Pioglitazone time-dependently reduces tumour necrosis factor-alpha level in muscle and improves metabolic abnormalities in Wistar fatty rats

In order to evaluate the relationship between tumour necrosis factor-alpha (TNF-alpha) level in muscle and metabolic abnormalities in obesity and diabetes mellitus, pioglitazone, a novel insulin-sensitizing agent, was administered to Wistar fatty rats and time-dependent changes in muscle TNF-alpha content and plasma indicators of diabetes and obesity were measured. Wistar fatty rats were hyperglycaemic, hyperlipidaemic and hyperinsulinaemic, and their plasma and muscle TNF-alpha levels were two or more times higher than those in normal lean rats at 16 weeks of age. When pioglitazone was administered to fatty rats at a dose of 3 mg kg(-1) day(-1), the plasma triglyceride level and TNF-alpha levels in plasma and muscle decreased time-dependently, and reached the levels of lean rats within 4 days. Plasma glucose and insulin levels also decreased time-dependently with pioglitazone, but on day 4, these levels were still much higher than the levels in lean rats. Neutral sphingomyelinase (SMase) activity in muscle of fatty rats was two times higher than that in lean rats and was lowered to the level of that in lean rats by 4 days' pioglitazone administration. The plasma leptin level in fatty rats was 8 times higher than that in lean rats, but pioglitazone did not affect the level during the 4-day administration period. These results suggest that an increase in TNF-alpha production and subsequent activation of SMase in muscle leads to metabolic abnormalities in obesity and diabetes and that antidiabetic activity of pioglitazone is deeply associated with the suppression of TNF-alpha production.

A simplified method for the quantitative analysis of 99Tc(m)-GSA liver scintigraphy using spectral analysis

The aim of this study was to develop a simplified method for quantitative analysis of liver scintigraphy with 99Tc(m)-diethylenetriamine pentaacetic acid-galactosyl-human serum albumin (GSA) using spectral analysis. Dynamic liver scintigraphy using GSA was performed in three normal volunteers and 19 patients with chronic liver disease. Dynamic data were obtained with a gamma camera for 30 min after the injection of approximately 185 MBq GSA. The rate constant for the liver uptake of GSA from the blood (Ku, min(-1)), total excretion rate (Ke, min(-1)) and non-specific volume of distribution (Vh) were obtained by spectral analysis. Vh was defined as the volume in the liver region of interest (ROI) occupied by GSA which was in equilibrium with that in the blood. It should be noted that Vh had no units, since the counts in both the liver and heart ROIs were normalized by scan length to obtain counts pixel(-1) min(-). For comparison, compartmental analysis was also performed. A receptor index (LHL15) was calculated by dividing the radioactivity of the liver ROI by that of the liver plus heart ROIs 15 min post-injection. The Ku values obtained by spectral analysis (y) agreed well with those obtained by compartmental analysis (x) (y = 0.953x - 0.013, r = 0.992, S.E.E. = 0.016 min(-1)). The Ke and Vh values obtained by spectral analysis (y) correlated significantly with those obtained by compartmental analysis (x) (y = 1.149x - 0.016, r = 0.826, S.E.E. = 0.017 min(-1) for Ke; y = 1.191x + 0.044, r = 0.975, S.E.E. = 0.021 for Vh). The Ku values obtained by spectral analysis decreased as the severity of liver disease progressed, and were non-linearly related to the LHL15 values, suggesting that Ku is more sensitive to liver damage than LHL15, especially in the early stages of liver damage. These results suggest that spectral analysis applied to dynamic liver scintigraphy with GSA provides a simple, non-invasive and useful tool for the quantitative evaluation of liver function.

