BACKGROUND & AIMS: The objective of this study was to determine whether exposure of early suckling young of the opossum Monodelphis domestica to ultraviolet A (UVA) radiation (320-400 nm) can lead to the development of melanocytic lesions similar to those induced after exposure to ultraviolet B (UVB) radiation (280-320 nm) to total doses as low as 380 J/m2. A total of 576 sucklings received nine exposures of 0.6, 2.6 or 15.5 kJ/m2 per dose (total doses approximately 6, 23 and 140 kJ/m2, respectively) from a Blak Ray lamp source with a narrow range emission at 365 nm. A further 280 sucklings were exposed in the same way to doses of 2.6 kJ/m2 per dose (total approximately 23 kJ/m2) broad-band UVA with visible wavelengths from a Dermalight lamp. Frequency of litter loss following all of the UVA-exposure protocols was similar to that within the same stocks in the colony at large. Only one of the 856 UVA-exposed individuals possessed a melanocytic lesion at the 5 month assessment point. No radiation-induced lesions of any type were evident on the skin of the other animals exposed as sucklings. The affected male was from a group of 70 individuals exposed to the highest total dose (140 kJ/m2) from the Blak Ray light source. The melanocytic hyperplasia was provisionally identified as a potential melanoma but it slowly regressed as the animal aged. We conclude that in the opossum suckling exposure system, the potency of UVA for melanoma induction is extremely low compared with that of UVB. Possible explanations, amenable to further investigations, are given for the low UVA sensitivity of the suckling model compared to the adult exposure model of Ley (Ley, R. D. [1997] Cancer Res. 57, 3682-3684).

背景与目标： 这项研究的目的是确定是否暴露于紫外线A (UVA) 辐射 (320-400 nm) 的负鼠的早期乳鼠幼仔会导致黑素细胞病变的发展，类似于暴露于紫外线B (UVB) 辐射 (280-320 nm) 后引起的黑素细胞病变。总剂量低至380 J/m2。总共576只乳类从具有365纳米窄范围发射的Blak射线灯源中接受了每剂量0.6、2.6或15.5 kJ/m2的九次曝光 (总剂量分别约为6、23和140 kJ/m2)。以同样的方式将另外的280乳类暴露于每剂量2.6 kJ/m2的剂量 (总计约23 kj/m2) 具有来自dermallight灯的可见波长的宽带UVA。遵循所有UVA暴露方案的凋落物流失频率与整个殖民地中相同种群中的凋落物流失频率相似。856个暴露于UVA的个体中只有一个在5个月的评估点具有黑素细胞病变。在其他以哺乳形式暴露的动物的皮肤上，没有任何类型的辐射引起的病变。受影响的男性来自暴露于来自Blak射线光源的最高总剂量 (140 kJ/m2) 的70个人。暂时将黑素细胞增生确定为潜在的黑色素瘤，但随着动物的衰老而缓慢消退。我们得出的结论是，在负鼠哺乳暴露系统中，与UVB相比，UVA诱导黑色素瘤的效力极低。与Ley的成人暴露模型相比，哺乳模型的UVA敏感性低 (Ley，R. D. [1997] Cancer Res。57,3682-3684)。

BACKGROUND & AIMS: :Oxytocin (OT) is essential for parturition and milk ejection, and OT-containing fibers are present in several regions of the brain and in the spinal cord. During lactation, activation of spinal cord neurons by suckling stimulation involves deep laminae III-X including sympathetic preganglionic neurons of the intermedio-medial cell column. In the present study, experiments were designed to determine if the suckling provided by the litter increased OT levels in the spinal cord of dams, as determined by competitive immunoassay. In addition, we investigated if OT fibers reach neurons of the spinal cord that are known to respond to suckling. The OT content was higher in the hypothalamus than in the spinal cord in animals from all experimental groups. After 6 h of pup separation, OT levels decreased and suckling for 5 min induced a significant increase of OT levels in the spinal cord. Double immunostaining for Fos and OT showed OT-positive fibers adjacent to neurons that had Fos-positive nuclei, located mostly in laminae III, IV, and X. The present data support the notion that OT is released within the spinal cord in response to suckling, suggesting a role for this peptide in modulating the afferent and/or efferent responses generated by suckling.

