Maternal hormonal manipulations in rats cause obesity and increase medial hypothalamic norepinephrine release in male offspring

Maternal obstructive sleep apnea aggravates metabolic dysfunction-associated fatty liver disease via HMGB1-TLR4 signaling-mediated endoplasmic reticulum stress in male offspring rats

AIMS/HYPOTHESIS

Maternal obstructive sleep apnea (MOSA) may inflict long-term metabolic effects on offspring. We hypothesize that MOSA increases the propensity for metabolic dysregulation in offspring and thus facilitates the development of metabolic dysfunction-associated fatty liver disease (MAFLD). This study aims to test the hypothesis and explore the underlying mechanism.

METHODS

The MOSA rat model of upper airway obstruction was established and fecundated. The postweaning male offspring (n = 171) from both the control group and MOSA group were randomly fed the normal chow diet (NCD, n = 89) or high-fat diet (HFD, n = 82) for the next 5 months. Liver function, lipid profile, glucose, and insulin levels were measured. Expression levels of fibrosis-related proteins and endoplasmic reticulum (ER) stress-related proteins in liver tissues were assessed using immunohistochemistry and western blotting.

RESULTS

MOSA increased body and liver weight in male offspring, along with augmented liver organ coefficient. Serum levels of aminotransferases, low-density lipoprotein, high-density lipoprotein, triglycerides, total cholesterol, total bile acid, fasting glucose, and insulin increased significantly. MOSA exacerbated HFD-induced hepatic steatosis and fibrosis. These effects were driven by the overactivated double-stranded RNA-activated protein kinase (PKR)-like eukaryotic initiation factor 2(PERK)-activating transcription factor (ATF)4-C/EBP homologous protein (CHOP) signaling pathway-induced ER stress, and hyperacetylation and release of high mobility group box-1(HMGB1) elicited above signaling in a TLR4-dependent manner.

CONCLUSIONS

These findings indicate that MOSA can exert prolonged adverse effects manifested as metabolic dysfunction in male offspring. Therefore, surveillance and management of OSA during pregnancy may be necessary to prevent and alleviate MAFLD in offspring.

Therapeutic potential of dopamine agonists in the treatment of type 2 diabetes mellitus

Diabetes is a global health concern that has affected almost 415 million people globally. Bromocriptine is a dopamine D2 agonist, which is a Food and Drug Administration (FDA)-approved drug to treat type 2 diabetes mellitus (T2DM) patients. However, it is considered that a novel treatment therapy is required which can be used in the treatment of diabetes with or without other antidiabetic agents. Dopamine agonists are usually used in neurological disorders like Parkinson's disease (PD), restless leg syndrome, and hyperprolactinemia. However, dopamine agonists including bromocriptine and cabergoline are also effective in reducing the glycemic level in T2DM patients. Bromocriptine was formerly used for the treatment of PD, hyperprolactinemia, and restless leg syndrome, but now it is used for improving glycemic levels as well as reducing free fatty acids and triglycerides. In addition, cabergoline has been found to be effective in glycemic control, but this drug is yet to be approved by the FDA due to its limitations and lack of study. Findings of the clinical trials of bromocriptine have suggested that it reduces almost 0.4-0.8% glycated hemoglobin and cardiovascular risk by 40% in insulin-resistant patients. Moreover, the safe use of bromocriptine in obese T2DM patients makes it a more attractive option as it causes weight loss. Indeed, bromocriptine is a novel therapy for T2DM patients, as its mechanism of action is unique in T2DM patients with minimal adverse effects. This review summarizes the potential of dopamine agonists in the treatment of T2DM.

Developmental programming of hypothalamic neuroendocrine systems

There is increasing evidence to suggest that the perinatal environment may alter the developmental programming of hypothalamic neuroendocrine systems in a manner that predisposes offspring to the development of metabolic syndrome. Although it is unclear how these effects might be mediated, it has been shown that changes in neuroendocrine programing during critical periods of development, either via maternal metabolic programming or other factors, can alter a fetus's metabolic fate. This review summarizes the hypothalamic circuits that mediate energy homeostasis and discusses the various factors that may influence the development and functioning of these neural systems, as well as the possible cognitive impairments that may arise as a result of these metabolic influences.

Early life origins of metabolic disease: Developmental programming of hypothalamic pathways controlling energy homeostasis

A wealth of animal and human studies demonstrate that perinatal exposure to adverse metabolic conditions - be it maternal obesity, diabetes or under-nutrition - results in predisposition of offspring to develop obesity later in life. This mechanism is a contributing factor to the exponential rise in obesity rates. Increased weight gain in offspring exposed to maternal obesity is usually associated with hyperphagia, implicating altered central regulation of energy homeostasis as an underlying cause. Perinatal development of the hypothalamus (a brain region key to metabolic regulation) is plastic and sensitive to metabolic signals during this critical time window. Recent research in non-human primate and rodent models has demonstrated that exposure to adverse maternal environments impairs the development of hypothalamic structure and consequently function, potentially underpinning metabolic phenotypes in later life. This review summarizes our current knowledge of how adverse perinatal environments program hypothalamic development and explores the mechanisms that could mediate these effects.

Programming of fetal insulin resistance in pregnancies with maternal obesity by ER stress and inflammation

The global epidemics of obesity during pregnancy and excessive gestational weight gain (GWG) are major public health problems worldwide. Obesity and excessive GWG are related to several maternal and fetal complications, including diabetes (pregestational and gestational diabetes) and intrauterine programming of insulin resistance (IR). Maternal obesity (MO) and neonatal IR are associated with long-term development of obesity, diabetes mellitus, and increased global cardiovascular risk in the offspring. Multiple mechanisms of insulin signaling pathway impairment have been described in obese individuals, involving complex interactions of chronically elevated inflammatory mediators, adipokines, and the critical role of the endoplasmic reticulum (ER) stress-dependent unfolded protein response (UPR). However, the underlying cellular processes linking MO and IR in the offspring have not been fully elucidated. Here, we summarize the state-of-the-art evidence supporting the possibility that adverse metabolic postnatal outcomes such as IR in the offspring of pregnancies with MO and/or excessive GWG may be related to intrauterine activation of ER stress response.

Organizational actions of metabolic hormones

Brain development is a complex and dynamic process, and many environmental factors have been found to influence the normal development of neural pathways. Cumulative evidence suggests that metabolic hormones that regulate the hypothalamic circuits that control energy homeostasis function in much the same way that sex steroids act on sexually dimorphic circuits. For example, although the effects of the adipocyte-derived hormone leptin were originally thought to be limited to the neural control of energy homeostasis in adult animals, it is now becoming increasingly clear that leptin can also determine patterns of neurogenesis, axon growth, and synaptic plasticity in the developing hypothalamus. More recent studies have also extended the role of the metabolic hormones ghrelin and insulin in various aspects of brain development. Examining how metabolic hormones control hypothalamic development will help our understanding of the developmental origin of adult metabolic diseases and, hopefully, improve our ability to predict adverse outcomes.