Mechanotransduction and intracellular signaling mechanisms of stretch-induced remodeling in endothelial cells

We investigated the signaling mechanism of stretch-induced cell remodeling in human umbilical vein endothelial cells (HUVECs). Freshly dissociated HUVECs were cultured on an elastic silicon membrane and subjected to uniaxial cyclic stretch (20% in length, 1 Hz). The cells started to change their morphology as early as 15 min after stretch onset, and most cells eventually aligned perpendicularly to the stretch axis within 1 h. This remodeling was dependent on the increase in intracellular calcium concentration ([Ca2+]i) via a Ca(2+)-permeable stretch-activated (SA) channel. During the process of remodeling, extensive rearrangement of stress fibers and focal adhesions was observed, which may be close to the final step in the intracellular signaling cascade. This event was [Ca2+]i-dependent, suggesting the existence of a Ca(2+)-dependent intermediate cascade that links [Ca2+]i to the rearrangement of cytoskeletons and focal adhesions. We found that some proteins, including pp125FAK (focal adhesion kinase) and paxillin, were tyrosine phosphorylated during cyclic stretch in a Ca(2+)-dependent manner. Inhibition of this tyrosine phosphorylation prohibited the stretch-dependent rearrangement of cytoskeletons and focal adhesions as well as the remodeling. Finally the tyrosine kinase src, which could phosphorylate pp125FAK, was found to be activated in a [Ca2+]i-dependent way during stretch. All of the above molecular events were consistently Ca(2+)-dependent, which led us to propose the signaling cascade: SA channel activation-->[Ca2+]i increase-->src activation-->protein tyrosine phosphorylation-->rearrangement of cytoskeletons and focal adhesions-->cell remodeling.

[Estimation of integral value of input function for the quantification of cerebral blood flow with 123I-IMP using one-point arterial blood sampling]

Cerebral blood flow (CBF) has been measured using a microsphere model with octanol-extracted radioactivity counts (integral value of input function). We developed a new method estimating the integral value of input function. First, we fitted the whole brain time-activity curves early after intravenous injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) by the least-squares method. Second, we differentiated this equation. Third, we calibrated it using octanol-extracted radioactivity counts of the arterial blood sampled at 5 min. Finally, we integrated it. A significant correlation was found between the integral values obtained using a new method and those obtained using the continuous arterial blood sampling data (y = 1.048x-1206, r = 0.984). The errors between the CBF values obtained using a new method and those obtained using the 5-min continuous arterial blood sampling was 6.88 +/- 4.78%. Measurement of integral values of the input function using a new method with one-point arterial blood sampling is less invasive and convenient, and is not influenced by cardiopulmonary disease or smoking. Therefore, it would be useful for the routine measurement of CBF.

[Simplified method to quantitate regional cerebral blood flow by 123I-IMP microsphere model: validity of input counts by using the whole brain time-activity curve and one point arterial blood sampling]

We developed a new microsphere method using 123I-IMP in which arterial blood is collected at one time point early after 123I-IMP injection instead of conventional continuous arterial blood sampling, and the input count is estimated using a whole brain time-activity curve until that time point. The differential curve dCb(t)/dt of the brain time-activity curve Cb(t) early after 123I-IMP injection (when the microsphere model is established) approximates the arterial time-activity curve Ca(t) as an input function. The input count as the integral value of Ca(t) at 0-5 min was estimated using the 50 min whole brain activity Cb(5 min) and the differential value dCb(5 min/dt and the 5-min octanol-extracted count of arterial samples obtained at one time point Ca(5 min). The input counts calculated by this method were very closely correlated with measurement values obtained by continuous arterial sampling. This method is more convenient and less invasive than the continuous arterial sampling method.

Spectral analysis applied to hepatobiliary dynamic scintigraphy with 99Tcm-N-pyridoxyl-5-methyltryptophan

This study was performed to evaluate the application of spectral analysis (SA) to hepatobiliary dynamic scintigraphy with 99Tcm-N-pyridoxyl-5-methyltryptophan (99Tcm-PMT) in 82 patients with a wide range of liver function, and to compare it with compartment analysis (CA) and deconvolution analysis (DA). The rate of uptake of PMT by the liver from the blood (k1) obtained by SA (y, min-1) agreed well with the k1 value obtained using CA (x, min-1) (y = 1.079x + 0.000, r = 0.993, standard error of the estimate (S.E.E.) = 0.042 min-1). The mean residence time (MRT) of PMT in the liver obtained by SA (y, min) also agreed well with the MRT value obtained by DA (x, min) (y = 1.036x - 0.759, r = 0.967, S.E.E.-1.014 min) and that obtained by CA (x, min) (y = 0.859x + 1.006, r = 0.931, S.E.E. = 1.428 min). The fraction of the measured blood activity superimposed on the true liver activity (f) obtained by SA (y) correlated well with the f value obtained by CA (x) (y = 1.168x - 0.004, r = 0.924, S.E.E. = 0.043). We conclude that the application of SA to hepatobiliary dynamic scintigraphy with PMT appears to be useful in evaluating the functional status of the liver, since it facilitates the interpretation of the kinetic behaviour of PMT in the liver and allows us to extract quantitative parameters corresponding to those obtained by CA or DA.

