Long-term effects of foetal undernutrition on intermediary metabolism in growing lambs

The objective of this study was to investigate the effects of foetal undernutrition on the metabolism in growing lambs. Seven-month-old lambs whose mothers had been fed either restrictively (RN; n = 14) or adequately (AN; n = 6) in late gestation were fasted for three days. One hour before fasting and after 48 h and 72 h fasting, changes in plasma concentrations of metabolites, i.e. glucose, nonesterified fatty acids (NEFA), 3-beta-hydroxybutyrate (BOHB) and urea as well as hormones, i.e. insulin, the insulin-like growth factor (IGF-I) and leptin, were determined. Blood glucose, NEFA, urea, insulin, IGF-I and leptin were not different between the two groups of lambs. Unexpectedly, at the end of the 3 d fasting, in spite of lower NEFA concentration (1.6 +/- 0.03 vs. 1.9 +/- 0.05 mM in Groups RN and AN, respectively), the BOHB concentration in RN lambs (0.94 +/- 0.02 mM) was significantly higher than that in AN lambs (0.78 +/- 0.04 mM). This higher rate of BOHB production might be interpreted as perturbations in ketone body metabolism potentially induced by undernutrition during foetal life. However, more investigations are necessary to clarify this interrelationship.     

Reduction of Plasma Leptin Concentrations by Arginine but Not Lipid Infusion in Humans

Objective: We examined short-term effects of arginine infusion on plasma leptin in diabetic and healthy subjects. Research Methods and Procedures: Arginine stimulation tests were performed in C-peptide negative type 1 [DM1; hemoglobin A_1c; 7.3 ± 0.3%], hyperinsulinemic type 2 diabetic (DM2; 7.6 ± 0.7%), and nondiabetic subjects (CON; 5.4 ± 0.1%). Results: Fasting plasma leptin correlated linearly with body mass index among all groups (r = 0.61, p = 0.001). During arginine infusion, peak plasma insulin was lower in DM1 than in DM2 (p < 0.05) and CON (p < 0.01). Plasma leptin decreased within 30 minutes by ∼11% in DM1 (p < 0.001), DM2 (p < 0.01), and CON (p < 0.005), slowly returning to baseline thereafter. Plasma free fatty acids (FFAs) were higher in DM1 (0.6 ± 0.1 mM) and DM2 (0.6 ± 0.1 mM) than in CON (0.4 ± 0.1 mM, p < 0.05) and transiently declined by ∼50% (p < 0.05) at 45 minutes in all groups before rebounding toward baseline. To examine the direct effects of FFAs on plasma leptin, we infused healthy subjects with lipid/heparin and glycerol during fasting, and somatostatin-insulin (∼35 pM) -glucagon (∼90 ng/mL) clamps were performed. In both protocols, plasma leptin continuously declined by ∼25% (p < 0.05) during 540 minutes without any difference between the high and low FFA conditions. Discussion: Arginine infusion transiently decreased plasma leptin concentrations both in insulin-deficient and hyperinsulinemic diabetic patients, indicating a direct inhibitory effect of the amino acid but not of insulin or FFAs.     

Leptin concentrations in plasma and follicular fluid from prepubertal gilts as influenced by fasting, refeeding and insulin.

This study's aim was to examine whether fasting and refeeding would influence leptin levels in both plasma and follicular fluid from prepubertal gilts, and whether insulin affects leptin levels in fasting gilts. In experiment 1, four gilts were fasted for 72 h and then refed. Blood samples were withdrawn during normoalimentation, at the end of fasting, and for 4 h after refeeding. All samples were assayed for leptin; alternate samples were assayed for insulin, glucose and non-esterified fatty acids (NEFA). Fasting caused a decrease in leptin, glucose and insulin levels in plasma, while NEFA concentrations increased. In experiment 2, four gilts were given insulin as a bolus (0.2 IU/kg body weight) after 68 h of fasting. Blood samples were collected every 15 min around insulin administration and were assayed for leptin, insulin and glucose. This experiment shows that insulin administration increases leptin levels during fasting. In experiment 3, gilts were ovariectomized during normal alimentation (n=4), after 48 h of fasting (n=4), and after 48 h of realimentation following 48 h of fasting (n=4). Leptin levels in both plasma and follicular fluid collected after 48 h of fasting were significantly lower than those observed during normoalimentation or refeeding. In conclusion, a transient increase in insulin during fasting is effective in restoring leptin concentrations; in addition, leptin levels in follicular fluid parallel those in plasma.     

