Electronic Library of Scientific Literature



ENDOCRINE REGULATIONS



Volume 31 / No. 2 / 1997



DISTRIBUTION OF SOMATOSTATIN RECEPTOR TYPE 4 IN THE RAT: AN IMMUNOHISTOCHEMICAL STUDY

T. Mitsuma, N. Rhue, Y. Hirooka M. Kayama, K. Adachi, Y. Mori, M. Ohtake, J. Tagaki, Jing Ping, T. Nogimori J. Sakai

Fourth Department of Internal Medicine,
Department of Laboratory Medicine,
First Department of Physiology, Aichi Medical University, Nagakute, Aichi, Aichi 480-11, Japan and
Department of Internal Medicine, Konanshowa Hospital, Konan, Aichi, Japan

Somatostatin receptor type 4 (SSTR-4) was identified immunohistochemically in the rat tissues using specific antipeptide serum raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-4 peptide (32-44) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. SSTR-4 immunoreactivity was visualized in the central nervous system, anterior pituitary, retina, adrenal gland, gastric mucosa, Auerbach's and Meissner's nervous branches of the stomach, small intestine and colon. When using antiserum preincubated with synthetic SSTR-4 peptide (32-44) or rat anterior pituitary homogenate which contains SSTR-4 peptide, no significant stain of the anterior pituitary was detected. These findings suggest that SSTR-4 is widely distributed and that the method used is valuable for studying the distribution of SSTR-4 in rats.

Key words: Somatostatin receptor type 4 - Organ Distribution - Immunohistochemistry - Rat
pp. 67-71

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OBSERVATIONS ON BODY WEIGHT AND METABOLISM IN NEWBORN INFANTS OF MOTHERS WITH DIFFERENT TYPES OF DIABETES DURING PREGNANCY

R. Kohlhoff, T. Harder, A. Plagemann W. Rohde, G. Doerner

Clinic of Obstetrics and Gynaecology, Berlin-Kaulsdorf, and Institute of Experimental Endocrinology, Humboldt University Medical School (Charité), Berlin, Germany

Anthropometric and metabolic features were compared between newborn infants of pregestational insulin-dependent diabetic mothers (IDM) and those of gestational diabetic mothers (IGDM). In both groups, despite normal absolute birth weight, the frequency of overweight determined by the symmetry index (SI), as well as plasma insulin and frequency of hypoglycaemia, were clearly increased. However, insulin (P<0.001), glucose (P<0.005), thickness of interscapular skinfold (P<0.05) and the prevalence of obesity (P<0.05) were higher in IDM than in IGDM. SI was positively correlated to insulin levels (P<0.005) and interscapular skinfold (P<0.001), with interscapular skin fold was positively correlated to insulin (P<0.005). In conclusion, both IDM but also IGDM represent important risk groups of elevated neonatal morbidity with possible consequences for later development.

Key words: Newborns of Diabetic Mothers - Hyperinsulinism - Hypoglycaemia - Obesity
pp. 73-78

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EFFECT OF EXOGENOUS PORCINE PROLACTIN ON PLASMA STEROID HORMONES AND OVARIAN MORPHOLOGY IN PREPUBERTAL GILTS

B. Jana, L. Dusza, J. Sobczak, T. Doboszynska

Division of Endocrinology and Pathophysiology of Reproduction, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland;
Institute of Animal Physiology, University of Agriculture and Technology, Olsztyn

The influence of exogenous porcine prolactin (pPRL) on plasma concentrations of steroid hormones and morphology of ovaries in prepubertal gilts was studied. The animals (155 days old) were treated with pPRL (5 mg) or saline for 21 days (one i.m. injection per day). Blood samples from the jugular vein were withdrawn three times daily during the entire experiment and more frequently during the 4 h sampling periods (days 1, 7, 15 and 21). Plasma was analysed for androstenedione (A4), testosterone (T) and oestradiol-17ß (E2) by radioimmunoassay (RIA). Ovaries for histological examination were collected immediately after sacrifice (176th day of age). Plasma A4, T and E2 fluctuated slightly in control animals. In PRL-treated gilts plasma the androgens were significantly decreased and plasma E2 significantly increased in the last week in comparison with the first week of the experiment. After PRL administration the concentrations of A4 and T were also significantly decreased during the consecutive 4 h sampling periods whereas the levels of E2 were unchanged. The treatment with PRL did not affect the peak frequency and peak amplitude of all examined steroids during four sampling periods. Histological examination of ovarian tissues revealed that PRL-treated gilts had higher number of medium follicles (2 to 6 mm) as well as lower number of both small follicles (1 mm) and atretic follicles in comparison with the control group. These results are in agreement with the hypothesis that PRL may participate in the regulation of developmental processes leading to puberty in gilts.

Key Words: Prolactin - Steroid hormones - Ovarian morphology - Prepubertal gilts
pp. 79-87

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EFFECT OF INSULIN ON GLUCOSE TRANSPORT IN RAT ADIPOCYTES IN RELATION TO AGE AND NEONATAL NUTRITION

L. Macho, M. Fickova, S. Zorad

Institute of Experimental Endocrinology, Slovak Academy of Sciences, 833 06 Bratislava, Slovakia