Unraveling the mechanisms responsible for the comorbidity between metabolic syndrome and mental health disorders

The increased prevalence and high comorbidity of metabolic syndrome (MetS) and mental health disorders (MHDs) have prompted investigation into the potential contributing mechanisms. There is a bidirectional association between MetS and MHDs including schizophrenia, bipolar disorder, depression, anxiety, attention-deficit/hyperactivity disorder, and autism spectrum disorders. Medication side effects and social repercussions are contributing environmental factors, but there are a number of shared underlying neurological and physiological mechanisms that explain the high comorbidity between these two disorders. Inflammation is a state shared by both disorders, and it contributes to disruptions of neuroregulatory systems (including the serotonergic, dopaminergic, and neuropeptide Y systems) as well as dysregulation of the hypothalamic-pituitary-adrenal axis. MetS in pregnant women also exposes the developing fetal brain to inflammatory factors that predispose the offspring to MetS and psychopathologies. Due to the shared nature of these conditions, treatment should address aspects of both mental health and metabolic disorders. Additionally, interventions that can interrupt the transfer of increased risk of the disorders to the next generation need to be developed. © 2013 S. Karger AG, Basel.

Maternal high fat diet consumption during the perinatal period programs offspring behavior

The environment that a developing offspring experiences during the perinatal period is markedly influenced by maternal health and diet composition. Evidence from both epidemiological studies and animal models indicates that maternal diet and metabolic status play a critical role in programming the neural circuitry that regulates behavior, resulting in long-term consequences for offspring behavior. Maternal diet and metabolic state influence the behavior of offspring directly by impacting the intrauterine environment and indirectly by modulating maternal behavior. The mechanisms by which maternal diet and metabolic profile shape the perinatal environment remain largely unknown, but recent research has found that increases in inflammatory cytokines, nutrients (glucose and fatty acids), and hormones (insulin and leptin) affect the environment of the developing offspring. Offspring exposed to maternal obesity and high fat diet consumption during development are more susceptible to developing mental health and behavioral disorders such as anxiety, depression, attention deficit hyperactivity disorder, and autism spectrum disorders. Recent evidence suggests that this increased risk for behavioral disorders is driven by modifications in the development of neural pathways involved in behavioral regulation. In particular, research indicates that the development of the serotonergic system is impacted by exposure to maternal obesity and high fat diet consumption, and this disruption may underlie many of the behavioral disturbances observed in these offspring. Given the high rates of obesity and high fat diet consumption in pregnant women, it is vital to examine the influence that maternal nutrition and metabolic profile have on the developing offspring.

Effect of food restriction and leptin supplementation on fetal programming in mice

Metabolic disease is a significant global health and economic problem. In a phenomenon referred to as fetal programming, offspring of underweight or overweight mothers have an increased incidence of adulthood obesity and metabolic disease. Undernourished individuals have decreased levels of leptin, a regulator of energy balance, whereas obese people develop hyperleptinemia and leptin resistance. We hypothesize that alterations in circulating leptin during pregnancy contribute to programming events caused by maternal nutritional status. To test this hypothesis, pregnant mice were randomly placed in one of three treatment groups: ad libitum feed plus saline injection (control, n = 5), 50% food restriction plus saline injection (restricted, n = 4), or 50% food restriction plus 1 mg/kg · d leptin injection (restricted, leptin treated, n = 4). Mice were treated from 1.5 to 11.5 d after conception and then returned to ad libitum feeding until weaning. At 19 wk after weaning, offspring were placed on a 45% fat diet and then followed up until 26 wk after weaning, at which time they were killed, and samples were collected for further analysis. Our results demonstrate that males are more negatively impacted by high-fat diet than females, regardless of maternal treatment. We provide evidence that differential response to leptin may mediate the sexual dimorphism observed in fetal programming in which male offspring are more affected by maternal undernutrition and female offspring by maternal overnutrition. We show that female offspring born to food-restricted, leptin-supplemented mothers are obese and insulin resistant. This may mimic fetal programming events seen in offspring of overweight women.

The Impact of Maternal High-Fat Diet Consumption on Neural Development and Behavior of Offspring

Maternal diet and metabolic state are important factors in determining the environment experienced during perinatal development. Epidemiological studies and evidence from animal models provide evidence that a mother's diet and metabolic condition are important in programming the neural circuitry that regulates behavior, resulting in a persistent impact on the offspring's behavior. Potential mechanisms by which maternal diet and metabolic profile influence the perinatal environment include placental dysfunction and increases in circulating factors such as inflammatory cytokines, nutrients (glucose and fatty acids) and hormones (insulin and leptin). Maternal obesity and high-fat diet (HFD) consumption exposure during development have been observed to increase the risk of developing serious mental health and behavioral disorders including anxiety, depression, attention deficit hyperactivity disorder and autism spectrum disorder. The increased risk of developing these behavioral disorders is postulated to be due to perturbations in the development of neural pathways that regulate behavior, including the serotonergic, dopaminergic and melanocortinergic systems. It is critical to examine the influence that a mother's nutrition and metabolic profile have on the developing offspring considering the current and alarmingly high prevalence of obesity and HFD consumption in pregnant women.

The association between in utero hyperinsulinemia and adolescent arterial stiffness

AIM

To determine the relationship between in utero hyperinsulinemia and children's arterial stiffness at adolescence.

METHODS

Indices of arterial stiffness were measured using the SphygmoCor apparatus in 129 adolescents (42 offsprings of mother with gestational diabetes and 87 offsprings of mother with normal glucose tolerance during pregnancy) at 15 years of age.

RESULTS

Adolescent of mothers with gestational diabetes had similar central aortic blood pressure, augmentation pressure (AP), augmentation index (AI), and carotid-femoral pulse wave velocity (PWV) as that of controls. However, both umbilical cord C-peptide and insulin levels correlated positively AI (R=0.28 and 0.24; p=0.011 and 0.035, respectively), and umbilical insulin level correlated positively with AP (R=0.25; p=0.025). The correlations were significant between umbilical cord C-peptide and AP (R=0.24; p=0.035) and AI (R=0.29; p=0.011) after adjustment for subjects' age, sex, body weight and height. Adolescents who had umbilical cord C-peptide levels at highest quartile (n=25), based on the reference ranges of the original cohort, had a significant greater PWV (5.26±0.12 m/s vs 4.98±0.12 m/s; p=0.0049) than those with C-peptide levels at the lower 3 quartiles (n=57) after adjustment for age, sex, body weight and height.

CONCLUSIONS

In utero hyperinsulinemia appears to increase the offspring's arterial stiffness at early adolescence.

Altered health outcomes in adult offspring of Sprague Dawley and Wistar rats undernourished during early or late pregnancy

BACKGROUND

Birth weight in humans has been inversely associated with adult disease risk. Results of animal studies have varied depending on species, strain, and treatment.

METHODS

We compared birth weight and adult health in offspring following 50% maternal undernutrition on gestation days (GD) 1-15 (UN1-15) or GD 10-21 (UN10-21) in Sprague Dawley and Wistar rats. Offspring from food-deprived dams were weighed and cross-fostered to control dams. Litters were weighed during lactation and initiating at weaning males were fed either control or a high-fat diet. Young and mature adult offspring were evaluated for obesity, blood pressure (BP), insulin response to oral glucose, and serum lipids. Nephron endowment, renal glucocorticoid receptor, and renin-aldosterone-angiotensin system components were measured.

