重组生长激素与谷氨酰胺协同促进短肠大鼠小肠的代偿

目的　研究添加生长激素(rhGH)及谷氨酰胺(Gln)的肠外营养(PN)对短肠大鼠残存小肠代偿的作用及机制。方法　按2×2析因实验方案,将SD大鼠随机分成STD、Gln、rhGH及rhGH+Gln组,建立PN短肠动物模型。PN6d后行小肠黏膜形态学检查,并行细胞增殖核心抗原(PCNA)测定、原位末端标记(TUNEL)染色及胰岛素样生长因子-1(IGF-1)mRNA的Northernb1ot测定。结果　rhGH+Gln组残余小肠黏膜形态学上呈显著代偿表现。析因分析表明,rhGH与Gln间存在协同作用(P＜0.01)。其PCNA表达显著高于rhGH、Gln与STD组,分别为24.95±3.93、19.28±3.25、17.27±3.38与8.37±2.23(P＜0.01);凋亡指数显著降低,分别为5.68±2.07、8.06±2.33、10.00±2.24及22.32±3.84(P＜0.01);小肠IGF-1mRNA表达在rhGH+Gln组显著高于rhGH、Gln及STD组,分别为0.73±0.05、0.62±0.04、0.51±0.04及0.41±0.22(P＜0.05)。结论　rhGH与Gln通过促进肠黏膜上皮细胞增生与抑制其凋亡,协同促进短肠大鼠残存小肠代偿,小肠IGF-1在二者协同作用的发挥中起重要的介导作用。     

Recombinant human growth hormone and glutamine synergistically improve the adaptation of the remnant small intestine in rats with short bowel syndrome

OBJECTIVE : To study the effects and the underlying mechanism of recombinant human growth hormone (rhGH) and glutamine (Gln) on the adaptation of the remnant small intestine in parenterally nourished, short bowel syndrome (SBS) rats. METHOD : Four parenteral nutrition (PN) treatment groups of SBS rats were randomly arranged in a 2 × 2 factorial design as follows: (i) STD (standard PN) group (–rhGH, –Gln); (ii) Gln group (–rhGH, +Gln); (iii) rhGH group (+rhGH, –Gln); and (iv) rhGH + Gln group (+rhGH, +Gln). Morphological changes of the intestinal mucosa were investigated and the expression of proliferating cell nuclear antigen (PCNA) and the occurrence of apoptosis were observed by immunohistochemical staining and terminal deoxynucleotidyl transfer‐mediated dUTP‐biotin nick end‐labeling (TUNEL) methods. The level of intestinal insulin‐like growth factor‐1 (IGF‐1) mRNA was determined by northern blotting. RESULTS : The mucosal thickness, villous height, crypt depth and villous surface area of the remnant small intestine in the rhGH + Gln group were increased significantly as compared with the other three experimental groups, and there were synergistic effects between rhGH and Gln (P < 0.01). The expression of PCNA was higher in the rhGH + Gln group than in the rhGH, Gln and STD groups (24.95 ± 3.93 vs 19.28 ± 3.25, 17.27 ± 3.38, and 8.37 ± 2.23 positive cells per crypt of Lieberkuhn, respectively; P < 0.01) but the rate of apoptosis was lower in the rhGH + Gln group than in the rhGH, Gln and STD groups (5.68 ± 2.07 vs 8.06 ± 2.33, 10.00 ± 2.24 and 22.32 ± 3.84 positive cells per 100 cells, respectively; P < 0.01). The intestinal IGF‐1 mRNA was also expressed at a higher level in the rhGH + Gln group than in the rhGH, Gln and STD groups (0.73 ± 0.05 vs 0.62 ± 0.04 vs 0.51 ± 0.04 and 0.41 ± 0.22, respectively; P < 0.05). CONCLUSION : The synergistic combination of rhGH and Gln can significantly improve the adaptation of the remnant small intestine in parenterally fed SBS rats. An increase in cell proliferation and a decrease in cell apoptosis are both responsible for the intestinal adaptation. An increase in local IGF‐1 plays an important role in this process.     

Regulation of circulating levels of IGF-I in pregnant rats: changes in nitrogen balance correspond with changes in serum IGF-I concentrations