背景与目标： : 催产素 (OT) 对于分娩和乳汁排出至关重要，并且含OT的纤维存在于大脑和脊髓的多个区域。在哺乳期，哺乳刺激激活脊髓神经元涉及深层iii-x，包括中间细胞柱的交感神经节前神经元。在本研究中，设计了实验来确定垫料提供的哺乳是否增加了大坝脊髓中的OT水平，这是通过竞争性免疫测定法确定的。此外，我们研究了OT纤维是否到达已知对哺乳有反应的脊髓神经元。在所有实验组的动物中，下丘脑的OT含量均高于脊髓。幼崽分离6小时后，OT水平降低，哺乳5分钟后脊髓中OT水平显着增加。Fos和OT的双重免疫染色显示OT阳性纤维与具有Fos阳性核的神经元相邻，主要位于laminae III，IV和X中。目前的数据支持OT响应哺乳而在脊髓内释放的观点，这表明该肽在调节哺乳产生的传入和/或传出反应中的作用。

BACKGROUND & AIMS: :Intestinal amino acid (AA) transport is critical for the supply of AA to other tissues. Few studies regarding AA intestinal transport systems during the period from postnatal intense development of piglets until weaning are available. In the present study, we measured the intestinal expression of b(0,+)AT according to developmental stage using the suckling Huanjiang piglet model, and documented the effect of intra-uterine growth restriction (IUGR) on such expression using real-time PCR and Western blot analysis. Suckling piglets that recovered after IUGR and those with normal body weights (NBW) were used after birth or at 7, 14 and 21 d of age. Blood samples were used for the measurement of plasma AA concentrations, and the jejunum was collected for the measurement of b(0,+)AT expression. In NBW piglets, b(0,+)AT expression was markedly decreased from days 0 to 21 (P< 0.01) and remained at a low level during all the suckling periods. In IUGR piglets, there was a marked decrease in b(0,+)AT expression at birth, which remained lower, when compared with NBW piglets, during the suckling period. These results coincided with decreased plasma arginine concentration at birth and decreased lysine concentration in 21-d-old piglets (P< 0.05). It is concluded that the high expression of b(0,+)AT at birth decreases during the suckling period, and that IUGR is associated with decreased expression of this apical AA transporter. The possible causal relationship between decreased b(0,+)AT expression and lower body weight of IUGR piglets in the suckling period is discussed.

背景与目标： : 肠道氨基酸 (AA) 运输对于向其他组织供应AA至关重要。从仔猪出生后到断奶期间，关于AA肠道运输系统的研究很少。在本研究中，我们使用哺乳环江仔猪模型根据发育阶段测量了b(0，) 的肠道表达，并使用real-time PCR和Western blot记录了子宫内生长限制 (IUGR) 对这种表达的影响。IUGR后恢复的哺乳仔猪和体重正常 (NBW) 的仔猪在出生后或7、14和21 d时使用。血液样本用于测量血浆AA浓度，并收集空肠用于测量b(0，) AT表达。在NBW仔猪中，b(0，+)AT表达从第0天到第21天明显降低 (P< 0.01)，并在所有哺乳期间保持在低水平。在IUGR仔猪中，出生时表达的b(0，) 显着降低，与NBW仔猪相比，在哺乳期间仍然较低。这些结果与21 d仔猪出生时血浆精氨酸浓度降低和赖氨酸浓度降低相吻合 (P< 0.05)。结论是，在哺乳期间，出生时b(0，) 的高表达降低，并且IUGR与这种顶端AA转运蛋白的表达降低有关。讨论了乳期IUGR仔猪b(0，+)AT表达降低与体重降低之间的可能因果关系。

BACKGROUND & AIMS: :The postnatal development of intestine is associated with a decline in brush border lactase activity in rodents. This is similar to adulthood hypolactasia, a phenomenon prevalent in humans worldwide. In the present study, the effect of luminal proteases from adult rat intestine was studied in vitro on intestinal lactase activity in saline control, thyroxine, insulin and cortisone treated rat pups. Lactase levels were determined by enzyme analysis and Western blotting. mRNA levels encoding lactase were determined by Northern blotting. Administration of thyroxine for 4 days reduced (P<0.05) lactase activity, but insulin treatment had no effect in 8-day-old rat intestine. However, cortisone administration augmented (P<0.01) lactase activity, under these conditions. Western blot analysis showed decreased lactase signal corresponding to 220-kDa protein band in thyroxine treated animals. However, the intensity of lactase signal was high in cortisone treated animals compared to controls. mRNA levels encoding lactase showed a 6.8-kb mRNA transcript in saline and hormone treated rats. mRNA levels encoding lactase were increased in cortisone treated animals but were reduced in thyroxine injected pups compared to controls. Microvillus membranes from saline (P<0.01) and thyroxine (P<0.05) or insulin (P<0.01) treated rats upon incubation with luminal wash from adult rat intestine showed a significant decline in lactase activity. These findings suggest that thyroxine, insulin or cortisone induced changes in lactase expression in suckling rat intestine make it susceptible to luminal proteases, which may in part be responsible for observed maturational decline in lactase activity in adult rat intestine.

