Post-weaning protein malnutrition in the rat produces short and long term metabolic impairment, in contrast to earlier and later periods

Pharmacological Investigation of Hypoalbuminemia on the Prolonged and Potentiated Action of Midazolam in Rats

Midazolam (MDZ) is clinically used for its sedative and anticonvulsant properties. However, its prolonged or potentiated effects are sometimes concerning. The main binding protein of MDZ is albumin, and reduced serum albumin levels could lead to MDZ accumulation, thereby potentiating or prolonging its effects. Previous investigations have not thoroughly examined these phenomena from a behavioral pharmacology standpoint. Consequently, this study aimed to evaluate both the prolonged and potentiated effects of MDZ, as well as the effects of serum albumin levels on the action of MDZ in low-albumin rats. Male Wistar rats were classified into control (20% protein diet), low-protein (5% protein), and non-protein groups (0% protein diet) and were fed the protein-controlled diets for 30 d to obtain low-albumin rats. The locomotor activity and muscle relaxant effects of MDZ were evaluated using the rotarod, grip strength, and open-field tests conducted 10, 60, and 120 min after MDZ administration. Serum albumin levels decreased significantly in the low-protein and non-protein diet groups compared with those in the control group. Compared with the control rats, low-albumin rats demonstrated a significantly shorter time to fall, decreased muscle strength, and a significant decrease in the distance traveled after MDZ administration in the rotarod, grip strength, and open-field tests, respectively. Decreased serum albumin levels potentiated and prolonged the effects of MDZ. Hence, serum albumin level is a critical parameter associated with MDZ administration, which should be monitored, and any side effects related to decreased albumin levels should be investigated.

Postweaning cafeteria diet induces a short-term metabolic disfunction and a differential vulnerability to develop anxiety-like and depressive-like behaviors in male but not female rats

Children and adolescents are high consumers of Western diets (rich in fat and sugars), which is a risk factor for overweight and obesity. Moreover, the presence of anxiety and depression among this population has increased significantly. This study explores in young postweaning rats the association between Western diet consumption and the development of metabolic and behavioral disturbances. At postnatal day (PN) 24, Wistar rats of both sexes were weaned and assigned to a control or cafeteria diet (CAF) group. After short-term exposure, a group of rats was euthanized at PN31 to obtain abdominal fat pads and blood samples. Another group of rats was tested in the open-field test, splash test, anhedonia test, and social play across 11 days (PN32-42). The CAF groups exhibited a significantly high level of body fat, serum glucose, triglycerides, leptin, and HOMA index when compared to the control groups. Only CAF males exhibited anxiety-like and depression-like behavior. Present results indicate that postweaning short-term exposure to a CAF diet has immediate detrimental effects on metabolism in both sexes. However, only CAF males showed mood disturbances. This study provides evidence that a CAF diet exerts immediate effects on behavior and metabolism in the postweaning period and that sexes present differential vulnerability.

Prenatal exposure to the Chinese famine of 1959-62 and risk of cardiovascular diseases in adulthood: findings from the China PEACE million persons project

AIMS

Much remains unknown about the role of prenatal exposure to environmental stressors in the development of cardiovascular diseases (CVD). The current study aimed to investigate whether exposure to famine early in life was associated with a higher risk of CVD in adulthood.

METHODS AND RESULTS

Among 71 667 men and women participated in the Patient-centred Evaluative Assessment of Cardiac Events (PEACE) Million Persons Project in southern China, specific years of birth were used to define two cohorts: the exposed group (born during the famine of 1959-62) and the non-exposed group [born before the famine (1949-58) or after the famine (1963-72)]. Multivariable-adjusted generalized linear models were used to examine the associations of famine exposure with the risk of developing CVD, as well as with the 10-year CVD risk defined by well-established risk scores. Compared with the non-famine group, early-life exposure to the Chinese famine was significantly associated with increased risks of total CVD (odds ratio, OR = 1.28, 95% confidence interval: 1.16-1.41), coronary heart disease [OR: 1.23 (1.07-1.41)], acute myocardial infarction [OR: 1.32 (1.01-1.70)], heart failure [OR: 2.01 (1.53-2.60)], and stroke [OR: 1.28 (1.12-1.45)] in adulthood. In those without established CVD, early-life exposure to the famine was associated with higher levels of total cholesterol, systolic blood pressure, waist circumference, risk of diabetes, and therefore 10-year CVD risk.