Serum IGF-I concentrations in rats decrease significantly in late pregnancy. To determine if the reduction in serum IGF-I concentrations is attributable to circulating GH or maternal nutritional status, we investigated the effect of treatment with recombinant human GH (rhGH: 100 microgram/rat per day) on IGF-I concentrations during late pregnancy, and evaluated the relationship between maternal nitrogen balance and IGF-I concentrations. Serum IGF-I concentrations and maternal nitrogen balance ((nitrogen intake)-(nitrogen content in faeces and urine)-(nitrogen content in fetus and placenta)) were measured by RIA and the Dumas method. In non-pregnant rats treated with rhGH for 3 days, serum IGF-I concentrations (835.4+/-59.5 ng/ml; P<0.01) were significantly greater than in those animals treated with saline (319.6+/- 95.6 ng/ml). In the pregnant rats, however, there was no significant difference in serum IGF-I between those treated with rhGH (151. 1+/-43.0 ng/ml) and those treated with saline (142.0+/- 39.9 ng/ml) from day 17 to 19 of pregnancy. Maternal nitrogen balance in the pregnant rats increased significantly from day 4 to day 10 of pregnancy (169.5+/-57.4 and 196.1+/- 33.4 mg/day, respectively; P<0. 05) compared with non-pregnant controls (31.9+/-19.9 mg/day) and decreased markedly from day 12 of pregnancy (79.8+/-60.1 mg/day; P<0. 05) onwards, to 14.9+/-47.8 mg/day on day 20 of pregnancy (P<0.01), significantly different from the value on day 10 of pregnancy. The mean difference in maternal nitrogen balance between pregnant and non-pregnant rats was positively correlated (r=0.87, P<0.01) with the mean difference in maternal IGF-I concentrations, using linear regression analysis. These results support the conclusion that the circulating concentration of IGF-I in pregnant rats is associated with the change in nitrogen balance, but not with circulating GH.     

Growth responses to patterned GH delivery

We have investigated the effects of different patterns of administration of recombinant human growth hormone (rhGH) on weight gain, organ growth, serum GH binding protein (GHBP) and insulin-like growth factor-l (IGF-1) levels in a series of studies using hypophysectomized (Hx) or GH-deficient dwarf (dw/dw) rats. Animals were given rhGH either by subcutaneous (s.c.) injections (1 or 2 per day) or s.c. infusions and rhlGF-1 (2 mg/kg/day) by s.c. infusion. In Hx rats, all rhGH regimes increased body weight, tibial epiphyseal plate width, and organ weights in a dose-related manner. Dwarf rats showed a smaller growth response to rhGH than Hx rats, whereas rhGH induced greater elevations in serum GHBP in drarf rats. Growth responses depended on the pattern of rhGH administration (twice daily injections > continuous infusions > daily injections). The shape of the body growth curves also differed; rhGH injections increased weight gain linearly, whereas infusions gave an initial rapid weight gain which slowed with time (a curvilinear response). For both regimens, tibial epiphyseal plate width increased linearly with rhGH dose but infusions were 5-fold more potent than daily injections. Spleen and thymus weights were markedly increased by rhGH and were also affected by the pattern of GH exposure. At 5 mg rhGH/kg/day, thymus weights were 390±35 mg for injectionsvs. 613 ± 34 mg for infusions (P<0.001) compared with 248 ± 16 mg in vehicle-treated Hx controls. Infusions of rhlGF-1 also stimulated specific organ growth but caused less weight gain. RhlGF-1 additively increased the weight gain caused by rhGH injections but not by rhGH infusions. Circulating IGF-1 and GHBP levels were increased in a dose-dependent manner by rhGH infusion, whereas daily injections were ineffective. Thus, differential organ growth could be related to the higher serum IGF-1 concentrations induced by continuous rhGH administration. These studies show that whole body growth is best maintained by intermittent rhGH exposure, whereas, paradoxically, differential organ growth is most pronounced with continuous rhGH administration.     

Insulin-like growth factor-1 and growth hormone (GH) have distinct and overlapping anabolic effects in GH-deficient rats

The anabolic activity of recombinant human growth hormone (rhGH) and insulin-like growth factor 1 (rhlGF-1) given either alone or together were studied in two models of GH deficiency, hypophysectomized and GH-deficient dwarf rats. A range of rhGH doses (0.08 to 50 mg/kg/day, seven daily sc injections) were given either alone or together with one dose of rhIGF-l (2.4 mg/kg/day, sc infusion). When given alone, or co-administered with rhlGF-1, rhGH produced dose dependent increases in weight gain, bone growth and organ weights. Weight gain in response to rhGH given with rhlGF-1 was comparable to that obtained by a 25-fold higher dose of rhGH given alone. In both animal models absolute weights of the kidneys, liver, spleen and thymus were increased by rhlGF-1 while kidney and liver weight were increased by rhGH. In the hypophysectomized rat, spleen and thymus weights were increased by rhGH but the relative potency of the combination was a 1000-fold that of rhGH alone. The effects of rhlGF-1 and rhGH were additive indicating that the effects of GH or IGF-1 can be greatly increased by their co-administration.     

