A free-choice high-fat, high-sucrose diet induces hyperphagia, obesity, and cardiovascular dysfunction in female cycling and pregnant rats

Oleaster oil (Olea europaea sylvestris) effects on the efficiency of the reproductive system of diet-induced obese male Wistar rats

OBJECTIVES

Obesity is the result of oxidative stress (OS), which appears to be linked to male infertility. Oleaster oil has multiple therapeutic virtues due to its richness in natural bioactive compounds. This study aimed to evaluate the effect of Algerian oleaster oil on the reproductive system effectiveness of diet-induced obese male Wistar rats.

METHODS

The oil was extracted with an oleodoseur from the oleaster fruits. Rats were fed for 28 weeks two diets: a normal diet (NC group, n=8) and a high-fat, high-sucrose diet (HFHS group, n=32). The obese rats in the HFHS group were then split into three groups at random: the HFHS group, which continued to receive the HFHS diet; the HFHS L-OO group; and the HFHS H-OO group, which received for 6 weeks, respectively, in combination with the HFHS diet, oleaster oil at 1.5 and 3 mL/100 g body weight (BW). Then, the animals were sacrificed. Semen and testes were removed for semen analysis, OS, and histopathological evaluation.

RESULTS

The oleaster oil diet induces an improvement in sperm count and viability and a decrease in the percentage of fragmented sperm DNA compared to the group fed the HFHS diet, preserving the testes against OS with a highly significant decrease in testicular MDA. This beneficial effect of oleaster oil on the reproductive efficiency of rats fed the HFHS diet was dose-dependent.

CONCLUSIONS

The results showed that the oil decreased body weight, prevented OS and improved male reproductive indicators in HFHS-fed animals. The potential positive effects of oleaster oil on fertility biomarkers may be attributed to its ability to mitigate OS.

Elderly rats fed with a high-fat high-sucrose diet developed sex-dependent metabolic syndrome regardless of long-term metformin and liraglutide treatment

Aim/Introduction

The study aimed to determine the effectiveness of early antidiabetic therapy in reversing metabolic changes caused by high-fat and high-sucrose diet (HFHSD) in both sexes.

Methods

Elderly Sprague-Dawley rats, 45 weeks old, were randomized into four groups: a control group fed on the standard diet (STD), one group fed the HFHSD, and two groups fed the HFHSD along with long-term treatment of either metformin (HFHSD+M) or liraglutide (HFHSD+L). Antidiabetic treatment started 5 weeks after the introduction of the diet and lasted 13 weeks until the animals were 64 weeks old.

Results

Unexpectedly, HFHSD-fed animals did not gain weight but underwent significant metabolic changes. Both antidiabetic treatments produced sex-specific effects, but neither prevented the onset of prediabetes nor diabetes.

Conclusion

Liraglutide vested benefits to liver and skeletal muscle tissue in males but induced signs of insulin resistance in females.

Exosomes facilitate intercellular communication between uterine perivascular adipose tissue and vascular smooth muscle cells in pregnant rats

Perivascular adipose tissue (PVAT) is distinct from other adipose depots as it has differential gene and protein profiles and vasoactive functions. We have shown that pregnancy affects the morphology of PVAT surrounding the uterine arteries (utPVAT) differentially than the morphology of non-perivascular reproductive adipose depots (i.e., periovarian adipose tissue, OVAT). Here, we hypothesized that pregnancy modifies the profile (size and molecular weight) of exosome-like extracellular vesicles released by utPVAT (Exo-utPVAT) compared to OVAT (Exo-OVAT) and that primary uterine vascular smooth muscle cells (utVSMCs) can internalize Exo-utPVAT. Our findings indicate that utPVAT from pregnant and non-pregnant rats secrete exosome-like vesicles. Exo-utPVAT from pregnant rats were smaller (i.e., molecular size) and heavier (i.e., molecular weight) than those from non-pregnant rats, while pregnancy did not affect the size of Exo-OVAT. Immunocytochemistry and confocal microscopy showed that primary utVSMCs internalized Exo-utPVAT (both tissues from the same pregnant rat) labeled by the lipophilic tracer DiO. Treatment of isolated uterine arteries with Exo-utPVAT did not affect relaxation responses to acetylcholine (ACh) in pregnant or non-pregnant rats. Collectively, these findings demonstrate a novel type of intercellular communication between Exo-utPVAT and utVSMCs and indicate pregnancy modulates the morphology and cargo of Exo-utPVAT.