CONCLUSION

Early-life exposure to the Chinese famine is associated with an elevated CVD risk later in life, independent of known risk factors.

Association between famine exposure in early life and risk of hospitalization for heart failure in adulthood

Background

Few studies have reported the association of early life exposure to famine with the risk of heart failure. The current study aimed to investigate whether exposure to famine in early life is associated with a higher risk of hospitalization for heart failure in adulthood.

Methods

We used data from participants included in the sub-cohort of the China Patient-centered Evaluative Assessment of Cardiac Events Million Persons Project in Guangdong Province. Specific years of birth were used to define the famine-exposed group (born during the famine of 1959-1962), the pre-famine group (born before the famine [1954-1957], and the post-famine group (born after the famine [1964-1967]). Multivariable-adjusted generalized linear models were used to examine the associations of early life famine exposure with the risk of hospitalization for heart failure.

Results

A total of 36,212 participants were enrolled in this analysis with a median age of 57.4 years and 37.5% of them were men. Compared with the post-famine group, famine births and pre-famine births were associated with increased risk of heart failure (OR: 1.96 [1.56-2.48] and OR: 1.62 [1.07-2.47], respectively). When compared with the age-balanced non-exposed group, the famine-exposed group was also significantly associated with increased risk of heart failure (OR: 1.32 [1.11-1.57]). The associations were stronger in participants with better economic status and in participants with hypertension, diabetes, and dyslipidemia (P for interaction < 0.05).

Conclusion

Early life exposure to the Chinese famine is associated with an elevated risk of hospitalization for heart failure in adulthood.

Protein Restriction in the Peri-Pubertal Period Induces Autonomic Dysfunction and Cardiac and Vascular Structural Changes in Adult Rats

Perturbations to nutrition during critical periods are associated with changes in embryonic, fetal or postnatal developmental patterns that may render the offspring more likely to develop cardiovascular disease in later life. The aim of this study was to evaluate whether autonomic nervous system imbalance underpins in the long-term hypertension induced by dietary protein restriction during peri-pubertal period. Male Wistar rats were assigned to groups fed with a low protein (4% protein, LP) or control diet (20.5% protein; NP) during peri-puberty, from post-natal day (PN) 30 until PN60, and then all were returned to a normal protein diet until evaluation of cardiovascular and autonomic function at PN120. LP rats showed long-term increased mean arterial pressure (p = 0.002) and sympathetic arousal; increased power of the low frequency (LF) band of the arterial pressure spectral (p = 0.080) compared with NP animals. The depressor response to the ganglion blocker hexamethonium was increased in LP compared with control animals (p = 0.006). Pulse interval variability showed an increase in the LF band and LF/HF ratio (p = 0.062 and p = 0.048) in LP animals. The cardiac response to atenolol and/or methylatropine and the baroreflex sensitivity were similar between groups. LP animals showed ventricular hypertrophy (p = 0.044) and increased interstitial fibrosis (p = 0.028) compared with controls. Reduced protein carbonyls (PC) (p = 0.030) and catalase activity (p = 0.001) were observed in hearts from LP animals compared with control. In the brainstem, the levels of PC (p = 0.002) and the activity of superoxide dismutase and catalase (p = 0.044 and p = 0.012) were reduced in LP animals, while the levels of GSH and total glutathione were higher (p = 0.039 and p = 0.038) compared with NP animals. Protein restriction during peri-pubertal period leads to hypertension later in life accompanied by sustained sympathetic arousal, which may be associated with a disorganization of brain and cardiac redox state and structural cardiac alteration.

