Characterization of key genes of the renin–angiotensin system in mature feline adipocytes and during in vitro adipogenesis

Obesity is a growing health problem in humans as well as companion animals. In the development and progression of obesity‐associated diseases, the members of the renin–angiotensin system (RAS) are proposed to be involved. Particularly, the prevalence of type 2 diabetes mellitus in cats has increased enormously which is often been linked to obesity as well as to RAS. So far, reports about the expression of a local RAS in cat adipocytes are missing. Therefore, we investigated the mRNA expression of various RAS genes as well as the adipocyte marker genes adiponectin, leptin and PPAR‐γ in feline adipocytes using quantitative PCR. To characterize the gene expression during adipogenesis, feline pre‐adipocytes were differentiated into adipocytes in a primary cell culture and the expression of RAS key genes measured. All major RAS components were expressed in feline cells, but obvious differences in the expression between pre‐adipocytes and the various differentiation stages were found. Interestingly, the two enzymes ACE and ACE2 showed an opposite expression course. In addition to the in vitro experiments, mature adipocytes were isolated from subcutaneous and visceral adipose tissue. Significant differences between both fat depots were found for ACE as well as AT1 receptor with greater expression in subcutaneous than in visceral adipocytes. Visceral adipocytes had significantly higher adiponectin and PPAR‐γ mRNA level compared to the subcutaneous fat cells. Concerning the nutritional status, a significant lower expression of ACE2 was measured in subcutaneous adipocytes of overweight cats. In summary, the results show the existence of a potentially functional local RAS in feline adipose tissue which is differentially regulated during adipogenesis and dependent on the fat tissue depot and nutritional status. These findings are relevant for understanding the development of obesity‐associated diseases in cats such as diabetes mellitus.     

Comparing mRNA levels of genes encoding leptin,leptin receptor,and lipoprotein lipase between dairy and beef cattle

Body weight and fat mass vary distinctly between German Holstein (dairy cattle) and Charolais (beef cattle). The aim of this study was to determine whether the expression of the obese (Ob) gene and lipoprotein lipase (LPL) gene in fat tissues and expression of the long isoform leptin receptor (Ob-Rb) gene in the hypothalamus were different between these two cattle breeds. Body weight and the area of longissimus muscle cross-section of German Holstein were lower (P<0.001), while body fat content, as well as the omental and perirenal fat mass were higher (P<0.001), compared to Charolais. Plasma insulin and leptin levels between two cattle breeds were determined by radioimmunoassay. Compared to Charolais, plasma insulin concentrations were significantly higher (P<0.01), and plasma leptin levels were tended to be higher (P<0.1) in German Holstein. Ob mRNA levels in subcutaneous and perirenal fat depots, but not in the omental fat depot, were significantly higher (P<0.05) in German Holstein than in Charolais. LPL mRNA expression in the perirenal fat depot of German Holstein was greater in abundance than that of Charolais. No significantly different LPL mRNA levels were found in subcutaneous and omental fat depots, and Ob-Rb mRNA levels in the hypothalamus between these two cattle breeds (P<0.05). Both Ob and LPL expression was greater in perirenal and omental fat depots than in the subcutaneous fat depot (P<0.05). Data indicated that in bovine the Ob and LPL gene expression levels in perirenal fats are an important index that is associated with body fat content, while Ob-Rb in hypothalamus is not.     

Effect of short-term fasting on plasma concentrations of leptin and other hormones and metabolites in dairy cattle

