A high-fat diet aggravates tubulointerstitial but not glomerular lesions in obese Zucker rats

A high-fat diet aggravates tubulointerstitial but not glomerular lesions in obese Zucker ratsBackgroundDespite a large body of evidence that manipulation of dietary fat alters glomerular lesions, reports regarding the effects of dietary fat on tubulointerstitial lesions are limited. Obese Zucker rats (OZR) spontaneously develop glomerular and tubulointerstitial lesions in association with hyperlipidemia. We sought to elucidate the effects of dietary fat on glomerular and tubulointerstitial lesions in OZR versus lean Zucker rats (LZR) and to assess the involvement of macrophages in the development of these lesions.MethodsWe fed LZR and OZR either a low- (1%) or high-fat (20%) diet. After 30 weeks of the specified diet, the creatinine clearance (CCr) and renal histology as well as plasma lipid concentrations were examined. For morphological evaluation, glomerular sclerosis (GSI) and tubulointerstitial indices (TII) were each determined by a point-counting method. Infiltrating macrophages were stained immunohistochemically using an avidin-biotin complex technique.ResultsThe high-fat diet increased the plasma low-density lipoprotein concentration in OZR. Both low- and high-fat OZR groups had higher GSI and TII than LZR receiving either diet. The high-fat diet aggravated TII but not GSI or CCr in OZR; conversely, high fat intake worsened GSI and CCr but not TII in LZR. Tubulointerstitial macrophages were most prominent in the high-fat OZR group, followed by the low-fat OZR group. Glomerular macrophages were similar in number in all groups.ConclusionsThe manipulation of dietary fat has diverse effects on the kidney. A high-fat diet aggravated macrophage-mediated tubulointerstitial lesions in OZR, whereas in LZR, the diet induced glomerulosclerosis

Evidence for the possible involvement of the P2Y6 receptor in Ca2+ mobilization and insulin secretion in mouse pancreatic islets

Subtypes of purinergic receptors involved in modulation of cytoplasmic calcium ion concentration ([Ca2+]i) and insulin release in mouse pancreatic β-cells were examined in two systems, pancreatic islets in primary culture and beta-TC6 insulinoma cells. Both systems exhibited some physiological responses such as acetylcholine-stimulated [Ca2+]i rise via cytoplasmic Ca2+ mobilization. Addition of ATP, ADP, and 2-MeSADP (each 100 µM) transiently increased [Ca2+]i in single islets cultured in the presence of 5.5 mM (normal) glucose. The potent P2Y1 receptor agonist 2-MeSADP reduced insulin secretion significantly in islets cultured in the presence of high glucose (16.7 mM), whereas a slight stimulation occurred at 5.5 mM glucose. The selective P2Y6 receptor agonist UDP (200 µM) transiently increased [Ca2+]i and reduced insulin secretion at high glucose, whereas the P2Y2/4 receptor agonist UTP and adenosine receptor agonist NECA were inactive. [Ca2+]i transients induced by 2-MeSADP and UDP were antagonized by suramin (100 µM), U73122 (2 µM, PLC inhibitor), and 2-APB (10 or 30 µM, IP3 receptor antagonist), but neither by staurosporine (1 µM, PKC inhibitor) nor depletion of extracellular Ca2+. The effect of 2-MeSADP on [Ca2+]i was also significantly inhibited by MRS2500, a P2Y1 receptor antagonist. These results suggested that P2Y1 and P2Y6 receptor subtypes are involved in Ca2+ mobilization from intracellular stores and insulin release in mouse islets. In beta-TC6 cells, ATP, ADP, 2-MeSADP, and UDP transiently elevated [Ca2+]i and slightly decreased insulin secretion at normal glucose, while UTP and NECA were inactive. RT-PCR analysis detected mRNAs of P2Y1 and P2Y6, but not P2Y2 and P2Y4 receptors

Mechanically induced electrical responses in murine mammary epithelial cells in primary culture

AbstractIn mouse mammary epithelial cells in primary culture, mechanical stimulation of a cell induced in other cells within the same colony a short depolarization of less than 15 m V with a duration of 1–8 s and a subsequent, prominent hyperpolarization of 6 m V lasting 10–40 s. Epidermal growth factor induces a spontaneous hyperpolarizing response in cultured mammary cells, and in cells treated with EGF mechanical stimulation produced a greater hyperpolarization, while the amplitude of the depolarizing response was not affected. The amplitude of the mechanically induced hyperpolarization was markedly reduced by quinine and tetraethylammonium, blockers of the Ca2+-dependent K+ channel. The results suggest that the Ca2+-dependent K+ channel was involved in the hyperpolarization

