Ketogenic diet improves low temperature tolerance in mice by up-regulating PPARα in the liver and brown adipose tissue / 生理学报

The aim of the present study was to investigate the effects of short-term ketogenic diet on the low temperature tolerance of mice and the involvement of peroxisome proliferator-activated receptor α (PPARα). C57BL/6J mice were divided into two groups: normal diet (WT+ND) group and ketogenic diet (WT+KD) group. After being fed with normal or ketogenic diet at room temperature for 2 d, the mice were exposed to 4 °C low temperature for 12 h. The changes in core temperature, blood glucose, blood pressure of mice under low temperature condition were detected, and the protein expression levels of PPARα and mitochondrial uncoupling protein 1 (UCP1) were detected by Western blot. PPARα knockout mice were divided into normal diet (PPARα-/-+ND) group and ketogenic diet (PPARα-/-+KD) group. After being fed with the normal or ketogenic diet at room temperature for 2 d, the mice were exposed to 4 °C low temperature for 12 h. The above indicators were also detected. The results showed that, at room temperature, the protein expression levels of PPARα and UCP1 in liver and brown adipose tissue of WT+KD group were significantly up-regulated, compared with those of WT+ND group. Under low temperature condition, compared with WT+ND, the core temperature and blood glucose of WT+KD group were increased, while mean arterial pressure was decreased; The ketogenic diet up-regulated PPARα protein expression in brown adipose tissue, as well as UCP1 protein expression in liver and brown adipose tissue of WT+KD group. Under low temperature condition, compared to WT+ND group, PPARα-/-+ND group exhibited decreased core temperature and down-regulated PPARα and UCP1 protein expression levels in liver, skeletal muscle, white and brown adipose tissue. Compared to the PPARα-/-+ND group, the PPARα-/-+KD group exhibited decreased core temperature and did not show any difference in the protein expression of UCP1 in liver, skeletal muscle, white and brown adipose tissue. These results suggest that the ketogenic diet promotes UCP1 expression by up-regulating PPARα, thus improving low temperature tolerance of mice. Therefore, short-term ketogenic diet can be used as a potential intervention to improve the low temperature tolerance.

Role of brown adipose tissue in phlegm-dampness metabolic syndrome based on infrared thermal imaging / 中国中药杂志

This study aimed to explore the infrared manifestation and role of brown adipose tissue(BAT) in phlegm-dampness me-tabolic syndrome(MS), and to provide objective basis for clinical diagnosis and treatment of phlegm-dampness MS. Subjects were selected from the department of endocrinology and ward in the South District of Guang'anmen Hospital, China Academy of Chinese Medical Sciences from August 2021 to April 2022, including 20 in healthy control group, 40 in non phlegm-dampness MS group and 40 in phlegm-dampness MS group. General information, height and weight of the subjects were collected and body mass index(BMI) was calculated. Waist circumference(WC), systolic blood pressure(SBP) and diastolic blood pressure(DBP) was measured. Triglyceride(TG), high density lipoprotein cholesterol(HDL-C), fasting blood glucose(FBG), fasting insulin(FINS), leptin(LP), adiponectin(ADP) and fibroblast growth factor-21(FGF-21) were detected. The infrared thermal image of the supraclavicular region(SCR) of the subjects before and after cold stimulation test was collected by infrared thermal imager and the changes of infrared thermal image in the three groups were observed. In addition, the differences in the average body surface temperature of SCR among the three groups were compared, and the changes of BAT in SCR were analyzed. The results showed compared with the conditions in healthy control group, the levels of WC, SBP, DBP, TG and FPG in MS groups were increased(P<0.01), and the HDL-C level was decreased(P<0.01). Compared with non phlegm-dampness MS group, phlegm-dampness MS group had higher conversion score of phlegm dampness physique(P<0.01). According to the infrared heat map, there was no difference in the average body surface temperature of SCR among the three groups before cold stimulation. while after cold stimulation, the average body surface temperature of SCR in MS groups was lower than that in healthy control group(P<0.05). After cold stimulation, the maximum temperature of SCR and its arrival time in the three groups were as follows: healthy control group(3 min)>non phlegm-dampness MS group(4 min)>phlegm-dampness MS group(5 min). The thermal deviation of SCR was increased and the average body surface temperature of left and right sides were higher(P<0.01) in healthy control group and non phlegm-dampness MS group, while the thermal deviation of SCR did not change significantly in the phlegm-dampness MS group. Compared with that in healthy control group, the elevated temperature between left and right sides was lower(P<0.01, P<0.05), and compared with that in non phlegm-dampness MS group, the elevated temperature of left side was lower(P<0.05). The changes of the average body surface temperature of SCR in the three groups were in the order of healthy control group>non phlegm-dampness MS group>phlegm-dampness MS group. Compared with the conditions in healthy control group and non phlegm-dampness MS group, FINS, BMI and FGF-21 levels were increased(P<0.01,P<0.05), while ADP level was decreased(P<0.01, P<0.05) in phlegm-dampness MS group. Moreover, the LP level in phlegm-dampness MS group was higher than that in non phlegm-dampness MS group(P<0.01). It was observed in clinical trials that after cold stimulation, the average body surface temperature of SCR in MS patients was lower than that of the healthy people; the thermal deviation of SCR did not change significantly in the phlegm-dampness MS patients, and the difference in their elevated temperature was lower than that in the other two groups. These characteristics provided objective basis for clinical diagnosis and treatment of phlegm-dampness MS. With abnormal BAT related indicators, it was inferred that the content or activity of BAT in SCR of phlegm-dampness MS patients were reduced. There was a high correlation between BAT and phlegm-dampness MS, and thus BAT might become an important potential target for the intervention in phlegm-dampness MS.