We determined the effects of short-term fasting and refeeding on temporal changes in plasma concentrations of leptin, insulin, insulin-like growth factor- 1 (IGF-1), growth hormone (GH), glucose, and nonesterified fatty acids (NEFA), in early lactating cows, non-lactating pregnant cows, and postpubertal heifers. In experiment 1, Holstein cows in early lactation were either fed ad libitum (Control, n=5) or feed deprived for 48 h (Fasted, n=6). Plasma leptin, insulin, and glucose concentrations rapidly declined (P<0.05) within 6h, and IGF-1 by 12h, but all these variables sharply returned to control levels (P>0.10) within 2h of refeeding. Plasma NEFA and GH concentrations were elevated (P<0.05) by 4 and 36 h of fasting and returned to control levels (P>0.10) by 8 and 24h after refeeding, respectively. In experiment 2, four ruminally cannulated pregnant non-lactating Holstein cows were used in a cross-over design and were fasted for 48 h (Fasted) or fasted with partial evacuation of rumen contents (Fasted-Evac). The plasma variables measured did not differ (P>0.10) between Fasted and Fasted-Evac cows. Plasma leptin, insulin, and IGF-1 concentrations were reduced by 10, 6, and 24h of fasting, respectively, in Fasted-Evac cows; and these variables were reduced by 24h in Fasted cows (P<0.05). Plasma glucose levels were reduced (P<0.05) by 48 h of fasting in both groups of fasted animals. Plasma NEFA and GH levels were increased (P<0.05) by 12 and 48 h of fasting, respectively. In experiment 3, postpubertal Holstein heifers were either fed ad libitum (Control, n=4) or feed deprived for 72 h (Fasted, n=5). Concentrations of leptin, insulin, IGF-1, and glucose in plasma were reduced (P<0.05) by 24, 10, 24, and 48 h of fasting, respectively. Plasma NEFA concentrations increased (P<0.05) by 4h, of fasting while GH levels were not significantly (P>0.10) affected by fasting. Collectively, our data provide evidence that plasma leptin concentrations are reduced with short-term fasting and rebound on refeeding in dairy cattle with the response dependent on the physiological state of the animals. Compared to the rapid induction of hypoleptinemia with fasting of early lactation cows, the fasting-induced hypoleptinemia was delayed in non-lactating cows and postpubertal heifers.     

Effects of selection for rapid postweaning gain on maturing patterns of fat depots in mice

Correlated responses to selection for rapid 3 to 6-wk postweaning gain in male mice were estimated for five fat depots weighed at specific degrees of maturity in body weight (37.5, 50.0, 62.5, 75, 87.5 and 100%). Fat pads measured were from regions of the subcutaneous hindlimb, subcutaneous forelimb, epididymides, mesentery and kidneys. At the same degree of maturity, selected mice (M16) were older (P less than .01) than controls (ICR). M16 had heavier (P less than .01) fat depots than ICR for all sites at each degree of maturity. From 62.5 to 100% maturity, M16 was larger than ICR in fat depot weight as a percentage of body weight at all sites. Mesenteric fat made up the largest percentage of total fat in both lines and perirenal fat the smallest percentage. Development of degree of maturity in each fat depot relative to degree of maturity in body weight was studied using the constrained quadratic and standardized allometric models. Both models showed similar trends, but the latter identified more significant line differences. The standardized allometric analysis indicated that total fat and all individual fat depots except mesenteric fat matured at a slower rate (P less than .01) in M16 than in ICR. Bivariate allometric analyses of ln fat depot weight on ln body weight showed that M16 exceeded (P less than .01) ICR in relative growth of all fat depots except mesenteric fat; at lower body weights, ICR had larger fat depots than M16, but the reverse was true at higher body weights.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mapping QTL for fat area ratios and serum leptin concentrations in a Duroc purebred population

The reduction of extra subcutaneous, intermuscular and abdominal fat is important to increase the carcass lean percentage of pigs. Image analyses of fat area ratios were effective for estimation of separated fat in pig carcasses. Serum concentrations of leptin are useful as physiological predictors of fat accumulation in pigs. The objectives of the present study were to perform a quantitative trait locus (QTL) analysis for fat area ratios and serum leptin concentrations in a Duroc purebred population. Pigs (n = 226 to 538) were measured for fat area ratios of carcass cross‐sections at the fifth to sixth thoracic vertebrae, half body length and last thoracic vertebra using an image analysis system, and serum leptin concentration. In total, animals were genotyped for 129 markers and used for QTL analysis. For fat area ratios, four significant and 12 suggestive QTLs were detected on chromosomes 1, 6, 7, 8, 9, 12 and 13. Significant QTLs were detected on the same region of chromosome 6, which was located near a leptin receptor gene. For serum leptin concentrations, two significant and two suggestive QTLs were detected on chromosomes 6, 9, and 16, and the QTLs on chromosome 6 were also in the same region for fat area ratios.     