背景与目标： : 出生后肠道发育与啮齿动物刷状缘乳糖酶活性下降有关。这类似于成年性低乳酸症，这是全世界人类普遍存在的现象。在本研究中，在体外研究了成年大鼠肠道的luminal蛋白酶对盐水对照，甲状腺素，胰岛素和可的松处理的大鼠幼崽的肠乳糖酶活性的影响。通过酶分析和蛋白质印迹法确定乳糖酶水平。编码乳糖酶的mRNA水平通过Northern印迹测定。给予甲状腺素4天降低 (P<0.05) 乳糖酶活性，但胰岛素治疗对8天大的大鼠肠道没有影响。然而，在这些条件下，给予可的松增加 (P<0.01) 乳糖酶活性。Western印迹分析显示甲状腺素处理的动物中对应于220-kDa蛋白带的乳糖酶信号减少。然而，与对照组相比，可的松治疗的动物的乳糖酶信号强度很高。编码乳糖酶的mRNA水平在盐水和激素处理的大鼠中显示6.8-kb mRNA转录本。与对照组相比，经可的松处理的动物中编码乳糖酶的mRNA水平升高，但经甲状腺素注射的幼崽中编码乳糖酶的mRNA水平降低。用来自成年大鼠肠的管腔洗涤液孵育后，来自盐水 (P<0.01) 和甲状腺素 (P<0.05) 或胰岛素 (P<0.01) 处理的大鼠的微绒毛膜显示乳糖酶活性显着下降。这些发现表明，甲状腺素，胰岛素或可的松诱导乳鼠肠道中乳糖酶表达的变化使其对腔蛋白酶敏感，这可能部分是成年大鼠肠道中乳糖酶活性成熟下降的原因。

BACKGROUND & AIMS: :Currently, in pre and postnatal development studies or in juvenile rat studies, bone growth is assessed "for cause" by simple measurements of long bone length in vivo and at termination. This manuscript compares two radiographic methods for in vivo assessment of long bones in suckling rats; 2D imaging using a Faxitron™ and 3D imaging using μCT. This paper illustrates that it is possible to image the unanaesthetised postnatal day 1 rat by Faxitron™ using a simple Micropore™ tape restraint method. With isoflurane anaesthesia, it was possible to obtain high quality μCT images of pups from day of birth. No pups were rejected by their mothers following either technique. The Faxitron™ was straightforward and fast, however the μCT 3D images were of greater overall utility. Either method could be used for longitudinal investigation of long bone observations made previously in embryofetal development studies, or for other mechanistic work.

背景与目标： : 目前，在产前和产后发育研究或幼年大鼠研究中，通过简单测量体内和终止时的长骨长度来评估骨骼生长的 “原因”。本手稿比较了两种用于哺乳大鼠长骨体内评估的射线照相方法; 使用Faxitron进行2D成像™和使用 μ ct的3D成像。本文说明了通过Faxitron可以对未麻醉的出生后第1天的大鼠进行成像。™使用简单的微孔™胶带约束法。使用异氟醚麻醉，可以从出生之日起获得高质量的 μ ct幼崽图像。任何一种技术的母亲都没有拒绝幼崽。传真™简单明了，快速，但是 μ ct 3D图像具有更大的整体实用性。两种方法均可用于先前在胚胎发育研究中进行的长骨观察的纵向研究，或用于其他机械工作。

BACKGROUND & AIMS: Epidermal growth factor (EGF) is contained in breast milk, is transported intact across the gastrointestinal mucosa during the suckling period, retains its biological activity, and affects hepatic growth. Whether or not EGF also influences postnatal hepatic development by affecting nonparenchymal cells or by modifying intrahepatic blood is not clear. As a result, the effect of EGF on the hepatic microvasculature was studied in suckling rats fed rat milk substitute (RMS) with and without EGF (100 ng/ml, i.e. twice the normal intake in breast milk) between days 11 and 14 and compared to pups breast-fed for 14 days. The livers of anesthetized pups were examined by in vivo microscopy to determine the numbers of sinusoids with flow (SCF) in each of 10 microscopic fields and the numbers of phagocytic Kupffer cells (KC) in the same fields following an intraportal injection of fluorescent 1-micron latex particles. Phagocytic activity was expressed as the ratio KC/SCF. In pups fed RMS without EGF, SCF and KC/SCF was 75 and 45%, respectively, of that in breast-fed animals. The addition of EGF to the RMS restored SCF and KC/SCF nearly to the levels measured in breast-fed pups. Thus, the results suggest that milk-borne EGF plays a role in the development of KC phagocytic function and affects the amount of blood that perfuses the sinusoidal bed in the suckling.

