Morphology and gene expression in mouse placentas lacking leptin receptors.

In the pregnant mouse, the hormone leptin is primarily produced by adipose tissue and does not significantly cross the placenta into fetal circulation. Nonetheless, leptin treatment during gestation affects offspring phenotypes. Leptin treatment also affects placental trophoblast cells in vitro, by altering proliferation, invasion and nutrient transport. The goal of the present study was to determine whether the absence of placental leptin receptors alters placental development and gene expression. Leprdb-3j+ mice possessing only one functional copy of the leptin receptor were mated to obtain wildtype, Leprdb-3j+ and Leprdb-3j/db-3j conceptuses, which were then transferred to wildtype recipient dams. Placentas were collected at gestational d18.5 to examine placental morphology and gene expression. Placentas lacking functional leptin receptor had reduced weights, but were otherwise morphologically indistinguishable from control placentas. Relative mRNA levels, however, were altered in Leprdb-3j/db-3j placentas, particularly transcripts related to amino acid and lipid metabolism and transport. Consistent with a previous in vitro study, leptin was found to promote expression of stathmin, a positive regulator of trophoblast invasion, and of serotonin receptors, potential mediators of offspring neurological development. Overall placental leptin receptor was found not to play a significant role in morphological development of the placenta, but to regulate placental gene expression, including in metabolic pathways that affect fetal growth.

Prehospital amputation: An experimental comparison of techniques.

OBJECTIVE: Prehospital limb amputation is a rare but potentially life-saving intervention. When patients cannot be extricated due to limb entrapment or have hemodynamic compromise that precludes a prolonged extrication, they may benefit from an emergent prehospital amputation. The objective was to experimentally compare three prehospital amputation techniques on porcine legs. METHODS: The three techniques studied were a scalpel with a Gigli saw, a hacksaw, and a reciprocating saw. For the first technique, a scalpel was used to make a circumferential incision in the soft tissue and a Gigli wire saw to cut through the bone. The second and third techniques only used a saw and did not require soft tissue incision with a scalpel. Three providers including an emergency medicine physician, a paramedic, and a medical student performed three amputations of each technique, resulting in twenty-seven total amputations. The primary outcome was amputation time. Secondary outcomes were rate of instrument malfunction and cleanliness of cut. RESULTS: The primary outcome of amputation time was different between techniques. The Gigli saw technique took 32.86 ± 16.53 s (mean ± SD), hacksaw technique 6.28 ± 0.76 s, and reciprocating saw technique 2.84 ± 0.40 s. There were no differences in amputation time between participants for a given amputation technique. The Gigli saw technique had an instrument malfunction on 3/9 trials which was distinct from the other techniques. Differences in cleanliness of cut were nonsignificant. CONCLUSIONS: Prehospital limb amputation with a hacksaw or reciprocating saw may result in faster completion of the time-sensitive procedure with fewer instrument malfunctions.

Effects of acute exposure to a high-fat, high-sucrose diet on gestational glucose tolerance and subsequent maternal health in mice.

Gestational diabetes mellitus (GDM) is a common obstetric complication. Half of women who have GDM will go on to develop type 2 diabetes. Understanding the mechanisms by which this occurs requires an animal model of GDM without ongoing diabetes at conception. C57Bl/6J mice react acutely to a high-fat, high-sucrose (HFHS) challenge. Here, we hypothesized that a periconceptional HFHS challenge will induce glucose intolerance during gestation. C57Bl/6J female mice were placed on an HFHS either 1 or 3 weeks prior to mating and throughout pregnancy. Intraperitoneal glucose tolerance tests, insulin measurements, and histological analysis of pancreatic islets were used to assess the impact of acute HFHS. C57Bl/6J females fed HFHS beginning 1 week prior to pregnancy became severely glucose intolerant, with reduced insulin response to glucose, and decreased pancreatic islet expansion during pregnancy compared to control mice. These GDM characteristics did not occur when the HFHS diet was started 3 weeks prior to mating, suggesting the importance of acute metabolic stress. Additionally, HFHS feeding resulted in only mild insulin resistance in nonpregnant females. When the diet was discontinued at parturition, symptoms resolved within 3 weeks. However, mice that experienced glucose intolerance in pregnancy became glucose intolerant more readily in response to a HFHS challenge later in life than congenic females that experienced a normal pregnancy, or that were fed the same diet outside of pregnancy. Thus, acute HFHS challenge in C57Bl/6 mice results in a novel, nonobese, animal model that recapitulates the long-term risk of developing type 2 diabetes following GDM.

Maternal Hyperleptinemia Is Associated with Male Offspring's Altered Vascular Function and Structure in Mice.