Effect of body fat mass and nutritional status on 24-hour leptin profiles in ewes

This study was designed to determine the effect of feeding or fasting of fat or thin ewes on 24-h leptin profiles. Ewes were assigned, based on ultrasonic assessments of last-rib subcutaneous fat measurements, into fat (fat thickness > 1 cm; mean = 1.52 +/- 0.03 cm; range 1.14 to 2.18 cm) or thin (fat thickness < 1 cm; mean = 0.25 +/- 0.03 cm; range 0.03 to 0.84 cm) groups. Fat and thin ewes were then assigned to either fed or fasted (deprived of feed) groups consisting of five ewes per group. Thus, four groups existed and were designated as fat-fed, fat-fasted, thin-fed, and thin-fasted. Fed ewes had ad libitum access to feed throughout the study. Fasted ewes were prohibited access to feed beginning 48 h preceding the experiment. Plasma samples were collected for leptin analysis from ewes every 15 min for 24 h beginning 48 h after the initiation of feed restriction or the congruent interval in fed ewes. Data were subjected to CLUSTER pulse analysis procedures. Profiles of plasma concentrations of leptin were episodic in nature and did not differ in a diurnal manner. Fed ewes had greater mean concentrations of leptin, area under the curve, number of peaks, peak height, peak nadir, and a shorter interval between peaks than fasted ewes (P < or = 0.05). Fat ewes had greater mean concentrations of leptin, area under the curve, number of peaks, peak height, peak nadir, and a shorter interval between peaks than thin ewes (P < 0.02). There also was a tendency for a body condition x treatment interaction for number of peaks (P = 0.073) and interval between peaks (P = 0.056). These results provide evidence that plasma concentrations of leptin are episodic in nature and are influenced by nutritive state and fat thickness over the ribs, but display no circadian variation.     

Fat depot‐specific differences in leptin mRNA expression and its relation to adipocyte size in steers

ABSTRACT This experiment was conducted to investigate leptin mRNA expression, adipocyte size, and their relationship in several adipose tissues of fattening steers. Subcutaneous, perirenal, intermuscular and intramuscular adipose tissues were collected from three crossbred steers (Japanese Black cattle X Holstein) aged 21 months. The mRNA level and adipocyte diameter were determined in these adipose tissues. The intramuscular adipose tissue had a lower leptin mRNA level than the intermuscular and perirenal adipose tissues (P < 0.05). Leptin mRNA level was lower in the subcutaneous depot than in the intermuscular depot (P < 0.05). Adipocyte diameter was larger in the intermuscular adipose tissue than in the subcutaneous and intramuscular adipose tissues (P < 0.05). Leptin mRNA level was positively correlated with adipocyte diameter (r² = 0.81, P < 0.05). These results suggest that the cattle have fat depot‐specific differences in leptin gene expression, which are a result of a difference in adipocyte size.     

Proinflammatory Cytokine and Chemokine Gene Expression Profiles in Subcutaneous and Visceral Adipose Tissue Depots of Insulin‐Resistant and Insulin‐Sensitive Light Breed Horses

Background: Insulin resistance has been associated with risk of laminitis in horses. Genes coding for proinflammatory cytokines and chemokines are expressed more in visceral adipose tissue than in subcutaneous adipose tissue of insulin‐resistant (IR) humans and rodents. Hypothesis/Objectives: To investigate adipose depot‐specific cytokine and chemokine gene expression in horses and its relationship to insulin sensitivity (SI). Animals: Eleven light breed mares. Methods: Animals were classified as IR (SI = 0.58 ± 0.31 × 10^?4 L/min/mU; n = 5) or insulin sensitive (IS; SI = 2.59 ± 1.21 × 10^?4 L/min/mU; n = 6) based on results of a frequently sampled intravenous glucose tolerance test. Omental, retroperitoneal, and mesocolonic fat was collected by ventral midline celiotomy; incisional nuchal ligament and tail head adipose tissue biopsy specimens were collected concurrently. The expression of tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐1β, IL‐6, plasminogen activator inhibitor‐1 (PAI‐1), and monocyte chemoattractant protein‐1 (MCP‐1) in each depot was measured by real‐time quantitative polymerase chain reaction. Data were analyzed by 2‐way analysis of variance for repeated measures (P < .05). Results: No differences in TNF‐α, IL‐1β, IL‐6, PAI‐1, or MCP‐1 mRNA concentrations were noted between IR and IS groups for each depot. Concentrations of mRNA coding for IL‐1β (P= .0005) and IL‐6 (P= .004) were significantly higher in nuchal ligament adipose tissue than in other depots. Conclusions and Clinical Importance: These data suggest that the nuchal ligament depot has unique biological behavior in the horse and is more likely to adopt an inflammatory phenotype than other depots examined. Visceral fat may not contribute to the pathogenesis of obesity‐related disorders in the horse as in other species.     