Fat augments leptin-induced uterine contractions by decreasing JAK2 and BKCa channel expressions in late pregnant rats

Altered lipid metabolism in obesity causes pregnancy complications in humans and animals. Leptin levels increase in pregnancy, as well as obesity. However, the effect of obesity on uterine leptin receptors and its distal signaling is not clear. The present study aimed to understand the effect of increased fat on leptin signaling in rat uterus. Wistar female rats were fed with an HF diet (40% Fat, 17% Sucrose, 1.25% Cholesterol, 0.75% Cholic acid) for 6 weeks before the mating and during pregnancy. HF diet significantly increased the fat depots, liver weight, serum, and tissue cholesterol levels. It produced fatty degeneration in the liver and caused infiltration of inflammatory cells, cystic endometrial glands, and sub endometrial fibrosis of the uterus. In isometric tension experiments, leptin caused a significant increase in uterine contractions in high fat-fed animals compared to control animals. Analysis of receptor expressions revealed no significant difference between the groups. However, a significant decrease in the JAK2 and BKCaα mRNA expression was observed in the uterus of high fat-fed rats. No change in the BKCaβ, eNOS, iNOS, MLCP, and MLCK mRNA expressions was noticed in the HF group compared to the control. The findings of the present study suggest that the contractile response to leptin in the uterus of high fat-fed rats may be attributed to reduced signaling through JAK2 and, lowered expressions of BKCa channel α subunits.

Neurobiological Mechanisms Modulating Emotionality, Cognition and Reward-Related Behaviour in High-Fat Diet-Fed Rodents

Affective and substance-use disorders are associated with overweight and obesity-related complications, which are often due to the overconsumption of palatable food. Both high-fat diets (HFDs) and psychostimulant drugs modulate the neuro-circuitry regulating emotional processing and metabolic functions. However, it is not known how they interact at the behavioural level, and whether they lead to overlapping changes in neurobiological endpoints. In this literature review, we describe the impact of HFDs on emotionality, cognition, and reward-related behaviour in rodents. We also outline the effects of HFD on brain metabolism and plasticity involving mitochondria. Moreover, the possible overlap of the neurobiological mechanisms produced by HFDs and psychostimulants is discussed. Our in-depth analysis of published results revealed that HFDs have a clear impact on behaviour and underlying brain processes, which are largely dependent on the developmental period. However, apart from the studies investigating maternal exposure to HFDs, most of the published results involve only male rodents. Future research should also examine the biological impact of HFDs in female rodents. Further knowledge about the molecular mechanisms linking stress and obesity is a crucial requirement of translational research and using rodent models can significantly advance the important search for risk-related biomarkers and the development of clinical intervention strategies.

Effect of artemisinin on improving islet function in rats fed with maternal high-fat diet

BACKGROUND

Maternal high-fat diet (HFD) is a detrimental factor in developing glucose intolerance, obesity, and islet dysfunction. However, the effect of artemisinin on maternal HFD and whether it is related to the alterations of islet function is seldom studied since artemisinin treatments not only attenuate insulin resistance (IR) and restore islet ß cell function in Diabetes mellitus type 2.

METHODS

Female rats were randomly fed a HFD (45% kcal from fat), HFD + artemisinin, or a regular chow diet (RCD) before pregnancy and during gestation. Glucose metabolism and the β cell phenotypes were assessed.

RESULTS

Maternal HFD increased islet load in female rats, proliferation of pancreatic β cells, increased insulinogen, and decreased insulin secretion response to high glucose stimulation with delayed insulin release, increased fasting glucose, and glucose area under the curve compared with the general diet group. HFD inhibited expression of Foxo1 and PAX6 in female rats. Under the effect of both HFD and pregnancy, islet load was further increased, insulinogen was further increased, and fasting insulin level and fasting glucose were higher than RCD fed general-pregnancy group. ALDH1a3 transdifferentiation and PAX6, Foxo1, and PDX1 expression were increased in islets of high-fat pregnant rats. When adding artemisinin in HFD treated pregnant rats, islet function was significantly improved.

CONCLUSIONS

Intervention with artemisinin in maternal HFD resulted in reduced islet size, decreased number of β-cells and improved islet microcirculation, insulin processing shear process, decreased insulinogen/insulin ratio, and restored islet function through increased expression of PC1/3.