[Tachykinin receptor subtypes involved in endothelium-dependent and -independent responses in rabbit intrapulmonary arteries]

In the present study, it was demonstrated that SP, neurokinin A (NKA), neurokinin B (NKB), SP methyl ester (SPME), [Ala5, beta-Ala8]-alpha-neurokinin fragment 4-10 (AANF) at 10(-8) M all caused contraction in non-contracted endothelium-intact arteries. SP- and SPME-induced contraction were reduced by removal of endothelium. All the peptides with the exception of AANF induced transient relaxation in the precontracted arteries. The relaxation were attenuated by removal of endothelium. The potency orders for endothelium-dependent contraction (EDC), -dependent relaxation (EDR) and -independent contraction (EIC) were SP > SPME >> NKA [symbol: see text] NKB [symbol: see text] AANF, SP > SPME > NKA > NKB >> AANF and NKA > AANF > NKB >> SP [symbol: see text] SPME, respectively. SP-induced EDC and EDR were attenuated by an NK1 antagonist but not by an NK2 antagonist. The SP-induced EIC was reduced by an NK2 antagonist. SP-induced EDC was attenuated by aspirin, OKY-046, and S-1452. The EDR was attenuated by L-NAME and methylene blue. The EDC induced by SPME was non-competitively attenuated by CP-99994, an NK1 antagonist. EDR was competitively inhibited by CP-99994. In conclusion, SP and related peptides caused EDC via NK1 receptors and TXA2 production, EDR via NK1 receptors and NO release and EIC via NK2 receptors in rabbit intrapulmonary arteries.

Types of potassium channels involved in coronary reactive hyperemia depend on duration of preceding ischemia in rat hearts

This study was undertaken to clarify factors other than nitric oxide involved in reactive hyperemia after a short (30 sec) and a long (300 sec) coronary global no-flow ischemia in isolated rat hearts perfused at a constant pressure (90 mmHg) with special focuses on the contribution of various K channels including large and small conductance Ca-activated K (KCa) channels as well as ATP-sensitive K (KATP) channels. Reactive hyperemia was induced following 30 sec and 300 sec of no-flow ischemia of the heart. Coronary reactive hyperemia was observed even after the inhibition of nitric oxide synthase by N(omega)-nitro-L-arginine methylester (L-NAME). Selected K channel blockers, none of which affected the basal flow, were used to evaluate contribution of K channels to this L-NAME-resistant reactive hyperemia. After 30-sec ischemia, tetraethylammonium (TEA: a non-selective K channel blocker), glibenclamide (Gli: a KATP channel blocker) and alpha,beta-methylene adenosine 5'-diphosphonate (AOPCP: an inhibitor of ecto 5'-nucleotidase) all suppressed both peak flow/basal flow (%PF) and repayment of flow debt (%RFD). After 300-sec ischemia, TEA and charybdotoxin (ChTX: a large conductance KCa channel blocker) decreased %PF and %RFD; AOPCP decreased both %RFD and duration, 4-aminopyridine (a voltage-dependent K channel blocker) decreased only duration. Neither apamin (a small conductance KCa channel blocker) nor indomethacin (a cyclooxygenase inhibitor) affected the both types of reactive hyperemia. These findings suggest that opening of KATP channel contributes to coronary vasodilation in reactive hyperemia after short 30-sec ischemia, and that opening of KCa, but not KATP, channel contributes to it after long 300-sec ischemia. These results also suggest that adenosine may partly be involved in both types of reactive hyperemia.