Weight Loss and Leptin Changes in Individuals with Type 2 Diabetes

WILLIAMS, KATHERINE V., MONICA MULLEN, WE1 LANG, ROBERT V. CONSIDINE, AND RENA R. WING. Weight loss and leptin changes in individuals with type 2 diabetes. Obes Res. Objective To identify variables associated with leptin change in subjects with type 2 diabetes after 3 weeks and 20 weeks of weight loss. Research Methods and Procedures Subjects with type 2 diabetes treated with diet or sulfonylureas (n = 54) were enrolled in a 20-week behavioral weight control program. Sulfonylureas were stopped ≥2 weeks before study entry. Seven subjects who restarted sulfonylureas after week 3 had their data analyzed separately after this point. Results Leptin, fasting plasma glucose, and insulin levels were measured at baseline and at 3, 10, and 20 weeks. After 3 weeks, subjects lost 2.7±2.0 kg (p<0.001), and had significant decreases in leptin (5.2±7.0 ng/mL, p<0.001), fasting plasma glucose (1.8±1.8 mmol/L, p<0.001), and insulin (23±60 pmol/L, p<0.03). Between week 3 and week 20, subjects lost an additional 6.3±4.4 kg (P<0.001), but had no further changes in leptin. The primary determinants of leptin change at all time-points were weight loss and initial leptin level. Changes in insulin were not related to changes in leptin after controlling for the effects of weight loss. At week 20, more recent weight loss (week 10 to week 20) was as strong a predictor of overall change in leptin as overall weight loss (baseline to 20 week). Subjects who restarted sulfonylureas had an increase in both leptin levels (+1.9±9.0 ng/mL, p<0.05) and insulin levels (+23±65 pmol/L, p<0.05), despite significant overall weight loss (-7.4±4.0 kg, p<0.01). Initial changes in leptin (0 weeks to 3 weeks) did not affect subsequent ability to lose weight. Discussion Both short- and long-term changes in weight had an effect on leptin changes in individuals with type 2 diabetes. Although physiological insulin changes did not independently influence changes in leptin concentration with weight loss, increases in insulin levels with sulfonyl-urea therapy were associated with increases in leptin levels despite weight loss.     

Feed deprivation in Merino and Terminal sired lambs: (1) the metabolic response under resting conditions

The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P < 0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032 mmol/l. From 6 h NEFA concentration increased (P < 0.05) from 0.15 ± 0.021 mmol/l by almost 10-fold to 1.34 ± 0.021 mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P < 0.05) from 0.15 ± 0.010 mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P < 0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P < 0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P < 0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.     

Effects of Metformin and Vanadium on Leptin Secretion from Cultured Rat Adipocytes

