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The insulin antagonistic effect of GH does not affect myocardial glucose uptake in healthy human subjects
GRS '98 Abstracts
327
and vs Con (1.2 _+ 0.3 ng/ml, P = 0.0001). IGF-I was lower in cCHF (124 _+9 ng/ml) vs ncCHF (150 + 8 ng/ml, P = 0.08) and vs Con (151 + 9 ng/ml, P = 0.12). LogIGF-I/GH was significantly decreased in cCHF (1.7 -- 0.2), vs ncCHF (2.8 _+0.1, P < 0.0001) and vs Con (2.7 _+ 0.2, P = 0.0002). ivGTT: mean GH levels decreased from 1.2 _+0.3 ng/ml to a m i n i m u m of 0.5 + 0.2 ng/ml after 90 min in Con, from 1.4 _+0.5 ng/ml to 0.7 +_0.2 ng/ml after 90 min in ncCHE but in cCHF only from 6.5 _+2.0 ng/ml to 4.1 + 1.3 ng/ml after 120 rain. Seven out of 17 cCHF-patients retained GH levels higher thin1 3 ng/ml under ivGTT conditions. Glucose-assimilation-scores were normal in all groups (not shown). These data indicate an impaired GH sensitivity and disturbed GH regulation in CHF-patients with cachexia in the sense of lacking glucose-suppressibility of GH-levels. These findings should be taken into account in studies of therapeutical intervention with GH in CHF-patients.
the peripheral GH level and central GH gene expressions. ASH extracts (Lymphazyme, Bio cell Matelia Co., Ltd. 500 mg/kg/ ml/day) were orally administered to adult male Sprague-Dawley rats (10 weeks old) for 2 weeks, and rats were killed by decapitation and the trunk blood was collected. The cerebrum was promptly removed from the cerebellum and pituitary gland, and quickly frozen in liquid nitrogen until used. Serum GH concentration and GH mRNA expression in the pituitary were both significantly increased by orally administered ASH as compared to H20 treatment. The brain GH mRNA expression was also markedly enhanced by ASH. These results suggest that a part of ASH-induced effects as nourishment or euphoriant might be mediated by central or peripheral GH molecules acting on CNS directly.
0 - 5 6 T H E I N S U L I N A N T A G O N I S T I C EFFECT OF G H D O E S NOT AFFECT MYOCARDIAL GLUCOSE UPTAKE IN HEALTHY HUMAN SUBJECTS
ICAF Robinson, DF Carmignac, and PA Bennett. Division of Neurophysiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London UK.
HE Botker 1, H Wiggers ~, M Bottcher *,JS Christiansen2, A Gjedde 2, TT Nielsen ~, O Schmitz 2. ~Skejby Hospital; 2Aarhus Kommunehospital, Aarhus, Denmark. Insulin resistance is localized to skeletal muscle in insulin-resistant syndromes. This abnormality also affects cardiac muscle in heart diseases such as coronary artery disease and the cardiac syndrome X, but apparently not in generalized disorders like diabetes mellitus and essential hyportension when cardiac complications are absent. To examine whether the Insulin antagonistic effect of GH acts upon the heart, we compared insulin stimulated whole body and myocardial glucose uptake {MGLo with and without GH administration during a 3.5-h euglycemic hyperinsulinemic (1.2 lnU/kgknin) clamp in eight healthy males {mean age _+ SD 24 _+ 3 years). GH was infused at a rate of 45 ng/kg/min 2 h before and during the clamp. Myocardial laFluorodeoxyglucose uptake was measured with positron emission tomography during the final 90 min of the study. The data were converted to MGU by trucer kinetic analysis. GH did not change the rate pressure product, a valid index of cardiac work. GH decreased whole-body insulin-stimulated glucose disposal by 26% (control: 11 34 _+ 1.10 vs GH: 8.54 _+ 2.00 mg/kg/min, P < 0.02). Free fatty acids and [3-hydroxybutyrate were suppressed to a similar extent with and without GH during the insulin clamp. Insulin stimulated MGU was similar in the presence and in the absence of GH (0.31 -- 0.03 and 0.34 _+ 0.05 Ltol/100g/min, P = 0.18). In conclusion, GH changes neither cardiac work during short-term iiffusion nor impair insulin stimulated MGU. Thus, whole body insulin resistance is not always accompanied by myocardial insulin resistance suggesting that myocardial insulin resistance may be a distinct feature of specific heart diseases.