Dopaminergic transmitter up-regulation of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) synthesis in mouse astrocytes in culture

We developed a highly sensitive enzyme immunoassay (EIA) system for brain-derived neurotrophic factor (BDNF) based on a biotin-streptavidin detection system capable of measuring concentrations as low as 1.0 pg/ml with high reproducibility. Using this EIA system, we examined the effect of dopaminergic transmitters such as dopamine and epinephrine on BDNF synthesis in mouse astrocytes in culture. These drugs had a stimulating effect on BDNF synthesis and showed a stronger promoting activity toward BDNF synthesis than toward nerve growth factor (NGF) synthesis. This is the first reported study in which BDNF synthesis was shown to be strongly stimulated by dopaminergic transmitter in mouse astrocytes. Then, we measured BDNF levels in the developing rat brain (striatum and midbrain). BDNF levels were relatively higher than NGF and NT-3 levels in these tissues. The BDNF level was high at the early stage in which neurons were proliferating, migrating, and differentiating, and it generally decreased as these cells matured.

[CT-ventriculography: a new application of the helical CT]

The authors proposed a new application of helical CT, namely, CT-ventriculography that can obtain 2D and 3D images of different cardiac phases. CT-ventriculography could assess wall motion, systolic thickening and chamber volume. From a single breath hold helical CT 50-rotation), about 500 transaxial slices were obtained by applying overlapping reconstruction (0.1 pitch, 0.08 sec = 0.2 mm interval). All transaxial slices were recordered to separate different cardiac phases. Then, long and short axial 2D tomograms and 3D images in different cardiac phases were reformatted. CT-ventriculography is a promising new application for the assessment of heart function.

[Postoperative electroencephalographic change in old patients with cardiac surgery]

The purpose of this study was to evaluate cerebral dysfunction in aged patients associated with cardiac surgery using quantitative electroencephalograph (QEEG). Seventeen consecutive patients undergoing cardiac surgery were investigated. There were nine males and eight females whose ages ranged from 65 to 77 years (mean 70.6 years). The cardiac procedures consisted primarily of coronary artery bypass (eleven patients) and valve replacement (six patients). They had good postoperative course, no complications were recognized. Each patient had an EEG examination using digital EEG equipment in first day before operation. Follow up investigations were repeated three times (first day, fifth day and one month after operation). QEEG analysis consisted of fast Fourier transform method was performed in each record. A fall in the peak frequency at basic rhythm was seen in 1st and 5th postoperative day. A power spectra corresponding to slow wave showed an increase at parieto-occipital area in 1st and 5th postoperative day. Alpha activity at occipital area was increased in one month after operation. The EEG change in first or fifth postoperative day suggested the patients had cerebral dysfunction without clinical findings.

Response characteristics of nucleus submedius neurons to colo-rectal distension in the rat

The effects of colorectal distension (CRD) were examined on neurons located in and around the nucleus submedius (Sm) in the medial thalamus of urethane-anesthetized rats. A total of 66 units (49 in the Sm and 17 in immediately surrounding regions) responding to cutaneous pinch were tested to examine their responsiveness to the CRD. All the neurons that responded to cutaneous stimulation were nociceptive specific (NS) neurons. Based on their responses to the CRD the Sm neurons were classified into three types as follows: 23 (47%) of 49 neurons in the Sm and three (18%) of 17 neurons near the Sm had tonic excitatory responses with long-lasting after-discharges (type I); nine (18%) Sm neurons and four (24%) peri-Sm neurons were tonically excited but had no after-discharge (type II); and seven (14%) Sm neurons were inhibited (type III). Ten (20%) Sm neurons and 10 (59%) peri-Sm neurons did not respond to CRD. All the excitatory and inhibitory responses to CRD increased with increasing CRD pressure. Simultaneous application of CRD and cutaneous pinch did not produce a reduced response (nocigenic inhibition). These results demonstrate that most of the Sm neurons receive convergent viscerosomatic inputs from the colon and/or rectum and from the skin, suggesting that the Sm may participate in visceral nociception.