Palatable high-fat diet intake influences mnemonic and emotional aspects in female rats in an estrous cycle-dependent manner

Worldwide, the excessive consumption of fat and/or sugar has increased considerably. Palatable high-fat diets (HFDs) lead to metabolic disturbances and obesity, and impact emotional and cognitive processes. Previous studies in rodent models suggested that HFDs often cause multiple behavioral alterations, such as learning and memory deficits, and anxiety-like behaviors. Different sexes imply different behavioral and cognitive abilities; yet, most of these studies dealt with male or ovariectomized rats. We evaluated HFD effects in female rats submitted to different behavioral tasks, considering the effects of endogenous hormonal variations throughout estrous cycle. Female Wistar rats in each phase of the estrous cycle using commercial chow (CC) or HFD for 32 days. During treatment, behavioral assessments using sucrose preference (SP), elevated plus-maze (EPM), open field (OF) and novel-object recognition (NOR). At the end of the behavioral tests, animals were euthanized, and performed an immunohistochemical analysis of the brains by brain-derived neurotrophic factor (BDNF) and tyrosine hydroxylase (TH). The main results demonstrated that (1) HFD-fed rats had higher body mass gain and food intake, without altering caloric intake, (2) rats in diestrus had lower sucrose intake, (3) females in metestrus and diestrus showed deficits in the novel-object recognition memory. Furthermore, TH-immunoreactivity decreased in the dorsal striatum and BDNF in the hippocampus in HFD-fed females. These results suggest that HFD alters neurochemical and metabolic aspects that may induce phase-dependent behavioral changes in female rats.

Lifestyle, Maternal Nutrition and Healthy Pregnancy

Healthy lifestyle habits spanning from preconception to postpartum are considered as a major safeguard for achieving successful pregnancies and for the prevention of gestational diseases. Among preconception priorities established by the World Health Organization (WHO) are healthy diet and nutrition, weight management, physical activity, planned pregnancy and physical, mental and psychosocial health. Most studies covering the topic of healthy pregnancies focus on maternal diet because obesity increases the risks for adverse perinatal outcomes, including gestational diabetes mellitus, large for gestational age newborns, or preeclampsia. Thus, foods rich in vegetables, essential and polyunsaturated fats and fibre-rich carbohydrates should be promoted especially in overweight, obese or diabetic women. An adequate intake of micronutrients (e.g. iron, calcium, folate, vitamin D and carotenoids) is also crucial to support pregnancy and breastfeeding. Moderate physical activity throughout pregnancy improves muscle tone and function, besides decreasing the risk of preeclampsia, gestational diabesity (i.e. diabetes associated with obesity) and postpartum overweight. Intervention studies claim that an average of 30 min of exercise/day contributes to long-term benefits for maternal overall health and wellbeing. Other factors such as microbiome modulation, behavioural strategies (e.g. smoking cessation, anxiety/stress reduction and sleep quality), maternal genetics and age, social class and education might also influence the maternal quality of life. These factors contribute to ensure a healthy pregnancy, or at least to reduce the risk of adverse maternal and foetal outcomes during pregnancy and later in life.

Offspring of Obese Dams Exhibit Sex-Differences in Pancreatic Heparan Sulfate Glycosaminoglycans and Islet Insulin Secretion

Offspring of obese mothers suffer higher risks of type 2 diabetes due to increased adiposity and decreased β cell function. To date, the sex-differences in offspring islet insulin secretion during early life has not been evaluated extensively, particularly prior to weaning at postnatal day 21 (P21). To determine the role of maternal obesity on offspring islet insulin secretion, C57BL/6J female dams were fed chow or western diet from 4 weeks prior to mating to induce maternal obesity. First, offspring of chow-fed and obese dams were evaluated on postnatal day 21 (P21) prior to weaning for body composition, glucose and insulin tolerance, and islet phasic insulin-secretion. Compared to same-sex controls, both male and female P21 offspring born to obese dams (MatOb) had higher body adiposity and exhibited sex-specific differences in glucose tolerance and insulin secretion. The male MatOb offspring developed the highest extent of glucose intolerance and lowest glucose-induced insulin secretion. In contrast, P21 female offspring of obese dams had unimpaired insulin secretion. Using SAX-HPLC, we found that male MatOb had a decrease in pancreatic heparan sulfate glycosaminoglycan, which is a macromolecule critical for islet health. Notably, 8-weeks-old offspring of obese dams continued to exhibit a similar pattern of sex-differences in glucose intolerance and decreased islet insulin secretion. Overall, our study suggests that maternal obesity induces sex-specific changes to pancreatic HSG in offspring and a lasting effect on offspring insulin secretion, leading to the sex-differences in glucose intolerance.