Protective effects of recombinant human growth hormone on cirrhotic rats

AIM: To investigate the effects and molecular mechanisms of recombinant human growth hormone (rhGH) on protecting liver function and alleviating portal hypertension of liver cirrhotic rats. METHODS: Liver cirrhosis of male Sprague-Dawley rats was induced by administration of thioacetamide. The rats with or without liver cirrhosis were randomly divided into four groups. Group A consisted of the normal rats was treated with normal saline (NS), group B consisted of the normal rats was treated with rhGH, group C consisted of cirrhotic rats was treated with NS, and group D consisted of cirrhotic rats was treated with rhGH. The rats of different groups were subcutaneously injected with 0.5 mL of NS or 333 ng/kg of rhGH daily for 7 d. After treatments, the following parameters were examined, including GH-binding capacity (R(T)) by (125)I-hGH binding, growth hormone receptor mRNA(GHR mRNA) expression by RT-PCR, relative content of collagen (RCC) by histomorphomertry, and level of malon-dialdehyde (MDA) and superoxide dismutase (SOD) in liver tissue by thiobarbituric acid reaction and pyrogallic acid self-oxidation, respectively. Serum albumin (ALB), alanine transaminase (ALT) and portal vein pressure (PVP) were also examined. RESULTS: rhGH up-regulated both the GH-binding capacity (R(T)) and the expression of GHR mRNA in vivo. R(T) in group A (72+/-12 fmol/mg protein) was significantly higher than that in group C (31+/-4 fmol/mg protein) (P<0.05). R(T) in group B (80+/-9 fmol/mg protein) increased markedly compared to group A (P<0.05). R(T) in group D (40+/-7 fmol/mg protein) raised remarkably compared with group C (P<0.05), but less than that in group A, and there was no significant GH binding affinity contrast (Kd) change. The GHR mRNA level (iOD, pixel) in group A (29+/-3) was significantly higher than that in group C (23+/-3) (P<0.05). GHR mRNA levels were significantly raised in group B (56+/-4) and group D (42+/-8) compared with groups A and C (29+/-3 and 23+/-3, respectively) (P<0.05). Compared with the normal liver, MDA level was higher and SOD level was lower in cirrhotic livers. After rhGH treatment, MDA level was significantly declined to 12.0+/-2.2 nmol/mg protein and SOD was raised to 1 029+/-76 U/mg protein in group D (P<0.05). ALB levels in groups B and D (42+/-7 g/L and 37+/-7 g/L, respectively) were significantly raised compared with those in groups A and C (35+/-5 g/L and 29+/-4 g/L, respectively) (P<0.05). ALT level was markedly lower in group D (69+/-7 U/L) compared to group C (89+/-15 U/L) (P<0.05), and close to group A (61+/-10 U/L). RCC in group C (22.30+/-3.86%) was significantly higher than that in group A (1.14+/-0.21%) and group D (14.70+/-2.07%) (P<0.05). In addition, rhGH markedly alleviated portal hypertension in liver cirrhotic rats (group D vs C, 9.3+/-1.5 cmH(2)O vs 14.4+/-2.0 cmH(2)O) (P<0.05). CONCLUSION: Pharmacological doses of rhGH can increase R(T) and GHR mRNA expression, ameliorate liver functions, repress fibrosis and decline portal hypertension, suggesting it has potentially clinical usage as a hepatotropic factor.     

Combined human growth hormone and lactulose for prevention and treatment of multiple organ dysfunction in patients with severe chronic hepatitis B

AIM: To evaluate the efficiency and safety of combined recombinant human growth hormone (rhGH) and lactulose for treatment and/or prevention of multiple organ dysfunction in patients with chronic severe hepatitis B. METHODS: Forty-eight inpatients with chronic severe hepatitis B were randomly divided into rhGH group (n = 28) and control group (n = 20). In rhGH group, 4-4.5 IU of rhGH was injected intramuscularly once daily for 2-4 wk, and 100 mL of enema containing 30 mL of lactulose, 2 g of metronidazole and 0.9% saline was administered every 2 d for 2-4 wk. Their symptoms and complications were noted. Liver and kidney functions were analyzed by an Olympus analyzer. Serum GH, IGF-1, IGFBP1 and IGFBP3 were measured by ELISA. RESULTS: Clinical symptoms of 90% of these patients in rhGH group were obviously improved. The total effectiveness in rhGH group was better than that in control group (75% vs 40%, P<0.05). After 2- and 4-wk treatment of rhGH respectively, serum albumin (26.1±4.1 vs 30.2±5.3, 31.9±5.1 g/L), prealbumin (79.6±28.0 vs 106.6±54.4, 108.4±55.0 g/L), cholesterol (76.3±16.7 vs 85.6±32.3, 96.1±38.7 mg/dL), and IGFBP1 (56.8±47.2 vs 89.7±50.3 ng/mL after 2 wk) were significantly increased compared to control group (P<0.05). However, serum GH was decreased. The increase of serum IGF1 and IGFBP3 after rhGH treatment was also observed. CONCLUSION: rhGH in combination with lactulose may be beneficial to the prevention and treatment of multiple organ dysfunction in patients with chronic severe hepatitis.     