[Compton-scatter correction using the triple energy window (TEW) method in conventional single photon emission computed tomography without TEW acquisition hardware]

We devised a method which allowed the triple energy window (TEW) method to be applied for Compton-scatter correction in conventional single photon emission computed tomography (SPECT) systems without any hardware for TEW acquisition. In this method, the data within two subwindows located at both sides of the main window were acquired together. The effectiveness of this method was investigated by phantom experiments. The integral and differential uniformities measured using a flood phantom filled with 123I were minimized when the energy width of subwindows was 5 keV (5.8% and 4.2%, respectively). When this method was applied to a brain phantom filled with 123I in which the relative activities in white and gray matter were assigned as 1: 4.3, the ratio of SPECT values between them was more accurate (1:4.26) than that obtained without this method (1:208). This method appears to be useful for Compton-scatter correction in SPECT, because it can be applied to conventional SPECT systems without any hardware for TEW acquisition and is available for routine clinical use for its simplicity.

Biphasic effects of D3-receptor agonists, 7-OH-DPAT and PD128907, on the D1-receptor agonist-induced hyperactivity in mice

Effects of D3-receptor agonists, 7-OH-DPAT and PD128907, on the D1-receptor agonist SKF81297-induced hyperactivity in mice were examined. 7-OH-DPAT and PD128907 significantly suppressed the SKF81297-induced hyperactivity at low doses, but significantly potentiated the hyperactivity at high doses. These D3-agonists alone had no effect on the motor activity. A kappa-receptor agonist that reduces dopamine release had no effect on the SKF81297-induced hyperactivity. These results suggest that lower doses of 7-OH-DPAT and PD128907 may negatively influence the D1-receptor mediated behaviors via post synaptic D3-receptors. On the other hand, higher doses of these compounds may positively influence these behaviors via D2- or D3-receptors.

Expression of neurotrophic factors in cultured human retinal pigment epithelial cells

PURPOSE

To see if cultured human retinal pigment epithelial (RPE) cells have the capacity to synthesize neurotrophins, including nerve growth factor (NGF), brain-derived growth factor (BDNF), and neurotrophin-3 (NT-3).

METHODS

Expression of mRNAs for the neurotrophins was studied by the reverse transcription polymerase chain reaction (PCR) method. Quantitative analysis of the gene expression was done by using a semiquantitative PCR method. Secretion of NGF-like immunoreactivity (NGF-LI) into the culture medium was analyzed by enzyme immunoassay (EIA).

RESULTS

Cultured human RPE cells were found to express mRNAs for NGF, BDNF and NT-3. In the conditioned culture medium of the human RPE, 9.44 +/- 0.62 pg/ml (mean +/- SEM, n = 6) NGF-LI was found. Pretreatment of human RPE cells with interleukin-l (IL-1) (20 ng/ml), phorbol myristate acetate (PMA) (100 ng/ml) or tumor necrosis factor-alpha (TNF-alpha) (40 ng/ml) was found to increase the mRNA expression of neurotrophins and also to increase secretion of NGF-LI into the culture medium.

CONCLUSIONS

Our data demonstrate that cultured human RPE cells have the capacity to synthesize neurotrophins, and that various stimulations can up-regulate gene and protein expression of NGF by these cells.

Compartmental analysis of asialoglycoprotein receptor scintigraphy for quantitative measurement of liver function: a multicentre study

A multicentre study on multicompartmental analysis of hepatic scintigraphy using technetium-99m labelled galactosyl serum albumin (GSA), which binds to the asialoglycoprotein receptor, was carried out at seven institutions in Japan. Seventy-four patients with liver disease received 3 mg (185 MBq) of 99mTc-GSA by intravenous injection. Sequential scanning was performed 30 min after injection to obtain anterior images of the heart and liver, followed by single-photon emission tomography (SPET). The indices included in this analysis were hepatic blood flow (Q) and maximal receptor binding rate (Rmax), which showed a good correlation with semiquantitative ratio indices for 99mTc-GSA, namely the retention rate in blood (HH15) and the hepatic uptake rate (LHL15). Q and Rmax also showed a significant correlation with other measures of hepatic function. When patients were grouped according to the severity of chronic liver damage (hepatocellular functional damage), Q was reduced in the moderate and severe groups, while Rmax was reduced in proportion to the functional stage. Both parameters showed no inter-institution difference using analysis of co-variance with the functional stage as a co-variant. With regard to the hepatic uptake rate, anterior planar images and SPET images gave similar results for Q and Rmax. Acquisition times of 15 or 30 min provided the same results. The multicompartmental model analysis permitted comparable results to be obtained at institutions using different gamma cameras, and is therefore considered a universally applicable method. These results indicate that Q and Rmax are useful general indices for evaluating the functional reserve capacity of the liver.