背景与目标： 表皮生长因子 (EGF) 包含在母乳中，在哺乳期间完整地跨胃肠道粘膜转运，保留其生物学活性，并影响肝脏的生长。EGF是否还通过影响非实质细胞或通过改变肝内血液来影响产后肝脏发育尚不清楚。结果，在第11天和第14天之间，在哺乳大鼠中研究了EGF对肝微血管系统的影响，该哺乳大鼠饲喂有EGF和不饲喂EGF (100 ng/ml，即母乳中正常摄入量的两倍)，并与母乳喂养14天的幼崽进行比较。通过体内显微镜检查麻醉幼崽的肝脏，以确定在门内注射荧光后，在10个显微场中的每个场中流动的正弦曲线 (SCF) 的数量以及在相同场中的吞噬库普弗细胞 (KC) 的数量1微米乳胶颗粒。吞噬活性表示为KC/SCF的比率。在没有EGF的饲喂的幼崽中，SCF和KC/SCF分别为母乳喂养动物的RMS的75和45%。在RMS中添加EGF可使SCF和KC/SCF几乎恢复到母乳喂养幼崽的水平。因此，结果表明，牛奶传播的EGF在KC吞噬功能的发展中起作用，并影响在乳汁中灌注正弦床的血液量。

BACKGROUND & AIMS: :The effect of feeding 8% protein (low-protein; LP) diet to lactating rats has been studied on the absorption of macromolecules and the glycosylation of enterocytes in suckling animals. The absorption of 125I-labelled bovine serum albumin, gamma-globulin and alpha-lactalbumin was 24-314% more in pups nursed on mothers fed LP diet compared to the pair-fed controls. The observed enhancement in protein absorption was associated with a significant increase in the binding of these proteins to microvillus membranes (MVM). The sialic acid content of brush borders was unaltered but the fucose level was augmented (p less than 0.01) in pups nursed on rats fed LP diet. The binding of 125I-labelled wheat germ agglutinin and Ulex europeus agglutinin I to MVM was in agreement to the data on sialic acid and fucose levels of the membranes. The binding of peanut agglutinin to MVM was 30% low in pups from LP-diet-fed animals. The incorporation of (14C) D-mannose into MVM was essentially unaffected but that of (14C) N-acetylglucosamine was reduced in pups reared on mothers given LP diet. These findings suggest that the quality of maternal nutrition affects the absorption of macromolecules and the glycosylation in developing rat intestine.

背景与目标： : 研究了喂养8% 蛋白 (低蛋白; LP) 饮食对哺乳大鼠的大分子吸收和哺乳动物肠细胞糖基化的影响。与成对喂养的对照组相比，用LP饮食喂养的母亲喂养的幼崽对125i标记的牛血清白蛋白，γ-球蛋白和 α-乳白蛋白的吸收多24-314%。观察到的蛋白质吸收增强与这些蛋白质与微绒毛膜 (MVM) 的结合显着增加有关。饲喂LP饮食的幼崽中，刷状边界的唾液酸含量没有改变，但岩藻糖水平增加 (p小于0.01)。125i标记的小麦胚芽凝集素和Ulex europeus凝集素I与MVM的结合与膜的唾液酸和岩藻糖水平的数据一致。在来自LP饮食喂养的动物的幼崽中，花生凝集素与MVM的结合30% 低。在接受LP饮食的母亲饲养的幼崽中，(14C) D-甘露糖掺入MVM基本上不受影响，但 (14C) N-乙酰葡萄糖胺的掺入减少。这些发现表明，母体营养的质量会影响发育中的大鼠肠道中大分子的吸收和糖基化。

BACKGROUND & AIMS: :The modification induced by interferon (IFN) in brown adipose tissue (BAT) was studied by high spatial resolution magnetic resonance imaging (MRI), histology, and transmission electron microscopy (TEM). In IFN-treated mice, at MRI, the interscapular BAT was slightly enlarged and showed non-homogeneous areas of lipid accumulation. The thickness of the subcutaneous white adipose tissue was reduced with respect to control mice. In the liver, MRI showed a lipid accumulation. In IFN-treated mice, by light microscopy, brown adipocytes showed a larger lipid deposit with respect to control mice. At TEM, in BAT, the mitochondria were reduced in number, smaller and the number of cristae was also significantly reduced with respect to the controls (9.1 +/- 1.5 vs 20.1 +/- 1.9, P < 0.01). The inclusions in the mitochondrial matrix were significantly less numerous in IFN-treated than in control animals (1.9 +/- 0.7 vs 0.9 +/- 0.7 for mitochondrial section, P < 0.01). Abnormalities of endoplasmic reticulum described in hepatocytes were not found in brown adipocytes of IFN-treated mice. The present work demonstrates that, in the BAT of suckling mice, IFN-treatment induces morphologic alterations and that brown adipocytes have MRI and TEM features resembling those found in the lipid laden BAT of aged animals.