Objective: We have reported that glucose utilization regulates leptin expression and secretion from isolated rat adipocytes. In this study, we employed two antidiabetic agents that act to increase glucose uptake by peripheral tissues, metformin and vanadium, as pharmacological tools to examine the effects of altering glucose utilization on leptin secretion in primary cultures of rat adipocytes. Research Methods and Procedures: Isolated adipocytes (100 μL of packed cells per well) were anchored in a defined matrix of basement membrane components (Matrigel) with media containing 5.5 mM glucose and incubated for 96 hours with metformin or vanadium. Leptin secretion, glucose utilization, and lactate production were assessed. Results: Metformin (0.5 and 1.0 mM) increased glucose uptake in the presence of 0.16 nM insulin by 37 ± 10% (p < 0.005) and 62 ± 8% (p < 0.0001) over insulin alone, respectively. Metformin from 0.5 to 5.0 mM increased lactate production by 105 ± 43% (p < 0.025) to 202 ± 52% (p < 0.0025) and at 1.0 and 5.0 mM increased the proportional rate of glucose conversion to lactate by 78 ± 18% (p < 0.005) and 166 ± 41% (p < 0.0025), respectively. At concentrations less than 0.5 mM, metformin did not affect leptin secretion, but at 0.5 mM, the only concentration that significantly increased glucose utilization without increasing glucose conversion to lactate, leptin secretion was modestly stimulated (by 20 ± 9%; p < 0.05). Concentrations from 1.0 to 25 mM inhibited leptin secretion by 25 ± 8% (p < 0.005) to 89 ± 4% (p < 0.0001). Across metformin doses, leptin secretion was inversely related to the percentage of glucose taken up and released as lactate (r = ?0.74; p < 0.0001). Vanadium (5 to 20 μM) increased glucose uptake from 20 ± 7% (p < 0.01) to 34 ± 13% (p < 0.02) and increased lactate production at 5 μM by 17 ± 8% (p < 0.025) and 10 μM by 61 ± 20% (p < 0.02) but did not alter the conversion of glucose to lactate. Vanadium (5 to 50 μM) inhibited leptin secretion by 33 ± 6% (p < 0.0025) to 61 ± 8% (p < 0.0001). Discussion: Both metformin and vanadium increase glucose uptake and inhibit leptin secretion from cultured adipocytes. The inhibition of leptin secretion by metformin is related to an increase in the metabolism of glucose to lactate. The inhibition by vanadium most likely involves direct effects on cellular phosphatases. We hypothesize that the effect of glucose utilization to stimulate leptin production involves the metabolism of glucose to a fate other than anaerobic lactate production, possibly oxidation or lipogenesis.     

Programming of intermediate metabolism in young lambs affected by late gestational maternal undernourishment

Effects of moderate maternal undernourishment during late gestation on the intermediary metabolism and maturational changes in young lambs were investigated. 20 twin-bearing sheep, bred to two different rams, were randomly allocated the last 6 wk of gestation to either a NORM diet [barley, protein supplement, and silage ad libitum approximately 15 MJ metabolizable energy (ME)/day] or a LOW diet (50% of ME intake in NORM, offered exclusively as silage approximately 7 MJ ME/day). Post partum, ewes were fed to requirement. After weaning, lambs were fed concentrate and hay ad libitum. At 10 and 19 wk of age, lambs were subjected to an intravenous glucose tolerance test (IGTT) followed by 24 h of fasting. Heat energy (HE) was determined in a respiration chamber at 9 or 20 wk of age. LOW lambs had a lower birth weight and continued to be lighter throughout the experiment. Glucose tolerance did not differ between groups. However, 19-wk-old LOW lambs secreted less insulin during IGTT, released more NEFA, and tended to have lower leptin during fasting than NORM. Surprisingly, several metabolite and hormone responses during IGTT and fasting were greatly influenced by the paternal heritage. In conclusion, when lambs entered adolescence (19 wk) programming effects of late prenatal malnutrition on the glucose-insulin homeostasis and metabolism were manifested: LOW lambs had less insulin-secretory capacity, but this was apparently compensated for by increased target tissue sensitivity for insulin, and adipose lipolytic capacity increased during fasting. Thereby, glucose may be spared through increased lipid oxidation, but overall energetic efficiency is apparently deteriorated rather than improved.     

Effect of beta-hydroxybutyrate and acetoacetate on insulin and glucagon secretion from perfused rat pancreas

To elucidate the physiological significance of ketone bodies on insulin and glucagon secretion, the direct effects of beta-hydroxybutyrate (BOHB) and acetoacetate (AcAc) infusion on insulin and glucagon release from perfused rat pancreas were investigated. The BOHB or AcAc was administered at concentrations of 10, 1, or 0.1 mM for 30 min at 4.0 ml/min. High-concentration infusions of BOHB and AcAc (10 mM) produced significant increases in insulin release in the presence of 4.4 mM glucose, but low-concentration infusions of BOHB and AcAc (1 and 0.1 mM) caused no significant changes in insulin secretion from perfused rat pancreas. BOHB (10, 1, and 0.1 mM) and AcAc (10 and 1 mM) infusion significantly inhibited glucagon secretion from perfused rat pancreas. These results suggest that physiological concentrations of ketone bodies have no direct effect on insulin release but have a direct inhibitory effect on glucagon secretion from perfused rat pancreas.     