RESULTS

The UN10-21 groups had birth weights lower than controls and transient catch up growth by weaning. Neither strain demonstrated obesity or dyslipidemia following prenatal undernutrition, but long-term body weight deficits occurred in the UN groups of both strains. High-fat diet fed offspring gained more weight than control offspring without an effect of prenatal nutrition. Sprague Dawley were slightly more susceptible than Wistar rats to altered insulin response and increased BP following gestational undernutrition. Nephron endowment in Sprague Dawley but not Wistar offspring was lower in the UN10-21 groups. Glucocorticoid and renin-aldosterone-angiotensin system pathways were not altered.

CONCLUSIONS

The most consistent effect of maternal undernutrition was elevated BP in offspring. Long-term health effects occurred with undernutrition during either window, but the UN10-21 period resulted in lower birth weight and more severe adult health effects.

Perinatal exposure to high-fat diet programs energy balance, metabolism and behavior in adulthood

The perinatal environment plays an important role in programming many aspects of physiology and behavior including metabolism, body weight set point, energy balance regulation and predisposition to mental health-related disorders such as anxiety, depression and attention deficit hyperactivity disorder. Maternal health and nutritional status heavily influence the early environment and have a long-term impact on critical central pathways, including the melanocortinergic, serotonergic system and dopaminergic systems. Evidence from a variety of animal models including rodents and nonhuman primates indicates that exposure to maternal high-fat diet (HFD) consumption programs offspring for increased risk of adult obesity. Hyperphagia and increased preference for fatty and sugary foods are implicated as mechanisms for the increased obesity risk. The effects of maternal HFD consumption on energy expenditure are unclear, and future studies need to address the impact of perinatal HFD exposure on this important component of energy balance regulation. Recent evidence from animal models also indicates that maternal HFD consumption increases the risk of offspring developing mental health-related disorders such as anxiety. Potential mechanisms for perinatal HFD programming of neural pathways include circulating factors, such as hormones (leptin, insulin), nutrients (fatty acids, triglycerides and glucose) and inflammatory cytokines. As maternal HFD consumption and obesity are common and rapidly increasing, we speculate that future generations will be at increased risk for both metabolic and mental health disorders. Thus, it is critical that future studies identify therapeutic strategies that are effective at preventing maternal HFD-induced malprogramming.

Developmental gene x environment interactions affecting systems regulating energy homeostasis and obesity

Most human obesity is inherited as a polygenic trait which is largely refractory to medical therapy because obese individuals avidly defend their elevated body weight set-point. This set-point is mediated by an integrated neural network that controls energy homeostasis. Epidemiological studies suggest that perinatal and pre-pubertal environmental factors can promote offspring obesity. Rodent studies demonstrate the important interactions between genetic predisposition and environmental factors in promoting obesity. This review covers issues of development and function of neural systems involved in the regulation of energy homeostasis and the roles of leptin and insulin in these processes, the ways in which interventions at various phases from gestation, lactation and pre-pubertal stages of development can favorably and unfavorably alter the development of obesity n offspring. These studies suggest that early identification of obesity-prone humans and of the factors that can prevent them from becoming obese could provide an effective strategy for preventing the world-wide epidemic of obesity.

Perinatal environment and its influences on metabolic programming of offspring

The intrauterine environment supports the development and health of offspring. Perturbations to this environment can have detrimental effects on the fetus that have persistent pathological consequences through adolescence and adulthood. The developmental origins of the health and disease concept, also known as the "Barker Hypothesis", has been put forth to describe the increased incidence of chronic disease such as cardiovascular disease and diabetes in humans and animals exposed to a less than ideal intrauterine environment. Maternal infection, poor or excess nutrition, and stressful events can negatively influence the development of different cell types, tissues and organ systems ultimately predisposing the organism to pathological conditions. Although there are a variety of conditions associated to exposure to altered intrauterine environments, the focus of this review will be on the consequences of stress and high fat diet during the pre- and perinatal periods and associated outcomes related to obesity and other metabolic conditions. We further discuss possible neuroendocrine and epigenetic mechanisms responsible for the metabolic programming of offspring. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

Interaction of perinatal and pre-pubertal factors with genetic predisposition in the development of neural pathways involved in the regulation of energy homeostasis

A majority of human obesity is inherited as a polygenic trait. Once obesity develops, over 90% of individuals repeatedly regain lost weight after dieting. Only surgical interventions offer long lasting weight loss. Thus, clinical data suggest that some individuals have a predisposition to develop and maintain an elevated body weight set-point once they are provided with sufficient calories to gain weight. This set-point is mediated by an integrated neural network that controls energy homeostasis. Unfortunately, currently available tools for identifying obesity-prone individuals and examining the functioning of these neural systems have insufficient resolution to identify specific neural factors that cause humans to develop and maintain the obese state. However, rodent models of polygenically inherited obesity allow us to investigate the factors that both predispose them to become obese and that prevent or enhance the development of such obesity. Maternal obesity during gestation and lactation in obesity-prone rodents enhances offspring obesity and alters their neural pathways involved in energy homeostasis regulation. Early postnatal exposure of obesity-resistant offspring to the milk of genetically obese dams alters their hypothalamic pathways involved in energy homeostasis causing them to become obese when fed a high fat diet as adults. Finally, short-term exercise begun in the early post-weaning period increases the sensitivity to the anorectic effects of leptin and protects obesity-prone offspring from becoming obese for months exercise cessation. Such studies suggest that early identification of obesity-prone humans and of the factors that can prevent them from becoming obese could provide an effective strategy for preventing the world wide epidemic of obesity.

Prenatal stress or high-fat diet increases susceptibility to diet-induced obesity in rat offspring

OBJECTIVE

Perturbations to the prenatal environment have been associated with the development of adult chronic disease, findings that gave rise to the "Barker Hypothesis" or the "developmental origins of adult disease" concept. In this study, we used an animal model to determine the metabolic consequences of maternal prenatal stress and high-fat feeding on the developing offspring.

RESEARCH DESIGN AND METHODS

Pregnant female Sprague-Dawley rats were maintained on standard chow or 60% high-fat diet throughout gestation and lactation. Half of each group were exposed to a novel variable stress paradigm during the 3rd week of gestation, whereas control dams were left undisturbed. Body weight, body composition, glucose tolerance, and endocrine parameters were measured in offspring through early adulthood.

RESULTS

Male and female pups from dams that experienced prenatal stress and/or were on a high-fat diet weighed more beginning on postnatal day 7 compared with standard chow-control pups. Access to high-fat diet at weaning increased the body weight effect through early adulthood and was attributable to greater adiposity. Pups weaned onto standard chow diet showed no significant difference in glucose clearance or insulin secretion. However, pups weaned onto high-fat diet had impaired glucose tolerance if their dams were on a high-fat diet, experienced prenatal stress, or both.