A comprehensive morphometric study of visceral and subcutaneous adipose tissue depots in mice, hamsters and rats / Un estudio morfométrico completo de los depósitos de tejido adiposo visceral y subcutáneo en ratones, hámsters y ratas

SUMMARY: Adipose tissue morphology of different fat tissue depots can be described using the number of adipocytes and cell surface of adipocytes. This study deals with characteristics and morphometric analysis of white and brown adipose tissue depots in healthy adult laboratory mice, hamsters and rats of both sexes. The number of unilocular adipocytes in white adipose tissue differs from one adipose tissue depot to another, with the largest number of adipocytes in mice and a similar number in hamsters and rats. The smallest surface area and the largest percentage of small unilocular adipocytes were found in mice. White adipose tissue in hamsters and rats was predominantly made out of a larger percentage of medium-sized adipocytes and a smaller percentage of small and medium-sized adipocytes. Uncoupling protein 1 positive multilocular adipocytes were found in classic brown adipose tissue depots with larger percentages in mice (93.20 %) and hamsters (91.30 %), while rats had a smaller percentage (78.10 %). In white and brown adipose tissue, significant differences between species and both sexes within the same species were found, indicating the influence of sexual dimorphism. The presented morphometric results could serve as a basis for further studies concerning experimental animal models of metabolic disorders and obesity.

RESUMEN: La morfología del tejido adiposo de diferentes depósitos de tejido graso se puede describir utilizando el número de adipocitos y la superficie celular de los adipocitos. Este estudio analiza las características y el análisis morfométrico de los depósitos de tejido adiposo blanco y marrón en ratones, hamsters y ratas de laboratorio, adultos sanos de ambos sexos. El número de adipocitos uniloculares en el tejido adiposo blanco difiere de un depósito de tejido adiposo a otro, con el mayor número de adipocitos en ratones y un número similar en hámsteres y ratas. La superficie más pequeña y el mayor porcentaje de adipocitos uniloculares pequeños se encontraron en ratones. El tejido adiposo blanco en hámsteres y ratas estaba compuesto predominantemente por un mayor porcentaje de adipocitos de tamaño mediano y un porcentaje menor de adipocitos de tamaño pequeño y mediano. Los adipocitos multiloculares positivos para la proteína desacopladora 1 se encontraron en depósitos de tejido adiposo marrón clásico con mayores porcentajes en ratones (93,20 %) y hámsters (91,30 %), mientras que las ratas tenían un porcentaje menor (78,10 %). En el tejido adiposo blanco y pardo se encontraron diferencias significativas entre especies y entre ambos sexos dentro de una misma especie, lo que indica la influencia del dimorfismo sexual. Los resultados morfométricos presentados podrían servir como base para futuros estudios sobre modelos animales experimentales de trastornos metabólicos y obesidad.