VIII GH BASIC O-57 E N H A N C E M E N T OF G R O W T H H O R M O N E G E N E E X P R E S S I O N I N T H E P I T U I T A R Y A N D B R A I N BY ACANTHOPANAX SENTICOSUS HARMS
H Yoshizato, T Fujikawa, J Iwasaki, K Nakashima, M Shibata, M Tanaka. Department of Biochemistry, Mie University Faculty of Medicine, Mie, Japan Growth hormone (GH) has attracted increasing interest in its neuronal or neuroendocrine actions on the central nervous system (CNS). Many investigations have also suggested the involvement of GH in the regulation of emotion, memory, behavior and the quality of life in man. On the other hand, as well as Panax ginseng, Acanthopanax senticosus HARMS (ASH) has been generally used as nourishment, tonics or euphoriant. It is also reported that ASH has actually stimulatory or inhibitory effects on the CNS. In this study, we have examined its effects on
0 - 5 8 P I T U I T A R Y CELL T R A N S P L A N T A T I O N I N D W A R F RATS
Anterior pituitary tissue grafted under the kidney capsule remains viable and can induce hyperprolactinemia, probably resulting from removal of hypothalamic dopamine inhibition. Such ectopic pituitary grafts also contain somatotrophs, respond to GHRH, and can secrete enough GH to stimulate growth in hypophysectomized animals. Dwarf dw/dw rats bearing pituitary cell grafts in the third ventricle also grow faster than shamgrafted rats. These rats show somatotroph hypoplasia, and a poor adenylate cyclase response to GHRH. As a consequence of their GH deficiency, they show elevated GHRH expression. We reasoned that this could provide a strong proliferative signal to normal pituitary GH cells grafted into dw/dw rats. To study this, pituitary cells were prepared from normal male rats of the same (AS) strain and microinjected as cell suspensions (2 x 105/gl) into the pituitary gland of dw/dw female rats under anesthesia. Growth acceleration was observed in many, but not all, of the injected rats. Dwarf rats showed aggregates of cells staining intensely for GH by immunocytochemistry in the region of the transplant. They also secreted increased amounts of GH when challenged i.v. with GHRH, when compared with sham- transplanted rats. The transplanted cells can be distinguished from host cells by prelabelling them with stable fluorescent markers before injection, or by chromosomal markers. This model provides an opportunity to study the factors that control somatotroph proliferation within the pituitary gland in vivo. 0 - 5 9 I D E N T I F I C A T I O N OF A S E R U M FACTOR T H A T B I N D S A N D A L T E R S T H E G H B I N D I N G P R O P E R T I E S OF R A T GH-BINDING PROTEIN
KC Leung 1, I Markus 1, WR Baumbach 2, KKY HoL ~Garvan Inst of Med Res, Sydney, NSW, Australia; 2Molecular & Cellular Biology Group, American Cyanamid Co, Princeton, NJ, USA. We have previously shown that rat serum decreases the binding affinity (Ka) and increases binding capacity (N) for GH of recombinant rat GH-binding protein (rGHBP). The present study investigates the mechanism involved. The binding properties of rGHBP in buffer, GHBP-free rat or h u m a n serum, and BSA at concentration mimicMng serum protein content were studied by immunoprecipitation and Scatchard analysis. Compared to buffer, rat serum decreased K and increased N by about 10-fold. H u m a n serum had significant but less potent effects, whereas BSA had no effect. To investigate whether the serum effects might arise from association of rGHBP with another serum factor, ~2SI-rGHBPwas incubated with buffer, rat or h u m a n serum, and subjected to gel filtration chromatography. ~25I-rGHBP in buffer eluted as a major peak of the free form. A second peak accounting for 1Z5 + 0.7% of total radioactivity (mean _+ SEM) eluted at the void volume with rat serum. A similar but smaller peak was detected with h u m a n serum. Addition of unlabeled rGHBP reduced this peak and increased the free rGHBP peak in