The effects of metabolizable energy intake on body fat depots of adult Pelibuey ewes fed roughage diets under tropical conditions

The objective of this work was to evaluate the effect of metabolizable energy intake (MEI) on changes in fat depots of adult Pelibuey ewes fed roughage diets under tropical conditions. Eighteen 3-year-old Pelibuey ewes with similar body weight (BW) of 37.6 ± 4.0 kg and body condition score (BCS) of 2.5 ± 0.20 were randomly assigned to three groups of six ewes each in a completely randomized design. Ewes were housed in metabolic crates and fed three levels of MEI: low (L), medium (M), and high (H) for 65 days to achieve different BW and BCS. At the end of the experiment, the ewes were slaughtered. Data recorded at slaughter were: weights of viscera and carcass. Internal fat (IF, internal adipose tissue) was dissected, weighed, and grouped as pelvic (around kidneys and pelvic region), omental, and mesenteric regions. Carcass was split at the dorsal midline in two equal halves, weighed, and chilled at 6°C during 24 h. After refrigeration, the left half of the carcass was completely dissected into subcutaneous and intermuscular fat (carcass fat). Dissected carcass fat (CF) of the left carcass was adjusted as whole carcass. At low levels of MEI, proportion of IF and CF was approximately 50%; however, as the MEI was increased, the proportion of IF was increased up to 57% and 60% for M and H, respectively. Omental and pelvic fat depots were those which increased in a larger proportion with respect to the mesenteric fat depot. Regression equations between the weight of each body fat depot and BW had a coefficient of determination (r ²) that ranged between 0.37 for mesenteric fat and 0.87 for CF. The regression with BCS had a r ² that ranged between 0.57 for mesenteric and 0.71 for TBF. BW was the best predictor for TBF, CF, omental fat, and pelvic fat; whereas, BCS was better than BW in predicting IF and mesenteric fat. Inclusion of both BW and BCS in multiple regressions improved the prediction for all fat depots, except for pelvic fat, which was best estimated by BCS alone. The greater slope of the regression for the pelvic fat depot equation, relative to TBF (1.40), EBW (4.02), and BCS (2.36), suggested that pelvic fat has a greater capacity to accumulate and mobilize fat. These results indicated that adult Pelibuey ewes seem to store a considerable proportion of absorbed energy in the IF depots rather than in the carcass.     

九龙牦牛PPARγ基因的克隆及其表达谱分析

根据普通牛(Bos tarus)过氧化物酶体增殖物激活受体γ(PPARγ)基因序列设计引物,用成年九龙牦牛(Bos grunniens)脂肪组织总RNA,经RT-PCR扩增获得了PPARγ基因序列(GenBank登陆号:GU061328),其中cDNA的ORF为1 428 bp,编码475个氨基酸,与普通牛PPARγ氨基酸的同源性达99%,有2个氨基酸发生突变。利用半定量RT-PCR分析九龙牦牛PPARγ基因的mRNA表达特性。结果表明:在脂肪、背最长肌、心、肝、肾、脾和肺脏中均检测到PPARγ基因的表达,并且在脂肪组织中表达量极显著高于其他组织(P0.01),在肝脏和脾脏中亦有较高表达。PPARγ基因在背最长肌中的表达5.5岁九龙牦牛显著高于0.5、3.5岁和9岁以上,其表达与背最长肌的肌内脂肪含量未见显著相关性。     

Development and evaluation of empirical equations to interconvert between twelfth-rib fat and kidney, pelvic, and heart fat respective fat weights and to predict initial conditions of fat deposition models for beef cattle