背景与目标： : 通过高空间分辨率磁共振成像 (MRI)，组织学和透射电子显微镜 (TEM) 研究了干扰素 (IFN) 在棕色脂肪组织 (BAT) 中诱导的修饰。在IFN处理的小鼠中，在MRI上，肩胛间BAT略微增大，并显示出脂质积聚的非均质区域。相对于对照小鼠，皮下白色脂肪组织的厚度减少了。在肝脏中，MRI显示脂质积聚。在接受IFN处理的小鼠中，通过光学显微镜检查，相对于对照小鼠，棕色脂肪细胞显示出更大的脂质沉积。在TEM，在BAT中，相对于对照，线粒体数量减少，较小，并且cristae的数量也显着减少 (9.1/- 1.5 vs 20.1/- 1.9，P <0.01)。在IFN处理过的线粒体基质中的内含物明显少于对照动物 (线粒体切片的1.9/- 0.7 vs 0.9/- 0.7，P <0.01)。在IFN处理的小鼠的棕色脂肪细胞中未发现肝细胞中描述的内质网异常。目前的工作表明，在哺乳小鼠的蝙蝠中，IFN处理会诱导形态学改变，并且棕色脂肪细胞的MRI和TEM特征类似于老年动物的脂质蝙蝠中的MRI和TEM特征。

BACKGROUND & AIMS: Total pyruvate dehydrogenase complex activity is low in white adipose tissue during the suckling period and increases markedly at weaning on to a high-carbohydrate diet. This is concomitant with an increase in the E1 alpha, E1 beta and E2 subunit protein concentration and their respective mRNAs, suggesting a pretranslational control of this phenomenon. The most marked change is seen for the E1 alpha subunit (17-fold increase in protein concentration). The changes in pyruvate dehydrogenase complex activity and subunit abundance induced by weaning on to a high-carbohydrate diet are precluded if the animals are weaned on to a high-fat diet, suggesting that the nutritional and/or related hormonal changes rather than a developmental stage are responsible for the observed adipose-tissue pyruvate dehydrogenase complex pattern.

背景与目标： 在哺乳期间，白色脂肪组织中的丙酮酸脱氢酶复合物总活性较低，而在断奶为高碳水化合物饮食时显着增加。这伴随着E1 α，E1 β 和E2亚基蛋白浓度及其各自mrna的增加，表明这种现象的翻译前控制。最明显的变化是E1 α 亚基 (蛋白质浓度增加17倍)。如果动物断奶高脂饮食，则排除了因断奶而导致的丙酮酸脱氢酶复合物活性和亚单位丰度的变化，表明营养和/或相关的激素变化而不是发育阶段是观察到的脂肪组织丙酮酸脱氢酶复合物模式的原因。

BACKGROUND & AIMS: :It is well established that the suckling stimulus sensitizes or primes the anterior pituitary to PRL-releasing stimuli. It is also recognized that PRL-secreting cells from a given animal are not all alike but instead exhibit a considerable degree of functional heterogeneity. The goal of the present study was to determine whether the suckling-induced priming phenomenon is manifest at the cellular level by shifts in the relative abundance of various mammotrope subpopulations. This was accomplished by using reverse hemolytic plaque assays to evaluate the secretory characteristics of individual PRL secretors derived from lactating rats either before or after the transient application of a suckling stimulus. Groups of day 10 lactating rats separated from their litters for 4 h were either killed immediately or were reunited briefly (10 min) with their pups before death. Adenohypophyseal cells obtained after trypsin dispersion were then subjected to plaque assays for PRL. Mammotropes derived from suckled rats were, on average, considerably more responsive to the stimulatory actions of TRH and angiotensin II and less susceptible to inhibition by dopamine. Mammotropes from nonsuckled rats exhibited a bimodal frequency distribution in which plaques from the second mode were roughly 6-8 times larger (released considerably more PRL) than those from the first. Superimposition of suckling (or in vitro treatment with dopamine) caused the second mode to disappear. Suckling also enhanced greatly the fraction of PRL cells that shifted from the first to the second mode (i.e. released more hormone) after treatment with TRH or angiotensin II. Taken together, our results demonstrate that the suckling-induced sensitization of pituitary tissue to PRL-releasing stimuli is manifest at the cellular level as proportional shifts toward those cells most responsive to stimulatory secretagogues and away from those most susceptible to inhibition by dopamine.