Basal and Stimulated Plasma Leptin in Diabetic Subjects

LIU, JIANMEI, HASAN ASKARI, AND SAMUEL DAGOGO-JACK. Basal and stimulated plasma leptin in diabetic subjects. Obes Res. Objective: To determine whether leptin secretion is impaired in diabetes, we compared basal and stimulated plasma leptin levels in diabetic subjects and healthy controls. Research Methods and Procedures: Blood samples for assay of leptin and other hormones were obtained at baseline in 54 diabetic patients and 65 controls, and 8 hours, 16 hours, and 40 hours following ingestion of dexamethasone (4 mg) in 6 healthy and 12 controls. C-peptide status was defined as “negative” if ≤0.1 ng/mL or “positive” if ≥0.3 ng/mL, in fasting plasma. Results: Basal plasma leptin levels were 19. 7±2. 2 ng/mL in nondiabetic subjects, 13. 4±1. 5 ng/ml in C-peptide negative (n = 28) and 26. 1±23. 7 ng/mL in C-peptide positive (n = 26, p = 0. 001) diabetic patients. Dexamethasone increased leptin levels of controls (n = 6) to 145±17% of baseline values at 8 hours (p = O. O3), 224±18% at 16 hours (p = 0. 01), and 134218% at 40 hours (p = 0. 05). The corresponding changes were 108±13%, 126±23%, and 98±16% in C-peptide negative (n = 6), and 121±10%, 144±16% (p = 0. 03), and 147±23% (p = 0. 11) in C-peptide positive (n = 6) diabetic patients, respectively. The peak stimulated leptin levels were lower in the diabetic patients, compared with controls. Plasma insulin increased (p = 0. 02) in controls, but not in the diabetic patients, following dexamethasone. Discussion: Although diabetic patients have normal plasma leptin levels under basal conditions, their leptin responses to glucocorticoid are impaired, probably because of the concomitant insulin secretory defect. A subnormal leptin secretory response could worsen obesity and insulin resistance in diabetes.     

Leptin Response to Glucocorticoid Occurs at Physiological Doses and Is Abolished by Fasting

Objective: To examine the effects of graded doses of hydrocortisone (HC) on leptin secretion, and determine the effect of fasting. Research Methods and Procedures: This was a randomized, placebo‐controlled, crossover study, with a 1‐week “washout” period between interventions. Eight healthy subjects [age = 36 ± 2.3 years (±SE), body mass index = 31.5 ± 1.6 kg/m²] completed the dose‐response study in which an intravenous infusion of saline (placebo) or HC (30 or 100 mg) was administered for 24 hours. Four healthy subjects (age = 35.2 ± 3.0 years, body mass index = 27.1 ± 2.1 kg/m²) completed the fasting study, which entailed continuous infusion of saline, HC (300 mg/24 hours) in the fed state, or HC (300 mg/24 hours) with total caloric deprivation for 24 hours. Blood sampling was performed every 1 to 2 hours for measurement of leptin, cortisol, insulin, and glucose levels. Results: Peak hyperleptinemia occurred after 16 hours of HC infusion; peak/baseline leptin levels were 129% (placebo), 140% (30 mg of HC for 24 hours, p = 0.05), and 185% (100 mg of HC for 24 hours, p < 0.01). During infusion of HC (300 mg/24 hours or placebo), the peak/baseline plasma leptin levels were 16.1 ± 5.8/12.8 ± 5.9 ng/mL (placebo with food, 126%), 14.6 ± 6.0/12.5 ± 6.5 ng/mL (HC fasting, 117%), and 32.5 ± 12.5/12.0 ± 8.4 ng/mL (HC with food, 271%, p < 0.001). Discussion: Leptin secretory responses occur at physiological doses of HC, are obliterated by fasting, and thus may be of metabolic significance.     

