GRS '98 Abstracts 333 evaluated for IGF-I and IGFBP-3. Baseline characteristics for the group overall (ALL), as well as for MK-0677 low responder (LS; peak Gt-I<5 ng/ml) and high responder (HS;) strata (peak GH >5 ng/ml) are shown. MK-677 Age Stim.test IGF-I IGFBP3 Peak GH (years) GH (ng/ml) (ng/ml) (r~g/m/) (ng/ml) ALL 74 8,5 (2.7) 5.3 (3.5) 73 (59) 1.7 (1,1) 32 (35) HS 50 8.1 (2.5) 7.0 (3.0) 96 (58) 2.2 (1.0) 45 (35) LS 24 9.3 (3.0) 1.9 (1.4) 25 (13) 0.8 (0.3) 3 (1) mean (SD); n=71, 48, 23 for All, HS and LS Peak GH level after stimulation with a single dose of MK-0677 provides information consistent with other methods of assessing the GH axis in GHDC. Use of a peak stimulated value <5 ng/ml appears to select for a subset of more severely GHDC. [Funded by Merck & Co., Inc.] P-13 TREATMENT OF OBESE SUBJECTS WITH THE ORAL GROWTH HORMONE (GH) SECRETAGOGUE MK-677 DOES NOT INCREASE LIPOPROTEIN(A) CONCENTRATIONS J Svensson ~, M Ottosson 2 J-O Jansson ~, O Wiklund2, B-A Bengtsson I. ~Research Centre for Endocrinology and Metabolism; 2 Wallenberg Laboratory, Sahlgrenska University Hospital, GOteborg, Sweden. Obesity is associated with a blunted growth hormone (GH) secretion and an unfavorable lipoprotein pattern. The objective of this study was to investigate the effects of treatment with the oral GH secretagogue MK-677 on lipoproteins in otherwise healthy obese males. The effect of MK-677 on lipoprotein(a) [Lp(a)] is of special interest since it has been suggested that the mode of GH administration is of importance for the increase in Lp(a) observed during GH treatment and that MK-677 release GH more physiologically than a subcutaneous injection of GH. The study was randomized, double-blind, parallel, and placebo- controlled. Twenty-four obese males, aged 18 to 50 years, with BMI > 30 kg/m 2 and waist:hip ratio >0.95 were treated with MK- 677 25 mg (n=12) or placebo (tt=12) daily for 8 weeks. Serum Lp(a) as well as total cholesterol (TC) was not significantly changed by MK-677 treatment at 2 and 8 weeks (P=NS vs placebo). Serum HDL-cholesterol and triglycerides were increased at 2 weeks of MK-677 treatment (P<0.01 and P<0.05 vs placebo, respectively), but not at 8 weeks. Mean LDL-choles- terol (LDL-C) was not significantly changed while LDL-C/TC ratio was significantly reduced at 2 and 8 weeks (P<0.05 vs placebo). Apolipoproteins A-I and E were significantly increased at 2 weeks (/~0.001 and /M0.01, respectively) but were not changed at study end. In conclusion, 8 weeks of MK-677 treat- merit did not significantly increase Lp(a). MK-677 treatment did not significantly reduce LDL-C, but LDDC in relation to TC was decreased. II GH ACTION P-14 INVOLVEMENT OF MITOGEN-ACTIVATED PROTEIN KINASE (MAPK AND THE INSULIN-LIKE GROWTH FACTOR-I RECEPTOR (IGF-IR) IN APOPTOSIS CEH Stewart ~, EJ Griffiths 2 JMP HollyL University Divisions of ~Surgery & 2Cardiac Surgery, Level7, Bristol Royal Infirmary, Bristol, England, UK. Since the IGFs are capable of blocking apoptosis in many cell lines in vitro, we have investigated the roIe of the IGF-IR in con- veying this protective effect. IGF-IR positive, negative and mutant fibroblasts were induced to undergo apoptosis in the presence of increasing doses of the sphingolipid analogue, C2 ceramide. Despite this apoptotic cell death, all cells showed enhanced activity as assessed by MTT assay, and all cells showed MAPK activation even in the absence of the IGF-I receptor. In order to determine whether the increased activity was due to enhanced