Acute effects of insulin-like growth factor-1 and recombinant growth hormone on liporotein(a) levels in baboons

Elevated lipoprotein(a) [Lp(a)] is an established factor for coronary artery disease (CAD) that acts possibly by increasing cholesterol deposition in arterial wall and promoting thrombosis. The only known Lp(a)-lowering agents, niacin and neomycin, often produce intolerable side effects. We observed that administration of growth hormone (GH) increases but insulin-like growth factor-1 (IGF-1) decreases Lp(a) levels in patients with GH deficiency. To explore the mechanisms for the hormonal effects and to search for an effective pharmaceutical agent, we examined the suitability of the baboon as an animal model by investigating the effects of GH and IGF-1 on Lp(a). We selected 5 baboons with high (group 1) and 5 with low (group 2) Lp(a) levels. Group 1 baboons first received a bolus subcutaneous injection of IGF-1 (300 microg/kg body weight). After a period of 7 days, they were given a bolus infusion of recombinant human (rh)GH (300 microg/kg body weight). For group 2 baboons, the order of injection was reversed, and rhGH was given first and followed by IGF-1. Blood samples were collected during the day before and for 3 days following each injection. Levels of plasma Lp(a), insulin, GH, and IGF-1 were measured for each time point. While rhGH appeared not to raise Lp(a) levels among baboons with extremely low levels (6.8 +/- 1.1 mg/dL at baseline v 6.6 +/- 0.9 mg/dL, n = 5), IGF-1 significantly reduced Lp(a) levels among those with high levels within 2 hours of injection (57.0 +/- 6.6 mg/dL v 37.4 +/- 6.2 mg/dL, or a 34% reduction, n = 3, P =.013). Our study for the first time demonstrated that IGF-1 can lower plasma Lp(a) levels by more than 30% within 2 hours in baboons and the effects are sustained for at least 1 week. The effect is likely mediated through increased Lp(a) degradation, but the responsible organs remain to be identified. On the other hand, rhGH appeared to have no effect on those animals with very low Lp(a) levels.     

Chronic treatment by the calcium channel blocker +/- PN 200-110 in the rat counteracts the stimulations of pituitary weight, prolactin release and pituitary C-kinase activity induced by a chronic estradiol treatment, in vivo

In order to investigate whether a calcium channel blocker could modulate the protein kinase C activity in normal and estradiol pretreated rat pituitary, female Wistar rats were treated or not (controls) with +/- PN 200-110 (3 mg.kg-1.day-1, sc) for 8 days or with estradiol cervical implants for 8 or 15 days, alone or in combination with PN 200-110 the last 8 days. Estradiol treatment induced a significant increase in plasma prolactin levels and pituitary weight. PN 200-110 administered to normal rats did not modify these parameters, whereas it reduced the effects of the 15 days estradiol treatment on prolactin levels (53.1 +/- 4.9 vs 95.0 +/- 9.1 micrograms/l, p less than 0.0001) and pituitary weight (19.9 +/- 0.4 vs 23.0 +/- 0.6 mg, p less than 0.001), to values statistically comparable to those measured after 8 days of estradiol treatment. PN 200-110 alone did not induce any change in protein kinase C activity as compared with controls. In contrast, PN 200-110 treatment significantly counteracted the large increase in soluble activity and the decrease in the particulate one induced by estradiol between day 8 and day 15. We conclude that PN 200-110 opposed the stimulatory effects of chronic in vivo estradiol treatment on plasma prolactin levels and pituitary weight and that this regulation was related to a concomitant modulation of the protein kinase C activity.     

重组人生长激素和骨髓间质干细胞移植联合治疗阿霉素性心肌病心力衰竭的实验

目的 对比重组人生长激素(rhGH)与骨髓间质干细胞(MSCs)单用或联用对阿霉素性心肌病心力衰竭(心衰)大鼠的疗效.方法 将Wistar大鼠分为正常组6只、心衰组9只、rhGH组6只、MSCs组7只和rhGH与MSCs联合治疗(G+M)组7只.MSCs移植经心肌内点状注射,rhGH2 mg/kg,隔日1次,皮下注射.1个月后行左室功能、全心质量指数(HW/BW)及左室质量指数(LW/BW)测定.免疫组化观察MSCs在心肌内的分布,聚丙烯酰胺凝胶电泳分离心肌肌球蛋白重链(MHC)同工酶V1和V3型.治疗前后测定血清生长激素(GH)和B型利钠肽(BNP)浓度.结果 与心衰组比较,MSCs组心功能各指标均无有统计学意义的改变,rhGH组左室收缩压和左室内压力最大上升速率升高,G+M组左室收缩压和左室内压力最大上升及下降速率均升高,均为P<0.05.三个治疗组HW/BW和LW/BW均较心衰组有降低,但P>0.05.G+M组心肌内MSCs数量多于MSCs组.与心衰组比较,rhGH组V1型MHC(V1)、v3型MHC(V3)、V1/V3比值差异无统计学意义,MSCs组V3增加,G+M组V1和V3增加,均为P<0.05;与rhGH组比较,MSCs组V3增加,G+M组V1和V3均增加,均为P<0.05;与MSCs组比较,G+M组V1增加,P<0.05.GH水平在治疗前均较正常组降低,P<0.05;治疗后均较心衰组增高,P<0.05,但仅接近正常水平,各组间比较差异无统计学意义.BNP水平在治疗前均较正常组升高,P<0.05;治疗前后比较,rhGH组和G+M组差异有统计学意义,P<0.05和P=0.001.结论 rhGH治疗可改善阿霉素性心肌病心衰大鼠的心脏收缩功能,MSCs移植未见明显疗效;二者联合治疗可提高MSCs存活率,增加MHC含量,改善心脏收缩和舒张功能.     

