Fasting and sampling time affect liver gene expression of high-fat diet-fed mice

Several physiological and biological variables are known to affect peroxisome proliferator-activated receptor (PPAR)-α-dependent signaling pathway and plasma biochemical profiles. However, less is known about the effect of these variables on high-fat diet-fed mice. In a 5-week study, C57BL/6 mice were divided into control (C) and high-fat diet-fed (H) groups, whereby before dissection, each group was subdivided into non-fasted (nC and nH) and a 15-h fasted mice (fC and fH) killed in the early light cycle, and a 15-h fasted mice (eC and eH) killed in the late phase of the light cycle. Liver and blood from the vena cava were collected. Non-fasted nC and nH mice have a marginal difference in their body weight gain, whereas significant differences were found for fasted mice. In nH mice, PPAR-α, acyl-CoA oxidase and insulin-like growth factor-binding protein expressions were significantly elevated, in contrast to fatty acid synthase (Fasn), stearoyl CoA-desaturase (SCD)-1, and elongase (ELOVL)-6 expressions. Fasn was profoundly induced in fH mice, while decreased sterol regulatory-binding protein-1 and SCD-1 were found only in eH mice. Different from the gene expression profiles, plasma total cholesterol level of the eH mice was higher than controls, whereas nH mice have increased plasma non-esterified fatty acids. Only glucose level of the fH mice was higher than that observed for controls. Results showed that fasting and sampling time have significantly affected liver gene expression and plasma biochemical indices of the high-fat diet-treated mice. An overlook in these aspects can cause serious discrepancies in the experimental data and their interpretations.     

Combined effect of high-fat diet and copper deficiency during gestation on fetal copper status in the rat

We have previously shown that a low-copper (Cu) diet produced alterations in placental Cu transport and fetal Cu stores. Because Cu deficiency has been associated with lipid deposition in rat dam liver, we hypothesized that a high fat intake, a prevalent dietary habit in many populations, may worsen fetal Cu status and its closely linked iron (Fe) deposits. Pregnant rats were fed one of four diets during the second half of gestation: NFNCu: normal fat (7%), normal Cu (6 mg/kg); HFNCu: high fat (21%), normal Cu; NFLCu: normal fat, low Cu (0.6 mg/kg), and HFLCu: high fat, low Cu. One day before delivery, dams were anesthetized, and maternal as well as fetal plasma and tissues were obtained. Maternal, fetal, and placental weights were indistinguishable regardless of the group. Dam plasma Cu and placental Cu were lower in both LCu groups than in the NFNCu or the HFNCu groups. However, fetal plasma Cu was similar in all treatment groups. Dam and fetal liver Cu stores were reduced in the LCu groups compared to the NCu groups. This resulted in lower fetal/maternal liver Cu ratios in the NFLCu (1.79 ± 0.14,p < 0.05) and HFLCu (1.59 ± 0.21,p < 0.05) as compared to the NFNCu (4.12 ± 0.44) and the HFNCu (4.15 ± 0.27). Dam liver Fe was higher in the NFNCu than in HFNCu group (1.10 ± 0.8 vs. 0.89 ± 0.06 μmol/g,p < 0.05); fetal liver Fe from HFNCu and NFLCu dams was lower than that from NFNCu fetuses (NFNCu: 2.42 ± 0.14; HFNCu: 1.92 ± 0.15,p < 0.05; NFLCu: 1.81 ± 0.10,p < 0.01). Fetuses of the HFLCu group had a lower heart Fe than the NFNCu group (0.56 ± 0.03 vs. 44.0 ± 3.0 μg/g,p < 0.01). These data indicate that a maternal high-fat diet can potentially aggravate the effects of Cu deficiency by further altering fetal Cu and Fe tissue stores.     

The effects of boron-supplemented diets on adipogenesis-related gene expressions,anti-inflammatory,and antioxidative response in high-fat fed rats