Assessment of left ventricular volume using ECG-gated SPECT with technetium-99m-MIBI and technetium-99m-tetrofosmin

We evaluated ECG-gated SPECT (g-SPECT) in the measurement of absolute left ventricular (LV) volume by comparing it with left ventriculography (LVG) and with cine-MRI.

METHODS

Projection data from 31 patients were acquired with a three-headed SPECT system in 12 min using a 64 x 64 matrix with 1.5 zoom (1 pixel = 4.27 mm). The R-R interval from simultaneously acquired ECG was divided into eight frames. The end-diastolic and end-systolic volumes (EDV; ESV) and LV mass were assessed by an area-length method with manual delineation of the epi- and endocardial LV borders using midventricular vertical and horizontal long-axis images. The stroke volume, LVEF and cardiac output (CO) were generated from the EDV, ESV and heart rate during the study. The g-SPECT LV values were compared with those of LVG (25 patients) and cine-MRI (18 patients).

RESULTS

The g-SPECT values correlated well with those from LVG (r = 0.83 to 0.92; p < 0.001) and cine-MRI (r = 0.76 to 0.99; p < 0.001). The g-SPECT technique provides an assessment of LV volumes (EDV, ESV, stroke volume, LVEF, CO, LV mass).

CONCLUSION

Despite potential problems that may cause inaccuracy and require improvements such as an accurate and reproducible automatic edge detection algorithm, g-SPECT has clinical utility in assessing global LV volumes and function.

Effects of chronic treatment with a cyclic AMP-selective phosphodiesterase inhibitor, rolipram, on excitatory amino acid neurotransmission systems in young and aged rat brains

Rolipram selectively inhibits cyclic AMP-specific phosphodiesterase, and leads to an increase in cyclic AMP levels in the brain. In this study, we investigated the effects of chronic rolipram treatment on excitatory and inhibitory amino acid neurotransmission systems in young and aged Wistar rat brains. We used in vitro autoradiography with [3H]MK-801, [3H]glycine, D[3H]aspartate, and [3H]muscimol to label N-methyl-D-aspartate (NMDA) receptors, glycine modulatory sites, glutamate transport sites, and gamma-aminobutyric acid-A (GABA) receptors, respectively. Rolipram (0.01 or 0.1 mg/kg, per os) or its vehicle (distilled water) was administered once a day for 4 weeks. The highest binding of [3H]MK-801, [3H]glycine, and D-[3H]aspartate was seen in the hippocampus in vehicle-treated rats. No significant differences in these binding activities were seen between young and aged rat brains. [3H]Muscimol binding was the highest in the cerebellum, and decreased in many brain regions in aged rats. The chronic rolipram treatment resulted in (1) an increase in [3H]MK-801 binding in the dentate gyrus in both young and aged rats, (2) remarkable reductions in D-[3H]aspartate binding in many regions of both young and aged rats, and (3) no or minimal changes in [3H]glycine and [3H]muscimol binding. These results suggest that the chronic rolipram treatment modifies the excitatory amino acid neurotransmission system.

Previous inflammation alters the response of the rat colon to stress

BACKGROUND & AIMS

Patients with inflammatory bowel disease have symptoms of irritable bowel syndrome (IBS) with a higher than expected prevalence. Stress is an important factor in the pathogenesis of IBS. Thus, previous inflammation may predispose to IBS by rendering the bowel more susceptible to the impact of stress. The aim of this study was to examine the effect of previous colitis on stress-induced responses in rats.

METHODS

Acute colitis was induced in rats by intrarectal administration of trinitrobenzene sulfonic acid (TNBS), and the rats were allowed to recover for 6 weeks before application of mild restraint stress for 3 consecutive days. In vitro measurements included myeloperoxidase activity, plasma corticosterone levels, interleukin 1 beta messenger RNA expression, and [3H]noradrenaline release from the myenteric plexus.