The Davis growth model (DGM) simulates growth and body composition of beef cattle and predicts development of 4 fat depots. Model development and evaluation require quantitative data on fat weights, but sometimes it is necessary to use carcass data that are more commonly reported. Regression equations were developed based on published data to interconvert between carcass characteristics and kilograms of fat in various depots and to predict the initial conditions for the DGM. Equations include those evaluating the relationship between the following: subcutaneous fat (SUB, kg) and 12th-rib fat thickness (mm); visceral fat (VIS, kg) and KPH (kg); DNA (g) in intermuscular, intramuscular, subcutaneous, and visceral fat depots and empty body weight; and contributions of fat (kg) in intramuscular (INTRA), SUB, and VIS fat depots and total body fat (kg). The intermuscular fat (INTER, kg) contribution was found by difference. The linear regression equations were as follows: SUB vs. 12th-rib fat thickness (n = 75; P < 0.01) with R(2) = 0.88 and SE = 10.00; VIS vs. KPH (kg; n = 78; P < 0.01) with R(2) = 0.95 and SE = 2.82; the DNA (g) equations for INTER, INTRA, SUB, and VIS fat depots vs. empty body weight (n = 6, 5, 6, and 6; P = 0.08, P < 0.01, P < 0.01, and P = 0.05) with R(2) = 0.57, 0.93, 0.93, and 0.66, and SE = 0.03, 0.003, 0.02, and 0.03, respectively; and initial contribution of INTRA, SUB, and VIS fat depots vs. total body fat (n = 23; P < 0.01) for each depot, with R(2) = 0.97, 0.99, and 0.97, and SE = 0.61, 0.93, and 1.41, respectively. All empirical equations except for DNA were challenged with independent data sets (n = 12 and 10 for SUB and VIS equations and n = 9 for the initial INTER, INTRA, SUB, and VIS fat depots). The mean biases were -2.21 (P = 0.12) and 2.11 (P < 0.01) kg for the SUB and VIS equations, respectively, and 0.05 (P = 0.97), -0.37 (P = 0.27), 1.82 (P = 0.08), and -1.50 (P = 0.06) kg for the initial contributions of INTER, INTRA, SUB, and VIS fat depots, respectively. The random components of the mean square error of prediction were 73 and 26% for the SUB and VIS equations, respectively, and similarly were 99, 85, 62, and 61% for the initial contributions of INTER, INTRA, SUB, and VIS fat depots, respectively. Both the SUB and VIS equations predicted accurately within the bounds of experimental error. The equations to predict initial fat contribution (kg) were considered adequate for initializing the fat depot differential equations for the DGM and other beef cattle simulation models.     

Adipose tissue capillary blood flow in relation to fatness in sheep

Capillary blood flow rate was measured in eight fat depots in eight Blackface and eight Clun lambs using the radiolabelled microsphere technique. Adipose tissue flow ranged from 3 to 47 ml 100 g-1 min-1 depending upon depot and degree of fatness. Blood flow declined with increasing fatness suggesting that perfusion was not an important constraint on the growth of fat. Blood flow rates were also measured in the fed and 26 hour fasted states but no effect from fasting was observed.     

Effect of chicken egg yolk antibody against adipose tissue plasma membranes on carcass composition and lipogenic hormones and enzymes in pigs