Severe malnutrition or famine exposure in childhood and cardiometabolic non-communicable disease later in life: a systematic review

INTRODUCTION

Child malnutrition (undernutrition) and adult non-communicable diseases (NCDs) are major global public health problems. While convincing evidence links prenatal malnutrition with increased risk of NCDs, less is known about the long-term sequelae of malnutrition in childhood. We therefore examined evidence of associations between postnatal malnutrition, encompassing documented severe childhood malnutrition in low/middle-income countries (LMICs) or famine exposure, and later-life cardiometabolic NCDs.

METHODS

Our peer-reviewed search strategy focused on 'severe childhood malnutrition', 'LMICs', 'famine', and 'cardiometabolic NCDs' to identify studies in Medline, Embase, Global Health, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases. We synthesised results narratively and assessed study quality with the UK National Institute for Health and Care Excellence checklist.

RESULTS

We identified 57 studies of cardiometabolic NCD outcomes in survivors of documented severe childhood malnutrition in LMICs (n=14) and historical famines (n=43). Exposure to severe malnutrition or famine in childhood was consistently associated with increased risk of cardiovascular disease (7/8 studies), hypertension (8/11), impaired glucose metabolism (15/24) and metabolic syndrome (6/6) in later life. Evidence for effects on lipid metabolism (6/11 null, 5/11 mixed findings), obesity (3/13 null, 5/13 increased risk, 5/13 decreased risk) and other outcomes was less consistent. Sex-specific differences were observed in some cohorts, with women consistently at higher risk of glucose metabolism disorders and metabolic syndrome.

CONCLUSION

Severe malnutrition or famine during childhood is associated with increased risk of cardiometabolic NCDs, suggesting that developmental plasticity extends beyond prenatal life. Severe malnutrition in childhood thus has serious implications not only for acute morbidity and mortality but also for survivors' long-term health. Heterogeneity across studies, confounding by prenatal malnutrition, and age effects in famine studies preclude firm conclusions on causality. Research to improve understanding of mechanisms linking postnatal malnutrition and NCDs is needed to inform policy and programming to improve the lifelong health of severe malnutrition survivors.

Comparison of cricket diet with peanut-based and milk-based diets in the recovery from protein malnutrition in mice and the impact on growth, metabolism and immune function

Some evidence suggests that edible insects could be used to treat malnutrition following protein deficiency. However, additional studies are needed to better assess the potential of edible insects as a therapeutic food supplement and their long-term impact on recovery from malnutrition. The goals of this study were to investigate the effectiveness of a cricket-based diet in recovery from protein-malnutrition in early life, and to compare cricket protein to more traditional sources used for food fortification and supplementation. Protein-malnutrition was induced by administration of an isocaloric hypoprotein diet (5% protein calories) in young male mice for two weeks during puberty, followed by a six-week recovery period using a cricket-, peanut- or milk-based diet. We examined the impact of protein-malnutrition and subsequent recovery on body weight, growth and select biomarkers of inflammation and metabolism. Protein-malnutrition resulted in growth retardation, downregulation of inflammatory markers in spleen tissue, decreased levels of serum triglycerides, and elevated serum levels of leptin and adiponectin. The cricket-based diet performed equally well as the peanut- and milk-based diets in body weight recovery, but there were differences in immune and metabolic markers among the different recovery diets. Results suggest edible crickets may provide an alternative nutrient-dense protein source with relatively low environmental demands for combating the effects of early-life malnutrition compared to more traditional supplementation and fortification sources. Additional investigations are needed to examine the short and long term impacts of different recovery diets on metabolism and immune function.