Molecular mechanism of Gegen Qinlian Decoction in promoting differentiation of brown adipose tissue to improve glucose and lipid metabolism disorders in diabetic rats / 中国中药杂志

This study explored the molecular mechanism underlying the Gegen Qinlian Decoction(GQD) promoting the differentiation of brown adipose tissue(BAT) to improve glucose and lipid metabolism disorders in diabetic rats. After the hypoglycemic effect of GQD on diabetic rats induced by high-fat diet combined with a low dose of streptozotocin was confirmed, the total RNA of rat BAT around scapula was extracted. Nuclear transcription genes Prdm16, Pparγc1α, Pparα, Pparγ and Sirt1, BAT marker genes Ucp1, Cidea and Dio2, energy expenditure gene Ampkα2 as well as BAT secretion factors Adpn, Fndc5, Angptl8, IL-6 and Rbp4 were detected by qPCR, then were analyzed by IPA software. Afterward, the total protein from rat BAT was extracted, and PRDM16, PGC1α, PPARγ, PPARα, SIRT1, ChREBP, AMPKα, UCP1, ADPN, NRG4, GLUT1 and GLUT4 were detected by Western blot. The mRNA expression levels of Pparγc1α, Pparα, Pparγ, Ucp1, Cidea, Ampkα2, Dio2, Fndc5, Rbp4 and Angptl8 were significantly increased(P<0.05) and those of Adpn and IL-6 were significantly decreased(P<0.05) in the GQD group compared with the diabetic group. In addition, Sirt1 showed a downward trend(P=0.104), whereas Prdm16 tended to be up-regulated(P=0.182) in the GQD group. IPA canonical pathway analysis and diseases-and-functions analysis suggested that GQD activated PPARα/RXRα and SIRT1 signaling pathways to promote the differentiation of BAT and reduce the excessive lipid accumulation. Moreover, the protein expression levels of PRDM16, PGC1α, PPARα, PPARγ, SIRT1, ChREBP, AMPKα, UCP1, GLUT1, GLUT4 and NRG4 were significantly decreased in the diabetic group(P<0.01), which were elevated after GQD intervention(P<0.05). Unexpectedly, the expression of ADPN protein in the diabetic group was up-regulated(P<0.01) as compared with the control group, which was down-regulated after the administration with GQD(P<0.01). This study indicated that GQD promoted BAT differentiation and maturity to increase energy consumption, which reduced the glucose and lipid metabolism disorders and thereby improved diabetes symptoms.

Histamine stimulates thermogenesis of brown and beige fat / 生理学报

β3-adrenergic agonists induce adaptive thermogenesis and promote beiging of white fat. However, it remains unclear which metabolites mediate the stimulatory effects of β3-adrenergic agonists on thermogenesis of brown and beige fat. In this study, adipose tissue was isolated from 8-week-old C57/BL6J male mice by intraperitoneal administration of β3-adrenergic agonist CL316,243 for RNA-Seq, which revealed that histidine decarboxylase, a key enzyme in histamine synthesis, was strongly induced in adipose by CL316,243. Therefore, we speculated that histamine might be involved in the process of thermogenesis in adipose tissue. We determined the physiological role and mechanism by which histamine promotes fat thermogenesis by intravenous administering histamine to C57BL/6J mice fed a normal or a high-fat diet. The results showed that intravenous injection of histamine into C57BL/6J mice fed a normal diet stimulated the expression of thermogenic genes, including peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and uncoupling protein 1 (UCP1), in brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT). H&E staining also suggested that histamine treatment decreased the size of lipid droplets in adipocytes. Moreover, histamine treatment also enhanced thermogenesis of fat in high-fat diet induced obese mice, and improved glucose intolerance and fatty liver phenotype. Finally, we demonstrated that the effects of histamine on the thermogenic program were cell autonomous. Our data suggest that histamine may mediate the effects of β3-adrenergic agonists on thermogenesis of fat.

Los colores del tejido adiposo / The colors of adipose tissue

Resumen El tejido adiposo es un órgano endocrino con gran actividad metabólica. A la fecha se han descubierto innumerables adipocinas y lipocinas, péptidos y lípidos con actividad biológica, secretadas por el tejido adiposo. Se sabe que tanto el tejido adiposo blanco como el pardo y el beige contribuyen a la homeostasis energética y a la regulación metabólica. Esta revisión tiene como finalidad comunicar los hallazgos más recientes relativos al tejido adiposo según su color y la relación de este con las alteraciones metabólicas asociadas a la obesidad. Después de la revisión de la literatura especializada, se identificó que en una misma estructura pueden coexistir poblaciones blancas, pardas y beige, que modifican el estado metabólico global en situaciones fisiológicas o patológicas.

