Loss of estrogen-mediated immunoprotection underlies female gender bias in experimental Crohn's-like ileitis.

The incidence and severity of Crohn's disease (CD) are increased in female patients. Using SAMP1/YitFc (SAMP) mice, a spontaneous model of chronic intestinal inflammation that displays histologic and pathogenic similarities to human CD, we investigated the potential mechanism(s) contributing to sex differences observed in CD. Similar to gender differences observed in CD patients, SAMP female (SAMP-F) mice displayed an earlier onset and more severe ileitis compared with SAMP male (SAMP-M) mice. Furthermore, T-regulatory cells (Tregs) from gut-associated lymphoid tissue (GALT) of SAMP-F mice were reduced in frequency and impaired in their in vitro and in vivo suppressive functions compared with that of SAMP-M mice. Given the interaction between sex hormones and Treg function, we investigated the possible role of estrogen (E2) in SAMP ileitis. SAMP-M mice responded to exogenous E2 administration by expanding Treg frequency and reducing ileal inflammation, whereas SAMP-F mice were resistant. Conventional T cells and Tregs responded differentially to estrogen signaling, leading to distinct immunoprotective effects mediated by distinct estrogen receptor (ER) isoforms. These mechanisms were impaired in T cells from SAMP-F mice. Thus, hormone signaling influences the expansion and function of GALT Tregs in an ER-dependent manner and contributes to gender-based differences in experimental CD.

Indinavir uncovers different contributions of GLUT4 and GLUT1 towards glucose uptake in muscle and fat cells and tissues.

AIMS/HYPOTHESIS: Insulin-dependent glucose influx in skeletal muscle and adipocytes is believed to rely largely on GLUT4, but this has not been confirmed directly. We assessed the relative functional contribution of GLUT4 in experimental models of skeletal muscle and adipocytes using the HIV-1 protease inhibitor indinavir. METHODS: Indinavir (up to 100 micro mol/l) was added to the glucose transport solution after insulin stimulation of wild-type L6 muscle cells, L6 cells over-expressing either GLUT4myc or GLUT1myc, 3T3-L1 adipocytes, isolated mouse brown or white adipocytes, and isolated mouse muscle preparations. RESULTS: 100 micro mol/l indinavir inhibited 80% of both basal and insulin-stimulated 2-deoxyglucose uptake in L6GLUT4myc myotubes and myoblasts, but only 25% in L6GLUT1myc cells. Cell-surface density of glucose transporters was not affected. In isolated soleus and extensor digitorum longus muscles, primary white and brown adipocytes, insulin-stimulated glucose uptake was inhibited 70 to 80% by indinavir. The effect of indinavir on glucose uptake was variable in 3T3-L1 adipocytes, averaging 45% and 67% inhibition of basal and maximally insulin-stimulated glucose uptake, respectively. In this cell, fractional inhibition of glucose uptake by indinavir correlated positively with the fold-stimulation of glucose uptake by insulin, and was higher with sub-maximal insulin concentrations. The latter finding coincided with an increase only in GLUT4, but not GLUT1, in plasma membrane lawns. CONCLUSION/INTERPRETATION: Indinavir is a useful tool to assess different functional contributions of GLUT4 to glucose uptake in common models of skeletal muscle and adipocytes.

Effects of internal globus pallidus stimulation on motor cortex excitability.

BACKGROUND: Deep brain stimulation is a promising treatment for PD, but its physiologic effects and mechanisms of action remain poorly understood. Magnetic stimulation studies have revealed abnormalities in several different excitatory and inhibitory circuits in the motor cortex in PD. METHODS: The physiologic effects of internal globus pallidus (GPi) stimulation in seven patients with PD and seven age-matched healthy volunteers were studied. The stimulators were set at the optimal parameters (ON), at half the optimal amplitude (Half-Amp), or switched off (OFF) in random order. Patients were taking their usual medications. Magnetic stimulation was applied to the motor cortex, and motor evoked potentials (MEP) were recorded from the contralateral first dorsal interosseous muscle. Several excitatory and inhibitory pathways that have been found to be abnormal in PD were tested. RESULTS: The motor threshold (MT), MEP recruitment curve (stimulus intensities from 100 to 150% of MT), short and long interval intracortical inhibition, and intracortical facilitation were similar in the three stimulator conditions tested both at rest and during voluntary contraction. The silent period (SP) was longer in the OFF and Half-Amp conditions than in normal control subjects. In the stimulator ON condition, the SP was significantly reduced compared with the OFF condition and became similar to that in normal control subjects. CONCLUSIONS: GPi stimulation while on dopaminergic medications reduced the SP following magnetic stimulation but did not change corticospinal excitability or other measures of intracortical inhibition and facilitation. The reduction of SP may be related to the antidyskinetic and levodopa-blocking effects of ventral GPi stimulation.

Impairment of motor cortex activation and deactivation in Parkinson's disease.