Direct and Long-Term Metabolic Consequences of Lowly vs. Highly-Digestible Starch in the Early Post-Weaning Diet of Mice

Starches of low and high digestibility have different metabolic effects. Here, we examined whether this gives differential metabolic programming when fed in the immediate post-weaning period. Chow-fed mice were time-mated, and their nests were standardized and cross-fostered at postnatal days 1⁻2. After postnatal week (PW) 3, individually housed female and male offspring were switched to a lowly-digestible (LDD) or highly-digestible starch diet (HDD) for three weeks. All of the mice received the same high-fat diet (HFD) for nine weeks thereafter. Energy and substrate metabolism and carbohydrate fermentation were studied at the end of the HDD/LDD and HFD periods by extended indirect calorimetry. Glucose tolerance (PW 11) and metabolic flexibility (PW14) were analyzed. Directly in response to the LDD versus the HDD, females showed smaller adipocytes with less crown-like structures in gonadal white adipose tissue, while males had a lower fat mass and higher whole body fat oxidation levels. Both LDD-fed females and males showed an enlarged intestinal tract. Although most of the phenotypical differences disappeared in adulthood in both sexes, females exposed to LDD versus HDD in the early post-weaning period showed improved metabolic flexibility in adulthood. Cumulatively, these results suggest that the type of starch introduced after weaning could, at least in females, program later-life health.

Transcriptomic responses of the liver and adipose tissues to altered carbohydrate-fat ratio in diet: an isoenergetic study in young rats

Background

To elucidate the effects of altered dietary carbohydrate and fat balance on liver and adipose tissue transcriptomes, 3-week-old rats were fed three kinds of diets: low-, moderate-, and high-fat diets (L, M, and H) containing a different ratio of carbohydrate-fat (C-F) (65:15, 60:20, and 35:45 in energy percent, respectively).

Methods

The rats consumed the diets for 9 weeks and were subjected to biochemical and DNA microarray analyses.

Results

The rats in the H-group exhibited lower serum triacylglycerol (TG) levels but higher liver TG and cholesterol content than rats in the L-group. The analysis of differentially expressed genes (DEGs) between each group (L vs M, M vs H, and L vs H) in the liver revealed about 35% of L vs H DEGs that were regulated in the same way as M vs H DEGs, and most of the others were L- vs H-specific. Gene ontology analysis of these L vs H DEGs indicated that those related to fatty acid synthesis and circadian rhythm were enriched. Interestingly, about 30% of L vs M DEGs were regulated in a reverse way compared with L vs H and M vs H DEGs. These reversed liver DEGs included M-up/H-down genes (Sds for gluconeogenesis from amino acids) and M-down/H-up genes (Gpd2 for gluconeogenesis from glycerol, Agpat9 for TG synthesis, and Acot1 for beta-oxidation). We also analyzed L vs H DEGs in white (WAT) and brown (BAT) adipose tissues and found that both oxidation and synthesis of fatty acids were inhibited in these tissues.

Conclusions

These results indicate that the alteration of dietary C-F balance differentially affects the transcriptomes of metabolizing and energy-storing tissues.

Electronic supplementary material

The online version of this article (doi:10.1186/s12263-017-0558-2) contains supplementary material, which is available to authorized users.

Changes in cardiovascular responses to chemoreflex activation of rats recovered from protein restriction are not related to AT1 receptors