CONCLUSIONS

Our data demonstrate that prenatal stress and/or high-fat diet during the intrauterine or postnatal environment affects offspring in a manner that increases their susceptibility to diet-induced obesity and leads to secondary adverse metabolic consequences.

Early life origins of obesity: role of hypothalamic programming

The incidence of obesity is increasing at an alarming rate and this worldwide epidemic represents an ominous predictor of increases in diseases such as type 2 diabetes and metabolic syndrome. Epidemiological and animals studies suggest that maternal obesity and alterations in postnatal nutrition are associated with increased risks for obesity, hypertension, and type 2 diabetes in the offspring. Furthermore, there is also growing appreciation that developmental programming of neuroendocrine systems by the perinatal environment represents a possible cause for these diseases. This review article provides a synthesis of recent evidence concerning the actions of perinatal hormones and nutrition in programming the development and organization of hypothalamic circuits that regulate body weight and energy balance. Particular attention is given to the neurodevelopmental actions of insulin and leptin.

beta(2)-Adrenoceptor-mediated facilitation of glutamatergic transmission in rat ventromedial hypothalamic neurons

Adrenergic modulation of glutamatergic spontaneous miniature excitatory postsynaptic currents (mEPSCs) was investigated in mechanically dissociated rat ventromedial hypothalamic (VMH) neurons using a conventional whole-cell patch clamp technique. Noradrenaline (NA) reversibly increased mEPSC frequency without affecting the current amplitude in a concentration-dependent manner, indicating that NA acts presynaptically to facilitate the probability of spontaneous glutamate release. NA (10 microM) action on glutamatergic mEPSC frequency was completely blocked by 1 microM ICI-188551 [(+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methyl-ethyl)amino]-2-butanol], a selective beta(2)-adrenoceptor antagonist, and mimicked by 1 microM formoterol, a selective beta(2)-adrenoceptor agonist. Neither alpha-adrenoceptor nor beta(1)-adrenoceptor blockers affected the NA-induced increase in mEPSC frequency. NA action on glutamatergic mEPSC frequency was completely occluded in the presence of either 10 microM forskolin, an adenylyl cyclase (AC) activator, or blocked by 1 microM SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine], a selective AC inhibitor. Furthermore, the NA-induced increase in mEPSC frequency was completely attenuated by either 1 muM KT5720 or 1 microM H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide), specific PKA inhibitors. However, NA still could increase mEPSC frequency either in the Ca(2+)-free external solution or in the presence of 1 microM thapsigargin. The results suggest that activation of presynaptic beta(2)-adrenoceptors facilitates spontaneous glutamate release to VMH neurons via cAMP/PKA signal transduction pathway. beta(2)-Adrenoceptor-mediated presynaptic modulation of excitatory glutamatergic transmission would therefore be expected to play a pivotal role in the regulation of a variety of behavioral functions, which are mediated by the VMH.

Metabolic imprinting: critical impact of the perinatal environment on the regulation of energy homeostasis

Epidemiological studies in humans suggest that maternal undernutrition, obesity and diabetes during gestation and lactation can all produce obesity in offspring. Animal models have allowed us to investigate the independent consequences of altering the pre- versus post-natal environments on a variety of metabolic, physiological and neuroendocrine functions as they effect the development in the offspring of obesity, diabetes, hypertension and hyperlipidemia (the 'metabolic syndrome'). During gestation, maternal malnutrition, obesity, type 1 and type 2 diabetes and psychological, immunological and pharmacological stressors can all promote offspring obesity. Normal post-natal nutrition can reduce the adverse impact of some of these pre-natal factors but maternal high-fat diets, diabetes and increased neonatal access to food all enhance the development of obesity and the metabolic syndrome in offspring. The outcome of these perturbations of the perinatal environmental is also highly dependent upon the genetic background of the individual. Those with an obesity-prone genotype are more likely to be affected by factors such as maternal obesity and high-fat diets than are obesity-resistant individuals. Many perinatal manipulations appear to promote offspring obesity by permanently altering the development of central neural pathways, which regulate food intake, energy expenditure and storage. Given their strong neurotrophic properties, either excess or an absence of insulin and leptin during the perinatal period are likely to be effectors of these developmental changes. Because obesity is associated with an increased morbidity and mortality and because of its resistance to treatment, prevention is likely to be the best strategy for stemming the tide of the obesity epidemic. Such prevention should begin in the perinatal period with the identification and avoidance of factors which produce permanent, adverse alterations in neural pathways which control energy homeostasis.

Developmental origins of the metabolic syndrome: prediction, plasticity, and programming

The "fetal" or "early" origins of adult disease hypothesis was originally put forward by David Barker and colleagues and stated that environmental factors, particularly nutrition, act in early life to program the risks for adverse health outcomes in adult life. This hypothesis has been supported by a worldwide series of epidemiological studies that have provided evidence for the association between the perturbation of the early nutritional environment and the major risk factors (hypertension, insulin resistance, and obesity) for cardiovascular disease, diabetes, and the metabolic syndrome in adult life. It is also clear from experimental studies that a range of molecular, cellular, metabolic, neuroendocrine, and physiological adaptations to changes in the early nutritional environment result in a permanent alteration of the developmental pattern of cellular proliferation and differentiation in key tissue and organ systems that result in pathological consequences in adult life. This review focuses on those experimental studies that have investigated the critical windows during which perturbations of the intrauterine environment have major effects, the nature of the epigenetic, structural, and functional adaptive responses which result in a permanent programming of cardiovascular and metabolic function, and the role of the interaction between the pre- and postnatal environment in determining final health outcomes.

Programming of obesity and cardiovascular disease

BACKGROUND

There is evidence that malnutrition in early life induces a growth retardation leading, in adult life, to manifest components of the metabolic syndrome. However, the impact on obesity seems less clearly established.

OBJECTIVE

To review the effects of foetal and postnatal malnutrition on the programming of obesity in the context of the metabolic syndrome, as well as the link between central obesity and cardiovascular diseases.

METHODS

Included in the review were recent papers exploring the mechanisms linking maternal nutrition with impaired foetal growth and later obesity, cardiovascular disease, hypertension and diabetes in humans and animals.

RESULTS

The programming of obesity during foetal and early postnatal life depends of the timing of maternal malnutrition as well as the postnatal environment. Obesity arises principally in offspring submitted to malnutrition during early stages of gestation and which presented early catch-up growth. The programming may involve the dysregulation of appetite control or the hormonal environment leading to a context favourable to obesity development (hypersecretion of corticosteroids, hyperinsulinaemia and hyperleptinaemia and anomalies in the IGF axis). Adipose tissue secretes actively several factors implicated in inflammation, blood pressure, coagulation and fibrinolysis. The programmed development of intra-abdominal obesity after early growth restriction may thus favour higher prevalence of hypertension and cardiovascular diseases.

CONCLUSIONS

Abdominal obesity appears in malnourished offspring and is aggravated by early catch-up growth. Higher rates of intra-abdominal obesity observed after growth restriction may participate to hypertension and create atherothrombotic conditions leading to the development of cardiovascular diseases.