背景与目标： : 众所周知，哺乳刺激使垂体前叶对PRL释放刺激敏感或引发。还认识到，来自给定动物的PRL分泌细胞并非全部相同，而是表现出相当程度的功能异质性。本研究的目的是确定哺乳诱导的引发现象是否在细胞水平上表现为各种猛犸象亚群相对丰度的变化。这是通过使用反向溶血斑块测定法来评估在短暂施加乳汁刺激之前或之后源自泌乳大鼠的单个PRL分泌物的分泌特性来实现的。与幼仔分开4小时的第10天哺乳期大鼠组被立即杀死或在死亡前与幼崽短暂团聚 (10分钟)。然后对胰蛋白酶分散后获得的腺垂体细胞进行PRL的斑块分析。平均而言，来自乳鼠的猛犸象对TRH和血管紧张素II的刺激作用的反应要高得多，并且不易受到多巴胺的抑制。来自未哺乳大鼠的猛犸象表现出双峰频率分布，其中第二种模式的斑块比第一种模式的斑块大约6-8倍 (释放的PRL明显更多)。乳汁的叠加 (或用多巴胺进行体外治疗) 导致第二种模式消失。在用TRH或血管紧张素II治疗后，哺乳还大大增强了从第一种模式转变为第二种模式 (即释放更多激素) 的PRL细胞的比例。综合而言，我们的结果表明，哺乳诱导的垂体组织对PRL释放刺激的敏感性在细胞水平上表现为向对刺激性促分泌剂最有反应的细胞成比例地转移，而远离那些最易受多巴胺抑制的细胞。

BACKGROUND & AIMS: BACKGROUND:The daily pattern of nursing of the rabbit pup by the doe is the most important event in the day for the newborn and is neatly anticipated by them. Such anticipation presumably needs a close correlation with changes in hormones that will allow the pups to develop an appropriate behavior. Although a number of circadian functions have been examined in newborn rabbits, there is no information on 24-h pattern of gonadotropin release or on possible sex-related differences in gonadotropin or prolactin (PRL) release of pups. This study examined the 24-h changes of plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) in 11 days old suckling female and male rabbits left with the mother or after short-term (i.e., 48 h) doe-litter separation. METHODS:Animals were kept under controlled light-dark cycles (16 h-8 h; lights on at 08:00 h). On day 9 post partum, groups of 6-7 female or male rabbit pups were separated from their mothers starting at 6 different time intervals in the 24 h cycle. Pups were killed 48 h after separation. At each time interval groups of male or female pups that stayed with the mother were killed as controls. Plasma, LH, FSH and PRL levels were measured by specific radioimmunoassays. RESULTS:In pups kept with their mother plasma FSH and LH maxima occurred at the first and second part of the light phase (at 13:00 and 17:00-21:00 h, respectively) (females) or as two peaks for each of the hormones (at 13:00 and 01:00 h) (males). PRL release was similar in female and male rabbit pups kept with their mother, showing a 24-h pattern with two peaks, at 13:00 and 01:00 h, respectively. Mean 24-h values of gonadotropins and PRL did not differ between sexes. Isolation of pups for 48 h augmented circulating gonadotropin and PRL levels and distorted hormone 24-h pattern to a similar extent in both sexes. CONCLUSION:Significant sex differences in 24-h changes in LH and FSH, but not in PRL, release occurred in rabbit pups kept with the doe. Separation of newborn pups from their mother augmented circulating gonadotropin and PRL levels and disrupted 24-h rhythmicity of gonadotropin and PRL release similarly in both sexes. The effect of pups' isolation can be attributed either to a modification of the circadian pacemaker or to a masking effect on some of its output overt rhythms.