RESULTS

Six weeks after administration of TNBS, stress caused a significant increase in myeloperoxidase activity in TNBS-treated rats but not in stressed controls; plasma corticosterone responses were similar. Stress also caused an exaggerated and significant suppression of [3H]noradrenaline release in TNBS-treated stressed rats compared with stressed controls. This was accompanied by a significant decrease in interleukin 1 beta messenger RNA expression in the colon.

CONCLUSIONS

Previous colitis rendered the colon more susceptible to effects of stress on enteric nerve function and also increased some parameters of inflammation in response to stress.

Impairment of antioxidants in colonic epithelial cells isolated from trinitrobenzene sulphonic acid-induced colitis rats. Protective effect of rebamipide

BACKGROUND

The functional status of glutathione, its related enzymes, and Cu,Zn-superoxide dismutase in colonocytes isolated from rats with trinitrobenzene sulphonic acid-induced colitis, and the effect of rebamipide (a scavenger) on these antioxidants and on colitis, were studied.

METHODS

The rats were treated with rebamipide, killed on day 14, and compared with controls. Glutathione and enzymatic activities were spectrophotometrically estimated. The effect of rebamipide on colitis was also assessed histologically and by myeloperoxidase activity.

RESULTS

In controls the concentration of glutathione and the activities of glutathione S-transferase and Cu,Zn-superoxide dismutase were decreased, but that of glutathione peroxidase was increased. Rebamipide prevented the impairment of these enzymes, restored the concentration of glutathione, and attenuated (low damage scores and myeloperoxidase activity) the severity of the colitis.

CONCLUSIONS

These features suggest that the impairment of antioxidants is closely related to the development of the inflammatory lesions, and rebamipide has a beneficial effect on experimental colitis.

Insulin increases distinct species of 1,2-diacylglycerol in isolated perfused rat heart

Insulin and glucose increase the synthesis of 1,2-diacylglycerol (1,2-DAG), the physiological activator of protein kinase C (PKC) in a variety of tissues and cells. The effects of insulin and glucose on the abundance and fatty acid composition of 1,2-DAG were investigated in isolated perfused rat hearts with the use of capillary gas chromatography and 1,2-dipentadecanoin as an internal standard. A high concentration of insulin (25 mU/ mL) significantly increased cardiac contractility and reduced coronary flow. In addition, perfusion with 25 mU/mL insulin induced significant increases of 18.2% and 26.4% in 1,2-DAG mass after 5 and 30 minutes, respectively, in the presence of 8.6 mmol/L glucose, whereas there was no increase in 1,2-DAG with 2.5 mU/mL insulin. Analysis of the fatty acid composition of 1,2-DAG showed that only species containing specific fatty acids (16:0, 18:1, and 18:2) were increased in response to insulin. In contrast, an increase in glucose concentration in the perfusion medium from 3 to 17 mmol/L had no effect on the total mass or fatty acid composition of 1,2-DAG, cardiac contractility, or coronary flow. Addition of a high insulin concentration to the high-glucose medium increased the abundance of 1,2-DAG containing 16:0, 18:1, and 18:2 fatty acids, as well as cardiac contractility. It is concluded that the effect of insulin on cardiac contractility may be related to the associated increase in 1,2-DAG abundance.

Effects of aluminum(III) on catechol-stimulated nerve growth factor biosynthesis by cultured mouse brain astroglial cells

The effects of aluminum and other metal ions on the synthesis of nerve growth factor (NGF) by cultured mouse brain astroglial cells have been investigated. Natural NGF formation was dependent on the AlCl3 concentration of the cell culture medium; it was stimulated at low concentrations but was inhibited at higher concentrations. Catechol-stimulated NGF formation was also inhibited at AlCl3/catechol molar ratios > 0.3, whereas ZnCl2 and CaCl2 had no effect under similar conditions. Ethylenediamine-N,N,N',N'-tetraacetate (EDTA) and citrate blocked the inhibitory effect of Al(III). These observations were explained by the complex formation between Al(III) and catechols.