Chicken egg yolk antibody against pig adipose tissue plasma membranes (AIgY) was raised and used in the present experiment to evaluate the effect of dietary AIgY supplementation on pig growth and carcass composition. 160 crossbred (Duroc–Jersey × Landrace·Meishan) pigs, with initial live body weight of 27.5 ± 2.4 kg, were treated with AIgY or non-immunized control egg yolk powder (NIgY) at the inclusion level of 75 mg/kg diet. Following a 104-day trial, the pigs were slaughtered for analyzing the carcass and meat quality traits. The perirenal, mesenteric and subcutaneous fat depots were weighed and the diameter of adipocytes from different fat depots was measured with histological methods. Serum concentrations of insulin and leptin as well as the activities of malic enzyme (ME) and lipoprotein lipase (LPL) in adipose tissue were measured. Dietary supplementation of AIgY enhanced average daily gain and feed efficiency by 13.03% (P < 0.01) and 7.49%, respectively, with no influence on feed consumption. AIgY increased the lean mass by 10.3% (P < 0.01) without affecting the dressing percentage. Backfat thickness at 6th–7th rib and the weights of perirenal, mesenteric and subcutaneous fat depots were reduced by 24.14% (P < 0.01), 27.27% (P < 0.05), 20.42% (P < 0.01) and 29.21% (P < 0.01), respectively. Dietary supplementation of AIgY reduced the size of adipocytes in all the three fat pads (P < 0.05). The meat color was improved whereas the marbling score, the intramuscular fat content, and pH₄₅ of the longissimus muscle remained unaffected. Serum concentration of non-esterified fatty acids (NEFA) was significantly increased (P < 0.01) while urea-N content was reduced (P < 0.05). No alterations were detected for the serum levels of triacylglycerides (TG) and glucose. Serum concentrations of insulin and leptin were decreased by 26.19% (P < 0.05) and 26.53% (P < 0.05), respectively. LPL activity in adipose tissue was depressed significantly (P < 0.05) without affecting ME activity. This study demonstrates that dietary supplementation of AIgY can effectively improve growth and carcass composition of pigs and the changes of serum insulin and leptin levels as well as the tissue LPL activity may be involved in the acting mechanism.     

Patterns of gene expression in pig adipose tissue: insulin-like growth factor system proteins, neuropeptide Y (NPY), NPY receptors, neurotrophic factors and other secreted factors

Although cDNA microarray studies have examined gene expression in human and rodent adipose tissue, only one microarray study of adipose tissue from growing pigs has been reported. Total RNA was collected at slaughter from outer subcutaneous adipose tissue (OSQ) and middle subcutaneous adipose tissue (MSQ) from gilts at 90, 150, and 210 d (n=5 age(-1)). Dye labeled cDNA probes were hybridized to custom porcine microarrays (70-mer oligonucleotides). Gene expression of insulin-like growth factor binding proteins (IGFBPs), hormones, growth factors, neuropeptide Y (NPY) receptors (NPYRs) and other receptors in OSQ and MSQ changed little with age in growing pigs. Distinct patterns of relative gene expression were evident within NPYR and IGFBP family members in adipose tissue from growing pigs. Relative gene expression levels of NPY2R, NPY4R and angiopoietin 2 (ANG-2) distinguished OSQ and MSQ depots in growing pigs. We demonstrated, for the first time, the expression of IGFBP-7, IGFBP-5, NPY1R, NPY2R, NPY, connective tissue growth factor (CTGF), brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF) genes in pig adipose tissue with microarray and RT-PCR assays. Furthermore, adipose tissue CTGF gene expression was upregulated while NPY and NPY2R gene expression were significantly down regulated by age. These studies demonstrate that expression of neuropeptides and neurotrophic factors in pig adipose tissue may be involved in regulation of leptin secretion. Many other regulatory factors were not influenced by age in growing pigs but may be influenced by location or depot.     

ORIGINAL ARTICLE: mRNA abundance of adiponectin and its receptors,leptin and visfatin and of G‐protein coupled receptor 41 in five different fat depots from sheep

Adipose tissue (AT) expresses adipokines, which are involved in the regulation of energy expenditure, lipid metabolism and insulin sensitivity. Visceral (v.c.) and subcutaneous (s.c.) depots largely differ concerning their metabolic characteristics as to the control of lipolysis and the sensitivity to insulin. The adipokines adiponectin, leptin and visfatin influence lipolysis and insulin sensitivity. Signalling by G‐protein coupled receptor 41 (GPR 41) stimulates leptin release via activation by short‐chain fatty acids. We hypothesized that the metabolic differences between v.c. and s.c. fat depots may also apply to the expression of adiponectin, its receptors, leptin, visfatin, insulin receptor (IR) and GPR 41. Therefore, we aimed to compare the mRNA expression of adiponectin, leptin and visfatin, of the adiponectin receptors 1 and 2 (AdipoR1/2) and IR as well of GPR 41 between several s.c. and v.c. fat depots in sheep. Samples from 10 rams were collected at slaughter (40 kg BW) from three s.c. depots, i.e. close to sternum (s.c.S), close to withers (s.c.W), and at the base of tail (s.c.T), and from two v.c. depots, i.e. from perirenal (v.c.P) and omental (v.c.O) fat. The mRNAs of both adiponectin receptors, as well as IR and putative GPR 41, were higher expressed in v.c. fat than in s.c. fat (p ≤ 0.05). Leptin mRNA abundance was greater in s.c. than in v.c. fat (mean ± SEM: s.c.: 2.55 ± 0.81; v.c.: 0.66 ± 0.21) and also differed among the five separately measured fat depots. Our results show differences in mRNA abundance for leptin, AdipoR1 and R2, as well as for IR and GPR 41 in s.c. compared with v.c. fat, thus confirming the need for individual consideration of distinct fat depots, when aiming to characterize adipose functions in ruminants.     