背景与目标：

BACKGROUND & AIMS: Saccharomyces boulardii (S. boulardii), a biotherapeutic agent effective in acute and chronic enterocolopathies, produces trophic intestinal effects at least in part mediated by the endoluminal release of polyamines. However, the effects of the yeast on peptide hydrolysis have not yet been studied. The objectives of this study were to assess in suckling rats the endoluminal and mucosal aminopeptidase activities in response to S. boulardii treatment and to analyze their related mechanisms. Peptidase activities were assayed on yeast cells by using several L-amino acid-p-nitroanilide substrates in the pH range of 2 to 10. A marked hydrolytic activity was found for L-leucine-p-nitroanilide that peaked at pH = 8 (K(m) = 0.334 mM, V(max) = 44.7 micromol.min(-1).g(-1) protein). N-terminal peptide hydrolysis was confirmed using as substrate L-Leu-Gly-Gly (K(m) = 4.71 mM, V(max) = 18.08 micromol.min(-1).g(-1) protein). Enzyme reactions were inhibited in the presence of 1 mM Zn(2+). Oral treatment of sucklings with S. boulardii significantly enhanced jejunal and ileal mucosal leucine-aminopeptidase activities by 24 and 34%, respectively, over controls. In concordance, aminopeptidase activity was enhanced in jejunal and ileal endoluminal fluid samples by 47 and 105%, respectively. By use of an IgG-purified antibody raised against the zinc-binding domain common to metalloproteases, the yeast aminopeptidase was immunoprecipitated and detected as an heteromeric enzyme of 108 and 87-kD subunits. S. boulardii, when given orally to suckling rats, is able to significantly enhance hydrolysis of N-terminal oligopeptides in both endoluminal fluid and intestinal mucosa by the endoluminal release of a leucine aminopeptidase that appears to be a zinc-binding metalloprotease belonging to the M1 family of peptidases.

背景与目标： 布拉氏酵母 (S. boulardii) 是一种对急性和慢性肠病有效的生物治疗剂，至少部分地通过多胺的腔内释放介导产生营养肠作用。然而，酵母对肽水解的影响尚未研究。这项研究的目的是评估乳鼠对S. boulardii治疗的反应的腔内和粘膜氨肽酶活性，并分析其相关机制。通过使用几种L-氨基酸-对-硝基苯胺底物在2至10的pH范围内测定酵母细胞上的肽酶活性。发现L-亮氨酸-对-硝基苯胺的显著水解活性在pH = 8时达到峰值 (K(m) = 0.334 mM，V(max) = 44.7微摩尔·分钟 (-1)·g(-1) 蛋白)。使用L-Leu-Gly作为底物 (K(m) = 4.71 mM，V(max) = 18.08 micromol.min(-1).g(-1) 蛋白) 确认N-末端肽水解。在1毫米Zn(2) 存在下，酶反应受到抑制。与对照组相比，用布拉迪链球菌口服哺乳动物的空肠和回肠粘膜亮氨酸-氨肽酶活性分别提高了24和34%。一致地，空肠和回肠腔内液样品中的氨肽酶活性分别提高了47和105%。通过使用针对金属蛋白酶共有的锌结合结构域产生的IgG纯化的抗体，免疫沉淀酵母氨肽酶，并检测为108和87-kd亚基的异聚酶。S. boulardii口服给哺乳大鼠时，能够通过亮氨酸氨肽酶的腔内释放显着增强腔内液和肠粘膜中N末端寡肽的水解，亮氨酸氨肽酶似乎是一种锌结合金属蛋白酶，属于M1肽酶家族。

BACKGROUND & AIMS: Morphine inhibits suckling-induced oxytocin (OT) release in lactating mice. Since beta-endorphin and enkephalins have several actions in common with morphine, the action of these opioid peptides on OT release was investigated. In anesthetized lactating rats, OT release was achieved by intraventricular injection of acetylcholine (ACh) or by the physiological stimulus of suckling. The amount of OT released was estimated by comparing milk-ejection responses to these stimuli to those following known amounts of intravenous (IV) OT. Both beta-endorphin and [D-Ala2]Met-enkephalin inhibited ACh-induced and suckling-induced OT release. Naloxone antagonized opiate inhibition in both cases.

背景与目标： 吗啡抑制哺乳小鼠乳汁诱导的催产素 (OT) 释放。由于 β-内啡肽和脑啡肽与吗啡具有多种共同作用，因此研究了这些阿片肽对OT释放的作用。在麻醉的泌乳大鼠中，OT释放是通过脑室内注射乙酰胆碱 (ACh) 或通过哺乳的生理刺激来实现的。通过将对这些刺激的乳汁排出反应与已知静脉内 (IV) OT的反应进行比较，可以估算出OT的释放量。Β-内啡肽和 [D-Ala2]Met-脑啡肽均抑制ACh诱导和哺乳诱导的OT释放。纳洛酮在两种情况下均拮抗阿片类药物的抑制作用。