The glucose transport into adipocytes and its stimulation by insulin were investigated in rats with different neonatal nutrition at the age of 30, 60 and 120 days. The changes of nutrition during the suckling period were performed by adjusting the number of suckling pups per litter to 4 (overfed - OF), 8 (control - C) and 14 (underfed - UF). The animals were weaned at the age of 30 days and later fed ad libitum. In 30-, 60- and 120- day-old rats the serum levels of glucose and insulin were determined. The adipocytes were isolated from epididymal fat tissues and the size of cells, basal glucose transport and its stimulation by increasing doses of insulin (from 10-11 to 10-6 M) were estimated. The increased glucose levels and lower insulin concentrations were found in 30-day-old non-fasting rats when compared to adult animals 120-day-old. An increase of basal values of glucose transport with increasing age was noted when transport was expressed per the number of cells. Because an augmentation of the size of adipocytes with age of rats was observed, the glucose transport was expressed per unit of cell surface. The significant decrease of glucose transport per unit of cell surface was demonstrated in 120-day-old rats when compared to young 30-day-old animals. The stimulation of glucose transport by insulin was significantly lower in 120-day-old as compared to 30-day-old rats. No significant differences were found in glucose and insulin serum levels of non-fasting rats of the same age but with different neonatal nutrition. The size of adipocytes was higher and the basal glucose transport was lower in neonatally overfed 60- and 120-day-old rats. The increased stimulatory effect of insulin on glucose transport was found in neonatally underfed 30- and 120-day-old rats. These results demonstrated the changes in basal and insulin stimulated glucose transport with increasing age of rats. Besides of the age, also the nutrition during the suckling period affected the basal and insulin stimulated glucose transport in isolated adipocytes.

Key words: Glucose transport - Insulin - Adipocytes - Age - Neonatal nutrition
pp. 89-94

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CIRCADIAN VARIATIONS OF NOREPINEPHRINE AND EPINEPHRINE IN HYPERTENSIVE AND NORMOTENSIVE OBESE WOMEN

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

1st Department of Pathophysiology and Clinical Biochemistry,
2nd Department of General and Vascular Surgery, Silesian Academy of Medicine, 41-800 Zabrze, Poland

Since the interrelations between the function of sympathetic nervous system and hypertension in obesity were repeatedly observed, the aim of this study was to evaluate serum norepinephrine (NE) and epinephrine (E) levels at 3 h intervals within 24 h in extremely obese women (BMI between 40 to 55 kg/m2) either with (14 cases) or without hypertension (15 cases). The control group consisted of 15 healthy women with normal body weight (BMI between 21 to 24.5 kg/m2). The age range of all subjects was 28 to 42 years (mean: 36.2 ± 3.3 years). In all obese women the elevation of the mean 24 h NE concentration and the decrease of mean 24 h E level was found without any disturbances in the circadian rhythm. No significant differences in 24 h oscillations of NE and E in hypertensive and normotensive obese women were observed. Mean 24 h concentrations of NE correlated significantly and positively with the values of BMI and WHR indexes. Significant and negative correlation was found between mean 24 h levels of E and the values of WHR ratio. Higher values of correlation indicators were generally found between NE, E levels and WHR values in hypertensive obese women.

Key Words: Norepinephrine - Epinephrine - Circadian Variations - Hypertensive and Normotensive Obese Women
pp. 95-101

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HYPERTRIGLYCERIDEMIA, INSULIN RESISTANCE AND HYPERTENSION IN RATS: ARE THEY RELATED?

I. Klimes, J. Zicha, J. Kunes, E. Sebokova

Diabetes and Nutrition Research Laboratory, Institute of Experimental Endocrinology, Slovak Academy of Sciences, SK-83306 Bratislava, Slovak Republic;
Institute of Physiology, Academy of Sciences of the Czech Republic, CZ-14220 Prague, Czech Republic

The association and the possible causal relationship between metabolic disturbances such as hypertriglyceridemia /HTg/, hyperinsulinemia, insulin resistance /IR/, glucose intolerance and hypertension have been extensively investigated. Perhaps the most controversial relationship in the IR syndrome has been the association between IR and blood pressure /BP/. This came out of studies of animal models of hypertension (e.g. SHR, Milan hypertensive rats, Dahl salt sensitive rats, etc.) and animal models of IR (e.g. obese Zucker rat, hereditary hypertriglyceridemic /hHTg/ rats, etc.) as well. However, it is interesting that dietary-induced IR and hyperinsulinemia (e.g. by high sucrose, fructose or fat feeding) are also associated with hypertriglyceridemia and hypertension in "normal" rats (e.g. Sprague-Dawley, Wistar, etc.). In rats, both acute and chronic hyperinsulinemia at euglycemia lead to a dose-dependent BP increase. Yet this effect of insulin may not be present in other animal species studied suggesting that hyperinsulinemia per se may not affect blood pressure without the contribution of other pressor mechanisms. The possible hypertensive effects of insulin seem to involve stimulation of the sympathetic nervous system (reflected by elevated plasma norepinephrine levels), sodium retention (which may not apply for several rat models studied), modulation of ion transport and vascular smooth muscle hypertrophy. Abnormalities in certain membrane ion transport systems (e.g. sodium transport) have been shown to correlate with plasma triglyceride levels in rat models of hypertension and IR (e.g. hHTg rats). Interventions (dietary or pharmacological) aimed to reduce IR or lipid availability very often lead to BP lowering. Nevertheless, considerable variation has been observed in the relationship of IR to BP in a number of inbred rat strains suggesting the crucial role of the genetic background for phenotypic expression of the individual components of the IR syndrome. Thus, a firm pathophysiological linkage among IR, hypertriglyceridemia and hypertension remains to be proven.

Key words: Insulin Resistance - Dietary Manipulations - Genetic Rat Models - Hereditary Hypertriglyceridemic Rat - Polyunsaturated Fatty Acids - Glucose Transport - Blood Pressure
pp. 103-120

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