The Effect of Prestudy Insulin Therapy on Safety and Efficacy of Human Regular U-500 Insulin by Pump or Injection: A Posthoc Analysis.

OBJECTIVE: We conducted a posthoc analysis of the VIVID study (Safety and Efficacy of Human Regular U-500 Insulin Administered by Continuous Subcutaneous Insulin Infusion Versus Multiple Daily Injections in Subjects With Type 2 Diabetes Mellitus: A Randomized, Open-Label, Parallel Clinical Trial), comparing 2 delivery methods of human regular U-500 insulin (U-500R), continuous subcutaneous insulin infusion (CSII) versus multiple daily injection (MDI), in type 2 diabetes requiring high insulin, to determine influence of prestudy insulin on glycemic outcomes. METHODS: We compared A1C, total daily insulin dose (TDD), weight, and hypoglycemia by subgroups of prestudy insulin (prestudy U-500R vs non-U-500R) and treatment (CSII vs MDI). RESULTS: At baseline, prestudy U-500R had higher TDD, higher body mass index, lower A1C and fasting plasma glucose, and higher rate of hypoglycemia compared to non-U-500R. Active titration of U-500R reduced A1C in both subgroups, with maximum benefit at 8 weeks. At 26 weeks, CSII provided the greatest reduction in A1C in both subgroups, with a greater reduction in non-U-500R. MDI provided an A1C reduction in both subgroups, with the greater reduction in non-U-500R. At 8 weeks, prestudy U-500R reached its lowest A1C; thereafter, A1C rebounded with MDI and remained stable with CSII. In non-U-500R, A1C continued to decrease to study end. In non-U-500R, hypoglycemia increased during active titration, but then decreased in the posttitration maintenance period. In both subgroups, TDD increased from baseline with MDI but not with CSII. Body weight increased in both subgroups but was greater in prestudy U-500R with CSII compared to MDI. CONCLUSION: Regardless of previous insulin, people on high-dose insulin could lower A1C with U-500R, with additional benefit from CSII. These results may provide guidance for use of U-500R in clinical practice.

The cytokine GDF15 signals through a population of brainstem cholecystokinin neurons to mediate anorectic signalling.

The cytokine, GDF15, is produced in pathological states which cause cellular stress, including cancer. When over expressed, it causes dramatic weight reduction, suggesting a role in disease-related anorexia. Here, we demonstrate that the GDF15 receptor, GFRAL, is located in a subset of cholecystokinin neurons which span the area postrema and the nucleus of the tractus solitarius of the mouse. GDF15 activates GFRALAP/NTS neurons and supports conditioned taste and place aversions, while the anorexia it causes can be blocked by a monoclonal antibody directed at GFRAL or by disrupting CCK neuronal signalling. The cancer-therapeutic drug, cisplatin, induces the release of GDF15 and activates GFRALAP/NTS neurons, as well as causing significant reductions in food intake and body weight in mice. These metabolic effects of cisplatin are abolished by pre-treatment with the GFRAL monoclonal antibody. Our results suggest that GFRAL neutralising antibodies or antagonists may provide a co-treatment opportunity for patients undergoing chemotherapy.

The metabolic effects of GDF15 are mediated by the orphan receptor GFRAL.

Growth/differentiation factor 15 (GDF15), also known as MIC-1, is a distant member of the transforming growth factor-ß (TGF-ß) superfamily and has been implicated in various biological functions, including cancer cachexia, renal and heart failure, atherosclerosis and metabolism. A connection between GDF15 and body-weight regulation was initially suggested on the basis of an observation that increasing GDF15 levels in serum correlated with weight loss in individuals with advanced prostate cancer. In animal models, overexpression of GDF15 leads to a lean phenotype, hypophagia and other improvements in metabolic parameters, suggesting that recombinant GDF15 protein could potentially be used in the treatment of obesity and type 2 diabetes. However, the signaling and mechanism of action of GDF15 are poorly understood owing to the absence of a clearly identified cognate receptor. Here we report that GDNF-family receptor α-like (GFRAL), an orphan member of the GFR-α family, is a high-affinity receptor for GDF15. GFRAL binds to GDF15 in vitro and is required for the metabolic actions of GDF15 with respect to body weight and food intake in vivo in mice. Gfral-/- mice were refractory to the effects of recombinant human GDF15 on body-weight, food-intake and glucose parameters. Blocking the interaction between GDF15 and GFRAL with a monoclonal antibody prevented the metabolic effects of GDF15 in rats. Gfral mRNA is highly expressed in the area postrema of mouse, rat and monkey, in accordance with previous reports implicating this region of the brain in the metabolic actions of GDF15 (refs. 4,5,6). Together, our data demonstrate that GFRAL is a receptor for GDF15 that mediates the metabolic effects of GDF15.