Abstract Adipose tissue is an endocrine organ with high metabolic activity. Countless adipose tissue-secreted adipokines and lipokines, as well as peptides and lipids with biological activity have thus far been discovered. Both white and brown and beige adipose tissue are known to contribute to energy homeostasis and metabolic regulation. The purpose of this review is to report on the most recent findings related to adipose tissue according to its color and its relationship with metabolic alterations associated with obesity. After a review of the specialized literature, white, brown and beige adipocyte populations were identified to be able to coexist within the same structure, and to modify global metabolic state in physiological or pathological situations.

Duodenal-jejunal bypass reduces lipid accumulation in the brown adipose tissue of hypothalamic obese rats / Derivação duodeno-jejunal reduz o acúmulo de lipídios no tecido adiposo marrom de ratos com obesidade hipotalâmica

ABSTRACT Background: Thermogenic activity in the brown adipose tissue (BAT) of obese individuals is reduced, and this condition may be modified by bariatric surgery (BS). Aim: To characterize fat deposition in BAT from hypothalamic obese (HyO) rats submitted to duodenal-jejunal-bypass (DJB) surgery. Methods: For induction of hypothalamic obesity, newborn male Wistar rats were treated with subcutaneous injections of monosodium glutamate (MSG). The control (CTL) group received saline solution. At 90 days, the HyO rats were submitted to DJB or sham operation, generating the HyO-DJB and HyO-SHAM groups. At 270 days, the rats were euthanized, and the BAT was weighed and submitted to histological analysis. Results: Compared to BAT from CTL animals, the BAT from HyO-SHAM rats displayed increased weight, hypertrophy with greater lipid accumulation and a reduction in nucleus number. DJB effectively increased nucleus number and normalized lipid deposition in the BAT of HyO-SHAM rats, similar to that observed in CTL animals. Conclusion: DJB surgery avoided excessive lipid deposition in the BAT of hypothalamic obese rats, suggesting that this procedure could reactivate thermogenesis in BAT, and contribute to increase energy expenditure.

RESUMO Racional: A atividade termogênica no tecido adiposo marrom (TAM) de indivíduos obesos encontra-se reduzida, condição que pode ser modificada pela cirurgia bariátrica(CB). Objetivo: Verificar o efeito da derivação duodeno-jejunal (DDJ) sobre a morfologia do TAM de ratos com obesidade hipotalâmica. Métodos: Para indução da obesidade hipotalâmica (OHi), ratos Wistar neonatos receberam injeções subcutâneas de glutamato monossódico (MSG). O grupo controle (CTL) recebeu solução salina. Aos 90 dias, os ratos OHi foram submetidos à DDJ (grupo OHi-DDJ) ou a falsa operação (grupo OHi-FO). Aos 270 dias, eles foram eutanasiados e o TAM foi pesado e submetido à análise histológica. Resultados: Em comparação com os animais CTL, o TAM dos ratos OHi-FO apresentou aumento do peso, hipertrofia dos adipócitos com acúmulo de lipídios e redução do número de núcleos. A DDJ reduziu a deposição de gordura e o número de núcleos no TAM de ratos OHi-DDJ em comparação com os OHi-FO, com valores similares aqueles dos animais CTL. Conclusões: A DDJ foi capaz de evitar a deposição excessiva de lipídios no TAM de ratos com obesidade hipotalâmica, sugerindo que a cirurgia bariátrica poderia reativar a termogênese neste tecido adiposo, contribuindo para aumentar o gasto energético.

Quantification of Fat Concentration and Vascular Response in Brown and White Adipose Tissue of Rats by Spectral CT Imaging

Propranolol inhibits myocardial infarction-induced brown adipose tissue D2 activation and maintains a low thyroid hormone state in rats