NEW FINDINGS

What is the central question of this study? In this study, we sought to investigate whether cardiovascular responses to peripheral chemoreflex activation of rats recovered from protein restriction are related to activation of AT₁ receptors. What is the main finding and its importance? This study highlights the fact that angiotensinergic mechanisms activated by AT₁ receptors do not support increased responses to peripheral chemoreflex activation by KCN in rats recovered from protein restriction. Also, we found that protein restriction led to increased resting ventilation in adult rats, even after recovery. The effects of a low-protein diet followed by recovery on cardiorespiratory responses to peripheral chemoreflex activation were tested before and after systemic angiotensin II type 1 (AT₁ ) receptor antagonism. Male Fischer rats were divided into control and recovered (R-PR) groups after weaning. The R-PR rats were fed a low-protein (8%) diet for 35 days and recovered with a normal protein (20%) diet for 70 days. Control rats received a normal protein diet for 105 days (CG₁₀₅ ). After cannulation surgery, mean arterial pressure, heart rate, respiratory frequency, tidal volume and minute ventilation were acquired using a digital recording system in freely moving rats. The role of angintensin II was evaluated by systemic antagonism of AT₁ receptors with losartan (20 mg kg^-1 i.v.). The peripheral chemoreflex was elicited by increasing doses of KCN (20-160 μg kg min^-1 , i.v.). At baseline, R-PR rats presented increased heart rate and minute ventilation (372 ± 34 beats min^-1 and 1.274 ± 377 ml kg^-1  min^-1 ) compared with CG₁₀₅ animals (332 ± 22 beats min^-1 and 856 ± 112 ml kg^-1  min^-1 ). Mean arterial pressure was not different between the groups. Pressor and bradycardic responses evoked by KCN (60 μg kg^-1 ) were increased in R-PR (+45 ± 13 mmHg and -77 ± 47 beats min^-1 ) compared with CG₁₀₅ rats (+25 ± 17 mmHg and -27 ± 28 beats min^-1 ), but no difference was found in the tachypnoeic response. These differences were preserved after losartan. The data suggest that angiotensin II acting on AT₁ receptors may not be associated with the increased heart rate, increased minute ventilation and acute cardiovascular responses to peripheral chemoreflex activation in rats that underwent postweaning protein restriction followed by recovery.

Evaluation of skeletal muscle regeneration in experimental model after malnutrition

The aim of this study was to analyze muscle regeneration after cryoinjury in the tibialis anterior muscle of young rats that were malnourished and then recovered. Forty Wistar rats were divided into a nourished group that received a normal protein diet (14% casein) for 90 days and a malnourished and recovered rats group (MR) that was submitted to 45 days of malnutrition with a hypoproteic diet (6% casein) followed by 45 days of a normal protein diet (14% casein). After the recovery period, all of the animals underwent cryoinjury in the right tibialis anterior muscle and euthanasia after 7, 14 and 21 days. The amount of connective tissue and the inflammation area was higher in the malnutrition recovered injury MR group (MRI) at 14 days post-injury (p < 0.05). Additionally, the cross-sectional area (CSA) of the regenerated fibers was decreased in the MRI (p < 0.05). The MyoD and myogenin protein levels were higher in the nourished injury group. Similar levels of TGF-β1 were found between groups. The proposed malnutrition protocol was effective in showing delayed changes in the regeneration process of the tibialis anterior muscle of young rats. Furthermore, we observed a delay in muscle repair even after nutritional recovery.

Exposure to increased levels of estradiol during development can have long-term effects on the response to undernutrition in female rats

OBJECTIVES

Undernutrition during development alters the expression of peptides that control energy expenditure and feeding behavior. Estrogens can also modulate these peptides. Here, we analyze whether the early postnatal administration of estradiol modulates the effects of undernutrition on neuroendocrine parameters in adult female Wistar rats.

METHODS

Control rats were fed a control diet. Undernourished pups were submitted to a restricted diet with half of the undernourished rats receiving 0.4 mg/kg s.c. of estradiol benzoate (EB) from postnatal day (P) 6 until P13. Quantitative real-time polymerase chain reaction was performed to determine expression in the hypothalamus of agouti-related peptide (AgRP), proopiomelanocortin (POMC), neuropeptide Y (NPY), and cocaine- and amphetamine-regulated transcript. Plasma estradiol, testosterone, and adiponectin levels were measured by enzyme-linked immunosorbent assay. Total and acylated ghrelin levels were measured in plasma by radioimmunoassay. Insulin and leptin were measured by mulitplex immunoassays.

RESULTS

Undernourishment decreased body weight, fat mass, plasma leptin and insulin levels, and hypothalamic POMC mRNA levels. An increase in orexigenic signals AgRP and NPY mRNA levels, and in plasma adiponectin levels were found in undernourished animals. Early postnatal treatment with EB to undernourished female rats reversed the effects of undernutrition on adult hypothalamic POMC mRNA levels. In addition, neonatal EB treatment to undernourished females significantly decreased adult plasma testosterone, estradiol, and acylated ghrelin levels.