Children of mothers with gestational diabetes have greater risk of developing hypertension but little is known about the mechanisms by which this occurs. The objective of this study was to test the hypothesis that high maternal concentrations of leptin during pregnancy, which are present in mothers with gestational diabetes and/or obesity, alter blood pressure, vascular structure and vascular function in offspring. Wildtype (WT) offspring of hyperleptinemic, normoglycemic, Leprdb/+ dams were compared to genotype matched offspring of WT-control dams. Vascular function was assessed in male offspring at 6, and at 31 weeks of age after half the offspring had been fed a high fat, high sucrose diet (HFD) for 6 weeks. Blood pressure was increased by HFD but not affected by maternal hyperleptinemia. On a standard diet, offspring of hyperleptinemic dams had outwardly remodeled mesenteric arteries and an enhanced vasodilatory response to insulin. In offspring of WT but not Leprdb/+ dams, HFD induced vessel hypertrophy and enhanced vasodilatory responses to acetylcholine, while HFD reduced insulin responsiveness in offspring of hyperleptinemic dams. Offspring of hyperleptinemic dams had stiffer arteries regardless of diet. Therefore, while maternal hyperleptinemia was largely beneficial to offspring vascular health under a standard diet, it had detrimental effects in offspring fed HFD. These results suggest that circulating maternal leptin concentrations may interact with other factors in the pre- and post -natal environments to contribute to altered vascular function in offspring of diabetic pregnancies.

Maternal Hyperleptinemia Improves Offspring Insulin Sensitivity in Mice.

Maternal obesity and gestational diabetes are prevalent worldwide. Offspring of mothers with these conditions weigh more and are predisposed to metabolic syndrome. A hallmark of both conditions is maternal hyperleptinemia, but the role of elevated leptin levels during pregnancy on developmental programming is largely unknown. We previously found that offspring of hyperleptinemic mothers weighed less and had increased activity. The goal of this study was to determine whether maternal leptin affects offspring insulin sensitivity by investigating offspring glucose metabolism and lipid accumulation. Offspring from two maternal hyperleptinemic models were compared. The first model of hyperleptinemia is the Lepr(db/+) mouse, which has a mutation in one copy of the gene that encodes the leptin receptor, resulting in a truncated long form of the receptor, and hyperleptinemia. Wild-type females served as the control for the Lepr(db/+) females. For the second hyperleptinemic model, wild-type females were implanted with miniosmotic pumps, which released leptin (350 ng/h) or saline (as the control) just prior to mating and throughout gestation. In the offspring of these dams, we measured glucose tolerance; serum leptin, insulin, and triglyceride levels; liver triglycerides; pancreatic α- and ß-cell numbers; body composition; incidence of nonalcoholic fatty liver disease; and the expression of key metabolic genes in the liver and adipose tissue. We found that the offspring of hyperleptinemic dams exhibited improved glucose tolerance, reduced insulin and leptin concentrations, reduced liver triglycerides, and a lower incidence of nonalcoholic fatty liver disease. Overall, maternal hyperleptinemia was beneficial for offspring glucose and lipid metabolism.

Hyperleptinemia During Pregnancy Decreases Adult Weight of Offspring and Is Associated With Increased Offspring Locomotor Activity in Mice.

Pregnant women who are obese or have gestational diabetes mellitus have elevated leptin levels and their children have an increased risk for child and adult obesity. The goals of this study were to determine whether offspring weights are altered by maternal hyperleptinemia, and whether this occurs via behavioral changes that influence energy balance. We used 2 hyperleptinemic mouse models. The first was females heterozygous for a leptin receptor mutation (DB/+), which were severely hyperleptinemic, and that were compared with wild-type females. The second model was wild-type females infused with leptin (LEP), which were moderately hyperleptinemic, and were compared with wild-type females infused with saline (SAL). Total food consumption, food preference, locomotor activity, coordinated motor skills, and anxiety-like behaviors were assessed in wild-type offspring from each maternal group at 3 postnatal ages: 4-6, 11-13, and 19-21 weeks. Half the offspring from each group were then placed on a high-fat diet, and behaviors were reassessed. Adult offspring from both groups of hyperleptinemic dams weighed less than their respective controls beginning at 23 weeks of age, independent of diet or sex. Weight differences were not explained by food consumption or preference, because female offspring from hyperleptinemic dams tended to consume more food and had reduced preference for palatable, high-fat and sugar, food compared with controls. Offspring from DB/+ dams were more active than offspring of controls, as were female offspring of LEP dams. Maternal hyperleptinemia during pregnancy did not predispose offspring to obesity, and in fact, reduced weight gain.