Plasma Leptin,Fatty Acids,and Tumor Necrosis Factor‐Receptor and Insulin Resistance in Children

Objective: To evaluate the effect of plasma leptin, nonsterified fatty acids (NEFAs), and tumor necrosis factor‐receptor 1 (TNFR1) on plasma insulin and insulin‐resistance status in children. Research Methods and Procedures: One thousand thirty‐two children (521 boys and 511 girls) were included in this study. We measured plasma insulin and leptin levels by radioimmunoassay, plasma NEFA levels by enzymatic acyl‐coenzyme A synthase—acyl‐coenzyme A oxidase spectrophotometric methods, and TNFR1 levels by enzyme‐linked immunosorbent assay. We calculated insulin resistance index (IRI) using homeostasis model assessment and calculated insulin‐resistance syndrome summary score (IRS) by adding the quartile ranks from the distribution of systolic blood pressure (BP), serum triglyceride, high‐density lipoprotein‐cholesterol (inverse), and insulin levels. Results: Overweight children had higher BP, plasma leptin, and insulin levels and higher IRI and IRS than normal‐weight children. Plasma leptin and TNFR1 were positively correlated with insulin levels, IRI, and IRS. The correlation coefficients of leptin and TNFR1 in IRI were 0.53 and 0.12, respectively, for boys and 0.25 and 0.18, respectively, for girls. In multivariate regression analyses, TNFR1 was positively associated with insulin level and IRI in girls; NEFA was positively associated only with IRS. Plasma leptin levels were significantly positively associated with insulin levels, IRI, and IRS, even after adjusting for BMI and other potential confounders. Discussion: Overweight children had higher BP, plasma insulin, and leptin levels and adverse insulin‐resistance status than normal‐weight children. Plasma leptin levels, rather than NEFA and TNFR1, may play a significant role in the development of hyperinsulinemia and insulin resistance in children.     

Increased insulin sensitivity in patients with anorexia nervosa: the role of adipocytokines

Anorexia nervosa (AN) is characterized by self-induced starvation leading to severe weight and fat loss. In the present study, we measured fasting plasma levels of adiponectin, leptin, resistin, insulin and glucose in 10 women with a restrictive type of AN and in 12 healthy women (C). Insulin sensitivity was determined according to homeostasis model assessment of insulin resistance (HOMA-R). Plasma resistin, leptin and insulin levels were significantly decreased, whereas plasma adiponectin levels were significantly increased in patients with AN compared to the C. HOMA-R was significantly decreased in patients with AN compared to the C group. Plasma adiponectin and leptin concentrations negatively and positively correlated with the body mass index and percentage body fat in both groups. Plasma adiponectin levels were negatively related to plasma insulin levels in the AN group only. In conclusion, we demonstrated that AN is associated with significantly decreased plasma leptin and resistin levels, markedly increased plasma adiponectin levels and increased insulin sensitivity. Plasma leptin and adiponectin levels were related to the body size and adiposity. Hyperadiponectinemia could play a role in increased insulin sensitivity of patients with AN. Neither body size and adiposity nor insulin sensitivity are the major determinants of plasma resistin levels in AN.     

Ethnic Differences in the Responsiveness of Adipocyte Lipolytic Activity to Insulin