DISCUSSION

Our results suggest that increased estradiol during a critical period of development has the capacity to modulate the alterations that undernutrition produces on energy metabolism.

Relative leg length is associated with type 2 diabetes differently according to pubertal timing: the Brazilian longitudinal study of adult health

OBJECTIVES

Studies from developed societies have shown that individuals with short legs relative to height have higher risk of type 2 diabetes. This has been much less explored in less developed populations where influences on relative leg length and diabetes may differ. The Brazilian Longitudinal Study of Adult Health (in Portuguese, ELSA-Brasil) allows us to test, in a cohort born (1934-1975) and raised when undernutrition was common, whether short legs relative to height is positively associated with diabetes, independent of early-life factors, including birth weight, age at menarche, and young-adult BMI.

METHODS

We used baseline, cross-sectional data from 15,105 participants aged 35-74 years participating in ELSA-Brasil. We created age-and-sex-specific Z scores for leg length index (leg length/height × 100) according to an external reference. Diabetes was defined by self-reported physician diagnosis, medication use, fasting and 2-h post-75-g-load glucose, and A1C.

RESULTS

A one-unit decrement in leg-length-index Z score was associated with 12% (8-17%) higher prevalence of diabetes in Brazilian adults, after adjustment through Poisson regression for confounders, including race, maternal education, and birth weight. This association persisted after further adjustment for menarche age, BMI (at age 20), buttocks circumference, and waist circumference. It was stronger among women with early menarche (P interaction = 0.02). Leg length index was also inversely associated with fasting glucose, fasting insulin, 2-h glucose, and A1C (P < 0.05).

CONCLUSIONS

In contemporary Brazilian adults, short legs relative to height is positively associated with diabetes independent of measures of intrauterine growth, pubertal timing, and young-adult adiposity. This association is stronger in women with early menarche.

Decreased rate of protein synthesis, caspase-3 activity, and ubiquitin–proteasome proteolysis in soleus muscles from growing rats fed a low-protein, high-carbohydrate diet

The aim of this study was to investigate the changes in the rates of both protein synthesis and breakdown, and the activation of intracellular effectors that control these processes in soleus muscles from growing rats fed a low-protein, high-carbohydrate (LPHC) diet for 15 days. The mass and the protein content, as well as the rate of protein synthesis, were decreased in the soleus from LPHC-fed rats. The availability of amino acids was diminished, since the levels of various essential amino acids were decreased in the plasma of LPHC-fed rats. Overall rate of proteolysis was also decreased, explained by reductions in the mRNA levels of atrogin-1 and MuRF-1, ubiquitin conjugates, proteasome activity, and in the activity of caspase-3. Soleus muscles from LPHC-fed rats showed increased insulin sensitivity, with increased levels of insulin receptor and phosphorylation levels of AKT, which probably explains the inhibition of both the caspase-3 activity and the ubiquitin–proteasome system. The fall of muscle proteolysis seems to represent an adaptive response that contributes to spare proteins in a condition of diminished availability of dietary amino acids. Furthermore, the decreased rate of protein synthesis may be the driving factor to the lower muscle mass gain in growing rats fed the LPHC diet.

Glucose metabolism in adult survivors of severe acute malnutrition

CONTEXT AND OBJECTIVES

The clinical syndromes of severe acute malnutrition may have early life origins because children with marasmus have lower birth weight than those with kwashiorkor. We hypothesized that resultant metabolic effects may persist into adulthood. We investigated whether marasmus survivors (MS) are more insulin resistant and glucose intolerant than kwashiorkor survivors (KS).

RESEARCH DESIGN AND SETTING

This was a case-control study in Jamaican adults.

SUBJECTS

We performed oral glucose tolerance tests on 191 adults (aged 17-50 y; 52% male; body mass index 24.2 ± 5.5 kg/m(2)). There were 43 MS; 38 KS; 70 age-, sex-, and body mass index-matched community controls; and 40 age- and birth weight-matched controls.