Synergistic action of famotidine and chlorpheniramine on acetic acid-induced chronic gastric ulcer in rats

AIM: To assess the synergistic action of famotidine (FMD) and chlorpheniramine (CPA) on acetic acid-induced chronic gastric ulcer in rats. METHODS: Chronic gastric lesions were induced in male Sprague-Dawley (SD) rats by serosal application of the acetic acid. Forty SD rats were randomly divided into blank group (n=8), control group (n=8), FMD group (n = 8), CPA group (n=8), and FMD+CPA group (n=8). Each group was given intraperitoneally (i.p.) 0.5 mL/100 g distilled water, 9 g/L NaCl saline, 4 mg/kg FMD, 10 mg/kg CPA, 4 mg/kg FMD+10 mg/kg CPA, respectively, daily for 10 d. On d 10, ulcer area was determined by planimetry. The level of myeloperoxidase (MPO) in the liver homogenation was determined by biochemical methods and the plasma levels of 6-ketoprostaglandin F1 alpha (6-keto-PGFia) and IL-8 were determined by radioimmunoassay. RESULTS: The synergistic effects of FMD+CPA group on the lesion, IL-8, 6-keto-PGFia and MPO were confirmed. The effect of FMD+CPA group was significantly different as compared to the control and FMD groups. The lesion (mm2) was reduced from 40.18±2.6 in control group to 6.83±2.97 in PMD+CPA group, P<0.01, and from 32.9±3.27 in FMD group to 6.83±2.97 in PMD+CPA group, P<0.01. The plasma levels of IL-8 decreased from 0.69±0.11 ng/L in control group to 0.4±0.04 ng/L in PMD+CPA group, P<0.01, and from 0.51±0.08 ng/L in FMD group to 0.4±0.04 ng/L in PMD+CPA group, P<0.05. The level of 6-keto-PGFia increased from 7.55±1.65 ng/L in control group to 16.62±0.97 ng/L in PMD+CPA group, P<0.01, and from 13.15±1.48 ng/L in FMD group to 16.62±0.97 ng/L in PMD+CPA group, P<0.05. The levels of MPO in the liver homogenate decreased from 9.12±2.05 u/L in control group to 4.33±0.95 u/L in PMD+CPA group, P<0.01, and from 8.3±1.29 u/L in FMD group to 4.33±0.95 u/L, P<0.01. CONCLUSION: The synergistic action of FMD and CPA on acetic acid-induced chronic gastric ulcer in rats decreases the incidence of ulcer and also enhances the healing of ulcer.     

Influence of beta-2 adrenergic receptor gene polymorphism on the hemodynamic response to propranolol in patients with cirrhosis

The beta-2-adrenergic receptor (beta(2-)-AR) has several single-nucleotide polymorphisms. These influence the functional response to adrenergic stimulation; genotypes homozygous for Gly16-Glu27 or Gly16-Gln27 alleles (Gly16-Glu/Gln27 haplotypes) are associated with enhanced response, whereas genotypes homozygous for Arg16-Gln27 alleles (Arg16-Gln27) show a decreased response. We hypothesized that gene polymorphisms at the beta2-AR may influence the hemodynamic response to propranolol in patients with cirrhosis. The beta2-AR gene polymorphisms were determined by direct sequencing of the polymerase chain reaction (PCR) products in 48 patients with cirrhosis. All patients also had hepatic and systemic hemodynamic studies before and after propranolol administration. Prevalence of Gly16-Glu/Gln27 haplotypes was 29.1%, Arg16-Gln27 haplotype was 16.7%, and 54.2% were compound heterozygotes. Patients with cirrhosis with Gly16-Glu/Gln27 haplotypes had a greater decrease in heart rate, cardiac index, and hepatic blood flow after propranolol administration than those with Arg16-Gln27 haplotype. However, the HVPG response to propranolol was similar in both groups, whereas estimated hepatic sinusoidal resistance increased significantly in Gly16-Glu/Gln27 haplotypes but not in Arg16-Gln27 (+27.1 +/- 17.8% vs -17.9 +/- 13.9%, P = .042), suggesting that unopposed vasoconstrictive activity at the intrahepatic circulation hinders the fall in HVPG despite enhanced hemodynamic response to propranolol in Gly16-Glu/Gln27 haplotypes. In conclusion, beta2-AR gene polymorphisms influence the response to beta-blockade. However, HVPG reduction cannot be predicted from polymorphism analysis. Patients with the Gly16-Glu/Gln27 haplotypes may benefit from the association of hepatic vasodilators to propranolol therapy.     