Objective: The goal of this study was to quantify differences in lipid metabolism and insulin sensitivity in black and white subjects to explain ethnic clinicopathological differences in type 2 diabetes. Research Methods and Procedures: The in vitro lipolytic activity of adipocytes isolated from obese black and white women was measured in the presence of insulin and isoproterenol. Insulin resistance was assessed in vivo using the euglycemic hyperinsulinemic clamp technique. Results: Fasting plasma levels of insulin and nonesterified fatty acid (NEFA) in black and white women were 67 ± 5 pM vs. 152 ± 20 pM (p < 0.01) and 863 ± 93 μM vs. 412 ± 34 μM (p < 0.01), respectively. Euglycemic hyperinsulinemic clamp studies showed that obese black subjects were more insulin‐resistant than their white counterparts (glucose infusion rates: 1.3 ± 0.2 vs. 2.2 ± 0.3 mg/kg per min; p < 0.05). Isolated adipocytes from white women were more responsive to insulin than those from black women with 0.7 nM insulin causing a 55 ± 4% inhibition of isoproterenol‐stimulated lipolysis compared with 27 ± 10% in black women (p < 0.05). Discussion: The low responsiveness of adipocyte lipolytic activity to insulin in black women in the presence of a relative insulinopenia may account for the high plasma NEFA levels seen in these women, which may, in turn, account for their higher in vivo insulin resistance. High NEFA levels may also contribute to the low insulin secretory activity observed in the obese black females. These data suggest that the pathogenesis of insulin resistance and type 2 diabetes within the black obese community is strongly influenced by their adipocyte metabolism.     

Maternal periconceptional undernutrition in Merinos d'Arles sheep: 1. Effects on pregnancy and reproduction results of dams and offspring growth performances

Maternal undernutrition during gestation can condition offspring adult health, with the periconceptional period pointed out as a key period. The aim of this study was to evaluate the effects of maternal periconceptional undernutrition on pregnancy and offspring growth performance in sheep.52 Merinos d'Arles ewes were fed to requirements (control group, C), whereas 64 ewes received 50% of their dietary needs from −15 to +30 days post-conception (restricted group, R). Thereafter, both groups were fed according to needs. Maternal body weight (BW), body condition score (BCS) and Non Esterified Fatty Acids (NEFA), progesterone, leptin and cortisol plasma concentrations were monitored weekly during the restriction period and the following month, then monthly until weaning. Lambs were weighed weekly until weaning at 22 kg BW, then monthly. Plasma leptin was monitored monthly in lambs.The BW, BCS, and leptin concentrations were significantly decreased, whereas NEFA and cortisol concentrations were increased in R dams. Maximum progesterone concentration was higher in R ewes that had a high (10-25%) vs. low (0-10%) BW loss during restriction (27.9 ± 2.59 vs. 20.8 ± 2.00 ng/mL, P < 0.05). Overall, gestation was significantly longer in the R group (151.0 ± 0.3 vs. 149.4 ± 0.4 days, P < 0.001). There was no difference between groups for pregnancy rates, prolificacy, birth weight and lamb mortality, but the proportion of male lambs was significantly higher in the R group, only for singletons (16/26 vs. 9/26, P < 0.05). Lamb growth was not significantly modified by treatment. Leptin concentrations at birth were significantly lower in R vs. C males (6.15 ± 0.13 ng/mL vs. 7.42 ± 0.36 ng/mL, P < 0.05), whereas in females, leptin concentrations were significantly higher in R vs. C lambs at 4 mo of age (7.31 ± 0.27 ng/mL vs. 6.41 ± 0.29 ng/mL, P < 0.05).These results indicate that maternal periconceptional undernutrition in a hardy breed does not significantly affect lamb birth weight and growth rates, in contrast to previous reports in other breeds, suggesting that caution must be taken when extrapolating programming data between breeds and breeding conditions.     

Restoration of acute insulin response in T2DM subjects 1 month after biliopancreatic diversion