Indole Glucocorticoid Receptor Antagonists Active in a Model of Dyslipidemia Act via a Unique Association with an Agonist Binding Site.

To further elucidate the structural activity correlation of glucocorticoid receptor (GR) antagonism, the crystal structure of the GR ligand-binding domain (GR LBD) complex with a nonsteroidal antagonist, compound 8, was determined. This novel indole sulfonamide shows in vitro activity comparable to known GR antagonists such as mifepristone, and notably, this molecule lowers LDL (-74%) and raises HDL (+73%) in a hamster model of dyslipidemia. This is the first reported crystal structure of the GR LBD bound to a nonsteroidal antagonist, and this article provides additional elements for the design and pharmacology of clinically relevant nonsteroidal GR antagonists that may have greater selectivity and fewer side effects than their steroidal counterparts.

Dual Exosite-binding Inhibitors of Insulin-degrading Enzyme Challenge Its Role as the Primary Mediator of Insulin Clearance in Vivo.

Insulin-degrading enzyme (IDE, insulysin) is the best characterized catabolic enzyme implicated in proteolysis of insulin. Recently, a peptide inhibitor of IDE has been shown to affect levels of insulin, amylin, and glucagon in vivo. However, IDE(-/-) mice display variable phenotypes relating to fasting plasma insulin levels, glucose tolerance, and insulin sensitivity depending on the cohort and age of animals. Here, we interrogated the importance of IDE-mediated catabolism on insulin clearance in vivo. Using a structure-based design, we linked two newly identified ligands binding at unique IDE exosites together to construct a potent series of novel inhibitors. These compounds do not interact with the catalytic zinc of the protease. Because one of these inhibitors (NTE-1) was determined to have pharmacokinetic properties sufficient to sustain plasma levels >50 times its IDE IC50 value, studies in rodents were conducted. In oral glucose tolerance tests with diet-induced obese mice, NTE-1 treatment improved the glucose excursion. Yet in insulin tolerance tests and euglycemic clamp experiments, NTE-1 did not enhance insulin action or increase plasma insulin levels. Importantly, IDE inhibition with NTE-1 did result in elevated plasma amylin levels, suggesting the in vivo role of IDE action on amylin may be more significant than an effect on insulin. Furthermore, using the inhibitors described in this report, we demonstrate that in HEK cells IDE has little impact on insulin clearance. In total, evidence from our studies supports a minimal role for IDE in insulin metabolism in vivo and suggests IDE may be more important in helping regulate amylin clearance.

LLY-2707, a novel nonsteroidal glucocorticoid antagonist that reduces atypical antipsychotic-associated weight gain in rats.

Weight gain and diabetes have been reported during treatment with atypical antipsychotic drugs (AAPDs). Patients treated with the glucocorticoid receptor antagonist (GRA) and the progesterone receptor antagonist (PRA) mifepristone [estra-4,9-dien-3-one, 11-[4-(dimethylamino)phenyl]-17-hydroxy-17-(1-propynyl)-(11ß,17ß)-(9CI)] experienced significant reduction in the weight gain observed when patients were treated with olanzapine or risperidone. To understand the pharmacology responsible for this finding, we discovered LLY-2707 [N-(5-(tert-butyl)-3-(2-fluoro-5-methylpyridin-4-yl)-2-methyl-1H-indol-7-yl)methanesulfonamide], a novel and selective GRA, and evaluated its utility in preclinical models of AAPD-associated weight gain and diabetes. In vitro, LLY-2707 was a highly selective and potent GRA. GR occupancy in vivo was assessed using ex vivo binding where LLY-2707 inhibited [(3)H]dexamethasone binding to the liver. Modest but statistically significant decreases in brain ex vivo binding were observed with high doses of CORT-108297 [(R)-4α-(ethoxymethyl)-1-(4-fluorophenyl)-6-((4-(trifluoromethyl)phenyl)sulfonyl)-4,4a,5,6,7,8-hexahydro-1H-pyrazolo[3,4-g]isoquinoline] and LLY-2707, but mifepristone inhibited at all doses. Central activity of the GRAs was confirmed by their ability to suppress amphetamine-induced increases in locomotor activity. The increases in the body weight of female rats treated with olanzapine (2 mg/kg PO) over 14 days were reduced in a dose-dependent manner by coadministration of LLY-2707. Similar decreases, although less robust, in body weight were seen with mifepristone and CORT-108297. In addition, sGRAs prevented the glucose excursion after intragastric olanzapine infusions consistent with a direct effect on the hyperglycemia observed during treatment with AAPDs. At doses effectively preventing weight gain, LLY-2707 did not substantially interfere with the dopamine D2 receptor occupancy by olanzapine. Therefore, GRA coadministration may provide a novel treatment modality to prevent the weight gain and diabetes observed during treatment with AAPDs.