OBJECTIVES: To examine the time course of corticospinal excitability before and after voluntary movement in Parkinson's disease (PD). METHODS: We studied 9 mild PD patients at least 12 h off medications and 11 healthy volunteers in a simple reaction time (RT) paradigm. Suprathreshold transcranial magnetic stimulation was delivered to the left motor cortex at intervals covering the periods before and after movement. RESULTS: PD patients (284+/-90 ms) and normal subjects (282+/-56 ms) had similar median RT. The time courses of both the premovement increase and the postmovement decrease in corticospinal excitability were significantly different between PD patients and normal subjects. The increase in motor-evoked potential (MEP) amplitudes began earlier for PD patients (200 ms before electromyographic (EMG) onset) than for normal subjects (150 ms before EMG onset), but the rate of increase was slower in PD patients than controls. After EMG offset, MEP amplitudes were increased for about 150 ms in normal subjects, but in PD patients this period was prolonged to about 350 ms. CONCLUSIONS: Impairment of motor cortex activation and deactivation is an early feature of PD and may be a physiological correlate of bradykinesia. The normal RT in our patients may be related to the earlier occurrence of the premovement increase in corticospinal excitability compensating for the slower rate of rise.

Interactions between two different inhibitory systems in the human motor cortex.

Intracortical inhibition in the human motor cortex has been previously demonstrated using paired-pulse transcranial magnetic stimulation (TMS) protocols at short intervals (1-6 ms; short interval intracortical inhibition, SICI) with a subthreshold conditioning pulse preceding a suprathreshold test pulse, and at long intervals (50-200 ms; long interval intracortical inhibition, LICI) with suprathreshold conditioning and test pulses. We investigated whether different circuits mediate these inhibitory phenomena and how they interact. In nine healthy volunteers, we applied TMS to the motor cortex and recorded motor evoked potentials from the first dorsal interosseous muscle. With increasing test pulse strength, LICI decreases but SICI tends to increase. There was no correlation between the degree of SICI and LICI. We tested the interactions between SICI and LICI. SICI was reduced or eliminated in the presence of LICI. Loss of SICI was seen even with a conditioning stimulus too weak to induce significant LICI. Our findings demonstrate that different cell populations mediate SICI and LICI. The results are consistent with the hypothesis that LICI inhibits SICI through presynaptic GABAB receptors. Testing of SICI in the presence of LICI may be a non-invasive way of evaluating inhibitory interactions in the human motor cortex.

Cloning of zebrafish activin type IIB receptor (ActRIIB) cDNA and mRNA expression of ActRIIB in embryos and adult tissues.

A full-length cDNA encoding for activin type IIB receptor (ActRIIB) was cloned from zebrafish embryos. It encodes a protein with 509 amino acids consisting of a signal peptide, an extracellular ligand binding domain, a single transmembrane region, and an intracellular kinase domain with predicted serine/threonine specificity. The extracellular domain shows 74-91% sequence identity to human, bovine, mouse, rat, chicken, Xenopus and goldfish activin type IIB receptors, while the transmembrane region and the kinase domain show 67-78% and 82-88% identity to these known activin IIB receptors, respectively. In adult zebrafish, ActRIIB mRNA was detected by RT-PCR in the gonads, as well as in non-reproductive tissues, including the brain, heart and muscle. In situ hybridization on ovarian sections further localized ActRIIB mRNA to cytoplasm of oocytes at different stages of development. Using whole-mount in situ hybridization, ActRIIB mRNA was found to be expressed at all stages of embryogenesis examined, including the sphere, shield, tail bud, and 6-7 somite. These results provide the first evidence that ActRIIB mRNA is widely distributed in fish embryonic and adult tissues. Cloning of zebrafish ActRIIB demonstrates that this receptor is highly conserved during vertebrate evolution and provides a basis for further studies on the role of activin in reproduction and development in lower vertebrates.

Effect of automobile exhaust on the distribution of trace elements and its modulation following Fe, Cu, and Zn supplementation.

The effect of automobile exhaust on the distribution of trace elements with special reference to Pb and its modulation following Cu, Zn, and Fe supplementation, in mouse organs, has been studied using Energy Dispersive X-ray Fluorescence technique. Seven elements, namely K, Fe, Cu, Zn, Br, Rb, and Pb, were detected in all the organs. The maximum concentration of Pb was found in lungs followed by that in liver and kidney. The effect of automobile exhaust was found to be significant on the concentrations of Fe and Pb; their concentrations were found to increase in all the organs. However, the concentrations of Cu and Zn were found to be decreased significantly in the liver. In the animals given Fe, Cu, or Zn supplementation along with motor exhaust, the percentage change in the concentration of Pb in lungs was decreased, and that of Fe was increased significantly. In kidney, no significant change was observed for the animals given Cu and Zn, whereas for animals given Fe, the level of Pb decreased significantly. In liver, the reduction in the level of Zn in the exhaust-exposed animals was made up and the level of Pb was reduced following Zn supplementation. These results clearly indicate that Fe and Zn play an important role in Pb metabolism and tend to lower the absorption of Pb. The effect of Fe is more pronounced than that of Zn, whereas the effect of Cu seems to be insignificant.