327
and vs Con (1.2 _+ 0.3 ng/ml, P = 0.0001). IGF-I was lower in cCHF (124 _+9 ng/ml) vs ncCHF (150 + 8 ng/ml, P = 0.08) and vs Con (151 + 9 ng/ml, P = 0.12). LogIGF-I/GH was significantly decreased in cCHF (1.7 -- 0.2), vs ncCHF (2.8 _+0.1, P < 0.0001) and vs Con (2.7 _+ 0.2, P = 0.0002). ivGTT: mean GH levels decreased from 1.2 _+0.3 ng/ml to a m i n i m u m of 0.5 + 0.2 ng/ml after 90 min in Con, from 1.4 _+0.5 ng/ml to 0.7 +_0.2 ng/ml after 90 min in ncCHE but in cCHF only from 6.5 _+2.0 ng/ml to 4.1 + 1.3 ng/ml after 120 rain. Seven out of 17 cCHF-patients retained GH levels higher thin1 3 ng/ml under ivGTT conditions. Glucose-assimilation-scores were normal in all groups (not shown). These data indicate an impaired GH sensitivity and disturbed GH regulation in CHF-patients with cachexia in the sense of lacking glucose-suppressibility of GH-levels. These findings should be taken into account in studies of therapeutical intervention with GH in CHF-patients.
the peripheral GH level and central GH gene expressions. ASH extracts (Lymphazyme, Bio cell Matelia Co., Ltd. 500 mg/kg/ ml/day) were orally administered to adult male Sprague-Dawley rats (10 weeks old) for 2 weeks, and rats were killed by decapitation and the trunk blood was collected. The cerebrum was promptly removed from the cerebellum and pituitary gland, and quickly frozen in liquid nitrogen until used. Serum GH concentration and GH mRNA expression in the pituitary were both significantly increased by orally administered ASH as compared to H20 treatment. The brain GH mRNA expression was also markedly enhanced by ASH. These results suggest that a part of ASH-induced effects as nourishment or euphoriant might be mediated by central or peripheral GH molecules acting on CNS directly.
0 - 5 6 T H E I N S U L I N A N T A G O N I S T I C EFFECT OF G H D O E S NOT AFFECT MYOCARDIAL GLUCOSE UPTAKE IN HEALTHY HUMAN SUBJECTS
ICAF Robinson, DF Carmignac, and PA Bennett. Division of Neurophysiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London UK.
HE Botker 1, H Wiggers ~, M Bottcher *,JS Christiansen2, A Gjedde 2, TT Nielsen ~, O Schmitz 2. ~Skejby Hospital; 2Aarhus Kommunehospital, Aarhus, Denmark. Insulin resistance is localized to skeletal muscle in insulin-resistant syndromes. This abnormality also affects cardiac muscle in heart diseases such as coronary artery disease and the cardiac syndrome X, but apparently not in generalized disorders like diabetes mellitus and essential hyportension when cardiac complications are absent. To examine whether the Insulin antagonistic effect of GH acts upon the heart, we compared insulin stimulated whole body and myocardial glucose uptake {MGLo with and without GH administration during a 3.5-h euglycemic hyperinsulinemic (1.2 lnU/kgknin) clamp in eight healthy males {mean age _+ SD 24 _+ 3 years). GH was infused at a rate of 45 ng/kg/min 2 h before and during the clamp. Myocardial laFluorodeoxyglucose uptake was measured with positron emission tomography during the final 90 min of the study. The data were converted to MGU by trucer kinetic analysis. GH did not change the rate pressure product, a valid index of cardiac work. GH decreased whole-body insulin-stimulated glucose disposal by 26% (control: 11 34 _+ 1.10 vs GH: 8.54 _+ 2.00 mg/kg/min, P < 0.02). Free fatty acids and [3-hydroxybutyrate were suppressed to a similar extent with and without GH during the insulin clamp. Insulin stimulated MGU was similar in the presence and in the absence of GH (0.31 -- 0.03 and 0.34 _+ 0.05 Ltol/100g/min, P = 0.18). In conclusion, GH changes neither cardiac work during short-term iiffusion nor impair insulin stimulated MGU. Thus, whole body insulin resistance is not always accompanied by myocardial insulin resistance suggesting that myocardial insulin resistance may be a distinct feature of specific heart diseases.