MEASUREMENTS

We measured insulin sensitivity with the whole-body insulin sensitivity index, and β-cell function with the insulinogenic index and the oral disposition index.

RESULTS

Fasting glucose was comparable across groups, but glucose intolerance was significantly more common in MS (19%) than in KS (3%), community controls (11%), and birth weight-matched controls (10%). The whole-body insulin sensitivity index was lower in MS than KS (P = .06) but similar between MS and controls. The insulinogenic index and oral disposition index were lower in MS compared with all three groups (P < .01).

CONCLUSIONS

Marasmus survivors tend to be less insulin sensitive, but have significantly lower insulin secretion and are more glucose intolerant compared with kwashiorkor survivors and controls. This suggests that poor nutrition in early life causes β-cell dysfunction, which may predispose to the development of diabetes.

In vitro TNF-α- and noradrenaline-stimulated lipolysis is impaired in adipocytes from growing rats fed a low-protein, high-carbohydrate diet

The aim of this study was to investigate tumor necrosis factor alpha (TNF-α)- and noradrenaline (NE)-stimulated lipolysis in retroperitoneal (RWAT) and epididymal (EAT) white adipose tissue as a means of understanding how low-protein, high-carbohydrate (LPHC) diet-fed rats maintain their lipid storage in a catabolic environment (marked by increases in serum TNF-α and corticosterone and sympathetic flux to RWAT and EAT), as previously observed. Adipocytes or tissues from the RWAT and EAT of rats fed an LPHC diet and rats fed a control (C) diet for 15 days were used in the experiments. The adipocytes from both tissues of the LPHC rats exhibited lower TNF-α- stimulated lipolysis compared to adipocytes from the C rats. The intracellular lipolytic agents IBMX, DBcAMPc and FSK increased lipolysis in both tissues from rats fed the C and LPHC diets compared to basal lipolysis; however, the effect was approximately 2.5-fold lower in adipocytes from LPHC rats. The LPHC diet induced a marked reduction in the β3 and α2-AR, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) content in RWAT and EAT. The LPHC diet did not affect TNF-α receptor 1 content but did induce a reduction in ERK p44/42 in both tissues. The present work indicates that RWAT and EAT from LPHC rats have an impairment in the lipolysis signaling pathway activated by NE and TNF-α, and this impairment explains the reduced response to these lipolytic stimuli, which may be fundamental to the maintenance of lipid storage in LPHC rats.

Effect of neonatal hypothyroidism on carbohydrate metabolism, insulin secretion, and pancreatic islets morphology of adult male offspring in rats

BACKGROUND

Neonatal hypothyroidism has serious effects on growth, development, and metabolism.

AIM

This study aims to investigate the effects of the neonatal hypothyroidism on carbohydrate metabolism, islet insulin secretion and morphology of the pancreatic islets in adult male offspring.

MATERIALS/SUBJECTS AND METHODS

Lactating mothers of Wistar rats consumed 0.02% solution of 6-propyl-2-thiouracil during the weaning period (neonatal hypothyroid group), while mothers of the control group drank merely tap water. Body weight and survival of pups were followed up. Intravenous glucose tolerance test was performed in adult male offspring and 5-6 weeks later, glucose-stimulated insulin secretion (GSIS) was evaluated.

RESULTS

During the glucose tolerance test, plasma glucose level of the neonatal hypothyroid group (13.18 ± 0.59 mmol/l) was significantly higher at 5 min compared to the control group (11.54 ± 0.47 mmol/l), whereas plasma insulin concentrations and GSIS of the groups was not significantly different. Homeostasis model assessment of insulin resistance of adult male offspring of the hypothyroid group (9.1 ± 1.0) was significantly higher as compared to the control group (4.5 ± 0.6). Area (14,613.0 ± 2646.3 μm2) and the diameter of the islets (147 ± 3.0 μm) of the neonatal hypothyroid group were significantly lower, as compared to the control group (32,886.3 ± 4690.3 and 206.6 ± 5.9 μm2 and μm, respectively).

