Citrus aurantium L. and synephrine improve brown adipose tissue function in adolescent mice programmed by early postnatal overfeeding.

Introduction and aims: Obesity is a multifactorial condition with high health risk, associated with important chronic disorders such as diabetes, dyslipidemia, and cardiovascular dysfunction. Citrus aurantium L. (C. aurantium) is a medicinal plant, and its active component, synephrine, a ß-3 adrenergic agonist, can be used for weight loss. We investigated the effects of C. aurantium and synephrine in obese adolescent mice programmed by early postnatal overfeeding. Methods: Three days after birth, male Swiss mice were divided into a small litter (SL) group (3 pups) and a normal litter (NL) group (9 pups). At 30 days old, SL and NL mice were treated with C. aurantium standardized to 6% synephrine, C. aurantium with 30% synephrine, isolated synephrine, or vehicle for 19 days. Results: The SL group had a higher body weight than the NL group. Heart rate and blood pressure were not elevated. The SL group had hyperleptinemia and central obesity that were normalized by C. aurantium and synephrine. In brown adipose tissue, the SL group showed a higher lipid droplet sectional area, less nuclei, a reduction in thermogenesis markers related to thermogenesis (UCP-1, PRDM16, PGC-1α and PPARg), and mitochondrial disfunction. C. aurantium and synephrine treatment normalized these parameters. Conclusion: Our data indicates that the treatment with C. aurantium and synephrine could be a promising alternative for the control of some obesity dysfunction, such as improvement of brown adipose tissue dysfunction and leptinemia.

Citrate enrichment in a Western diet reduces weight gain via browning of adipose tissues without resolving diet-induced insulin resistance in mice.

Citrate, a major component of processed foods, appears as either preservative or flavor enhancer. With no concentration limit, citrate is consumed in large quantities worldwide, principally in ultra-processed foods (UPF). UPF are encountered in Western diets (rich in saturated fat and sucrose), where consumption is directly associated with many conditions, such as obesity and diabetes, among others. Here, we administered a High-Fat, High-Sucrose (HFHS) diet to mice, enriched or not with citrate (67 mg g-1 diet), aimed to simulate UPF citrate consumption. Our results showed that citrate enrichment prevented the HFHS-induced lipid deposition in the liver and adipose tissues of the animals. Moreover, the treatment induced mitochondrial biogenesis in white adipose tissues, via upregulation of PCG1α. As a result, citrate enhancement upregulated UCP1, suggesting the browning of white adipose tissues. Nevertheless, the citrate-enhanced diet did not prevent HFHS-induced insulin resistance and causes further liver inflammation and injury. Altogether, our results clearly showed that, associated to UPF consumption, the excess of dietary citrate has caused harmful effects being associated to non-obesity related liver inflammatory diseases and insulin resistance.

Early weaning leads to specific glucocorticoid signalling in fat depots of adult rats.

PURPOSE: Early weaning (EW) is a stressful condition that programmes a child to be overweight in adult life. Fat mass depends on glucocorticoids (GC) to regulate adipogenesis and lipogenesis. We hypothesised that the increased adiposity in models of EW was due to a disturbed HPA axis and/or disrupted GC function. METHODS: We used two experimental models, pharmacological early weaning (PEW, dams were bromocriptine-treated) and non-pharmacological early weaning (NPEW, dams' teats were wrapped with a bandage), which were initiated during the last 3 days of lactation. Offspring from both genders was analysed on postnatal day 180. RESULTS: Offspring in both models were overweight with increased visceral fat mass, but plasma corticosterone was increased in both genders in the PEW group but not the NPEW group. NPEW males had increased GRα expression in visceral adipose tissue (VAT), and GRα expression decreased in PEW males in subcutaneous adipose tissue (SAT). Females in both EW groups had increased 11ßHSD1 expression in SAT. PEW males had increased C/EBPß expression in SAT. PEW females had lower PPARy and FAS expression in VAT than the NPEW females. We detected a sex dimorphism in VAT and SAT in the EW groups regarding 11ßHSD1, GRα and C/EBPß expression. CONCLUSIONS: The accumulated adiposity induced by EW exhibited distinct mechanisms depending on gender, specific fat deposition and GC metabolism and action. The higher proportion of VAT/SAT in both sets of EW males may be related to the action of GC in these tissues, and the higher conversion of GC in SAT in females may explain the differences in the fat distribution.

Thyroid redox imbalance in adult Wistar rats that were exposed to nicotine during breastfeeding.

