Secreted from Prepubertal Rat Sertoli Cells

L. Kancheva, N. Atanassova

Institute of Cell Biology and Morphology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Previously we have demonstrated dose-dependent stimulation of BALB/c 3T3 fibroblast proliferation by Sertoli cell secreted proteins (SCSP) isolated from 12 days old rats (Kancheva et al. 1990). In this study we have determined the response of early vitamin A deficient state in vivo on germ and Sertoli cell kinetics and on Sertoli cell function in culture. Vitamin A deficiency (VAD) reduced gradually the labelling index of germ cells and their number during different time points of the prepubertal period. The number of proliferating Sertoli cells and their labelling index in VAD rats were unchanged as compared with normal rats. We have shown up to 40 % dose-dependent reduction in the stimulation of 3T3 fibroblast proliferation by prepubertal SCSP derived from vitamin A deficient rats compared with the mitogenic effect of control rat SCSP. The obtained results confirm the assumption that vitamin A plays an important role in modulating the interactions between germ and Sertoli cells.

Key words: Vitamin A Deficiency – Sertoli Cells – Secreted Proteins – Germ Cells – Mitogenic Effect – Infantile Rats
pp. 51-55