Considering the recognized role of thyroid hormones on the cardiovascular system during health and disease, we hypothesized that type 2 deiodinase (D2) activity, the main activation pathway of thyroxine (T4)-to-triiodothyronine (T3), could be an important site to modulate thyroid hormone status, which would then constitute a possible target for β-adrenergic blocking agents in a myocardial infarction (MI) model induced by left coronary occlusion in rats. Despite a sustained and dramatic fall in serum T4 concentrations (60-70%), the serum T3 concentration fell only transiently in the first week post-infarction (53%) and returned to control levels at 8 and 12 weeks after surgery compared to the Sham group (P<0.05). Brown adipose tissue (BAT) D2 activity (fmol T4·min-1·mg ptn-1) was significantly increased by approximately 77% in the 8th week and approximately 100% in the 12th week in the MI group compared to that of the Sham group (P<0.05). Beta-blocker treatment (0.5 g/L propranolol given in the drinking water) maintained a low T3 state in MI animals, dampening both BAT D2 activity (44% reduction) and serum T3 (66% reduction in serum T3) compared to that of the non-treated MI group 12 weeks after surgery (P<0.05). Propranolol improved cardiac function (assessed by echocardiogram) in the MI group compared to the non-treated MI group by 40 and 57%, 1 and 12 weeks after treatment, respectively (P<0.05). Our data suggested that the beta-adrenergic pathway may contribute to BAT D2 hyperactivity and T3 normalization after MI in rats. Propranolol treatment maintained low T3 state and improved cardiac function additionally.

Timeliness of β3 adrenergic receptor agonist-induced browning of white adipose tissues in mice / 中南大学学报(医学版)

To characterize the timeliness of β3 adrenergic receptor agonist CL316,243-induced browning of white adipose tissues in mice.
 Methods: Male C57BL/6J mice at 10 weeks of age were housed in conventional cages and given sterile saline for the control group or CL316,243 (1 μg/g) for the experimental group via intraperitoneal injection for 1, 3, and 5 days. Food intake and body weight were measured daily. Interscapular brown adipose tissue (iBAT), inguinal subcutaneous white adipose (sWAT) and epididymal white adipose tissue (eWAT) were harvested for histological and gene expression analysis.
 Results: Compared with the control group, intraperitoneal injection of CL316,243 reduced the weight of eWAT on the first day. Meanwhile, CL316,243 continuously promoted the mRNA and protein expression of uncoupling protein-1 (UCP-1) in sWAT and eWAT. Furthermore, CL316,243 injection significantly decreased the food intake and weight gain of the mice, and reduced the diameter of adipocyte and accumulation of small lipid droplets in adipose tissues.
 Conclusion: CL316,243 can induce the brown-like remodeling in adipose tissues of mice in vivo, which show different time-dependent manners in different adipose tissues.

Supplementation of Fermented Barley Extracts with Lactobacillus Plantarum dy-1 Inhibits Obesity via a UCP1-dependent Mechanism / 生物医学与环境科学（英文）

OBJECTIVE@#We aimed to explore how fermented barley extracts with Lactobacillus plantarum dy-1 (LFBE) affected the browning in adipocytes and obese rats.@*METHODS@#In vitro, 3T3-L1 cells were induced by LFBE, raw barley extraction (RBE) and polyphenol compounds (PC) from LFBE to evaluate the adipocyte differentiation. In vivo, obese SD rats induced by high fat diet (HFD) were randomly divided into three groups treated with oral gavage: (a) normal control diet with distilled water, (b) HFD with distilled water, (c) HFD with 800 mg LFBE/kg body weight (bw).@*RESULTS@#In vitro, LFBE and the PC in the extraction significantly inhibited adipogenesis and potentiated browning of 3T3-L1 preadipocytes, rather than RBE. In vivo, we observed remarkable decreases in the body weight, serum lipid levels, white adipose tissue (WAT) weights and cell sizes of brown adipose tissues (BAT) in the LFBE group after 10 weeks. LFBE group could gain more mass of interscapular BAT (IBAT) and promote the dehydrogenase activity in the mitochondria. And LFBE may potentiate process of the IBAT thermogenesis and epididymis adipose tissue (EAT) browning via activating the uncoupling protein 1 (UCP1)-dependent mechanism to suppress the obesity.@*CONCLUSION@#These results demonstrated that LFBE decreased obesity partly by increasing the BAT mass and the energy expenditure by activating BAT thermogenesis and WAT browning in a UCP1-dependent mechanism.