5-HT1A receptor antagonists reduce food intake and body weight by reducing total meals with no conditioned taste aversion.

Serotonin acts through receptors controlling several physiological functions, including energy homeostasis regulation and food intake. Recent experiments demonstrated that 5-HT1A receptor antagonists reduce food intake. We sought to examine the microstructure of feeding with 5-HT1A receptor antagonists using a food intake monitoring system. We also examined the relationship between food intake, inhibition of binding and pharmacokinetic (PK) profiles of the antagonists. Ex vivo binding revealed that, at doses used in this study to reduce food intake, inhibition of binding of a 5-HT1A agonist by ~40% was reached in diet-induced obese (DIO) mice with a trend for higher binding in DIO vs. lean animals. Additionally, PK analysis detected levels from 2 to 24h post-compound administration. Male DIO mice were administered 5-HT1A receptor antagonists LY439934 (10 or 30 mg/kg, p.o.), WAY100635 (3 or 10mg/kg, s.c.), SRA-333 (10 or 30 mg/kg, p.o.), or NAD-299 (3 or 10mg/kg, s.c.) for 3 days and meal patterns were measured. Analyses revealed that for each antagonist, 24-h food intake was reduced through a specific decrease in the total number of meals. Compared to controls, meal number was decreased 14-35% in the high dose. Average meal size was not changed by any of the compounds. The reduction in food intake reduced body weight 1-4% compared to Vehicle controls. Subsequently, a conditioned taste aversion (CTA) assay was used to determine whether the feeding decrease might be an indicator of aversion, nausea, or visceral illness caused by the antagonists. Using a two bottle preference test, it was found that none of the compounds produced a CTA. The decrease in food intake does not appear to be a response to nausea or malaise. These results indicate that 5-HT1A receptor antagonist suppresses feeding, specifically by decreasing the number of meals, and induce weight loss without an aversive side effect.

Activation of mesolimbic dopamine neurons during novel and daily limited access to palatable food is blocked by the opioid antagonist LY255582.

An analog of the trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine series (LY255582) exhibits high in vitro binding affinity and antagonist potency for the mu-, delta-, and kappa-opioid receptors. In vivo, LY255582 exhibits potent effects in reducing food intake and body weight in several rodent models of obesity. In the present study, we evaluated the effects of LY255582 to prevent the consumption of a highly palatable (HP) diet (a high-fat/high-carbohydrate diet) both when the food was novel and following daily limited access to the HP diet. Additionally, we examined the effects of consumption of the HP diet and of LY255582 treatment on mesolimbic dopamine (DA) signaling by in vivo microdialysis. Consumption of the HP diet increased extracellular DA levels within the nucleus accumbens (NAc) shell. Increased DA in the NAc shell was not related to the quantity of the HP diet consumed, and the DA response did not habituate following daily scheduled access to the HP diet. Interestingly, treatment with LY255582 inhibited consumption of the HP diet and the HP diet-associated increase in NAc shell DA levels. Moreover, the increased HP diet consumption observed following daily limited access to the HP diet was completely prevented by LY255582 treatment. LY255582 may be a useful tool in understanding the neural mechanisms involved in the reinforcement mechanisms regulating food intake.

Synthesis and SAR of novel histamine H3 receptor antagonists.

The synthesis and biological evaluation of novel tetrahydroisoquinoline, tetrahydroquinoline, and tetrahydroazepine antagonists of the human and rat H(3) receptors are described. The substitution around these rings as well as the nature of the substituent on nitrogen is explored. Several compounds with high affinity and selectivity for the human and rat H(3) receptors are reported.

The effect of an acute elevation of NEFA concentrations on glucagon-stimulated hepatic glucose output.

