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Rhythmic expression of DEC1 and DEC2 in peripheral tissues: DEC2 is a potent suppressor for hepatic cytochrome P450s opposing DBP.

The mammalian master molecular clock consisting of several clock gene products in the suprachiasmatic nucleus (SCN) drives circadian rhythms in behaviour and physiology. Molecular clocks consisting of the same components also exist in various peripheral organs. DEC1 and DEC2, basic helix-loop-helix transcription factors, were recently reported to be involved in the central clock in the SCN. We examined the expression profile of DEC1 and DEC2 in the periphery and their roles in the regulation of oscillating target genes in the liver. Levels of DEC1 and DEC2 mRNA exhibited a day-night variation in various peripheral tissues of rats. In the liver, their expression was high during the subjective night. Transfection assays showed that DEC2, but not DEC1, suppressed the transcription of the cholesterol 7alpha-hydroxylase gene (CYP7A), overwhelming the potent enhancement by D-site binding protein (DBP). Electrophoretic mobility shift assays indicated that DEC2 binds to the E-box (CACATG) at the -219/-214 region of CYP7A. The transcriptional activities of the other sterol metabolizing cytochrome P450s (Cyps), CYP8B and CYP51, were also suppressed by DEC2 but not DEC1. DEC2, but not DEC1, works as a direct output mediator that transmits the circadian signals to the hepatic functions, including the CYP7A, CYP8B, and CYP51 expression.

Animals↗

Orexin-A expression in human peripheral tissues.

Orexin-A is a neuropeptide present in the brain and is known to regulate feeding and sleeping. In this study, we examined the systemic distribution of orexin-A in human tissues. Immunoreactivity for orexin-A was detected in ganglion cells of the thoracic sympathetic trunk, myenteric plexuses and endocrine cells of the gastrointestinal tract, islet cells of the pancreas and syncytiotrophoblasts and decidual cells of the placenta. In the gastrointestinal tract, orexin-A immunoreactivity was detected in the myenteric plexuses from 26 gestational weeks to birth. In double immunostaining in the pancreas, a great majority of insulin-positive cells was simultaneously positive for orexin-A. mRNA expression for prepro-orexin was also detected in the kidney, adrenal gland, pancreas, placenta, stomach, ileum, colon and colorectal epithelial cells. These results suggest the production of orexin-A in various human peripheral tissues and orexin-A may also play important roles in some peripheral organs.

Adolescent↗

Differential expression of alternative splice variants of beta-arrestin-1 and -2 in rat central nervous system and peripheral tissues.

Members of arrestin/beta-arrestin protein family are thought to participate in agonist-mediated desensitization of G-protein-coupled receptors, including rhodopsin and beta2-adrenergic receptor. Unlike in human and cow, splice variants of this protein family in rat have not been studied extensively, and there has been no report on their existence at protein level. Hence, a previous report by others on the localization of both beta-arrestin-1 and -2 in a wide range of innervated rat tissues could imply their broad receptor specificity. In this report we show the presence of two alternatively spliced forms of beta-arrestin-1 in several rat tissues using both reverse transcription-polymerase chain reaction and Western immunoblot. Splicing of beta-arrestin-1 pre-mRNA appears to be subject to differential regulation between the rat CNS and peripheral tissues. In contrast, we detected no splice variants of beta-arrestin-2 in rat. A comparison of the genomic DNA sequences of bovine and rat beta-arrestin-2, where the splicing of bovine beta-arrestin-2 mRNA has been reported, revealed a high degree of homology in their organization of exons and introns as well as certain differences that might be responsible for the different processing of beta-arrestin-2 mRNA in the two species. Our two-dimensional isoelectric focusing gels using rat spinal cord and heart tissues demonstrate isoelectric heterogeneity of rat beta-arrestin-1, suggesting that beta-arrestin-1 is subject to post-translational modification unlike beta-arrestin-2.

Alternative Splicing↗

Effects of high-fat diet intake on glucose uptake in central and peripheral tissues of non-obese rats.

