大仓鼠消化系统的形态学研究

为了解大仓鼠(Cricetulus triton)消化系统形态结构及其与食性的关系,对大仓鼠的消化系统进行测量和分析。结果表明,大仓鼠的消化管总长度(899.04±91.30)mm,体长总长度(148.96±15.89)mm,其中雌、雄鼠的小肠分别占消化管总长的55.0%±10.0%、54.0%±2.0%;分别是体长的3.54±0.22、3.17±0.59倍。雌、雄大仓鼠的消化道重量、长度差异明显,小肠最为发达,并与其食性相适应。     

7种荒漠啮齿动物食物组成与消化道长度的比较

对荒漠地带几种啮齿动物在自然环境中夏季主要食物组成以及消化道长度的适应性变化进行了比较。三趾跳鼠(Dipus sagitta)、五趾跳鼠(Allactage sibirica)、子午沙鼠(Meriones meridianus)和红耳鼠兔(Ochotona erythrotis)胃内的主要食物成分为当年生植物嫩茎、叶和部分灌木韧皮部分，灰仓鼠(Cricetulus migratorius)及黑线仓鼠(C．barabensis)食物组成中种子、花和浆果以及昆虫出现较高的频率，小家鼠(Mus musculus)的食物构成以种子类为主，与食物组成相适应，总消化道和各器官长度存在明显的种间差异，而且各器官间盲肠和大肠长度的种间差异明显大于小肠的种间差异，胃和盲肠及其内容物的重量也存在显著的种间差异，但小肠和大肠及其内容物重量的种间差异则不显著。其结果验证了下述假设：栖息于同一生境的植食性小哺乳类具有不同食物资源利用模式，而同域共存物种消化道形态结构的差异是对食物资源利用种间权衡的功能反应[动物学报49(2)：171—178，2003]。     

社鼠和褐家鼠消化道长度和重量的季节变化

测定了浙江金华的社鼠和褐家鼠消化道长度和重量的季节变化。野生社鼠消化道各器官无论长度不审重量都有明显季差异,在寒冷的冬季具有相对较大的小肠、大肠、盲肠、雄性社鼠的消化道长度在秋季由于食物条件的改善而明显下降,但雌性社鼠由于在秋季仍有繁殖负担,其消化道长度下降不明显,而家栖的褐家鼠只有总消化道、小肠和大肠的长度有季节差异,冬、春季高于夏、秋季。消化道形态季节变化与温度、食物条件和繁殖有关。     

嫩江下游人工林中黑线姬鼠与黑线仓鼠的消化道形态及其取食策略

对嫩江下游流域人工林区两同域共存优势种黑线姬鼠东北亚种(Apodemus agrarius mantchuricus)与黑线仓鼠三江平原亚种(Cricetulus barabensis manchuricus)夏季主要食物组成及消化道形态结构的适应性变化进行了比较分析.二者均以当年生植物嫩茎、叶、种子及昆虫为主要取食对象,但黑线姬鼠对茎和叶的采食频次小于黑线仓鼠,而种子、根和昆虫类在黑线姬鼠的食物中出现的频次则相对较高.与食物组成相适应,黑线仓鼠的胃、盲肠和大肠在长度及重量上均显著大于黑线姬鼠,这是黑线仓鼠对高纤维和低蛋白食物的适应性调整.研究结果表明,两种啮齿动物在长期的进化中产生了不同的食物资源利用模式,而其消化道形态结构的变化则可能是其在长期的种间竞争和进化压力下进行食物资源分享的一种功能性反应.     

中缅树鼩消化道长度和重量变化

为探讨栖息于昆明禄劝地区中缅树鼩(Tupaia belangeri)的消化道特征与环境之间的适应关系,在2008年6月和12月(夏季和冬季)分别对自然环境中缅树鼩的胃、小肠、大肠、盲肠的长度、含内容物重、去内容物重、干组织重等消化道指标进行了测定。结果表明,中缅树鼩消化道特征冬季和夏季存在变化,随着温度降低、食物质量下降,中缅树鼩的小肠长度和重量增加;各器官重量均在冬季最大;中缅树鼩在受到低温、食物质量下降等因子胁迫下,通过调节消化道长度和重量来满足能量需求的增加,维持正常的生理机能。中缅树鼩的消化道在冬季和夏季中表现出的变化模式及消化对策对其在自然环境中的生存是至关重要的。     