Time-sequential expression of lnc AK079912 during adipose tissue development and browning in mice / 南方医科大学学报

OBJECTIVE@#To investigate the time-sequential expression of a novel long non-coding RNA, lnc AK079912, in metabolically related tissues and during adipose tissue development and browning in mice.@*METHODS@#The interscapular brown adipose tissue (iBAT), subcutaneous white adipose tissue (sWAT), epididymal white adipose tissue (eWAT), liver tissues and muscular tissues were collected from 8-week-old C57BL/6J mice. The iBAT, sWAT and eWAT were also collected from the mice during development (0 day, 21 days, 8 weeks and 6 months after birth) and from 8- to 10-week- mice with cold exposure (4 ℃) and intraperitoneal injections of CL316, 243 (1 μg/g body weight) for 1 to 5 days. Trizol was used to extract the total RNA from the tissues, and RT-qPCR was performed to detect the expressions of lnc AK079912. Isolated mouse preadipocytes in primary culture were induced for adipogenic differentiation for 9 days and then treated with CL316, 243 (2 μmol/L) for different durations (no longer than 24 h); the expression of lnc AK079912 in the cells was detected using RT-qPCR at different time points of the treatment.@*RESULTS@#Lnc AK079912 was highly expressed in mouse adipose tissues, the highest in iBAT, followed by the muscular tissue, but was hardly detected in the liver tissue. The expression level of lnc AK079912 increased progressively in iBAT and sWAT during development of the mice, while its expression in eWAT showed an initial increase followed by a reduction at 8 weeks ( 0.05). The expression of lnc AK079912 was significantly decreased in iBAT and eWAT ( < 0.05) but increased in eWAT from mice with intraperitoneal injection of CL316, 243 for 1 to 5 days ( < 0.05). The expression level in the adipocytes in primary culture was significantly increased in response to treatment with CL316, 243 ( < 0.05).@*CONCLUSIONS@#Lnc AK079912 is highly expressed in mouse adipose tissue, and its expression gradually increases with the development of adipose tissue but with a depot-specific difference. Lnc AK079912 is significantly elevated in the early stage of adipose tissue browning, indicating its important role in the development and browning of adipose tissue.

Effects of caloric restriction on the expression of lipocalin-2 and its receptor in the brown adipose tissue of high-fat diet-fed mice

Obesity causes inflammation and impairs thermogenic functions in brown adipose tissue (BAT). The adipokine lipocalin 2 (LCN2) has been implicated in inflammation and obesity. Herein, we investigated the protective effects of caloric restriction (CR) on LCN2-mediated inflammation and oxidative stress in the BAT of high-fat diet (HFD)-fed mice. Mice were fed a HFD for 20 weeks and then either continued on the HFD or subjected to CR for the next 12 weeks. CR led to the browning of the white fat-like phenotype in HFD-fed mice. Increased expressions of LCN2 and its receptor in the BAT of HFD-fed mice were significantly attenuated by CR. Additionally, HFD+CR-fed mice had fewer neutrophils and macrophages expressing LCN2 and iron-positive cells than HFD-fed mice. Further, oxidative stress and mitochondrial fission induced by a HFD were also significantly attenuated by CR. Our findings indicate that the protective effects of CR on inflammation and oxidative stress in the BAT of obese mice may be associated with regulation of LCN2.

Effects of Genipin on the expression of uncoupling protein 1 in brown adipose and white adipose tissues in mice / 中国应用生理学杂志

OBJECTIVE@#To investigate the effects of genipin on promoting brown adipose tissue activation and white adipose tissue browning.@*METHODS@#The male C57BL/6J mice were divided into three groups: normal control group, genipin group and cold-stimulus group.Genipin group were treated consecutively with genipin at a dose of 15 mg/kg once a day for 9 days, normal control group were treated with the saline.The mice with cold-stimulus were exposed to 4℃ environment for 5 days.Daily food amount and body weight were measured.Morphological changes were observed in the subscapular region, inguinal region and epididymis around the adipose tissue.The expression of uncoupling protein 1 (UCP1) was determined by real-time PCR and Western blot respectively.@*RESULTS@#The wet weight of white fat in genipin-treated mice was decreased by 16% , and 28% in that of cold-stimulus mice, compared with the normal control group (P＜0.05).After treatments of genipin and cold-stimulus, the color of white adipose tissues was darker, and the size of lipid droplets in adipocytes was smaller, whereas the number was increased.Compared with the normal control group, UCP1 expression was increased obviously in fat tissues, including the subcutaneous and visceral white adipose tissues, and brown adipose tissue after treated with genipin and cold-stimulus (P＜0.05).@*CONCLUSION@#Genipin promoted activation of brown adipose tissue and browning of white adipose tissue by upregulating UCP1 expression, which could contribute to the loss of body weight against obesity.