The combination of insulin-like growth factor 1 and osteogenic protein 1 promotes increased survival of and matrix synthesis by normal and osteoarthritic human articular chondrocytes

OBJECTIVE: Although growth factor therapy could be an attractive method for stimulating the repair of damaged cartilage matrix, there is evidence that with aging and/or with the development of osteoarthritis (OA), articular chondrocytes may become unresponsive to growth factor stimulation. The aim of the current study was to compare the ability of insulin-like growth factor+(IGF-1) and osteogenic protein+(OP-1), alone and in combination, to stimulate human normal and OA chondrocytes in culture. METHODS: Chondrocytes isolated by enzymatic digestion of cartilage obtained from subjects undergoing knee replacement for OA (n = 6) or from normal ankle joints of tissue donors (n = 7) were cultured in alginate beads in serum-free medium and treated for 21 days with 100 ng/ml IGF-1, 100 ng/ml OP-1, or both. Controls were treated with vehicle alone. The cultures were evaluated for cell survival, cell number by DNA analysis, matrix production by particle exclusion assay, and level of accumulated proteoglycan by dimethylmethylene blue assay. RESULTS: After 21 days in serum-free alginate culture, survival of cells from OA cartilage was 65 +/- 2% (mean +/- SEM), while survival of cells from normal cartilage was significantly greater (82 +/- 3%). Treatment with either IGF-1 or OP-1 alone minimally improved survival, while the combination IGF +OP significantly improved survival, to 87 +/- 2% for OA cells and 95+/-1% for normal cells. Cell proliferation was noted only in the IGF+OP group; this was significant for both normal and OA cells ( approximately 2-fold increase in DNA levels). Matrix production, assessed by particle exclusion and by proteoglycan accumulation, was greatest in the cells treated with IGF + OP in both normal and OA cultures. When proteoglycan levels were corrected for cell numbers (mg proteoglycan/ng DNA), a significant increase over control was noted with OP-1 alone and IGF IGF-1 alone, in both normal and OA cultures, with the greatest levels in the combination group (3-fold increase over control). CONCLUSION: OP-1 was more potent than IGF-1 in stimulating proteoglycan production in both normal and OA cells. However, the best results were obtained with the combination, suggesting that combined therapy with IGF-1 and OP-1 may be an effective strategy for treating OA cartilage damage.     

Testosterone stimulates growth of tibial epiphyseal growth plate and insulin-like growth factor-1 receptor abundance in hypophysectomized and castrated rats

Puberty is associated with an increased in the plasma concentration of sex steroids, growth hormone (GH), and insulin-like growth factor-1 (IGF-1). Gonadal steroid hormones are important for the normal pubertal growth spurt and skeletal growth. The mechanism by which gonadal steroids induces skeletal growth is still not fully understood. To study the GH-independent effect of testosterone on growth, we investigated the effect of testosterone injections on the tibial epiphyseal growth plate (EGP) in an in vivo model of hypophysectomized and castrated male rats. Four groups (six animals each) of 28-d-old male rats were studied. Groups A, B, and C were hypophysectomized and castrated and received 500 μg/(kg·d) of hydrocortisone and 15 μg/(kg·d) of levothyroxine sodium. Groups A and B were also treated with daily sc injections of 10 μg of testosterone/100 g of body wt, and 100 μg of testosterone/100 g of body wt, respectively, for 7 d. Group C was injected with vehicle alone. Group D were intact animals injected with saline (controls). Animals were sacrificed on 8 d. As expected, serum GH levels were found to be very low (1.13±0.1 ng/mL) in the hypophysectomized animals (group C, hypopit), and testosterone treatment did not change them significantly. Serum IGF-1 decreased from 502.9± 13 ng/mL in group D to 167±41.4 ng/mL in group C (p<0.001). Testosterone therapy had no stimulatory effect on serum IGF-1 levels in the hypopit + low-dose group (A) (220±94.8 ng/mL) and had an inhibitory effect in the hypopit + high-dose group (B) (39.3±17.5). Histomorphometric determinations demonstrated an EGF width of 472.3±39 μm in the intact animals but only 336.9±1.6 μm in the hypopit group (C) (p<0.01). High-dose testosterone treatment (group B) significantly increased the EGP width (to 438.8±27.8), (p<0.001), whereas low-dose testosterone (group A) did not. Immunohistochemistry studies revealed that the levels of IGF-1 in the EGP of the control animals were almost negligible and that testosterone did not change them. However, testosterone increased in a dose-dependent manner the abundance of IGF-1 receptor EGP. We conclude that testosterone has a direct, local, GH-independent effect on the EGP growth and IGF-1 receptor abundance.     