High-fat diet from parental generation exaggerates body and adipose tissue weights in pregnant offspring

Parental high-fat diet (HFD) programs for obesity and hypertension in female offspring in rats, but it is unknown how the pregnancies of these offspring are impacted. Therefore, the hypothesis was tested that parental HFD exaggerates obesity and hypertension during pregnancy of the offspring. Wistar Hannover rat dams (the parental, P generation) were maintained on normal-fat diet (NFD) or HFD from weaning and were kept on respective diets through pregnancy and lactation. Their offspring (the first filial, F1 generation) were weaned onto the same diet as the P generation, or they were changed to the other diet to determine if combined HFD in the P and F1 generations exaggerates body weight and blood pressure levels during pregnancy in these offspring. This diet paradigm resulted in the following groups of pregnant F1 offspring: P-NFD/F1-NFD, P-HFD/F1-NFD, P-NFD/F1-HFD, and P-HFD/F1-HFD. Maternal body and adipose tissue weights were greatest in the P-HFD/F1-HFD group compared to the other 3 groups by the end of pregnancy. Plasma leptin and conscious mean arterial blood pressure were not significantly different between any group, although there was a main effect for increased blood pressure in the F1-HFD groups. Circulating levels of the antihypertensive pregnancy factor, placental growth factor (PlGF), were assessed. Although average PlGF levels were similar among all groups, correlative studies revealed that lower levels of PlGF were associated with higher blood pressure only in the P-HFD/F1-HFD group. In summary, HFD feeding from the P generation exaggerated HFD-induced body and adipose tissue weights in the pregnant offspring.

Development of a Predictive Model to Induce Atherogenesis and Hepato-Renal Impairment in Female Rats

Therapeutic approaches for the treatment of dyslipidemia and atherosclerosis have radically changed in recent decades. Part of this advance undeniably stems from basic biomedical research that has provided a better understanding and identification of new therapeutic targets. The aim of this work was to develop a model to induce atherogenesis and hepato-renal impairment in female Wistar rats. The following groups received the respective treatments for 60 days: control animals, non-ovariectomized rats that received an atherogenic diet (NEAD), ovariectomized rats that received an atherogenic diet (NOAD), non-ovariectomized rats that received an atherogenic diet and oral Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; LEAD), and ovariectomized rats that received an atherogenic diet and oral l-NAME (LOAD). Animals in the NEAD, NOAD, LEAD, and LOAD groups also received methimazole and cholecalciferol daily. Urinary, biochemical, hemodynamic, and electrocardiographic parameters and renal function were assessed. Samples of the liver, heart, kidney, and arteries were collected to investigate redox status and perform histopathological analyses. All of the groups developed dyslipidemia and hepatic steatosis. Only the NEAD group developed arterial lesions that were compatible with fatty streaks. Renal function was significantly impaired in the LEAD and NOAD groups. These results indicate a viable alternative to induce atherogenesis and hepato-renal impairment in female rats.

Uterine perivascular adipose tissue is a novel mediator of uterine artery blood flow and reactivity in rat pregnancy

KEY POINTS

In vivo, uterine perivascular adipose tissue (PVAT) potentiates uterine artery blood flow in pregnant rats, although not in non-pregnant rats. In isolated preparations, uterine PVAT has pro-contractile and anti-dilatory effects on uterine arteries. Pregnancy induces changes in uterine arteries that makes them responsive to uterine PVAT signalling.

ABSTRACT

An increase in uterine artery blood flow (UtBF) is a common and necessary feature of a healthy pregnancy. In the present study, we tested the hypothesis that adipose tissue surrounding uterine arteries (uterine perivascular adipose tissue; PVAT) is a novel local mediator of UtBF and uterine artery tone during pregnancy. In vivo experiments in anaesthetized Sprague-Dawley rats showed that pregnant animals (gestational day 16, term = 22--23 days) had a three-fold higher UtBF compared to non-pregnant animals. Surgical removal of uterine PVAT reduced UtBF only in pregnant rats. In a series of ex vivo bioassays, we demonstrated that uterine PVAT had pro-contractile and anti-dilatory effects on rat uterine arteries. In the presence of PVAT-conditioned media, isolated uterine arteries from both pregnant and non-pregnant rats had reduced vasodilatory responses. In non-pregnant rats, these responses were mediated at the level of uterine vascular smooth muscle, whereas, in pregnant rats, PVAT-media reduced endothelium-dependent relaxation. Pregnancy increased adipocyte size in ovarian adipose tissue but had no effect on uterine PVAT adipocyte morphology. In addition, pregnancy down-regulated the gene expression of metabolic adipokines in uterine but not in aortic PVAT. In conclusion, this is the first study to demonstrate that uterine PVAT plays a regulatory role in UtBF, at least in part, as a result of its actions on uterine artery tone. We propose that the interaction between the uterine vascular wall and its adjacent adipose tissue may provide new insights for interventions in pregnancies with adipose tissue dysfunction and abnormal UtBF.