We previously demonstrated that plasma glucose concentration was higher while plasma insulin concentration was lower in rats fed a high-fat diet. In the present study, we examined the effects of high-fat diet on glucose uptake in central and peripheral tissues in non-obese rats. Forty male Sprague-Dawley rats were fed high- or low-fat diets for 4 wk. Body weight and body fat accumulation were not different between the two diet groups after 4 wk. Glucose uptake in the skeletal muscles and adipose tissues, estimated by the 2-deoxy-D-glucose method, was lower in the rats fed the high-fat diet than that in the rats fed the low-fat diet, whereas uptake in the liver and pancreas did not differ between the two groups. Glucose uptake in the hypothalamus and cortex was higher in the high-fat diet group as compared with that in the low-fat diet group. These results suggest that increased plasma glucose levels in rats fed the high-fat diet were caused by a decrease in glucose uptake in the skeletal muscles and adipose tissues. Reduced plasma insulin level in the high fat diet group with no difference in glucose uptake in the pancreas may be due to increased sympathetic activity in the pancreas resulting from the increased glucose uptake in the brain regions involved in autonomic functions.

Adipose Tissue↗

Pro-melanin concentrating hormone messenger ribonucleic acid and peptides expression in peripheral tissues of the rat.

Melanin-concentrating hormone (MCH) is a cyclic peptide which is predominantly synthetized in the hypothalamus of fish and mammalian brains. In the present paper we examined the expression of MCH mRNA and pro-MCH-derived peptides, i.e. MCH and neuropeptide-(N)-glutamic acid (E) isoleucine (I) amide (NEI), in peripheral tissues of adult rodents. By means of polymerase chain reaction (PCR) of reverse-transcribed RNA, low levels of MCH gene transcripts were detected reliably in testis, stomach, and intestine of Sprague-Dawley and Wistar rats, whereas strong expression was found in hypothalamus. Subsequent sequence analysis of the PCR products verified the authenticity of MCH mRNA found in hypothalamus and stomach. The length of MCH RNA species was measured by Northern blot and multiple MCH RNA species were detected in both rat species. Shortest polyadenylated tails were found in MCH RNAs isolated from the peripheral organs by comparison with hypothalamus MCH RNAs of Wistar rats. In order to localize MCH expression in gastrointestinal and genital tracts of Wistar rats we performed in situ hybridization with specific 33P-labeled oligoprobes joined to immunocytochemical studies with rat MCH or NEI antisera. In testis, the MCH transcripts and pro-MCH-derived peptide immunoreactivities were found at the periphery of the seminiferous tubules, suggesting expression in Sertoli cells. Studies with MCH oligoprobes and antisera directed towards MCH, NEI and alpha A-inhibin revealed similar pattern of expression in isolated Sertoli cells from Swiss mice, indicating that MCH RNA species were actually synthesized and translated in these cells. In the gastrointestinal (GI) tract, the cells expressing MCH RNA species and pro-MCH-derived peptides were predominantly expressed in the antral portion of the stomach and duodenum. Strikingly, distinct oligoprobes, recognizing antisense MCH transcript, revealed a pattern of hybridization in the GI tract similar to this observed with oligoprobes revealing the mature MCH mRNA. Furthermore, total RNA from the pyloric junction, duodenum, jejunum, ileum and hypothalamus as well appeared to contain RNA complementary to MCH mRNA suggesting therefore that antisense MCH RNA species may play a general role in regulation of MCH synthesis. Taken together, our present and previous data indicate that authentic MCH RNA species and translational products are expressed in various rodent tissues at the periphery. The cellular location suggests that MCH and associated peptides may play a role in spermatogenesis and in digestive processes.

Animals↗

Distribution and molecular forms of brain natriuretic peptide in the central nervous system, heart and peripheral tissue of rat.

The amino acid sequence of rat brain natriuretic peptide (rBNP) precursor has recently been deduced by the cDNA cloning method (1). In the present study, a radioimmunoassay (RIA) system for rBNP was newly established, and regional distribution of rBNP in the central nervous system, heart and other peripheral tissue of rat was investigated. In heart, especially in cardiac atrium, a high concentration of immunoreactive (ir-) rBNP was detected and identified as rBNP-45 and gamma-rBNP. No significant amount of ir-rBNP was found in other tissues examined including the central nervous system. Especially in brain, no ir-rBNP was detected, while ir-rat atrial natriuretic peptide (rANP) was observed at a relatively high concentration. These results demonstrate a sharp contrast between rat and porcine brains in ir-BNP distribution.

Animals↗

Distribution pattern of somatostatin and cortistatin mRNA in human central and peripheral tissues.