CONCLUSION

Neonatal hypothyroidism can alter carbohydrate metabolism in euthyroid adult offspring, which may increase susceptibility to the development of glucose intolerance and occurrence of Type 2 diabetes later in life.

Early and post-weaning malnutrition impairs alpha-MSH expression in the hypothalamus: a possible link to long-term overweight

The present study explored the effects of early and post-weaning malnutrition and nutritional rehabilitation on orexigenic (orexin (ORX) and neuropeptide Y (NPY)) and anorexigenic peptides (alpha-melanocyte stimulating hormone (alpha-MSH)) expressed in hypothalamic nuclei. Male Wistar rats were malnourished during gestation-lactation (MGL) or from weaning to post-natal day 55 (MPW; P55). Two groups of rats were rehabilitated with a balanced diet until P90 (MGL-R and MPW-R, respectively). After a glucose tolerance test (GTT) brains were processed for immunohistochemistry. Malnourished groups were hyperglycemic after GTT. ORX expression did not display any difference. Only MGL rats showed increased NPY immunoreactivity in ARC and PVN nuclei, and both malnourished groups showed low alpha-MSH expression in the PVN and DMH, as compared with their controls. After nutritional rehabilitation rats showed normal GTT, increased rate of body and adipose tissue weights and high proportion of food ingestion. Both rehabilitated groups maintained low alpha-MSH expression in the PVN, indicating a deleterious long-lasting effect.

Bezold-Jarisch reflex in sino-aortic denervated malnourished rats

In this study we assessed the role of Bezold-Jarisch reflex (BJR) in the regulation of blood pressure (BP) of malnourished (MN) and control rats (CN) with sino-aortic denervation (SAD). Fischer rats were fed diets containing either 6% (MN) or 15% (CN) protein for 35 days after weaning. These rats underwent sham or SAD and catheterization of femoral artery and vein for BP measurements and drug injection. Phenylbiguanide (PBG 5 μg/kg, i.v.) for activation BJR, produced bradycardia (-317±22 bpm for CN vs. -372±16 bpm for MN) and hypotension (-57±4 mm Hg for CN vs. -54±6 mm Hg for MN. After SAD, MN rats had reduced hypotensive (-37±7 mm Hg for MN vs. -82±6 mm Hg for CN) and bradycardic (-124±17 for MN vs. -414±20 bpm CN) responses to BJR activation. To evaluate the contribution of the parasympathetic component due to BJR for the fall in BP, methyl atropine bromide, was given between two injections of PBG (5 μg/kg) separated by 10 min each other. Both bradycardic (-216±21 bpm before and -4±3 bpm after for CN -226±43 bpm before and -9±20 bpm after for MN) and hypotensive (-42±4 mm Hg before and -6±1 mm Hg after for CN -33±9 mm Hg before and -5±2 mm Hg after for MN) responses were abolished in CN and MN groups. These data indicate that dietary protein malnutrition changes the relation between baroreflex and BJR required for maintenance of the BP during malnourishment.

Effects of undernourishment on the hypothalamic orexinergic system

The present study examined the effects of a severely restricted diet during the pre- and postnatal periods with later nutritional rehabilitation on orexin hypothalamic neurons in male and female Wistar rats. Immunocytochemistry was used to reveal orexin-immunoreactive (orexin-ir) cells in the ventromedial hypothalamus (VMH), dorsomedial hypothalamus (DMH), lateral hypothalamic area (LH) and the perifornical nucleus (PF). Dietary restriction decreased the number of orexin-ir cells in the LH, whereas DMH or PF orexin-ir populations were not affected in either male or female rats. Nutritional rehabilitation resulted in a differential recovery that depended on the period during which rehabilitation occurred and on the sex of the animal. In summary, our study suggests that the hypothalamic nuclei implicated in eating behavior present a differential vulnerability to adverse environmental conditions during development. Specifically, among the studied nuclei only the LH orexin-ir cells were sensitive to severe food deprivation during development in male and female rats. These results suggest that starvation interferes with developmental events that occur during CNS sexual differentiation.