Early origins of obesity: programming the appetite regulatory system

There is evidence that changes in perinatal nutrition programme the development of relative fat mass and the regulation of appetite in adult life. These studies have been primarily in the rodent utilizing maternal overnutrition or undernutrition imposed at different stages of pregnancy and beyond, mapping of neuropeptide localization and activity and appropriate null mutant models. Whilst the rodent offers significant advantages in terms of a short gestation and the availability of useful transgenic and null mutant models, there are also advantages to using an animal model more akin to the human, in which all components of the 'fat-brain axis' are present before birth, such as the sheep. This review summarizes recent work on the expression and localization of the 'appetite regulatory' peptides in the fetal rodent and sheep hypothalamus and their potential role in the early programming of postnatal appetite and obesity.

Altered action of dopamine and cholecystokinin on lateral hypothalamic neurons in rats raised under different feeding conditions

Single-unit activity was recorded in the lateral hypothalamus (LH) of adult Wistar rats anaesthetized with urethane. The rats were differently nourished till weaning by raising in small (SL), control (CL) or large litters (LL). They gained significantly different body weight leading to overweight in SL (mean: 428.4 g on day 90) and underweight in LL rats (mean 399.5 g) compared to CLs (414.5 g). The mean basal firing rate of LH neurons differed, it was lowest in SL and highest in LL rats. The proportion of neurons changing their firing rate by more than 30% in response to iontophoretically administered dopamine (DA) was significantly greater in SL (76%) than LL rats (54%). Effects of DA were significantly more often blocked by a D1 receptor antagonist in LL than CLs. The responsiveness to cholecystokinin (CCK) alone and coadministered with DA was also greater in SL than LL. Furthermore, the proportion of neurons inhibited by DA alone and in the presence of CCK was significantly greater in SL than LL rats. In conclusion, litter size and difference in nourishment during early postnatal development of rats seem to determine LH basal firing rate. The increased neuronal responsiveness to exogenous DA and CCK in neonatally overfed SL rats may indicate a decreased activity of these endogenous signals which normally contribute to limitation of energy intake.

Ontogeny of the hypothalamic neuropeptide Y system

Early onset obesity and type II diabetes is rapidly becoming an epidemic, especially within the United States. This dramatic increase is likely due to many factors including both prenatal and postnatal environmental cues. The purpose of this review is to highlight some of the recent advances in our knowledge of the development of the hypothalamic circuits involved in the regulation of energy balance, with a focus on the neuropeptide Y (NPY) system. Unlike the adult rat, during the postnatal period NPY is transiently expressed in several hypothalamic regions, along with the expected expression within the arcuate nucleus (ARH). These transient populations of NPY neurons during the postnatal period may provide local NPY production to sustain the necessary energy intake during this critical growth phase. This may be physiologically important since ARH-NPY projections do not fully develop until the 3rd postnatal week. The significance of this ontogeny is that many peripheral metabolic signals have little effect of feeding prior to the development of the ARH projections. The essential questions now are whether prenatal and/or postnatal exposure to high levels of insulin or leptin during development can cause permanent changes in the function of hypothalamic circuits. It is vital to understand not only the natural development of the hypothalamic circuits that regulate energy homeostasis, but also their abnormal development caused by maternal and postnatal environmental cues. This will be pivotal for designing intervention and therapeutics to treat early onset obesity/type II diabetes, which may very well need to be different from those designed to prevent/treat adult onset obesity/type II diabetes.

Maternal obesity alters adiposity and monoamine function in genetically predisposed offspring

The impact of maternal obesity on brain monoamine function in adult offspring of dams selectively bred to express diet-induced obesity (DIO) or diet resistance (DR) was assessed by making dams obese or lean during gestation and lactation. After 12 wk on chow and 4 wk on a 31% fat diet, offspring hypothalamic nucleus size and [(3)H]nisoxetine binding to norepinephrine transporters (NET) and [(3)H]paroxetine binding to serotonin transporters (SET) were measured. Offspring of obese DIO dams became more obese than all other groups, but maternal obesity did not alter weight gain in DR offspring (25). Maternal obesity was associated with 10-17% enlargement of ventromedial nuclei (VMN) and dorsomedial nuclei in both DIO and DR offspring. Offspring of obese DIO dams had 25-88% lower NET binding in the paraventricular nuclei (PVN), arcuate nuclei, VMN, and the central amygdalar nuclei, while offspring of obese DR dams had 43-67% higher PVN and 90% lower VMN NET binding and a generalized increase in SET binding across all hypothalamic areas compared with other groups. Thus maternal obesity was associated with alterations in offspring brain monoamine metabolism, which varied as a function of genotype and the development of offspring obesity.

Plasma constituents and mortality in rat pups given chronic insulin via injection, pellet, or osmotic minipump

Two studies compared the glucose responses of 9-day-old rats given subcutaneous insulin, either continuously or via daily injection, for 10 days. In Experiment 1, implanted pellets released a total of 0, 1.9, or 5.7 U insulin/kg the first 24 h. Injected doses were larger, 0 or 8 U/kg. Injections caused no deaths, but insulin-releasing pellets caused high mortality within 24 h. Pups surviving the pellets were normoglycemic by treatment day 8. In Experiment 2, pups received 0.184 U of insulin daily, approximately 8 U/kg at 9 days, via either injection or osmotic minipump. All pups survived. Injected pups were hypoglycemic 2 h postinjection through treatment day 10, whereas pups with insulin minipumps were normoglycemic by day 5. Insulin injections, but not minipumps, lowered plasma triglycerides on day 10. To examine age differences in response to insulin, additional pups and adults received daily injections of 0 or 8 U/kg for 10 days. All survived. Insulin lowered plasma glucose more in pups than in adults and reduced triglycerides in pups but not in adults. The rapid development of normoglycemia in pups with insulin minipumps, compared with pups injected daily with the same dose, suggests that continuous early insulin may produce insulin resistance.

Differential involvement of dopamine D1 and D2 receptors and inhibition by dopamine of hypothalamic VMN neurons in early postnatally overfed juvenile rats

Dopamine is among the neurotransmitters involved in central regulation of food intake, and body weight control. To study possible changes in neuronal responses to dopamine, single unit activity of the ventromedial hypothalamic nucleus (VMN) was recorded in brain slices of normal and obese rats. The latter had developed overweight throughout juvenile life (p < 0.05) by early postnatal over-nourishment due to a reduction of litter size from 3rd to 21st day of life (small litters, SL). With effective concentrations of about 100-500 nM/I dopamine inhibited significantly more VMN neurons in obese than normal rats (Chi-square p < 0.05). While D2 receptors in the VMN are reported to mediate inhibition of food intake, the responses to dopamine were blocked by D2 receptor antagonists in significantly fewer neurons of SL than normal rats (p < 0.05). Furthemore, including results of action of D1 receptor agonists we found that significantly more neurons in SL than NL rats seem to express D1 receptors. Thus, increased suppression by dopamine of firing of VMN neurons that signal satiety with a rise in the discharge rate, and changed expression or activity of dopamine receptors might contribute to increased feeding behavior in juvenile rats hyperphagic and overweight due to early postnatal overfeeding.