BACKGROUND: Somatostatin receptors (sst) and their endogenous ligand, somatostatin (SS), are widely expressed throughout the human body. Recently, the cDNA of a novel SS-like peptide, named cortistatin (CST), has been cloned. This CST was found to be expressed in more restricted areas, like brain cortex, testes, kidney, stomach and leucocytes. Further studies demonstrated a selective expression of CST in tissues and cells of the human immune system, while SS was not expressed. OBJECTIVE: In the present study we investigated the expression pattern of both SS mRNA and CST mRNA in various human central and peripheral tissues by quantitative RT-PCR (Q-PCR), in order to evaluate whether CST is more widely expressed in man than described to date and to investigate the relationship between SS and CST expression levels in various tissues. Previously, two different CST mRNA isoforms have been described. Therefore, we investigated the expression of both isoforms by RT-PCR in the different tissues as well. RESULTS: We demonstrate for the first time that CST mRNA is widely expressed in the human body. Interestingly, a selective expression of CST mRNA and not SS mRNA was only found in isolated cells of the human immune system, whereas different tissues expressed both SS and CST mRNA. CONCLUSION: CST may have a broader functional role than previously assumed.

Humans↗

Localization of myomodulin-like immunoreactivity in the central nervous system and peripheral tissues of Aplysia californica.

The distribution of myomodulin-like peptides in the nervous system of Aplysia californica was examined by using immunocytochemical techniques. Neurons and cell clusters containing immunoreactive material were located in each of the major central ganglia. Myomodulin-like immunoreactivity was also present in fibers in each of the connectives between the ganglia and in peripheral nerves. Varicosities containing immunoreactive material were located on specific regions of peripheral tissues associated with the feeding, digestive, cardiovascular, and reproductive systems. Double-labeling experiments were used to demonstrate myomodulin-like immunoreactivity in two identified neurons, the motor neuron B16 in the buccal ganglion and the widely acting interneuron L10 in the abdominal ganglion. Structures in the eye and cerebral ganglion that may correspond to the optic circadian pacemaker system were also stained. The central and peripheral distribution of myomodulin-like immunoreactivity indicates that this family of neuropeptides is present in specific efferent, afferent, and interneuronal elements that participate in a diversity of neural circuits in Aplysia.

Amino Acid Sequence↗

Insulin stimulated glucose disposal in peripheral tissues studied with microdialysis and stable isotope tracers.

BACKGROUND & AIMS: Methods to study glucose kinetics in vivo in specific tissues or tissue beds in humans are often not feasible due to invasiveness or costs of equipment needed. Here we investigate whether the loss (fractional extraction) of 2H7-glucose infused via a microdialysis catheter can be used to study glucose disposal in skeletal muscle and subcutaneous adipose tissue. METHODS AND RESULTS: A perfusion period of 2 h was needed to ensure an isotopic steady state in the microdialysis catheters in skeletal muscle and adipose tissue. In six healthy volunteers the fractional extraction increased during a hyperinsulinemic euglycemic clamp in both skeletal muscle and adipose tissue. Following 48 h of starvation in the same subjects, insulin was not able to increase the fractional extraction of 2H7-glucose from the microdialysis in comparison with a baseline measurement. CONCLUSIONS: In response to insulin infusion, the fractional extraction of 2H7-glucose from a microdialysis catheter increases in skeletal muscle and subcutaneous adipose tissue and this increase is blunted during insulin resistance induced by starvation. These results validate that the fractional extraction of a glucose tracers infused via microdialysis can be used as an index of glucose disposal in peripheral tissues or tissue beds.

Adipose Tissue↗

[Influence of carbidine on the noradrenaline level in the adrenergic nerve fibers in the peripheral tissues].

By employing fluorescent histochemistry and spectrofluorimetry the influence of an original psychotropic substance -- carbidine on the level, localization and accumulation of the adrenergic mediator in Vas deferens, dura mater and the kidney capsule was studied "in vivo" and "in vitro". Carbidine was shown to capable of liberating the adrenergic mediator from the sympathetic nerve fibres of the peripheral tissues without affecting the capture and accumulation of exogenous norepinephrine by adrenergic nerve fibres.

Adipose Tissue↗

Immunological localization of m1-m5 muscarinic acetylcholine receptors in peripheral tissues and brain.