Neonatal tobacco smoke reduces thermogenesis capacity in brown adipose tissue in adult rats

Maternal smoking is a risk factor for progeny obesity. We have previously shown, in a rat model of neonatal tobacco smoke exposure, a mild increase in food intake and a considerable increase in visceral adiposity in the adult offspring. Males also had secondary hyperthyroidism, while females had only higher T4. Since brown adipose tissue (BAT) hypofunction is related to obesity, here we tested the hypothesis that higher levels of thyroid hormones are not functional in BAT, suggesting a lower metabolic rate. We evaluated autonomic nerve activity in BAT and its function in adult rats that were exposed to tobacco smoke during lactation. At birth, litters were adjusted to 3 male and 3 female pups/litter. From postnatal day (PND) 3 to 21, Wistar lactating rats and their pups were divided into SE group, smoke-exposed in a cigarette smoking machine (4 times/day) and C group, exposed to filtered air. Offspring were sacrificed at PND180. Adult SE rats of both genders had lower interscapular BAT autonomic nervous system activity, with higher BAT mass but no change in morphology. BAT UCP1 and CPT1a protein levels were decreased in the SE groups of both genders. Male SE rats had lower β3-AR, TRα1, and TRβ1 expression while females showed lower PGC1α expression. BAT Dio2 mRNA and hypothalamic POMC and MC4R levels were similar between groups. Hypothalamic pAMPK level was higher in SE males and lower in SE females. Thus, neonatal cigarette smoke exposure induces lower BAT thermogenic capacity, which can be obesogenic at adulthood.

Role of brown adipose tissue in metabolic syndrome, aging, and cancer cachexia / 医学前沿

Brown adipose tissue (BAT) plays a fundamental role in maintaining body temperature by producing heat. BAT that had been know to exist only in mammals and the human neonate has received great attention for the treatment of obesity and diabetes due to its important function in energy metabolism, ever since it is recently reported that human adults have functional BAT. In addition, beige adipocytes, brown adipocytes in white adipose tissue (WAT), have also been shown to take part in whole body metabolism. Multiple lines of evidence demonstrated that transplantation or activation of BAT or/and beige adipocytes reversed obesity and improved insulin sensitivity. Furthermore, many genes involved in BATactivation and/or the recruitment of beige cells have been found, thereby providing new promising strategies for future clinical application of BAT activation to treat obesity and metabolic diseases. This review focuses on recent advances of BAT function in the metabolic aspect and the relationship between BAT and cancer cachexia, a pathological process accompanied with decreased body weight and increased energy expenditure in cancer patients. The underlying possible mechanisms to reduce BAT mass and its activity in the elderly are also discussed.

Effects and mechanism of hypoxia exposure on related genes in brown fat tissue of obese mice based on mRNA expression profile microarray / 中国应用生理学杂志

OBJECTIVE@#This study intended to screen differentially expressed genes and pathways in Brown Adipose Tissue (BAT) of obese mice after the intervention of hypoxia by mRNA expression profile microarray, exploring the mechanism of hypoxia activated BAT.@*METHODS@#Thirty C57BL/6J male mice were divided into the normal diet control group (N, =8), high-fat diet control group (OB, =8) and high-fat diet hypoxia group (H, =8). Group H was intervened by hypoxia exposure in the oxygen concentration of 11.2% of the normal oxygen and hypoxia for 8 h/d, 6 d/w of 4 weeks. Blood lipid and blood glucose were detected after intervention; RNA microarray scan and bioinformation analysis were done of BAT from scapula. Genes significantly ( ≤ 0.05) regulated more than 1.5 fold were chosen to do Gene Ontology and enrichment analysis by KOBAS 2.0, and confirmation of genes participating in key biological process (BP) and pathway was done by real time qPCR.@*RESULTS@#After intervention, the body weight and blood lipid and glucose levels in group H were significantly lower than those of group OB. Comparing with group N, 802 genes were significantly up-regulated and 1 175genes were down-regulated. The BP of these genes mainly concerned with glucose and lipid metabolic process and inflammatory reaction. Comparing with group OB, 297 genes were significantly up-regulated and 228 genes were down-regulated. These genes participated in glucose and lipid metabolic process, lipid transport, muscle system process and cardiovascular system development. The pathways of regulating BAT by hypoxia exposure mainly concentrated on the HIF-1, PI3K-AKT, FoxO and ErbB signaling pathways.@*CONCLUSIONS@#A series of genes and pathways in BAT could be adjusted by hypoxia exposure, so that hypoxia could improve the activity of BAT, promoting obese organism to lose weight.