The fatty liver syndrome caused by nutritional factors is a common cause of hepatic dysfunction globally. This research was designed to study the shielding effect of boron in rats fed a diet having high fat. Overall, 40 Wistar albino male rats were placed into one control and four treatment groups, that is, each having eight rats. Group I was provided with a standard rat diet while group II was only provided a high-fat diet for 60 days. Groups III, IV, and V were provided with 5, 10, and 20 mg/kg/day boron, respectively, by gastric gavage besides a high-fat diet for 60 days. Malondialdehyde was increased significantly in rats' blood and tissue because of high-fat diets. Glutathione was decreased significantly in blood and tissues because of a high-fat diet. Moreover, the activities of superoxide dismutase (SOD) and catalase (CAT) were decreased in the blood and tissues of the high-fat-fed rats. The genes expression for C-reactive protein, interleukin-1β, leptin, and tumor necrosis factor-α were increased while gene expression for peroxisome proliferator-activated receptors was decreased in the liver of rats fed with a high-fat diet. Contrariwise, boron supplementation improves antioxidative response in terms of increased SOD and CAT activities, gene expression regulation, and improved anti-inflammatory activities. In a nutshell, boron has dose-dependent shielding antioxidative and tissue regenerative effects in rats.     

A high-fat diet and high-fat and high-cholesterol diet may affect glucose and lipid metabolism differentially through gut microbiota in mice

This study was conducted to investigate the effects of a high-fat diet (HFD) and high-fat and high-cholesterol diet (HFHCD) on glucose and lipid metabolism and on the intestinal microbiota of the host animal. A total of 30 four-week-old female C57BL/6 mice were randomly divided into three groups (n=10) and fed with a normal diet (ND), HFD, or HFHCD for 12 weeks, respectively. The HFD significantly increased body weight and visceral adipose accumulation and partly lowered oral glucose tolerance compared with the ND and HFHCD. The HFHCD increased liver weight, liver fat infiltration, liver triglycerides, and liver total cholesterol compared with the ND and HFD. Moreover, it increased serum high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol compared with the ND and HFD and upregulated alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase significantly. The HFHCD also significantly decreased the α-diversity of the fecal bacteria of the mice, to a greater extent than the HFD. The composition of fecal bacteria among the three groups was apparently different. Compared with the HFHCD-fed mice, the HFD-fed mice had more Oscillospira, Odoribacter, Bacteroides, and [Prevotella], but less [Ruminococcus] and Akkermansia. Cecal short-chain fatty acids were significantly decreased after the mice were fed the HFD or HFHCD for 12 weeks. Our findings indicate that an HFD and HFHCD can alter the glucose and lipid metabolism of the host animal differentially; modifications of intestinal microbiota and their metabolites may be an important underlying mechanism.     

The effect of high-fat diet and inhibition of ceramide production on insulin action in liver

Liver, as one of the most important organs involved in lipids and glucose metabolism, is perceived as a key tissue for pharmacotherapy of insulin resistance (IRes) and type 2 diabetes. Ceramides (Cer) are biologically active lipids, which accumulation is associated with the induction of muscle IRes. We sought to determine the role of intrahepatic bioactive lipids production on insulin action in liver of insulin-resistant rats and after myriocin administration. The experiments were conducted on male Wistar rats divided into three groups: Control, fed high-fat diet (HFD), and fed HFD and treated with myriocin (HFD/Myr). Before sacrifice, the animals were infused with a [U-¹³C]palmitate to calculate lipid synthesis rate by means of tracer incorporation technique in particular lipid groups. Liver Cer, diacylglycerols (DAG), acyl-carnitine concentration, and isotopic enrichment were analyzed by LC/MS/MS. Proteins involved in lipid metabolism and insulin pathway were analyzed by western blot analysis. An OGTT and ITT was also performed. HFD-induced IRes and increased both the synthesis rate and the content of DAG and Cer, which was accompanied by inhibition of an insulin pathway. Interestingly, myriocin treatment reduced synthesis rate not only of Cer but also DAG and improved insulin sensitivity. We conclude that the insulin-sensitizing action of myriocin in the liver is a result of the lack of inhibitory effect of lipids on the insulin pathway, due to the reduction of their synthesis rate. This is the first study showing how the synthesis rate of individual lipid groups in liver changes after myriocin administration.     