To determine the effect of nonesterified fatty acids (NEFA) on glucagon action, glucagon was infused intraportally (1.65 ng.min(-1).kg(-1)) for 3 h into 18-h-fasted, pancreatic-clamped conscious dogs in the presence [NEFA + glucagon (GGN)] or absence (GGN) of peripheral Intralipid plus heparin infusion. Additionally, hyperglycemic (HG), hyperglycemic-hyperlipidemic (NEFA + HG), and glycerol plus glucagon (GLYC + GGN) controls were studied. Arterial plasma glucagon concentrations rose equally in GGN, NEFA + GGN, and GLYC + GGN but remained basal in hyperglycemic controls. Peripheral infusions of Intralipid and heparin increased arterial plasma NEFA concentrations equally in NEFA + GGN and NEFA + HG and did not change in other protocols. After 15 min, glucagon infusion resulted in a rapid, brief increase in net hepatic glycogenolysis (NHGLY, mg.min(-1).kg(-1)) of approximately 6.0 in GGN and GLYC + GGN but only increased by 3.8 +/- 1.3 in NEFA + GGN. Thus increases in NHGLY, and consequently net hepatic glucose output (NHGO), were blunted by 40%, with no difference between the groups in the last 2.5 h of the study. NHGO and NHGLY did not significantly change in HG and NEFA + HG. Net hepatic gluconeogenic flux did not change in GGN, GLYC + GGN, or HG. However, Intralipid and heparin infusion resulted in similar increases in net hepatic gluconeogenic flux in NEFA + GGN and NEFA + HG. Thus elevated NEFA limit the initial increase in glucagon-stimulated HGO by blunting glycogenolysis, without having any effect on the gluconeogenic or glycogenolytic contributions or NHGO thereafter.

The relationship of in vivo central CB1 receptor occupancy to changes in cortical monoamine release and feeding elicited by CB1 receptor antagonists in rats.

RATIONALE: Cannabinoid type 1 (CB(1)) receptor antagonists are reportedly effective in reducing food intake both preclinically and clinically. This may be due in part to their effects on monoamine release in the brain. The level of central CB(1) receptor occupancy underlying these neurobiological effects is unclear. OBJECTIVES: We explored the relationship between in vivo CB(1) receptor occupancy in the frontal cortex and changes in both monoamine release in the medial prefrontal cortex (mPFC) and feeding behavior in rats in response to two orally administered CB(1) receptor antagonists presently in clinical trials, SR141716A (rimonabant) and SLV319. METHODS: CB(1) receptor occupancy was measured using [(3)H] SR141716A, and these occupancies were related to potencies to mediate increases in dopamine (DA) and norepinephrine (NE) release measured with microdialysis and decreases in consumption of a highly palatable diet (HP). RESULTS: High receptor occupancy levels (>65%) were required to detect increases in monoamine release that were achieved with 3 and 10 mg/kg of SR141716A and 10 mg/kg of SLV319 for DA and 10 mg/kg of SR141716A for NE. Decreases in HP consumption were seen at occupancies higher than 65% for SR141716A that were achieved with 3 and 10 mg/kg. In contrast, decreases in HP consumption were seen at relatively low CB(1) receptor occupancies (11%) for SLV319. CONCLUSIONS: The occupancy method described here is an effective tool for interrelating central CB(1) receptor occupancy with neurobiological actions of CB(1) receptor antagonists and for furthering our understanding of the role of CB(1) receptors in central nervous system physiology and pathology.

Attenuated feeding responses to circadian and palatability cues in mice lacking neuropeptide Y.

Neuropeptide Y (NPY) is a potent orexigenic peptide that is implicated in the feeding response to a variety of stimuli. The current studies employed mice lacking NPY (Npy-/-) and their wild-type (Npy+/+) littermates to investigate the role of this peptide in the feeding response to circadian and palatability cues. To investigate the response to a circadian stimulus, we assessed food intake during the 4-h period following dark onset, a time of day characterized by maximal rates of food consumption. Compared to Npy+/+ controls, intake of Npy-/- mice was reduced by 33% during this period (0.6+/-0.1g versus 0.9+/-0.1g; p

Central H3R activation by thioperamide does not affect energy balance.