Effect of EPO on PRDM16, FGF21 expression and STAT phosphorylation of brown adipose tissue in HFD mice / 中国应用生理学杂志

OBJECTIVE@#To investigate the effect of erythropoietin (EPO) on blood glucoseand plasma insulin level, index of insulin resistance (HOMA-IR), introperitoneal glucose tolerance test (IPGTT), the mRNA and protein level of PR domain-containing 16 (PRDM16), phosphorylated signal transducer and activator of transcription 3 (p-STAT3), fibroblast growth factor 21 (FGF21) of brown adipose tissue (BAT) in mice fed with high fat diet (HFD) in order to provide clues for the mechanism of obesity and complication.@*METHODS@#Twenty C57BL/6J male mice fed with HFD were randomly divided into control group (HFD-Con) and EPO group (HFD-EPO), mice in the two groups were injected intraperitoneally normal saline and EPO (200 IU/kg) res pectively, 3 times per week for consecutive 4 weeks.Then the body weight, blood glucose, plasma insulin level, HOMA-IR and IPGTT were detected.The mRNA and protein level of PRDM16, FGF21, p-STAT3/STAT3 in brown adipose tissue were detected by real-time quantitative RT-PCR and Western blot respectively.@*RESULTS@#After intraperitoneal injection of EPO for 4 weeks, the body weight of the mice in HFD-EPO and HFD-Con groups was (26.65±0.85) g and (31.50±1.6 0) g respectively.The blood glucose of the mice in HFD-EPO group[(62.79±8.09) mg/dl]was significantly decreased compared with that in HFD-Con group[(91.06±9.86) mg/dl].The plasmainsulin level in HFD-EPO group[(10.56±1.06)μU/ml]was significantly decreased compared with that in HFD-Con group[(13.2±1.1)μU/ml, < 0.01].The level of IPGTT in HFD-EPO group was significantly ameliorated and th e HOMA-IR decreased compared with those in HFD-Con group.The mRNA and protein expressions of PRDM16, FGF21 and the level of STAT3 of brown adipose tissue in HFD-E PO group were increased obviously.And there was no difference of FGF21 mRNA content in liver and FGF21 content in plasmabetween the two groups.@*CONCLUSIONS@#EPO could promote differentiation of brown adipose tissue by increase in the express ion of PRDM16, and decrease the blood glucose level, ameliorate glucose metabolism in obses mice.

The dark side of browning

The induction of brown-like adipocyte development in white adipose tissue (WAT) confers numerous metabolic benefits by decreasing adiposity and increasing energy expenditure. Therefore, WAT browning has gained considerable attention for its potential to reverse obesity and its associated co-morbidities. However, this perspective has been tainted by recent studies identifying the detrimental effects of inducing WAT browning. This review aims to highlight the adverse outcomes of both overactive and underactive browning activity, the harmful side effects of browning agents, as well as the molecular brake-switch system that has been proposed to regulate this process. Developing novel strategies that both sustain the metabolic improvements of WAT browning and attenuate the related adverse side effects is therefore essential for unlocking the therapeutic potential of browning agents in the treatment of metabolic diseases.

Metformin ameliorates experimental-obesity-associated autoimmune arthritis by inducing FGF21 expression and brown adipocyte differentiation

Rheumatoid arthritis (RA) is a systemic autoimmune disease involving excessive inflammation. Recently, RA associated with a metabolic disorder was revealed to be non-responsive to RA medications. Metformin has been reported to have a therapeutic effect on RA and obesity. The aim of this investigation was to study the therapeutic effect and the underlying mechanism of metformin's action in an experimental model of collagen-induced arthritis (CIA) associated with obesity. Metformin was administered daily for 13 weeks to mice with CIA that had been fed a high-fat diet. Metformin ameliorated the development of CIA in obese mice by reducing autoantibody expression and joint inflammation. Furthermore, metformin decreased the expression levels of pSTAT3 and pmTOR and had a small normalizing effect on the metabolic profile of obese CIA mice. In addition, metformin increased the production of pAMPK and FGF21. Metformin also induced the differentiation of brown adipose tissue (BAT), which led to a reciprocal balance between T helper (Th) 17 and regulatory T (Treg) cells in vitro and in vivo. These results suggest that metformin can dampen the development of CIA in obese mice and reduce metabolic dysfunction by inducing BAT differentiation. Thus, metformin could be a therapeutic candidate for non-responsive RA.