metabolism or mitochondrial activity, we repeated the assays in the presence cytochalasin B or dihydro-cytochalasin B. We found that ceramide-induced MTT activation occun'ed regardless of glucose uptake. However, signalling to MAPK was found to be important for increased MTT activity. Assessment of mitochondrial function via NADH fluorescence suggested that ceramide was eliciting its effects by altering respiratory chain activity Results in IGF-IR mutant cells indicated that MAPK sig- nalling to mitochondria occurred via interaction with the IGF- IR. Together these data suggest that cross talk exists between sphingolipid and MAPK signalling pathways and culminate in mitochondrial activity and apoptosis. [Zeneca Pharmaceuticals and MRC.] P-15 THE ROLE OF GH/IGF-I/CAMP/PROTEIN KINASE A AXIS IN THE CONTROL OF APOPTOSIS AND SECRETORY ACTIVITY OF BOVINE OVARIAN GRANULOSA CELLS A Sirotkin ~, A Makarevich 1, P-G Marnet 2, L Hetenyi l, J BullaL tRes. Inst. Anim. Prod., Nitra, Slovakia; 2INRA/ENSAR, Rennes, France. The aim of our work was to study the inter-relationships between GH, IGF-I, cAMP and protein kinase A (PKA), as well as the role of these substances in control of apoptosis and secretory activity of cultered bovine ovarian cells. Apoptosis was evaluated using TUNEL method, the release of substances into the medium was measured using RIA/IRMA, the level of PAK in the cells was evaluated using Western blotting and immuno- histochemistry. It was observed that addition of bGH signifi- cantly stimulated 1GF-I, cAMP and PAK production by cultured granulosa cells in a dose-dependent or a bell-shaped manner. IGF-I had the effects similar to GH. Both GH, IGF-I, dbcAMP and forskolin (stimulators of PAK) inhibited apoptosis and stimuIated release of IGF-I, progesterone, estradiol, oxytocin, prostaglandin F2-c~,and cAMP by these cells. Moreover, addition of Rp-cAMPS and KT5720 (inhibitors of PICA) reduced intracel- lular PKA level, and fully or partially blocked effects of GH and IGF-I mentioned above. The data suggest the existence of GH/IGF-IcAMP/PKA axis which prevents apoptosis and stimulates the secretion of peptide and steroid hormones and prostaglandin by bovine ovarian cells. P-16 THE ANABOLIC EFFECT OF RECOMBINANT GROWTH HORMONE (GH) ON OSTEOBLASTS IN DISTRACTION OSTEOGENESIS MAY BE IGF-I MEDIATED H Bail1, S Kolbeck ~, K Stosch-Wiechert ~, IA Roenne 2, PM Haar 2, CH Skjaerbaeck 3, K Raun 2, M RaschkeL ~Tranma & Reconstructive Surge1% Chart*e, Humboldt University Berlin, Germany; 2Novo Nordisk A/S, Gentofte, Denmark; 3Institute of Experimental Clinical Research and Medical Department M, University of Aarhus, Denmark. GH stimulation on mesenchylnal tissues is mediated by IGF-I. Osteoblastic activity is measured by the serum activity of [5-APa marker for bone formation. The GH-effect on serum IGF-I and [3-AP levels was investigated in an animal model of distraction osteogenesis. Methods: distraction osteogenesis was performed in 24 micropigs. 12 animals received a daily injection of rpGH (100 g/kg). The legs were distracted 2 ram/day for 10 days and consolidated for 10 days. 14 blood samples were taken during the 25-day experiment. [3-AP activity was determined by a RIA, IGF-I levels by immunofluorometric assay. ANOVA was per- formed on [5-AP and IGF-I levels between both groups. Linear regression analysis was computed to determine the correlation between the parameters. Resuks: throughout the experiment, levels of b-AP (90.7 + 30.7 U/l) and IGF-I (610.5 +_ 198.5 g/l) were