The central histamine 3 receptor (H3R) is a presynaptic autoreceptor that regulates neuronal release and synthesis of histamine, and is thought to play a key role in controlling numerous central nervous system (CNS)-mediated parameters, including energy homeostasis. Thioperamide, the prototypical selective H3R antagonist, was used to examine the role that H3R plays in regulating energy balance in vivo. Thioperamide was administered either intraperitoneally or orally to rats and the pharmacokinetic parameters were examined along with central H3R binding and histaminergic system activation. Food intake and metabolic parameters of either route of thioperamide administration were likewise examined. In a dose-dependent manner, both the intraperitoneal and oral route of administration resulted in similar ex vivo binding curves and tele-methylhistamine dose-response curves despite the route of administration. However, only intraperitoneal administration of 30 mg/kg thioperamide resulted in a significant decrease in 24-h food intake (60% lower than control) and respiratory quotient (RQ), while the oral route of delivery did not. Moreover, the decrease in RQ with the 30 mg/kg ip administration also decreased energy expenditure (EE) thus resulting in an unchanged energy balance. The decrease in food intake and EE was coupled with a conditioned taste aversion with the 30-mg/kg ip administration. These data indicate that the activation of the central H3R system by thioperamide does not play a direct role in decreasing food intake or altering energy homeostasis.

Neuropeptide Y is required for hyperphagic feeding in response to neuroglucopenia.

To investigate the role played by the orexigenic peptide, neuropeptide Y (NPY), in adaptive responses to insulin-induced hypoglycemia, we measured hypothalamic, feeding, and hormonal responses to this stimulus in both wild-type (Npy+/+) and NPY-deficient (Npy-/-) mice. After administration of insulin at a dose (60 mU ip) sufficient to cause moderate hypoglycemia (plasma glucose levels, 40 +/- 3 and 37 +/- 2 mg/dl for Npy+/+ and Npy-/- mice, respectively; P = not significant), 4-h food intake was increased 2.5-fold in Npy+/+ mice relative to saline-injected controls. By comparison, the increase of intake in Npy-/- mice was far smaller (45%) and did not achieve statistical significance (P = 0.08). Hyperphagic feeding in response to insulin-induced hypoglycemia was therefore markedly attenuated in mice lacking NPY, and a similar feeding deficit was detected in these animals after neuroglucopenia induced by 2-deoxyglucose (500 mg/kg ip). A role for NPY in glucoprivic feeding is further supported by our finding that Npy mRNA content (measured by real-time PCR) increased 2.4-fold in the hypothalamus of Npy+/+ mice by 7 h after insulin injection. Unlike the feeding deficits observed in mice lacking NPY, the effect of hypoglycemia to increase plasma glucagon and corticosterone levels was fully intact in these animals, as were both the nadir glucose value and time to recovery of euglycemia after insulin injection (P = not significant). We conclude that NPY signaling is required for hyperphagic feeding, but not neuroendocrine responses to moderate hypoglycemia.

Interaction of free fatty acids and epinephrine in regulating hepatic glucose production in conscious dogs.

To determine the effects of an increase in lipolysis on the glycogenolytic effect of epinephrine (EPI), the catecholamine was infused portally into 18-h-fasted conscious dogs maintained on a pancreatic clamp in the presence [portal (Po)-EPI+FFA, n = 6] and absence (Po-EPI+SAL, n = 6) of peripheral Intralipid infusion. Control groups with high glucose (70% increase) and free fatty acid (FFA; 200% increase; HG+FFA, n = 6) and high glucose alone (HG+SAL, n = 6) were also included. Hepatic sinusoidal EPI levels were elevated (Delta 568 +/- 77 and Delta 527 +/- 37 pg/ml, respectively) in Po-EPI+SAL and EPI+FFA but remained basal in HG+FFA and HG+SAL. Arterial plasma FFA increased from 613 +/- 73 to 1,633 +/- 101 and 746 +/- 112 to 1,898 +/- 237 micromol/l in Po-EPI+FFA and HG+FFA but did not change in EPI+SAL or HG+SAL. Net hepatic glycogenolysis increased from 1.5 +/- 0.3 to 3.1 +/- 0.4 mg x kg(-1) x min(-1) (P < 0.05) by 30 min in response to portal EPI but did not rise (1.8 +/- 0.2 to 2.1 +/- 0.3 mg x kg(-1) x min(-1)) in response to Po-EPI+FFA. Net hepatic glycogenolysis decreased from 1.7 +/- 0.2 to 0.9 +/- 0.2 and 1.6 +/- 0.2 to 0.7 +/- 0.2 mg x kg(-1) x min(-1) by 30 min in HG+FFA and HG+SAL. Hepatic gluconeogenic flux to glucose 6-phosphate increased from 0.6 +/- 0.1 to 1.2 +/- 0.1 mg x kg(-1) x min(-1) (P < 0.05; by 3 h) and 0.7 +/- 0.1 to 1.6 +/- 0.1 mg x kg(-1) x min(-1) (P < 0.05; at 90 min) in HG+FFA and Po-EPI+FFA. The gluconeogenic parameters remained unchanged in the Po-EPI+SAL and HG+SAL groups. In conclusion, increased FFA markedly changed the mechanism by which EPI stimulated hepatic glucose production, suggesting that its overall lipolytic effect may be important in determining its effect on the liver.