Modulation of lipid homeostasis in response to continuous or intermittent high-fat diet in pigs

A high-fat diet is known to induce atherosclerosis in animal models. Dietary factors and timing of atherogenic food delivery may affect plasma lipoprotein content composition and its potential atherogenic effect. Increasingly often, humans spend periods/days eating in a completely unregulated way, ingesting excessive amounts of food rich in oils and fats, alternating with periods/days when food intake is more or less correct. We investigate the effect on lipid homeostasis of a high-fat diet administered either continuously or intermittently. We investigated control pigs receiving standard diet (C, n=7), pigs receiving a high-fat diet every day for 10 weeks (CHF, n=5), and pigs receiving a high-fat diet every other week for 10 weeks (IHF, n=7). IHF animals were shown to have a different lipid profile compared with CHF animals, with a significant increase in high-density lipoproteins (HDL) levels with respect to C and CHF groups. CHF also showed significantly higher values of TC/HDL cholesterol compared with C and IHF. Hepatic expression analysis of genes involved in lipid homeostasis showed an increasing trend of nuclear receptor LXRα along with its target genes in the CHF group and in the IHF group, whereas SREBP2 and LDLr were significantly inhibited. A significant correlation was found between ABCA1 expression and circulating levels of HDL-C. Periodic withdrawals of a high-fat atherogenic diet compared with a regular administration results in a different adaptive response of lipoprotein metabolism, which leads to a significantly higher plasma level of HDL-C and lower TC/HDL-C.     

SD大鼠皮肤组织病理学观察

目的观察不同日龄SD大鼠皮肤组织学结构。方法10％甲醛固定,行石蜡切片,HE染色。结果新生大鼠皮肤较薄,透明层缺乏,皮脂腺发育良好。6月龄时表皮、真皮和皮下组织明显增厚,毛囊增粗,生长旺盛,毛囊深入皮下脂肪层。24月龄时,大鼠皮脂腺及汗腺萎缩,表皮变薄,真皮成纤维细胞、血管数量减少,弹力纤维变细。结论不同日龄SD大鼠皮肤组织学结构有差异。     

有氧运动联合黑果枸杞对高脂膳食大鼠心肌脂代谢某些指标的影响

目的:研究有氧运动联合黑果枸杞对高脂膳食大鼠心肌脂代谢某些指标的影响。方法:55只雄性Wistar大鼠经过适应性饲养4 d后进行20 min/d的无负重游泳训练,连续3 d,筛选淘汰5只不适应游泳训练的大鼠后,按体重以数字随机分组法分为5组:普通膳食+安静组(RDC组)、高脂膳食+安静组(HDC组)、高脂膳食+黑果枸杞+安静组(HDLC组)、高脂膳食+有氧运动组(HDM组)、高脂膳食+黑果枸杞+有氧运动组(HDLM),每组10只。HDM组和HDLM组进行6周每周6次60 min/d的无负重游泳训练。RDC组大鼠以普通饲料常规喂养;其余各组以高脂饲料喂养; HDLC组和HDLM组大鼠灌胃黑果枸杞,灌胃剂量为4.48 g/(kg·d),灌胃体积为5 ml/kg,其余各组灌胃等量蒸馏水。6周后,测定大鼠Lee’s指数,取血、心肌检测相关生化指标。结果:与RDC组比较,HDC组Lee’s指数,血清FFA、TNF-α、IL-6、TC、TG、LDL-C,心肌FFA、ICAM-1显著升高(P<0.01);血清HDL-C水平显著降低(P<0.01)。与HDC组比较,HDLC、HDM、HDL...     

HFD对不同性别SD大鼠肠道菌群及室旁核小胶质细胞激活的影响

【目的】通过建立雌、雄性SD (Sprague-Dawley)大鼠模型,研究高脂饮食(high fat diet,HFD)对不同性别大鼠肠道菌群及室旁核(hypothalamic paraventricular nucleus,PVN)区小胶质细胞激活的影响。【方法】选取24只3周龄的SD大鼠,雌雄各半,随机分成雄性对照组(CM)、雌性对照组(CF),雄性高脂组(HM)、雌性高脂组(HF),共4组,每组6只。喂养至10周龄,收集大鼠新鲜粪便并提取细菌总基因组DNA,通过PCR扩增16SrDNA的V3+V4区域,进行高通量测序;采用气相色谱法分析大鼠盲肠内容物中短链脂肪酸(short chain fatty acids,SCFAs)含量;以real-time PCR技术分析PVN区小胶质细胞激活标记物CD11b和炎性细胞因子TNF-α、IL-6的m RNA相对表达水平。【结果】雌、雄高脂组分别与对照组相比,HM组大鼠肠道菌群总数及菌群多样性明显减少(P<0.05),HF组大鼠肠道菌群丰度明显减少(P<0.05)。与CM组相比,HM组大鼠盲肠中乙酸含量显著下降(P<0.0...     