Insulin-like growth factors (IGF) 1 and 2 in human foetal plasma and relationship to gestational age and foetal size during midpregnancy

IGF-1 and IGF-2 were measured by specific radioimmunoassay after acid-ethanol extraction of plasma obtained by foetoscopy from 20 normal foetuses aged 15-23 weeks. IGF-1 and IGF-2 levels were 36 +/- 11 and 162 +/- 55 ng/ml, respectively. In comparison, levels in cord blood were 84 +/- 58 and 264 +/- 176 ng/ml, respectively, and in adult plasma were 410 +/- 106 and 818 +/- 272 ng/ml. Both IGF-1 and IGF-2 were in the normal foetal range in a further three foetuses with anencephaly and two foetuses with spina bifida. No sex difference was observed. IGF-1 was positively correlated with foetal body weight (P less than 0.001), placenta weight (P less than 0.02) and with body length measured crown-rump (P less than 0.01) or crown-heel (P less than 0.02). No correlation between IGF-2 and body weight, length, placenta weight or gestational age was found. Both IGF-1 and IGF-2 are present in the human foetal circulation earlier in gestation than has previously been demonstrated, the levels being low throughout this period of gestation in comparison with adult plasma.     

Administration of recombinant human growth hormone normalizes GH-IGF1 axis and improves malnutrition-related disorders in patients with anorexia nervosa

High serum level of GH in the presence of low plasma level of insulin-like growth factor-I (IGF-I) is one of the endocrinological features of anorexia nervosa (AN). Whether the amount of endogenous GH is not enough to increase IGF-I is not certain. We studied the effect of recombinant human growth hormone (rhGH) on the GH-IGF-I axis and on malnutrition-related disorders in this syndrome. Twenty patients with AN were divided into two groups; one (N = 13) was given rhGH (0.33 mg/day), and the other (N = 7) was given placebo for 6 or 12 months, respectively. During each treatment, levels of serum GH, plasma IGF-I, serum thyroid hormones, serum cholesterol, fasting plasma glucose and cardiac function were monitored. Changes in body mass index (BMI) and calorie taken were also evaluated. Plasma IGF-I level increased from 74.4 +/- 41.9 to 269.0 +/- 31.2 microg/L (P<0.001) during administration of rhGH, which associated with a decrease in serum GH level from 17.0 +/- 15.0 to 1.6 +/- 0.8 microg/L (P<0.001). Administration of rhGH increased BMI, body temperature, fasting plasma glucose level, and food intake. Serum level of triiodothyronine, but not thyroxine, increased during treatment with rhGH. The treatment decreased serum levels of both total and HDL-cholesterol. Studies with echocardiography showed an increase in cardiac output during the treatment with rhGH. These improvements were not observed in patients treated with placebo. Administration of rhGH is recommended as one of the methods of managing the patients with AN.     

The negative GH auto-feedback in childhood: effects of rhGH and/or GHRH on the somatotroph response to GHRH or hexarelin, a peptidyl GH secretagogue, in children

Aim of the present study was to further clarify the negative GH auto-feedback mechanisms in childhood. To this goal we studied the effects of rhGH and/or GHRH administration on the GH response to GHRH or hexarelin (HEX), a peptidyl GH secretagogue, in normal short children. In 34 prepubertal children (12 girls and 22 boys, age 8.2- 14.2 yr) with normal short stature (normal height velocity and IGF-I levels) the following tests were performed: group A (no.=11): GHRH (GHRH 1 - 29, Geref, Serono; 1 microg/kg iv at 150 min) preceded by saline or GHRH at 0 min; group B (no.=6): GHRH preceded by saline or rhGH (0.005 IU/kg iv at 0 min); group C (no.=6): GHRH preceded by rhGH alone or combined with GHRH; group D (no.=6): HEX (2 microg/kg iv at 150 min) alone or preceded by rhGH. In group A, the GH response to GHRH was not modified by pre-treatment with GHRH (GH peak, mean+/-SEM: 16.7+/-2.9 vs 15.1+/-2.3 microg/l, respectively). In group B, the GH response to GHRH was clearly inhibited by rhGH (8.7+/-2.3 vs 38.8+/-4.5 microg/l, p<0.001); the GH rise after rhGH in group B overlapped with that after GHRH in group A. In group C, the GH response to GHRH after pre-treatment with rhGH (13.2+/-4.0 microg/l) was similar to that in group B and was not significantly modified by pre-treatment with rhGH+ GHRH (6.9+/-2.7 microg/l); the GH rise after rhGH+GHRH was higher (p<0.05) than that after rhGH alone. In group D, the GH response to HEX was significantly blunted by pre-treatment with rhGH (34.1+/-11.7 vs 51.2+/-17.9 microg/l, p<0.05). Our results demonstrate that in childhood the somatotroph response to GHRH is preserved after GHRH while it is inhibited after rhGH administration, which is also able to blunt the GH response to HEX. Thus, the somatostatin-mediated negative GH auto-feedback is already operative in childhood; the reason why the GHRH- induced GH rise is not inhibited by GHRH pre-treatment is unexplained.     