Knowledge of the distributions and functions of native m1-m5 muscarinic acetylcholine receptors in tissues is limited. To characterize the family of m1-m5 proteins directly, a panel of subtype-selective antibodies was generated against divergent i3 loop-fusion proteins. Each antibody was shown to bind a single cloned receptor specifically. In peripheral tissues and brain, four receptor proteins (m1-m4) were found to account for the vast majority of the muscarinic binding sites using immunoprecipitation studies with the subtype-specific antibodies. The subtypes were differentially distributed, although most tissues were comprised of a complex mixture of receptors. Moreover, within tissues there were major differences in the precise localization of the subtypes, as determined by immunocytochemistry. The immunological methods described offer a novel approach with exquisite sensitivity and specificity for delineating the distribution of m1-m5 receptors in animal and human tissues.

Animals↗

Cholesterol and oxygenated cholesterol concentrations are markedly elevated in peripheral tissue but not in brain from mice with the Niemann-Pick type C phenotype.

Niemann-Pick disease type C (NP-C) is a rare genetic disorder characterized by progressive neurodegeneration, frequent developmental delay and early death. Tissues of affected individuals accumulate large quantities of free cholesterol in lysosomes. Because cytotoxic oxygenated derivatives of cholesterol are known to form readily when cholesterol concentrations are elevated, we searched for these compounds in liver, kidney, spleen and brain from mice with the NP-C phenotype. In order of abundance, we identified 7 alpha- and 7 beta-hydroxycholesterol, 5 alpha, 6 alpha-epoxycholestan-3 beta-ol, 4 beta-hydroxycholesterol, cholest-4-en-3 beta, 7 alpha-diol and cholest-4-en-3 beta, 6 beta-diol in most tissue samples. Cholesterol concentrations in affected mice were increased 3-fold in kidney and 7- to 8-fold in spleen and liver compared to controls (all p < 0.001) but were unchanged in brain. Although oxysterol levels were markedly elevated in nonbrain tissue, the oxysterol and cholesterol concentrations increased proportionally so that oxysterols expressed as percentage of total sterols were the same for all animals (0.34 +/- 0.19% averaged over all organs in affected animals vs 0.40 +/- 0.42% in control mice). In contrast to peripheral tissue, we could not detect any increase in either absolute or relative oxysterol levels in the brains of affected and control mice (49 +/- 61 vs 53 +/- 43 micrograms/g wet weight and 0.45 +/- 0.52 vs 0.47 +/- 0.37%, respectively). Thus, brain sterols are normal in NP-C mice and it is unlikely that an accumulation of cytotoxic oxygenated derivatives of cholesterol could account for the progressive neuropathology seen in the disease.

Animals↗

Overall fibromyalgia pain is predicted by ratings of local pain and pain-related negative affect--possible role of peripheral tissues.

OBJECTIVES: Despite variable numbers and intensities of local pain areas, fibromyalgia (FM) patients can provide overall clinical pain ratings. We hypothesized that the overall clinical pain is largely determined by the pain intensity of local body areas. Thus, we assessed the role of local body pains as predictors of overall clinical pain in FM patients. METHODS: Ratings of overall clinical pain intensity and pain-related negative affect (PRNA) were obtained from 277 FM patients. In addition, the patients identified painful body areas by shading a body pain diagram and rated the intensity of each pain area using a mechanical visual analogue scale (VAS). Hierarchical regression analyses were used to examine predictors of overall clinical FM pain intensity including PRNA, number of local pain areas, and maximal/average intensity of local pain areas. RESULTS: The average overall clinical pain rating of all FM patients was 4.6 (S.D. 2.3) VAS. The PRNA accounted for 19%, number of painful body areas for 9% and maximal/average local pain for 27% of the variance of overall clinical FM pain (P-values < 0.001). The combination of all factors predicted 55% of the variance in overall clinical pain intensity of FM patients. CONCLUSION: Peripheral factors (maximal/average local pain and number of painful body areas) predicted most of the variance of overall clinical FM pain, suggesting that the input of pain by the peripheral tissues is clinically relevant. About 19% of the pain variance was predicted by PRNA. Thus, peripheral pain and negative affect appear to be particularly relevant for overall FM pain and may represent important targets for future therapies.