Modulation of Monoaminergic Neural Circuits

A plethora of data from experimental animals provide strong support for the concept that reduced dopaminergic neuronal activity and enhanced noradrenergic tone in specific hypothalamic nuclei are involved in the pathogenesis of the metabolic syndrome. The available information on these neurotransmitter systems in insulin-resistant humans with obesity is in keeping with the postulate that analogous mechanisms may underlie their adverse metabolic profile. Treatment with bromocriptine, which has dopaminergic (D2 receptor agonist) and sympatholytic (alpha2-adrenoceptor agonistic and an alpha1-adrenoceptor antagonistic) actions, can reverse the metabolic anomalies in a variety of obese mammalian species. Combined D1/D2 receptor activation appears to exert even more powerful effects on fuel metabolism in various animal models of the metabolic syndrome. The currently available data on the metabolic effects of bromocriptine in humans with obesity and type 2 diabetes mellitus point in the same direction. Bromocriptine favorably affects glucose metabolism and various other components of the metabolic syndrome simultaneously to ameliorate the risk of damage to eyes, neural tissue, kidneys and the cardiovascular system in patients with type 2 diabetes mellitus. Moreover, a substantial number of studies indicate that bromocriptine lowers blood pressure in animals and humans with hypertension via its sympatholytic capacities. However, the effects of bromocriptine alone are relatively modest, the metabolic mechanism of action in humans remains uncertain, and the long-term efficacy and safety profiles of this compound are unknown. It seems important to seek for ways to boost the action of bromocriptine, by combining dopaminergic D2 and D1 receptor activation, for example. Notably, there is no antidiabetic drug that acts through central (dopaminergic) mechanisms. This novel approach may, therefore, result in synergistic actions with other available agents to favorably impact the risk of tissue damage in patients with type 2 diabetes mellitus.

Fetal programming of appetite and obesity

Obesity and related metabolic disorders are prevalent health issues in modern society and are commonly attributed to lifestyle and dietary factors. However, the mechanisms by which environmental factors modulate the physiological systems that control weight regulation and the aetiology of metabolic disorders, which manifest in adult life, may have their roots before birth. The 'fetal origins' or 'fetal programming' paradigm is based on the observation that environmental changes can reset the developmental path during intrauterine development leading to obesity and cardiovascular and metabolic disorders later in life. The pathogenesis is not based on genetic defects but on altered genetic expression as a consequence of an adaptation to environmental changes during fetal development. While many endocrine systems can be affected by fetal programming recent experimental studies suggest that leptin and insulin resistance are critical endocrine defects in the pathogenesis of programming-induced obesity and metabolic disorders. However, it remains to be determined whether postnatal obesity is a consequence of programming of appetite regulation and whether hyperphagia is the main underlying cause of the increased adiposity and the development of metabolic disorders.

Increased responsiveness to the hyperglycemic, hyperglucagonemic and hyperinsulinemic effects of circulating norepinephrine in ob/ob mice

OBJECTIVE

Several studies have implicated increased sympathetic tone as a contributing factor to the hyperglycemia and hyperglucagonemia of ob/ob mice. However, the responsiveness of plasma glucose, insulin and glucagon to circulating norepinephrine (NE) in ob/ob vs normal lean mice has never been described. Therefore, the present study investigated the effect of a 15 min intravenous NE infusion (1 pmol/min/g) on plasma glucose, insulin and glucagon in anesthetized lean, ob/ob, ob/ob-concurrent yohimbine (alpha(2) antagonist) treated, and ob/ob-chronically sympatholytic dopamine agonist treated (for 14 days prior to infusion) mice. In an effort to gain insight into a possible relation between norepinephrine, hyperglucagonemia and hyperinsulinemia in ob/ob mice, this study also examined the isolated islet responses to NE and glucagon in lean, ob/ob and ob/ob-sympatholytic dopamine agonist treated mice.

RESULTS

Basal humoral values of glucose, insulin and glucagon were all elevated in ob/ob vs lean mice (by 63, 1900 and 63%, respectively, P<0.01). However, NE infusion further increased levels of glucose, insulin and glucagon in ob/ob (by 80, 90 and 60%, respectively, P<0.05) but not in lean mice (between group difference for all parameters P<0.05). Acute concurrent yohimbine treatment as well as chronic prior sympatholytic dopamine agonist treatment (bromocriptine plus SKF38393) simultaneously strongly aborgated or abolished all these humoral hypersensitivity responses to intravenous NE in ob/ob mice (P<0.05). Clamping the plasma glucose level in untreated ob/ob mice at a high level (30 mM) established by NE infusion did not significantly alter the plasma insulin level, suggesting that some other influence of NE was responsible for this insulin effect. Direct NE administration at 1 microM to islets from lean and ob/ob mice inhibited 15 mM glucose-stimulated insulin secretion in both groups, but at 0.1 microM it was inhibitory only in islets from ob/ob mice. However, glucagon (10 nM) increased 15 mM glucose-stimulated insulin secretion in ob/ob (by 170%, P<0.05) but not lean mice (between group difference P<0.05).

CONCLUSION

These findings suggest that hypersensitivity to circulating NE may potentiate hyperglycemia and hyperglucagonemia in ob/ob mice, and the subsequent hyperglucagonemia coupled with increased islet beta-cell insulin secretory responsiveness to glucagon in ob/ob mice may support hyperinsulinemia, thus explaining the increased plasma insulin level response to intravenous NE in these animals. These findings further support a role for increased peripheral noradrenergic activities in the development and maintenance of the hyperglycemic, hyperglucagonemic and hyperinsulinemic state, characteristic of type 2 diabetes.

IGF-I treatment reduces hyperphagia, obesity, and hypertension in metabolic disorders induced by fetal programming

The discovery of a link between in utero experience and later metabolic and cardiovascular disease is one of the most important advances in epidemiology research of recent years. There is increasing evidence that alterations in the fetal environment may have long-term consequences on cardiovascular, metabolic, and endocrine pathophysiology in adult life. This process has been termed programming, and we have shown that undernutrition of the mother during gestation leads to programming of hyperphagia, obesity, hypertension, hyperinsulinemia, and hyperleptinemia in the offspring. Using this model of maternal undernutrition throughout pregnancy combined with postnatal hypercaloric nutrition of the offspring, we examined the effects of IGF-I therapy. Virgin Wistar rats (age 75 +/- 5 d, n = 20 per group) were time mated and randomly assigned to receive food either ad libitum or 30% of ad libitum intake (UN) throughout pregnancy. At weaning, female offspring were assigned to one of two diets (control or hypercaloric [30% fat]). Systolic blood pressure was measured at day 175 and following infusion with 3 microg/g per day recombinant human IGF-1 (rh-IGF-I) by minipump for 14 d. Before treatment, UN offspring were hyperinsulinemic, hyperleptinemic, hyperphagic, obese, and hypertensive on both diets, compared with ad libitum offspring and this was exacerbated by hypercaloric nutrition. IGF-I treatment increased body weight in all treated animals. However, systolic blood pressure, food intake, retroperitoneal and gonadal fat pad weights, and plasma leptin and insulin concentrations were markedly reduced with IGF-I treatment. IGF-I treatment resulted in a 3- to 5-fold increase in 38--44 kDa and 28--30 kDa IGF binding proteins, although in UN animals, there was an impaired and differential up-regulation of these insulin-like growth factor binding proteins following IGF-I treatment. The 24-kDa IGF binding protein representing IGF binding protein-4 was down-regulated in all IGF-I-treated animals, but the decrease was more marked in UN animals. Our data suggest that IGF-I treatment alleviates hyperphagia, obesity, hyperinsulinemia, hyperleptinemia, and hypertension in rats programmed to develop the metabolic syndrome X.