Attenuation of diabetic hyperphagia in neuropeptide Y--deficient mice.

The combined effects of increased hypothalamic signaling by neuropeptide Y (NPY) and decreased signaling by melanocortins are hypothesized to stimulate food intake when body fat stores are depleted. To investigate NPY's role in the hyperphagic response to uncontrolled diabetes, streptozotocin (STZ) (200 mg/kg intraperitoneally) or saline vehicle was given to NPY-deficient (Npy(--/--)) and wild-type (Npy(+/+)) mice. In Npy(+/+) mice, STZ-induced diabetes increased mean daily food intake to plateau values 50% above baseline intake (+2.0 +/- 0.6 g/day; P < or = 0.05), an effect that was not seen in STZ-treated Npy(--/--) mice (+0.8 +/- 0.1 g/day; NS), despite comparably elevated levels of plasma glucose and comparably decreased levels of body weight, fat content, and plasma leptin. Unlike the impaired feeding response to uncontrolled diabetes, Npy(--/--) mice exhibit intact hyperphagic responses to fasting (Erickson et al. [1], Nature 381:415-418, 1996). To investigate whether differences in hypothalamic melanocortin signaling can explain this discrepancy, we used in situ hybridization to compare the effects of STZ-diabetes and fasting on pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP) mRNA levels in the hypothalamic arcuate nucleus (ARC) of Npy(--/--) and Npy(+/+) mice. AgRP mRNA levels were increased by both fasting and STZ-diabetes, but the increase in STZ-diabetes was small (50-80%) compared with the effect of fasting (approximately 20-fold increase of AgRP mRNA). STZ-diabetes also lowered POMC mRNA levels by 65% in the ARC of Npy(+/+) mice (P less-than-or-equal 0.05) but by only 11% in Npy(--/--) mice (NS); fasting significantly lowered POMC mRNA levels in both genotypes. We conclude that NPY is required for both the increase of food intake and the decrease of hypothalamic POMC gene expression induced by uncontrolled diabetes. In contrast, NPY is not required for either of these responses when the stimulus is food deprivation. Moreover, fasting is a more potent stimulus to hypothalamic AgRP gene expression than is STZ-diabetes. Therefore, central nervous system melanocortin signaling appears to be suppressed more effectively by fasting than by uncontrolled diabetes, which provides a plausible explanation for differences in the feeding response to these two stimuli in mice lacking NPY.

Effects of free fatty acids on hepatic glycogenolysis and gluconeogenesis in conscious dogs.

The aim of this study was to determine the effect of high levels of free fatty acids (FFA) and/or hyperglycemia on hepatic glycogenolysis and gluconeogenesis. Intralipid was infused peripherally in 18-h-fasted conscious dogs maintained on a pancreatic clamp in the presence (FFA + HG) or absence (FFA + EuG) of hyperglycemia. In the control studies, Intralipid was not infused, and euglycemia (EuG) or hyperglycemia (HG) was maintained. Insulin and glucagon were clamped at basal levels in all four groups. The arterial blood glucose level increased by 50% in the HG and FFA + HG groups. It did not change in the EuG and FFA + EuG groups. Arterial plasma FFA increased by approximately 140% in the FFA + EuG and FFA + HG groups but did not change significantly either in the EuG or HG groups. Arterial glycerol levels increased by approximately 150% in both groups. Overall (3-h) net hepatic glycogenolysis was 196 +/- 26 mg/kg in the EuG group. It decreased by 96 +/- 20, 82 +/- 16, and 177 +/- 22 mg/kg in the HG, FFA + EuG, and FFA + HG groups, respectively. Overall (3-h) hepatic gluconeogenic flux was 128 +/- 22 mg/kg in the EuG group, but it was suppressed by 30 +/- 9 mg/kg in response to hyperglycemia. It was increased by 59 +/- 12 and 56 +/- 10 mg/kg in the FFA + EuG and FFA + HG groups, respectively. In conclusion, an increase in plasma FFA and glycerol significantly inhibited hepatic glycogenolysis and markedly stimulated hepatic gluconeogenesis.