高脂饮食对雄性SD大鼠肠道菌群的影响

目的探讨通过膳食饲喂高脂饲料诱发的高脂血症大鼠肠道菌群结构的变化。方法 24只SD（Spra-gue Dawley,SD）雄性大鼠随机分为A、B两组,分别连续饲喂基础饲料和高脂饲料42 d,并于第0、9、18、30和42天采集大鼠粪便,应用DGGE（Denaturing gradient gel electrophoresis）和q-PCR技术对肠道菌群进行定性定量分析。结果第42天时A、B组大鼠血清总胆固醇值（TC）分别为（2.01±0.14）mmol/L、（5.16±0.22）mmol/L,B组TC水平较A组明显增高（P〈0.05）。DGGE电泳图谱显示B组42 d时肠道菌群构成较0 d时变化显著,而A组不同时期肠道菌落构成无明显差异。q-PCR定量结果显示,随着饲喂高脂饲料天数的增加,B组小鼠肠道内乳杆菌属和双歧杆菌属较0 d明显降低（P〈0.01）,而拟杆菌门数量呈递减趋势且趋势比较平缓;梭菌属呈递增趋势且增幅相对拟杆菌门的变化较大。结论高脂饮食可导致肠道菌群结构的改变,这种改变会进一步促进高脂血症的形成。     

Low concentration of ethanol favors progenitor cell differentiation and neovascularization in high-fat diet-fed mice model

Endothelial progenitor cells (EPCs) and monocytic cells from bone marrow (BM) can be recruited to the injured endothelium and contribute to its regeneration. During metabolic diseases such as obesity and diabetes, progenitor cell function is impaired. Several studies have shown that moderate alcohol consumption prevents the development and progression of atherosclerosis in a variety of animal/mouse models and increases mobilization of progenitor cells. Along with these studies, we identify ethanol at low concentration as therapeutic tool to in vitro expand progenitor cells in order to obtain an adequate number of cells for their use in the treatment of cardiovascular diseases.We evaluated the effects of ethanol on the phenotype of BM-derived cells from mice fed with high-fat diet (HFD). HFD did not induce changes in weight of mice but induced metabolic alterations. HFD feeding increased the differentiation of monocytic progenitors but not EPCs. Whereas ethanol at 0.6% is able to increase monocytic progenitor differentiation, 1% ethanol diminished it. Furthermore, ethanol at 0.6% increased the ability of progenitor cells to promote in vivo angiogenesis as well as secretome of BM-derived cells from mice fed with HFD, but not in mice fed normal diet. In conclusion, ethanol at low concentration is able to increase angiogenic abilities of progenitor cells from animals with early metabolic alterations.     

有氧运动联合破壁蛋白核小球藻对高脂膳食大鼠脂代谢某些指标的影响

目的：研究有氧运动联合破壁蛋白核小球藻对高脂膳食大鼠脂代谢某些指标的影响。方法：55只雄性Wistar大鼠经过适应性饲养4 d后进行3 d、20 min/d的无负重游泳训练,筛选淘汰5只不适应游泳训练的大鼠后,按体重以数字随机分组法分为5组：普通膳食+安静对照组（C组）、高脂膳食+安静对照组（H组）、高脂膳食+小球藻+安静对照组（HC组）、高脂膳食+有氧运动组（HM组）、高脂膳食+有氧运动+小球藻组（HMC）,每组10只。HM组和HMC组进行6周每周6次60 min/d的无负重游泳训练。C组大鼠以普通饲料常规喂养;其余各组以高脂饲料喂养;HC组和HMC组大鼠灌胃破壁小球藻1次,灌胃剂量为3.9 g/（kg·d）,灌胃体积为5 ml/kg,其余各组ig等量生理盐水。6周后,测定大鼠Lee’s指数,取血、肝脏检测相关生化指标。结果：与C组比较,H组Lee’s指数,血清FFA、IL-6、TNF-α、TC、TG、LDL-c,肝脏FFA、IL-10显著升高（P<0.01）;血清HDL-c水平显著降低（P< 0.01）。与H组比较,HC、HM、HMC组Lee’s指数,血清FFA、IL-6、TNF-α、TC、TG、LDL-c,肝脏FFA、IL-10显著降低（P<0.05或P<0.01）;血清HDL-c水平显著升高（P<0.05或P<0.01）。与HC、HM组比较,HMC组Lee’s指数,血清FFA、IL-6、TNF-α、TC、TG、LDL-c,肝脏FFA、IL-10显著降低（P<0.05）;血清HDL-c水平显著升高（P<0.05）。结论：有氧运动和破壁蛋白核小球藻干预能够不同程度改善高脂膳食大鼠脂代谢,降低肥胖对肝脏造成的脂毒性。其中联合干预较单一干预更为有效。     