Metabolic imprinting on genetically predisposed neural circuits perpetuates obesity

There is an obesity epidemic in the industrialized world that is not simply explained by excess energy intake and decreased energy expenditure. Persistent obesity develops when genetically predisposed individuals are in a chronic state of positive energy balance. Once established, the obese body weight is avidly defended against both over- and underfeeding. Animal studies have shown that lean individuals who are genetically predisposed toward obesity have abnormalities of neural function that prime them to become obese when caloric density of the diet is raised. These neural abnormalities are gradually "corrected" as obesity becomes fully developed, suggesting that obesity is the normal state for such individuals. Thus, defense of the obese body weight may be perpetuated by the formation of new neural circuits involved in energy-homeostasis pathways that are not then easily abolished. Such neural plasticity can occur in both adult life and during nervous-system development. Early pre- and postnatal metabolic conditions (maternal diabetes, obesity, undernutrition) can lead genetically predisposed offspring to become even more obese as adults. This enhanced obesity is associated with altered brain neural circuitry, and these changes can then be passed on to subsequent generations in a feed-forward cycle of ever-increasing body weight. Thus, the metabolic perturbations associated with obesity during both brain development and adult life can produce "metabolic imprinting" on genetically predisposed neural circuits involved in energy homeostasis. Drugs that reduce body weight decrease the defended body weight and alter neural pathways involved in energy homeostasis but have no permanent effect on body weight or neural function in most individuals. Thus, early intervention in mothers, infants, children, and adults may be the only way to prevent the formation of permanent neural connections that promote and perpetuate obesity in genetically predisposed individuals.

Hypothalamic adrenergic receptor changes in the metabolic syndrome of genetically obese (ob/ob) mice

The genetically, seasonally, and diet-induced obese, glucose-intolerant states in rodents, including ob/ob mice, have each been associated with elevated hypothalamic levels of norepinephrine (NE). With the use of quantitative autoradiography on brain slices of 6-wk-old obese (ob/ob) and lean mice, the adrenergic receptor populations in several hypothalamic nuclei were examined. The binding of [(125)I]iodocyanopindolol to beta(1)- and beta(2)-adrenergic receptors in ob/ob mice was significantly increased in the paraventricular hypothalamic nucleus (PVN) by 30 and 38%, in the ventromedial hypothalamus (VMH) by 23 and 72%, and in the lateral hypothalamus (LH) by 10 and 15%, respectively, relative to lean controls. The binding of [(125)I]iodo-4-hydroxyphenyl-ethyl-aminomethyl-tetralone to alpha(1)-adrenergic receptors was also significantly increased in the PVN (26%), VMH (67%), and LH (21%) of ob/ob mice. In contrast, the binding of [(125)I]paraiodoclonidine to alpha(2)-adrenergic receptors in ob/ob mice was significantly decreased in the VMH (38%) and the dorsomedial hypothalamus (17%) relative to lean controls. This decrease was evident in the alpha(2A)- but not the alpha(2BC)-receptor subtype. Scatchard analysis confirmed this decreased density of alpha(2)-receptors in ob/ob mice. Together with earlier studies, these changes in hypothalamic adrenergic receptors support a role for increased hypothalamic NE activity in the development of the metabolic syndrome of ob/ob mice.

Chronic infusion of norepinephrine into the VMH of normal rats induces the obese glucose-intolerant state

Increases in ventromedial hypothalamic (VMH) norepinephrine (NE) levels and/or activities have been observed in a variety of animal models of the obese insulin-resistant condition. This study examined the metabolic effects of chronic NE infusion (25 nmol/h) into the unilateral VMH of normal rats. Within 4 days, VMH NE infusion significantly increased plasma insulin (140%), glucagon (45%), leptin (300%), triglyceride (100%), abdominal fat pad weight (50%), and white adipocyte lipogenic (100%) and lipolytic (100%) activities relative to vehicle-infused rats. Furthermore, isolated islet insulin secretory response to glucose (15 mM) within 4 days of such treatment was increased over twofold (P < 0.05). Among treated animals, fat stores continued to increase over time and plateaued at approximately 2 wk (3-fold increase), remaining elevated to the end of the study (5 wk). By week 4 of treatment, NE infusion induced glucose intolerance as evidenced by a 32% increase in plasma glucose total area under the glucose tolerance test curve (P < 0.01). Whole body fat oxidation rate measured after 5 wk of infusion was significantly increased among treated animals as evidenced by a reduced respiratory quotient (0.87 +/- 0.01) relative to controls (0. 90 +/- 0.01). VMH NE infusion induced hyperphagia (30%) only during the first week and did not affect body weight over the 5-wk period. Increases in VMH NE activity that are common among obese insulin-resistant animal models can cause the development of this obese glucose-intolerant (metabolic) syndrome.

Sexually dimorphic and radiation dose dependent effect of cranial irradiation on body mass index

OBJECTIVES

To investigate the relation between cranial irradiation received during treatment for childhood leukaemia and obesity at final height.

DESIGN

Retrospective cross sectional study.

SETTING

Paediatric oncology centres at Great Ormond Street Hospital for Children and the Royal Marsden Hospital.

SUBJECTS

Survivors of childhood leukaemia who received cranial irradiation, were in continuous first remission, and had reached final height. An unirradiated group of patients from the United Kingdom acute lymphoblastic leukaemia XI trial was also included; these patients were in continuous first remission and had been followed for at least four years from diagnosis.

MAIN OUTCOME MEASURES

Body mass index standard deviation score (BMI z score) at final height for irradiated patients and at most recent follow up for unirradiated patients. Regression analysis was used to examine the effect on BMI z score of sex, age at diagnosis, and the dose of radiation received.

RESULTS

For cranially irradiated patients, an increase in the BMI z score at final height was associated with female sex and lower radiation dose, but not with age at diagnosis. Severe obesity, defined as a BMI z score of > 3 at final height, was only present in girls who received 18-20 Gy irradiation and had a prevalence of 8%. Both male and female unirradiated patients had raised BMI z scores at latest follow up and there was no association with age at diagnosis.

CONCLUSIONS

These data are further evidence for a sexually dimorphic and dose dependent effect of radiation on the human brain.