VIII GH BASIC O-57 E N H A N C E M E N T OF G R O W T H H O R M O N E G E N E E X P R E S S I O N I N T H E P I T U I T A R Y A N D B R A I N BY ACANTHOPANAX SENTICOSUS HARMS
H Yoshizato, T Fujikawa, J Iwasaki, K Nakashima, M Shibata, M Tanaka. Department of Biochemistry, Mie University Faculty of Medicine, Mie, Japan Growth hormone (GH) has attracted increasing interest in its neuronal or neuroendocrine actions on the central nervous system (CNS). Many investigations have also suggested the involvement of GH in the regulation of emotion, memory, behavior and the quality of life in man. On the other hand, as well as Panax ginseng, Acanthopanax senticosus HARMS (ASH) has been generally used as nourishment, tonics or euphoriant. It is also reported that ASH has actually stimulatory or inhibitory effects on the CNS. In this study, we have examined its effects on
0 - 5 8 P I T U I T A R Y CELL T R A N S P L A N T A T I O N I N D W A R F RATS
Anterior pituitary tissue grafted under the kidney capsule remains viable and can induce hyperprolactinemia, probably resulting from removal of hypothalamic dopamine inhibition. Such ectopic pituitary grafts also contain somatotrophs, respond to GHRH, and can secrete enough GH to stimulate growth in hypophysectomized animals. Dwarf dw/dw rats bearing pituitary cell grafts in the third ventricle also grow faster than shamgrafted rats. These rats show somatotroph hypoplasia, and a poor adenylate cyclase response to GHRH. As a consequence of their GH deficiency, they show elevated GHRH expression. We reasoned that this could provide a strong proliferative signal to normal pituitary GH cells grafted into dw/dw rats. To study this, pituitary cells were prepared from normal male rats of the same (AS) strain and microinjected as cell suspensions (2 x 105/gl) into the pituitary gland of dw/dw female rats under anesthesia. Growth acceleration was observed in many, but not all, of the injected rats. Dwarf rats showed aggregates of cells staining intensely for GH by immunocytochemistry in the region of the transplant. They also secreted increased amounts of GH when challenged i.v. with GHRH, when compared with sham- transplanted rats. The transplanted cells can be distinguished from host cells by prelabelling them with stable fluorescent markers before injection, or by chromosomal markers. This model provides an opportunity to study the factors that control somatotroph proliferation within the pituitary gland in vivo. 0 - 5 9 I D E N T I F I C A T I O N OF A S E R U M FACTOR T H A T B I N D S A N D A L T E R S T H E G H B I N D I N G P R O P E R T I E S OF R A T GH-BINDING PROTEIN
KC Leung 1, I Markus 1, WR Baumbach 2, KKY HoL ~Garvan Inst of Med Res, Sydney, NSW, Australia; 2Molecular & Cellular Biology Group, American Cyanamid Co, Princeton, NJ, USA. We have previously shown that rat serum decreases the binding affinity (Ka) and increases binding capacity (N) for GH of recombinant rat GH-binding protein (rGHBP). The present study investigates the mechanism involved. The binding properties of rGHBP in buffer, GHBP-free rat or h u m a n serum, and BSA at concentration mimicMng serum protein content were studied by immunoprecipitation and Scatchard analysis. Compared to buffer, rat serum decreased K and increased N by about 10-fold. H u m a n serum had significant but less potent effects, whereas BSA had no effect. To investigate whether the serum effects might arise from association of rGHBP with another serum factor, ~2SI-rGHBPwas incubated with buffer, rat or h u m a n serum, and subjected to gel filtration chromatography. ~25I-rGHBP in buffer eluted as a major peak of the free form. A second peak accounting for 1Z5 + 0.7% of total radioactivity (mean _+ SEM) eluted at the void volume with rat serum. A similar but smaller peak was detected with h u m a n serum. Addition of unlabeled rGHBP reduced this peak and increased the free rGHBP peak in