Maternal nicotine exposure causes several consequences in offspring phenotype, such as obesity and thyroid dysfunctions. Nicotine exposure can increase oxidative stress levels, which could lead to thyroid dysfunction. However, the mechanism by which nicotine exposure during breastfeeding leads to thyroid gland dysfunction remains elusive. We aimed to investigate the long-term effects of maternal nicotine exposure on redox homeostasis in thyroid gland, besides other essential steps for thyroid hormone synthesis in rats from both sexes. Lactating Wistar rats were implanted with osmotic minipumps releasing nicotine (NIC, 6 mg/kg/day) or saline (control) from postnatal day 2 to 16. Offspring were analyzed at 180-day-old. NIC males showed lower plasma TSH, T3 and T4 while NIC females had higher T3 and T4. In thyroid, NIC males had higher sodium-iodide symporter protein expression, whereas NIC females had higher thyroid-stimulating hormone receptor (TSHr) and thyroperoxidase (TPO) protein expression. TPO activity was lower in NIC males. Hydrogen peroxide generation was decreased in NIC males. Activities of superoxide dismutase, catalase and glutathione peroxidase were compromised in NIC animals from both sexes. 4-Hydroxynonenal was higher only in NIC females, while thiol was not affected in NIC animals from both sexes. NIC offspring also had altered expression of sex steroid receptors in thyroid gland. Both sexes showed similar thyroid morphology, with lower follicle and colloid size. Thyroid from female offspring exposed to nicotine during breastfeeding developed oxidative stress, while the male gland seemed to be protected from redox damage. Thyroid dysfunctions seem to be associated with redox imbalance in a sex-dependent manner.

Programming of hepatic lipid metabolism in a rat model of postnatal nicotine exposure - Sex-related differences.

Maternal nicotine exposure during lactation induces liver damage in adult male rats. However, the mechanism in males is unknown and females have not been tested. Here, we determined the liver lipid composition and lipogenic enzymes in male and female offspring at two ages in a model of postnatal nicotine exposure. Osmotic minipumps were implanted in lactating Wistar rat dams at postnatal day (PND) 2 to release 6 mg/kg/day of nicotine (NIC group) or saline (CON group) for 14 days. Offspring received a standard diet from weaning until euthanasia at PND120 (1 pup/litter/sex) or PND180 (2 pups/litter/sex). At PND120, NIC males showed lower plasma triglycerides (TG), steatosis degree 1, higher hepatic cholesterol (CHOL) ester, free fatty acids, monoacylglycerol content as well as acetyl-coa carboxylase-1 (ACC-1) and fatty acid synthase (FAS) protein expression in the liver compared to CON males. At this age, NIC females had preserved hepatocytes architecture, higher plasma CHOL, higher CHOL ester and lower total CHOL content in the liver compared to CON females. At PND180, NIC males showed steatosis degrees 1 and 2, higher TG, lower free fatty acids and total CHOL content in the liver and an increase in ACC-1 hepatic protein expression. NIC females had higher plasma TG and CHOL levels, no change in hepatic morphology, lower CHOL ester and free fatty acids in the liver, which also showed higher total ACC-1 and FAS protein expression. Maternal nicotine exposure induces long-term liver dysfunction, with an alteration in hepatic cytoarchitecture that was aggravated with age in males. Concerning females, despite unchanged hepatic cytoarchitecture, lipid metabolism was compromised, which deserves further attention.

Short and long-term effects of bisphenol S (BPS) exposure during pregnancy and lactation on plasma lipids, hormones, and behavior in rats.

Bisphenol S (BPS) has replaced bisphenol A (BPA), a known non-persistent endocrine disrupting chemical, in several products. Considering that little is known regarding BPS effects, especially during critical windows of ontogenetic development, and that BPA, which is quite similar to BPS, is know to be transferred to the offspring via the placenta and milk, in the present study we investigated the behavioral, biochemical and endocrine profiles of Wistar rats born from dams that were BPS-exposed [groups: BPS10 (10 µg/kg/day), BPS50 (50 µg/kg/day)] during pregnancy and lactation. Due to the non-monotonic dose-response effect of bisphenol, the data of both BPS groups were directly compared with those of the controls, not to each other. Males and females were analyzed separately. At weaning, male BPS50 offspring had hypotriglyceridemia and hyperthyroxinemia, whereas BPS50 females showed higher 25(OH)D levels. At adulthood, BPS offspring of both sexes had lower food intake. BPS males showed lower visceral adiposity. BPS50 females had smaller fat droplets in brown adipocytes. BPS males showed higher anxiety and higher locomotor activity, while BPS10 females showed lower exploration. During a food challenge test at adulthood, BPS males consumed more high-fat diet at 30 min. BPS10 females initially (at 30 min) consumed more high-fat diet but, after 12 h, less of this diet was consumed. BPS50 males had hypertriglyceridemia and lower plasma T3, while BPS females showed lower plasma T4. BPS10 females had lower progesterone, whereas BPS50 females had higher plasma 25(OH)D. Maternal BPS exposure has adverse effects on the triacylglycerol, hormones levels and behavior of the progeny. Furthermore, the increased preference for the fat-enriched diet suggests an increased risk for obesity and its health consequences in the long term.