Objective: Biliopancreatic diversion (BPD) restores normal glucose tolerance in a few weeks in morbid obese subjects with type 2 diabetes, improving insulin sensitivity. However, there is less known about the effects of BPD on insulin secretion. We tested the early effects of BPD on insulin secretion in obese subjects with and without type 2 diabetes. Methods and Procedures: Twenty‐one consecutive morbid obese subjects, 9 with type 2 diabetes (T2DM) and 12 with normal fasting glucose (NFG) were evaluated, just before and 1 month after BPD, by measuring body weight (BW), glucose, adipocitokines, homeostasis model assessment of insulin resistance (HOMA‐IR), acute insulin response (AIR) to e.v. glucose and the insulinogenic index adjusted for insulin resistance ([ΔI5/ΔG5]/HOMA‐IR). Results: Preoperatively, those with T2DM differed from those with NFG in showing higher levels of fasting glucose, reduced AIR (57.9 ± 29.5 vs. 644.9 ± 143.1 pmol/l, P < 0.01) and reduced adjusted insulinogenic index (1.0 ± 0.5 vs. 17.6 ± 3.9 1/mmol², P < 0.001). One month following BPD, in both groups BW was reduced (by ～11%), but all subjects were still severely obese; HOMA‐IR and leptin decreased significanlty, while high‐molecular weight (HMW) adiponectin and adjusted insulinogenic index increased. In the T2DM group, fasting glucose returned to non‐diabetic values. AIR did not change in the NFG group, while in the T2DM group it showed a significant increase (from 58.0 ± 29.5 to 273.8 ± 47.2 pmol/l, P < 0.01). In the T2DM group, the AIR percentage variation from baseline was significantly related to changes in fasting glucose (r = 0.70, P = 0.02), suggesting an important relationship exists between impaired AIR and hyperglycaemia. Discussion: BPD is able to restore AIR in T2DM even just 1 month after surgery. AIR restoration is associated with normalization of fasting glucose concentrations.     

Secretory dynamics of leptin in adolescent girls with anorexia nervosa and healthy adolescents

Leptin, an adipocytokine that suppresses appetite and may regulate neuroendocrine pathways, is low in undernourished states like anorexia nervosa (AN). Although leptin exhibits pulsatility, secretory characteristics have not been well described in adolescents and in AN, and the contribution of hypoleptinemia to increased growth hormone (GH) and cortisol in AN has not been explored. We hypothesized that hypoleptinemia in AN reflects decreased basal and pulsatile secretion and may predict increased GH and cortisol levels. Sampling for leptin, GH, cortisol, and ghrelin was performed every 30 min (from 2000 to 0800) in 23 AN and 21 controls 12-18 yr old, and data were analyzed using Cluster and deconvolution methods. Estradiol, thyroid hormones, and body composition were measured. AN girls had lower pulsatile and total leptin secretion than controls (P < 0.0001) subsequent to decreased burst mass (P < 0.0001) and basal secretion (P = 0.02). Nutritional markers predicted leptin characteristics. In a regression model including BMI, body fat, and ghrelin, leptin independently predicted GH burst interval and frequency. Valley leptin contributed to 56% of the variability in GH burst interval, and basal leptin and fasting ghrelin contributed to 42% of variability in burst frequency. Pulsatile leptin independently predicted urine free cortisol/creatinine (15% of variability). Valley leptin predicted cortisol half-life (22% of variability). Leptin predicted estradiol and thyroid hormone levels. In conclusion, hypoleptinemia in AN is subsequent to decreased basal and pulsatile secretion and nutritionally regulated. Leptin predicts GH and cortisol parameters and with ghrelin predicts GH burst frequency. Low leptin and high ghrelin may be dual stimuli for high GH concentrations in undernutrition.     

Role of Insulin and Free Fatty Acids in the Regulation of ob Gene Expression and Plasma Leptin in Normal Rats

Objective: It is under debate whether free fatty acids (FFAs) play an independent role in the regulation of adipose cell functions. In this study, we evaluated whether leptin secretion induced by FFA is due directly to an increased FFA availability or whether it is mediated by insulin levels. Research Methods and Procedures: To test this hypothesis, we compared the effects of six different experimental designs, with different FFA and insulin levels, on plasma leptin: euglycemic clamp, euglycemic clamp + FFA infusion, FFA infusion alone, FFA + somatostatin infusion, somatostatin infusion alone, and saline infusion. Results: Our results showed that euglycemic clamp, FFA infusion, or both in combination induced a similar increment of circulating leptin (3.31 ± 0.30, 3.40 ± 0.90, and 3.35 ± 0.80 ng/mL, respectively). Moreover, the inhibition of FFA‐induced insulin increase by means of somatostatin infusion completely abolished the rise of leptin in response to FFA (1.05 ± 0.30 vs. 3.40 ± 0.90 ng/mL, p < 0.001). Discussion: In conclusion, our data showed that the effects of high FFA levels on plasma leptin were mediated by the rise of insulin concentration. These data confirm a major role for insulin in the regulation of leptin secretion from rat adipose tissue and support the hypothesis that leptin secretion is coupled to net triglyceride synthesis in adipose tissue.     