BACKGROUND & AIMS: :The enteric nervous system plays a role on the stimulation of secretory cells of intestinal epithelia. We have demonstrated that ablation of ENS stimulates epithelial cell proliferation. As goblet cells are important constituents of the epithelial sheet, it is mandatory to investigate separately this cell type. The myenteric plexus of the ileum of rats in postnatal development was partially removed by the serosal application of benzalkonium chloride (BAC). Three groups of animals were used: those where BAC application was at 13 days and sacrifice was at 15 (13/28-day-old) or 23 days after treatment (13/36-day-old), and those where BAC was applied at 21 days and rats were killed 15 days after treatment (21/36-day-old) . The number of goblet cells in the ileum was estimated in sections stained by periodic acid-Schiff (PAS) histochemistry. In the 13/28 and 21/36 groups, the number of goblet cells was significantly higher after BAC treatment. These results suggest that the myenteric denervation may have an acute effect on the number of goblet cell in suckling and weanling rats, probably through submucous plexus.

背景与目标： 肠神经系统在刺激肠上皮细胞分泌细胞方面发挥作用。我们已经证明，ENS的消融会刺激上皮细胞增殖。由于杯状细胞是上皮片的重要组成部分，因此必须单独研究这种细胞类型。通过使用苯扎氯铵 (BAC) 的浆膜部分去除出生后发育中大鼠回肠的肌间神经丛。使用了三组动物: BAC施用于13天，牺牲在15 (13/28天大) 或治疗后23天 (13/36天大) 的动物，以及在治疗后21天 (21/36天大) 施用BAC和杀死大鼠的那些。在通过高碘酸席夫 (PAS) 组织化学染色的切片中估计回肠中杯状细胞的数量。在13/28和21/36组中，BAC处置后杯状细胞的数目显著增高。这些结果表明，肌间神经支配可能对哺乳和断奶大鼠的杯状细胞数量有急性影响，可能是通过粘膜下丛。

BACKGROUND & AIMS: To determine the best and simplest method for cryopreservation of pig hepatocytes, we compared immediate cryopreservation with cryopreservation after short-term culture. Suckling pig hepatocytes were isolated by a modified 2-step in situ collagenase perfusion method, suspended in serum-free medium, and preserved for 10 da by two cryopreservation methods. Serial measurements were made of cell viability, LDH release, synthesis of protein, urea and glucose, glucose-6-phosphatase (G-6-Pase) activity, and diazepam transformation after thawing. These measurements were performed on both groups of cultured hepatocytes, and on freshly isolated hepatocytes, which served as a control. High viability (>95%)of thawed hepatocytes was obtained and maintained in both cryopreservation groups. There were no significant differences in cell viability, protein synthesis, glucose synthesis, G-6-Pase activity, or diazepam transformation between the two cryopreservation groups. In the immediate cryopreservation group, urea synthesis was less than in the group with cryopreservation after short-term culture. Protein synthesis, glucose synthesis, and diazepam transformation were lower in both cryopreserved groups than in the controls. The results showed that a protocol of immediate cryopreservation of hepatocytes in RPMI-1640 medium containing 10% DMSO, hormones, growth factors, and 10% newborn bovine serum, together with rate-controlled freezing and rapid thawing, provides indices of cell viability and function during subsequent serum-free culture that are comparable to hepatocytes cryopreserved after short-term culture, except for lower urea production. This simple procedure can be used in studies of bioartificial liver and hepatocyte transplantation.

背景与目标： 为了确定猪肝细胞冷冻保存的最佳，最简单的方法，我们将短期培养后的立即冷冻保存与冷冻保存进行了比较。采用改良的2步原位胶原酶灌注法分离乳猪肝细胞，悬浮于无血清培养基中，通过两种冷冻保存方法保存10 da。对细胞活力，LDH释放，蛋白质，尿素和葡萄糖的合成，葡萄糖-6-磷酸酶 (G-6-Pase) 活性以及解冻后的地西epa转化进行了连续测量。这些测量是在两组培养的肝细胞以及作为对照的新鲜分离的肝细胞上进行的。在两个冷冻保存组中获得并维持解冻的肝细胞的高活力 (>95%)。两个冷冻保存组之间的细胞活力，蛋白质合成，葡萄糖合成，G-6-Pase活性或地西epa转化均无显着差异。在短期培养后，立即冷冻保存组的尿素合成少于冷冻保存组。两个冷冻保存组的蛋白质合成，葡萄糖合成和地西epa转化均低于对照组。结果表明，在含有10% DMSO，激素，生长因子和10% 新生牛血清的RPMI-1640培养基中立即冷冻保存肝细胞的方案，以及速率控制的冷冻和快速解冻，在随后的无血清培养过程中提供细胞活力和功能的指标，这些指标与短期培养后冷冻保存的肝细胞相当，但尿素产量较低。这种简单的方法可用于生物人工肝和肝细胞移植的研究。