Leptin mRNA expression and serum leptin concentrations as influenced by age, weight, and estradiol in pigs

Two experiments (EXP) were conducted to determine the roles of age, weight and estradiol (E) treatment on serum leptin concentrations and leptin gene expression. In EXP I, jugular blood samples were collected from gilts at 42 to 49 (n = 8), 105 to 112 (n = 8) and 140 to 154 (n = 8) d of age. Serum leptin concentrations increased (P < 0.05) with age and averaged 0.66, 2.7, and 3.0 ng/ml (pooled SE 0.21) for the 42- to 49-, 105- to 112-, and 140- to 154-d-old gilts, respectively. In EXP II, RNase protection assays were used to assess leptin mRNA in adipose tissue of ovariectomized gilts at 90 (n = 12), 150 (n = 11) or 210 (n = 12) d of age. Six pigs from each age group received estradiol (E) osmotic pump implants and the remaining animals received vehicle control implants (C; Day 0). On Day 7, back fat and blood samples were collected. Estradiol treatment resulted in greater (P < 0.05) serum E levels in E (9 +/- 1 pg/ml) than C (3 +/- 1 pg/ml) pigs. Serum leptin concentrations were not affected by age, nor E treatment. Leptin mRNA expression was not increased by age in C pigs nor by F in 90- and 150-d-old pigs. However, by 210 d of age, leptin mRNA expression was 2.5-fold greater (P < 0.01) in E-treated pigs compared to C animals. Serum insulin concentrations were similar between treatments for 210-d-old pigs. However, insulin concentrations were greater (P < 0.05) in E than C pigs at 90 d and greater in C than E animals at 150 d. Plasma glucose and serum insulin-like growth factor-I concentrations were not influenced by treatment. These results demonstrate that serum leptin concentrations increased with age and E-induced leptin mRNA expression is age- and weight-dependent.     

Adipogenic gene expression and fatty acid composition in subcutaneous adipose tissue depots of Angus steers between 9 and 16 months of age

We have demonstrated that among carcass adipose tissue depots, brisket subcutaneous adipose tissue contains the greatest concentration of MUFA and lowest concentration of SFA. Therefore, we hypothesized that brisket subcutaneous adipose tissue depots would exhibit greater adipogenic gene expression over time than other major subcutaneous adipose tissue depots. Four Angus steers, each at 9, 12, 14, and 16 mo of age, were harvested and fresh subcutaneous adipose tissue samples were collected from over the brisket, chuck, rib, loin, sirloin, round, flank, and plate. Relative gene expression for C/EBPβ, PPARγ, carnitine palmitoyltransferase-1 beta (CPT-1β), stearoyl-coenzyme A desaturase (SCD), AMP-activated protein kinase alpha (AMPKα), and G-coupled protein receptor 43 (GPR43) was analyzed by quantitative real-time PCR. Expression of C/EBPβ, PPARγ, and CPT-1β was greatest at 12 to 14 mo of age (all P < 0.0001) and declined to very low abundance by 16 mo of age in all depots. Expression of PPARγ and CPT-1β was greater (P < 0.03) in flank, rib, and sirloin subcutaneous adipose tissues than in brisket and round adipose tissues. The expression of the SCD gene did not differ among the 4 age groups (P = 0.95). The palmitoleic:stearic acid ratio (an estimate of SCD activity) was greater (P < 0.001) in the subcutaneous adipose tissues from brisket, plate, and round than in the loin, rib, and sirloin. Conversely, subcutaneous adipose tissue from the loin, rib, and sirloin had greater (P < 0.001) SCD gene expression than the brisket, plate, and round. In general, subcutaneous adipose tissues with the highest concentration of MUFA and least SFA consistently exhibited the least SCD gene expression and adipogenic gene expression. We conclude that MUFA in the brisket and other depots with large SCD indices were deposited before 9 mo of age, during a time when the subcutaneous adipocytes were highly differentiated.     