Secretory dynamics of ghrelin in adolescent girls with anorexia nervosa and healthy adolescents

Ghrelin is an orexigenic peptide and a growth hormone (GH) secretagogue. Secretory dynamics of ghrelin have not been characterized in adolescents with anorexia nervosa (AN). We hypothesized that, compared with healthy adolescents, girls with AN would have increased ghrelin concentrations measured over 12 h of nocturnal sampling from increased basal and pulsatile secretion, and endogenous ghrelin would independently predict GH and cortisol. We examined ghrelin concentration and secretory dynamics in 22 girls with AN and 18 healthy adolescents 12-18 yr old. Associations between ghrelin, various hormones, and measures of insulin resistance were examined. On Cluster analysis, girls with AN had higher ghrelin concentrations than controls, including total area under the curve (AUC) (P = 0.002), nadir (P = 0.0006), and valley levels (P = 0.002). On deconvolution analysis, secretory burst amplitude (P = 0.03) and burst mass (P = 0.04) were higher in AN, resulting in higher pulsatile (P = 0.05) and total ghrelin secretion (P = 0.03). Fasting ghrelin independently predicted GH burst frequency (r = 0.44, P = 0.005). The nutritional markers body mass index and body fat predicted postglucose and valley ghrelin but not fasting levels. Ghrelin parameters were inversely associated with fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, and IGF-I. HOMA-IR was the most significant predictor of most ghrelin parameters. Valley ghrelin independently predicted cortisol burst frequency (52% of variability), and ghrelin parameters independently predicted total triiodothyronine and LH levels. Higher ghrelin concentrations in adolescents with AN are a consequence of increased secretory burst mass and amplitude. The most important predictor of ghrelin concentration is insulin resistance, and ghrelin in turn predicts GH and cortisol burst frequency.     

Effect of dried corn distillers’ grains with solubles and soybean meal supplements on physiological indicators and reproductive performance of ewes

This study aimed to evaluate the effects of adding dried distillers’ grains with solubles (DDGS) to the nutritional regimens of ewes at different time periods on reproductive traits, serum hormones and serum metabolites. In Experiment 1, 100 ewes were divided into 4 groups (n = 25) according to diet. The four diets were grass hay (H) alone (group H), H with barley (group H + B), H with DDGS for the whole feeding period (27 d) (group H + DDGS) or H and DDGS for 5 d (d 8–12 of oestrus cycle) (group H + DDGS5). Serum progesterone concentrations were affected by oestrus cycle (p < 0.001), but not by dietary treatments. However, feeding H + DDGS caused significant increases in serum insulin, leptin and growth hormone concentrations (p < 0.05). In Experiment 2, 30 ewes were divided into 2 groups (n = 15), receiving DDGS or soybean meal (SBM) during the prepartum period. Diets had no significant effect on weights of dams or lambs at birth; however, the weaning weights of lambs born from ewes of group DDGS were significantly higher (p < 0.05). Moreover, serum glucose, blood urea nitrogen, triglyceride and beta hydroxybutyric acid (BHBA) concentrations during the prepartum period were affected by dietary treatments and by time (p < 0.001). During the prepartum period, BHBA concentrations of ewes fed SBM were higher, while BHBA levels decreased during the last weeks of pregnancy regardless of diet. Lamb serum immunoglobulin G concentrations increased from 1 h to 24 h after birth (p < 0.001). Colostrum of ewes fed SBM had higher fat-free dry matter (DM) and protein contents in comparison to colostrum of ewes fed DDGS (p < 0.05). In conclusion, DDGS can be included as protein source in pregnancy rations up to 15% of DM to obtain reproductive performance outcomes equal to or exceeding those obtained with SBM.