2型糖尿病伴发高血压大鼠模型的建立

目的：建立一种2型糖尿病伴发高血压大鼠的模型。方法：65只SD雄性大鼠,随机分为正常对照组、1% NaCl饮水组、20 mg/kg STZ-1% NaCl组、30 mg/kg STZ-1% NaCl组、40 mg/kg STZ-1% NaCl组（n=13）。除正常对照组大鼠普通饮食喂养外,其余各组大鼠以高脂饲料4周+普通饲料结合1% NaCl饮水9周喂养。第4周末链脲霉素（STZ）组大鼠分别腹腔注射STZ （20 mg/kg、30 mg/kg、40 mg/kg）。实验周期13周。检测大鼠一般状况、体重、平均摄食量、血糖、血压、血脂和血浆胰岛素水平。结果：与正常对照组和1% NaCl饮水组比较,在STZ注射后仅30 mg/kg STZ-1% NaCl组、40 mg/kg STZ-1% NaCl组大鼠体重减少（P<0.05）、平均食量、空腹和随机血糖均增加（P<0.05）;第4周起血压显著升高（P<0.05）,收缩压均值达到150 mmHg进入高血压期,并在其后5周（实验结束前）稳定于150~170 mmHg;第9周血浆胰岛素水平升高（P<0.05）,血浆甘油三酯（TG）水平下降（P<0.05）。结论：高脂饲料喂养4周+腹腔注射STZ 30~40 mg/kg结合1% NaCl饮水喂养,能诱导出2型糖尿病伴发高血压的大鼠模型。     

Capsaicin suppresses liver fat accumulation in high-fat diet-induced NAFLD mice

ABSTRACT

Dietary capsaicin exhibits anti-steatosis activity in obese mice. High-fat diet (HFD)-induced mice is a highly studied approach to develop non-alcoholic fatty liver disease (NAFLD). In this study, we determined whether the topical application of capsaicin can improve lesions of NAFLD. The HFD-induced mice were treated with daily topical application of capsaicin for 8 weeks. Topical application of capsaicin reduced liver fat in HFD-fed mice. Capsaicin stimulated carnitine palmitoyl transferase (CPT)-1 and CD36 expression, which are associated with β-oxidation and fatty acids influx of liver while it decreased the expression of key enzymes involved in the synthesis of fatty acids, such as acetyl Co-A carboxylase (ACC) and fatty acid synthase (FAS). Immunohistochemical analysis revealed the elevated level of adiponectin in liver tissue of the capsaicin-treated mice. These results suggest that the topical application of capsaicin suppresses liver fat accumulation through the upregulation of β-oxidation and de novo lipogenesis in HFD-induced NAFLD mice.     

Attenuation by a Vigna nakashimae extract of nonalcoholic fatty liver disease in high-fat diet-fed mice

A Vigna nakashimae (VN) extract has been shown to have antidiabetic and anti-obesity effects. However, the mechanism underlying the effect of a VN extract on hepatic inflammation and endoplasmic reticulum (ER) stress remains unclear. In the present study, we investigated how a VN extract protects against the development of non-alcoholic fatty liver disease (NAFLD). A VN extract for 12 weeks reduced the body weight, serum metabolic parameters, cytokines, and hepatic steatosis in high-fat diet (HFD)-fed mice. A VN extract decreased HFD-induced hepatic acetyl CoA carboxylase and glucose transporter 4 expressions. In addition to the levels of high-mobility group box 1 and receptor for advanced glycation, the hepatic expression of ATF4 and caspase-3 was also reduced by a VN extract. Thus, these data indicate that a chronic VN extract prevented NAFLD through multiple mechanisms, including inflammation, ER stress, and apoptosis in the liver.     