七种鼠科啮齿动物消化道长度和重量的比较

测定浙江省金华地区7种鼠科啮齿动物的总消化道及各消化器官的长度和重量,与其食性和生境作比较,旨在检测近缘种之间消化道长度和重量的差异,家栖种类与野栖种类消化道形态的差异,野外捕获动物带回实验室处死,解剖分离消化道为胃,小肠,盲肠和大肠,精密直尺测定各器官的平展长度,纵剖肠道,生理盐水冲净内容物,65℃恒温干燥后称得干重,研究结果表明,消化道长度的种间差异明显大于消化道重量的种间差异;盲肠和大肠长度的种间差异明显大于小肠长度的种间差异,植食性野栖种类的胃,盲肠和大肠大于杂食性家栖种类,而两类动物小肠长度的差异不明显。     

肉鸡消化器官生长规律的研究

选艾维茵肉鸡商品雏２００只,按常规饲养管理,于初生和１～７周龄的周末,分性别各解剖８只,测量消化器官重量及消化道各部分长度,并进行与体重变化的回归分析。结果：消化器官重量及消化道各部分的长度随体重同步变化,约在４周龄时消化器官重超过饲养阶段的平均数。消化器官重量及消化道长度与体重变化的幂回归的相关系数最高。     

成年近交白化金黄仓鼠主要脏器及脏器系数测定

本文报告了成年近交白化金黄仓鼠８个主要脏器重量和脏器系数测定结果,还与封闭群金黄仓鼠主要脏器的测定值进行了比较。结果表明,雌、雄性白化金黄仓鼠的主要脏器重量,尤其是二者脾脏是差异极显著,白化金黄仓鼠肾脏的重量显著高于封闭群金黄仓鼠,特别是雌性间肾脏的重量差异更明显。     

生长抑素基因在不同性别和年龄黑线仓鼠哈氏腺的差异表达

哈氏腺作为“视网膜-松果体轴”的候补结构,介导了体外光信号与体内神经内分泌调控过程,具有多样性和复杂的生理功能,并受神经和体液因素的双重调控。生长抑素（somatostatin, SS）是调控动物生长发育的主要因子之一,检测SS基因在黑线仓鼠哈氏腺的差异表达模式,为光信号调控动物的生长发育机制提供理论依据。以野生黑线仓鼠（Cricetulus barabensis）为研究对象,测量了不同性别和年龄个体哈氏腺的形态学指标,克隆了哈氏腺SS cDNA序列,实时荧光定量PCR方法检测了哈氏腺中SS基因的表达变化。结果显示：（1）黑线仓鼠体重无性别差异,随年龄增长而增加;哈氏腺的长度和重量也随年龄增长而增加;调整体重影响后,哈氏腺的重量和长度没有年龄之间的差异,但哈氏腺重量存在性别间差异（P<0.05）。（2）克隆到黑线仓鼠哈氏腺SS cDNA序列489 bp ,并对序列结构进行分析,黑线仓鼠哈氏腺SS cDNA具有典型分泌蛋白cDNA的特征,并在进化上高度保守;（3）检测到SS mRNA在黑线仓鼠哈氏腺中均有表达,表达量存在年龄和性别差异（P<0.05）;（4）随着个体性成熟和衰老,黑线仓鼠哈氏腺中SS mRNA的相对表达量逐渐降低,其表达量分别与哈氏腺长度和重量的发育变化负相关（r=-0.557,P=0.022;r=-0.806,P＜0.001）。结果表明,黑线仓鼠哈氏腺重量和SS表达量均表现出两性异形,可能是对不同繁殖策略的适应;SS基因作为负调控因子参与野生黑线仓鼠哈氏腺的生长发育过程。     

甘肃鼢鼠适应地下生活的消化道形态和结构的季节可塑性

甘肃鼢鼠(Myospalax cansus)是终生营地下生活的小型哺乳动物,为研究其在自然环境中的消化对策和调节,探讨地下鼠消化道的可塑性,测定了不同季节消化道各器官长度、重量及各器官的组织结构。结果显示,甘肃鼢鼠总消化道长度、各消化器官长度和含内容物总重量无显著季节差异。总消化道及各器官的鲜重和干重多在春季最高,含内容物重量于秋季较高。组织结构有显著性季节变化,黏膜层和肌层的厚度及肠道绒毛高度春季最高。结果表明,甘肃鼢鼠主要依靠肠道重量的增加和组织结构的可塑性变化来适应相对稳定的地下生活环境,无需增加消化器官长度满足其能量需求。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.