Bromocriptine improves glycaemic control and serum lipid profile in obese Type 2 diabetic subjects: a new approach in the treatment of diabetes

Bromocriptine, a potent dopamine D(2) receptor agonist, has been shown to reduce insulin resistance, glucose intolerance and hyperlipidaemia in both numerous animal studies and in Phase II studies. Bromocriptine has been used worldwide for over 20 years to treat Parkinson's disease, macroprolactinoma and other disorders; it has been found to be generally safe. We therefore investigated the possible beneficial effects of Ergoset(R) (Ergo Science Corp.), a new quick release formulation of bromocriptine, on glycaemic control and serum lipid profile in obese Type 2 diabetic subjects in two large Phase III studies. A large, randomised, double-blind placebo-controlled study was conducted in which Ergoset was given once daily at 8 am. (4.8 mg maximum dose) for 24 weeks as adjunctive therapy to sulphonylurea (485 subjects) to obese Type 2 diabetics held on a weight- maintaining diet. Treatment efficacy parameters included change from baseline in glycated haemoglobin A(1c) (HbA(1c)), fasting and post-prandial serum glucose, insulin, triglyceride and free fatty acid levels. Baseline glycated haemoglobin, fasting glucose, insulin, triglyceride and free fatty acid levels did not differ between treatment groups. and on average were 9.4 +/- 0.05%, 222 +/- 2 mg/dl, 24 +/- 1 µU/ml, 248 +/- 11 mg/dl, and 850 +/- 32 µEq/l, respectively. A similarly designed study of Ergoset as monotherapy in Type 2 diabetics (154 subjects) with similar baseline clinical characteristics was conducted. Addition of Ergoset treatment to sulphonylurea reduced percent glycated HbA(1c) by 0.55 (P < 0.0001) (approximately 1.0 for responders, 65% of population), fasting and post-prandial glucose by 23 and 26 mg/dl (P < 0.0002), fasting and post-prandial triglycerides by 72 and 63 mg/dl (P < 0.005) and fasting and post-prandial free fatty acids by 150 and 165 µEq/l (P < 0.05), relative to placebo. Twelve percent of all Ergoset subjects, compared to 3% of placebo subjects, withdrew from the study due to adverse events. The most common events causing withdrawal were nausea, dizziness, asthenia, and rhinitis (representing 4.5, 3.3, 2.0, and 0.8% of the total Ergoset populations, respectively). The incidence of serious adverse events did not differ between Ergoset- (3.4%) and placebo- (4.3%) treated subjects. Ergoset as monotherapy also improved glycaemic control (0.56 HbA(1c) decrease relative to placebo after 24 weeks of treatment; P < 0.02). Once daily Ergoset treatment improves glycaemic control and serum lipid profile and is well-tolerated in obese Type 2 diabetics.

Alterations of hypothalamic catecholamines in the newborn offspring of gestational diabetic mother rats

Catecholamines are essential organizers of the developing brain. Throughout life, they are involved, e.g., in the regulation of body weight and metabolism by specific hypothalamic nuclei, which are suggested to be highly vulnerable to maternal gestational hyperglycemia. By application of streptozotocin (30 mg/kg, i.p.) gestational diabetes (GD) was induced in female rats. On the 1st day of life, male GD offspring were underweight (P<0.05) and hyperglycemic (P<0.05), while on the 21st day of life decreased body weight (P<0.001) and elevated pancreatic insulin (P<0.01) were observed. Using HPLC with electrochemical detection, hypothalamic catecholamines were determined in the newborns, and quantitative immunocytochemistry for tyrosine hydroxylase (TH) was performed. At birth, a tendency towards increased levels of norepinephrine (NE) and dopamine (DA) in the whole hypothalami of GD offspring was observed. In the 21-day-old offspring of GD mothers, NE was significantly increased in the ventromedial hypothalamic nucleus (VMN; P<0.05) and the lateral hypothalamic area (LHA; P<0.05), while DA was significantly elevated in the paraventricular hypothalamic nucleus (PVN; P<0.05) and the LHA (P<0.05). The NE/DA-ratio was found to be decreased in the PVN of GD offspring (P<0.01). Moreover, numerical density of TH-positive neurons was clearly increased within the parvocellular division of the PVN (P<0.0001) as well as in the periventricular hypothalamic area (PER; P<0.05). These data suggest specific alterations of catecholaminergic systems within hypothalamic regulators of body weight and metabolism during early development in the offspring of gestational diabetic mother rats.

Insulin during infancy attenuates insulin-induced hypoglycemia in adult male rats

To examine whether insulin during infancy affects later glucose regulation, 60 rat pups of both sexes were injected daily on postnatal Days 9-20 with either insulin (2 or 8 U/kg), 2-deoxy-D-glucose (2DG; 200 or 400 mg/kg), or saline. Two hours postinjection on Day 15, pups given insulin were hypoglycemic and pups given 2DG were hyperglycemic; both groups were normoglycemic at 6 h. The two insulin doses produced similar long-term effects, as did the 2DG doses, so doses were combined to make single insulin and 2DG groups. On Day 44, baseline plasma glucose for rats given insulin or 2DG during infancy was below saline control levels (111.3, 114.5, and 120.7 mg/dL, respectively, p < 0.05). On Days 60 and 62, plasma glucose was assessed 2 h after injection of 3 U/kg insulin; food was allowed between the insulin injection and the glucose test on only one of these days. When food was present after injection of insulin, the early treatments did not influence either amount of food ingested or plasma glucose levels. When food was withheld, however, males given insulin before weaning maintained a higher plasma glucose than did males given 2DG or saline before weaning (67.4, 40.1, and 16.4 mg/dL, respectively, p < 0.01); females were unaffected by the early treatment. Postweaning body weights did not differ from control values for rats given early insulin or 2DG. On Day 72, there were no effects of early treatment on plasma insulin, plasma glucose, liver weight, or kidney weight. These results suggest that preweaning exposure to insulin attenuates the hypoglycemia of adult males given insulin without food.

Maternal insulin manipulations in rats organize body weight and noradrenergic innervation of the hypothalamus in gonadally intact male offspring

In previous work it has been shown that adult male, but not female, offspring of rats that have been injected with protamine zinc insulin (6 IU/kg) on days 15-20 of gestation, develop significant obesity beginning about 50 days of age. This obesity is accompanied by elevated medial hypothalamic extracellular norepinephrine levels. To examine whether the expression of obesity in male offspring is mediated by perinatal testosterone levels, male offspring of insulin-treated or control dams were either castrated or received sham surgery on postnatal day 1. Castrated male offspring of insulin-treated dams did not become obese like their gonadally intact male littermates. This suggests that perinatal testosterone levels may interact with developmental processes mediating the obesity in male offspring of insulin-treated dams. A second question addressed was whether the elevated hypothalamic extracellular norepinephrine levels observed in our earlier work are evident as morphological changes in norepinephrine-containing systems in the medial hypothalamus and locus coeruleus. We found a significant enhancement of dopamine-beta-hydroxylase immunoreactivity in fibers innervating the paraventricular nucleus of the hypothalamus in 121-day-old, gonadally intact male offspring of insulin-injected dams. This suggests that the impact of maternal insulin injections on offspring obesity may be mediated through its organizing action on feeding-related fibers in the paraventricular nucleus.