大鼠动脉粥样硬化过程中抗HSP70抗体水平变化及其意义

目的：观察高脂诱导大鼠动脉粥样硬化形成过程中血浆HSP70抗体水平及其与动脉粥样硬化的关系。方法：将28只大鼠分为正常组和高脂组,动态测定了大鼠血清TC、TG、LDL,HE染色观察大鼠主动脉弓病理改变;通过ELISA方法检测大鼠血浆HSP70抗体水平及抗体亚型的变化。结果：2周时,高脂组大鼠血清TC、LDL显著升高,与对照组比较具有显著性差异（P〈0．01）;而TG水平显著降低（P〈0．01）。血浆HSP70抗体在第四周开始显著升高（与对照比较P〈0．01）,随着动脉粥样硬化的进程逐渐升高;HSP70抗体IgM亚型第四周达到峰值（与对照比较P〈0．01）;而IgG亚型第四周开始升高（与对照比较P〈0．01）,后逐渐升高。第12周时主动脉出现粥样斑块典型的动脉粥样硬化的病理改变．结论：高脂可以诱导大鼠动脉粥样硬化形成,高脂组大鼠血浆HSP70抗体IgG亚型水平随着疾病的进程逐渐升高,与动脉粥样硬化具有显著的相关性,表明血浆HSP70抗体与动脉粥样硬化发生发展具有密切关系。     

成年SD大鼠心肌原代成纤维细胞分离及培养的优化方案

目的:摸索及优选成年SD大鼠心肌原代成纤维细胞的体外分离、培养及鉴定的实验方法。方法:将成年SD大鼠心脏剪成小组织块,采用以下四种方案(A:0.08%胰酶+0.1%胶原酶II消化15 min,B:0.2%胶原酶II消化15 min,C:0.2%胶原酶II消化60min,D:0.2%胶原酶II消化90 min)提取成年大鼠心脏原代成纤维细胞,再通过差速贴壁分离方法培养原代成纤维细胞。采用倒置显微镜观察成纤维细胞的基本形态特征,并进行Vimentiin免疫荧光染色对培养的原代细胞进行荧光鉴定;采用台盼兰染色对培养的原代成纤维细胞存活率进行鉴定;采用细胞计数对培养的成纤维细胞生长趋势进行鉴定。结果:四种方法均能培养成纤维细胞,但单酶消化60 min可一次性提取较多细胞,并且细胞状态佳,3 d即可传代。72 h成纤维细胞Vimentin免疫荧光染色阳性率高达97%。台盼兰染色可见其细胞死亡率明显降低,并且细胞计数可见细胞生长状态极佳。结论:单酶消化60 min是提取成年SD大鼠心肌原代成纤维细胞的高效、快速、稳定的实验方法,为心脏疾病的基础及临床研究提供了较为理想的细胞学实验模型。     

清洁级SD大鼠血液生理生化指标的测定

目的建立清洁级SD大鼠血液生理生化正常值。方法应用动物芯片血球计数仪测试常规血细胞计数;采用全自动生化测定仪对清洁级SD大鼠的血液28项生化指标进行测定,并进行统计分析雌雄差异显著性检验。结果建立了清洁级SD大鼠血液生理和28项血液生化参考值,ALB、AST/ALT、AG雌雄之间差异显著;血液血球计数雌雄差异不显著。结论比较详细的建立了清洁级SD大鼠的血液生理生化指标参考值,为其应用提供基础数据。     

SD大鼠与巴马小型猪的皮肤组织学比较

目的研究及观察SD大鼠和巴马小型猪皮肤的正常比较组织学。方法取SD大鼠和巴马小型猪不同部位的皮肤进行石蜡切片、HE染色,光学显微镜观察。结果两种动物的皮肤组织学结构在以下方面存在着显著差异：1.SD大鼠的毛囊成簇分布,平均3～9成群,而巴马小型猪的毛囊较稀少;2.SD大鼠表皮较薄,没有透明层,基底细胞缺乏异质性,真皮与表皮连接面平坦,没有皮钉;而在巴马小型猪皮肤表皮和真皮连接区,有上下交错的表皮皮钉和真皮乳头;3.SD大鼠的真皮结构相对松散,真皮血管系统不发达,而巴马小型猪皮肤的真皮网织层和乳头层交界的地方,水平分布着很多的浅表小静脉和小动脉丛,这种血管分布的方式与人类皮肤中的血管分布极为类似;4.SD大鼠的汗腺只局限于足垫的皮肤,汗腺上皮只有一种细胞类型,腺细胞呈立方形或矮柱状,胞核圆形,导管短而弯曲,由两层上皮细胞组成。而巴马小型猪皮肤的汗腺是顶泌汗腺,分布于真皮和脂肪相接的真皮深层,分泌部为粗管,管腔大,盘曲成团。腺细胞呈立方形或扁平,胞核圆形或长梭形。腺细胞与基膜之间也有肌上皮细胞。导管较细而直,开口于毛囊上段。