Molecular and histological evidence of brown adipose tissue in adult cats

Brown adipose tissue (BAT) can influence glucose, lipid, and energy metabolism in rodents. Active BAT is now known to be present in adult humans, and interventions targeting BAT are being investigated for the treatment of human obesity and disorders of glucose and lipid metabolism. Domestic cats, like humans, are at increasing risk for obesity and diabetes but little is known about the presence and role of BAT in adult cats. The purpose of this study was to determine if brown adipocytes, identifiable by histological features and molecular markers, were present in the fat depots of adult cats. Adipose tissue samples from intrascapular, perirenal, and subcutaneous depots of eleven 8–12 year old cats (6 lean, 5 obese), were analyzed by real-time PCR for brown adipocyte markers uncoupling protein 1 (UCP1) and Type II iodothyronine 5′deiodinase (D2), by histological examination and by immunohistochemistry for UCP1.UCP1 mRNA was detectable in interscapular and subcutaneous depots in all cats, and in the perirenal depot in 10/11 cats. D2 mRNA was detectable in all depots from all cats. Multilocular adipocytes were identified in the interscapular depots of 4/11 cats and these were positive for UCP1 immunoreactivity. The results demonstrate that UCP1-expressing brown adipocytes are present in multiple depots of adult lean and long-term obese cats, even at 8–12 years of age. It is possible that dietary components or pharmacological agents that influence brown fat activity could exert a relevant biological effect in cats.     

Expression of adiponectin and its receptors in swine

Adiponectin is an adipocyte-derived hormone that plays an important role in lipid metabolism and glucose homeostasis. Objectives of this study were 1) to determine the presence and distribution of adiponectin and its receptors 1 and 2 (adipoR1 and adipoR2) in porcine tissues; 2) to characterize pig adiponectin, adipoR1, and adipoR2 mRNA levels in various fat depots from three different breeds of pigs; and 3) to study, in stromal-vascular cell culture, the effects of leptin and tumor necrosis factor-alpha (TNFalpha) on pig adiponectin, adipoR1, and adipoR2 gene expression. To this end, fat Chinese Upton Meishan (UM, n = 10), lean Ham Line (HL, n = 10), and Large White (LW, n = 10) gilts were used. We report the isolation of partial cDNA sequences of pig adipoR1 and adipoR2. Porcine-deduced AA sequences share 97 to 100% homology with human and murine sequences. Pig adipoR1 mRNA is abundant in skeletal muscle, visceral fat, and s.c. fat tissues, whereas adipoR2 mRNA is predominantly expressed in liver, heart, skeletal muscle, and visceral and s.c. fat tissues. Pig adiponectin mRNA levels in s.c. and visceral fat tissues were not associated with plasma insulin and glucose in fasting animals. Subcutaneous (r = -0.44, P < 0.05), visceral (r = -0.43, P < 0.05), and total body fat (r = -0.42, P < 0.05) weights were negatively correlated with adiponectin mRNA levels measured in visceral, but not s.c., fat. Pig adipoR1 and adipoR2 mRNA levels, in visceral fat, were less expressed in fat UM gilts than in the lean HL gilts (P < 0.05). Inverse associations were found between s.c. (r = -0.57, P < 0.01), visceral (r = -0.46, P < 0.05), and total body fat (r = -0.56, P < 0.01) weights and adipoR2 mRNA levels in visceral fat only. We were unable to find such associations for adipoR1 mRNA levels in the overall gilt population. The current study demonstrated that TNFalpha downregulates adiponectin and adipoR2, but not adi-poR1, mRNA levels in stromal-vascular cell culture. Moreover, leptin significantly decreased adiponectin mRNA levels, whereas there was no effect on adiponectin receptors. We conclude that adiponectin and adi-poR2 mRNA levels, but not adipoR1, are modulated in pig visceral fat tissues. Furthermore, our results indicate that TNFalpha interferes with adiponectin function by downregulation of adipoR2 but not of adipoR1 mRNA levels in pigs.