Changes in free insulin-like growth factor-1 and leptin concentrations during acute metabolic decompensation in insulin withdrawn patients with type 1 diabetes.

To determine the effect of acute insulin withdrawal and its subsequent replacement on components of the insulin-like growth factor (IGF)-1 binding protein system and on circulating leptin levels in patients with type 1 diabetes. Seventeen patients (age 31 yr +/-10) with type 1 diabetes treated with continuous subcutaneous insulin infusion (HbA1c 7.6% +/-1.0) were studied. The protocol consisted of two phases: acute insulin withdrawal of up to 8 h followed by a further 2-h period of insulin replacement. For the first phase the basal insulin infusion was stopped (at 0300 h), and for the second a single dose of either regular human or insulin lispro was given subcutaneously (0.2 U/kg). Plasma insulin, glucose, growth hormone, glucagon, IGF-1, free IGF-1, IGFBP-1, -2, -3 and leptin were measured. Results: After interruption of the basal insulin infusion, plasma free insulin levels fell from 60+/-12.0 pmol/L to 10.8+/-4.2 pmol/L, and plasma glucose rose from 5.6+/-0.4 mmol/L to 14.8+/-1.2 mmol/L (P< 0.01). During insulin withdrawal, IGFBP-1 increased by more than 6-fold (from 32+/-8 to 205+/-17 ng/mL, P<0.001), IGFBP-3 increased significantly (from 2631+/-118 to 3053+/-101 ng/mL, P<0.001), and total IGF-1 levels declined modestly (from 226+/-33 to 182+/-26 ng/mL, P<0.001). In contrast, free IGF-1 concentrations (0.72+/-0.22 ng/mL at baseline) were markedly suppressed during insulin withdrawal to values below the detection limit of the assay (0.08 ng/mL) in 15 of the 17 patients (P<0.001). Circulating plasma leptin declined markedly in females from 20+/-3 ng/mL to 11+/-2 ng/mL (P<0.0001) and in males from 10+/-2 ng/mL to 7+/-2 ng/mL (P<0.02). Within 2 h of insulin replacement, the changes in circulating concentrations of IGFBP-1 and IGFBP-3 were partially reversed, and free IGF-1 levels rebounded to 0.54+/-0.22 ng/mL (P<0.1 vs. insulin withdrawal). Growth hormone, glucagon, and IGFBP-2 levels did not change significantly throughout the study. Despite the rapid restoration of plasma insulin and substrate levels, circulating leptin levels continued to fall in the 2-h period after insulin replacement in both females and males. The marked reduction in circulating free IGF-1 after insulin withdrawal and its increase after insulin administration suggest that acute changes in IGFBP concentrations induced by insulin are important regulators of IGF-1 bioavailability in patients with type 1 diabetes. In both males and females, the rapid induction of severe insulin deficiency is associated with a consistent fall in plasma leptin levels.     

2-Tetradecylglycidic acid, an inhibitor of carnitine palmitoyltransferase-1, induces myocardial hypertrophy via the AT1 receptor.

Activation of the antiogensin II, type 1 (AT1) receptor mediates the myocardial response to numerous hypertrophic stimuli. This study tested the hypothesis that 2-tetradecylglycidic acid (TDGA), an oxirane carboxylate inhibitor of mitochondrial carnitine plamitoyltransferase-1, induces myocardial hypertrophy via the AT1 receptor system. Male Sprague-Dawley rats treated with 10 mg TDGA/kg/day for 7 days had a heart wet weight:body weight ratio of 3. 58+/-0.16 mg/g compared with a ratio of 2.79+/-0.07 for rats treated with vehicle (P<0.05). The plasma level of antiogensin II was 117. 75+/-17.39 pg/ml in rats treated with 10 mg TDGA/kg/day compared with 54.0+/-11.38 pg/ml for rats treated with vehicle (P<0.05). The plasma level of angiotensin I in these two groups of rats was not different statistically. Rats treated with TDGA and given drinking water containing 1 mg losartan/ml had a heart wet weight:body weight ratio of 2.84+/-0.05 mg/g. This value was not statistically different from the value measured in rats given drinking water containing 1 mg losartan/ml and treated with vehicle alone. No significant difference in the heart wet weight:dry weight ratio occurred among these groups of rats. Finally, treating rats with TDGA or giving rats drinking water that contained 1 mg losartan/ml altered neither their heart rate nor their mean arterial blood pressure when compared with untreated rats. This data, therefore, suggests that oxirane carboxylates induce myocardial hypertrophy by activating the AT1 receptor independent of changes in systemic hemodynamics.