Stat5 determines the development of mammary alveolar cells

Functional development of mammary epithelium during pregnancy depends on prolactin signaling. However, the underlying molecular and cellular events are not fully understood. We examined the specific contributions of the prolactin receptor (PrlR) and the signal transducers and activators of transcription 5a and 5b (referred to as Stat5) in the formation and differentiation of mammary alveolar epithelium. PrlR- and Stat5-null mammary epithelia were transplanted into wild-type hosts, and pregnancy-mediated development was investigated at a histological and molecular level. Stat5-null mammary epithelium developed ducts but failed to form alveoli, and no milk protein gene expression was observed. In contrast, PrlR-null epithelium formed alveoli-like structures with small open lumina. Electron microscopy revealed undifferentiated features of organelles and a perturbation of cell–cell contacts in PrlR- and Stat5-null epithelia. Expression of NKCC1, an Na-K-Cl cotransporter characteristic for ductal epithelia, and ZO-1, a protein associated with tight junction, were maintained in the alveoli-like structures of PrlR- and Stat5-null epithelia. In contrast, the Na-Pi cotransporter Npt2b, and the gap junction component connexin 32, usually expressed in secretory epithelia, were undetectable in PrlR- and Stat5- null mice. These data demonstrate that signaling via the PrlR and Stat5 is critical for the proliferation and differentiation of mammary alveoli during pregnancy

Signal transducer and activator of transcription (Stat) 5 controls the proliferation and differentiation of mammary alveolar epithelium

Functional development of mammary epithelium during pregnancy depends on prolactin signaling. However, the underlying molecular and cellular events are not fully understood. We examined the specific contributions of the prolactin receptor (PrlR) and the signal transducers and activators of transcription 5a and 5b (referred to as Stat5) in the formation and differentiation of mammary alveolar epithelium. PrlR- and Stat5-null mammary epithelia were transplanted into wild-type hosts, and pregnancy-mediated development was investigated at a histological and molecular level. Stat5-null mammary epithelium developed ducts but failed to form alveoli, and no milk protein gene expression was observed. In contrast, PrlR-null epithelium formed alveoli-like structures with small open lumina. Electron microscopy revealed undifferentiated features of organelles and a perturbation of cell–cell contacts in PrlR- and Stat5-null epithelia. Expression of NKCC1, an Na-K-Cl cotransporter characteristic for ductal epithelia, and ZO-1, a protein associated with tight junction, were maintained in the alveoli-like structures of PrlR- and Stat5-null epithelia. In contrast, the Na-Pi cotransporter Npt2b, and the gap junction component connexin 32, usually expressed in secretory epithelia, were undetectable in PrlR- and Stat5-null mice. These data demonstrate that signaling via the PrlR and Stat5 is critical for the proliferation and differentiation of mammary alveoli during pregnancy

Absorption Line Survey of H3+ toward the Galactic Center Sources II. Eight Infrared Sources within 30 pc of the Galactic Center

Infrared absorption lines of H3+, including the metastable R(3,3)l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic Center Cluster and the Quintuplet Cluster 30 pc to the east. The absorption lines with high velocity dispersion arise in the Galaxy's Central Molecular Zone (CMZ) as well as in foreground spiral arms. The temperature and density of the gas in the CMZ, as determined from the relative strengths of the H3+ lines, are T=200-300K and n=50-200cm^-3. The detection of high column densities of H3+ toward all eight stars implies that this warm and diffuse gaseous environment is widespread in the CMZ. The products of the ionization rate and path length for these sight lines are 1000 and 10 times higher than in dense and diffuse clouds in the Galactic disk, respectively, indicating that the ionization rate, zeta, is not less than 10^-15 s^-1 and that L is at least on the order of 50 pc. The warm and diffuse gas is an important component of the CMZ, in addition to the three previously known gaseous environments: (1) cold molecular clouds observed by radio emission of CO and other molecules, (2) hot (T=10^4-10^6K) and highly ionized diffuse gas (n_e=10-100cm^-3) seen in radio recombination lines, far infrared atomic lines, and radio-wave scattering, and (3) ultra-hot (T=10^7-10^8K) X-ray emitting plasma. Its prevalence significantly changes the understanding of the environment of the CMZ. The sight line toward GC IRS 3 is unique in showing an additional H3+ absorption component, which is interpreted as due to either a cloud associated with circumnuclear disk or the "50 km s^-1 cloud" known from radio observations. An infrared pumping scheme is examined as a mechanism to populate the (3,3) metastable level in this cloud.Comment: 15 pages, 5 figures, 4 tables Accepted for publication in the Astrophysical Journa

Reinforcement selection acting on the European house mouse hybrid zone

Behavioural isolation may lead to complete speciation when partial postzygotic isolation acts in the presence of divergent‐specific mate‐recognition systems. These conditions exist where Mus musculus musculus and M. m. domesticus come into contact and hybridize. We studied two mate‐recognition signal systems, based on urinary and salivary proteins, across a Central European portion of the mouse hybrid zone. Introgression of the genomic regions responsible for these signals: the major urinary proteins (MUPs) and androgen binding proteins (ABPs), respectively, was compared to introgression at loci assumed to be nearly neutral and those under selection against hybridization. The preference of individuals taken from across the zone regarding these signals was measured in Y mazes, and we develop a model for the analysis of the transition of such traits under reinforcement selection. The strongest assortative preferences were found in males for urine and females for ABP. Clinal analyses confirm nearly neutral introgression of an Abp locus and two loci closely linked to the Abp gene cluster, whereas two markers flanking the Mup gene region reveal unexpected introgression. Geographic change in the preference traits matches our reinforcement selection model significantly better than standard cline models. Our study confirms that behavioural barriers are important components of reproductive isolation between the house mouse subspecies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86873/1/j.1365-294X.2011.05106.x.pd