Adult↗

Effect of strict metabolic control on glucose handling by the liver and peripheral tissues in non-insulin-dependent diabetes mellitus.

To examine the effect of strict glycemic control on the insulin resistance of non-insulin-dependent diabetes mellitus (NIDDM), we applied euglycemic hyperinsulinemic clamp combined with an oral glucose load (OGL) to nine non-obese subjects with NIDDM and quantitated insulin-mediated glucose uptake by the liver (HGU) and peripheral tissues (PGU) simultaneously before and after 3 to 4 weeks of intimate glycemic control by preprandial regular insulin injections 3 times a day. The glucose infusion rate (GIR) required to maintain euglycemia during the clamp before OGL was considered as PGU. After OGL, the fraction of ingested glucose that is not extracted by the liver enters the systemic circulation and reduces the GIR required for the clamp. HGU was calculated from the difference between the amount of OGL and the cumulative decrements in GIR after OGL and was expressed as the ratio to the amount of OGL (%). Three to 4 weeks after initiation of strict metabolic control, FPG and HbA1c levels significantly improved (9.1 +/- 0.5 vs. 6.4 +/- 0.4 mmol/l, and 11.2 +/- 0.8 vs. 8.3 +/- 0.3%, P < 0.05). HGU significantly increased to 33.1 +/- 9.5 from 14.5 +/- 4.8%, while PGU did not change (38.2 +/- 5.2 vs. 37.4 +/- 3.9 mumol/kg.min). These data suggest that short-term strict metabolic control ameliorates insulin resistance in NIDDM mainly at the hepatic level.

Adult↗

[Effect of buflomedil perfusion on peripheral tissue oxygenation during transluminal angioplasty in patients with advanced arteriopathy of the lower limbs].

Randomized double-blind placebo controlled trial performed in two parallel groups of patients, aged 43 to 92, suffering from advanced arterial disease of the lower limbs to be treated with angioplasty. The aim was to compare the efficacy of infusions of buflomedil with placebo on peripheral tissue oxygenation following lower limb angioplasties. Treatments consisted of 3 hour infusion of buflomedil or isotonic saline combined with arterial disobstruction. The major outcome measures were transcutaneous oxygen tension (TCpO2) correlated to ankle systolic pressure index (SPI). An increase of TCpO2 values (p < 0.01) as well as the mean individual variations of TCpO2 (p < 0.05) before and after angioplasty were observed in the buflomedil-treated group, whereas SPI values varied similarly in both groups. No adverse event was shown. In conclusion, buflomedil infusions during angioplasties of the lower limbs may improve tissue oxygenation subsequent to arterial disobstruction and are well tolerated.

Aged↗

Long-term corticosteroid treatment but not chronic stress affects 11beta-hydroxysteroid dehydrogenase type I activity in rat brain and peripheral tissues.

Long-term treatment (21 days) of male rats with corticosterone in the drinking water caused a significant increase in the activity of the NADP-dependent form of 11beta-hydroxysteroid dehydrogenase (11-HSD1) in the pituitary, thymus, and spleen, (marginally in the hippocampus, amygdala and lymph nodes), without having any effect in a number of other central and peripheral tissues. In contrast, repeated restraint stress, although increasing plasma corticosterone to the same level as that observed after its administration, failed to change the activity of this key regulatory enzyme, which allows aldosterone to exert its specific effects in the presence of a large excess of corticosterone. This resistance to elevation in 11-HSD activity was also observed in the thymuses of subordinate rats during social stratification in a visible burrow system. In both cases, the circulating levels of corticosterone were much higher in stressed rats than in control animals. Factors which might account for these differences in response are discussed and compared with the situation in intact cells where, unlike in tissue homogenates, the reduction of 11-dehydrocorticosterone to corticosterone (reductase activity) appears to predominate.

11-beta-Hydroxysteroid Dehydrogenases↗

Quantification of endothelin receptor subtypes in peripheral tissues reveals downregulation of ET(A) receptors in ET(B)-deficient mice.

We have previously shown that in homozygous endothelin (ET)(B)-/- deficient mice, ET(A) receptor density is significantly downregulated in the brain by 45%. In these mice, plasma ET-1 levels are elevated. Our aim was to use quantitative autoradiography to establish the distribution of ET receptor subtypes in peripheral tissues from wild-type mice and to measure the density of the ET(A) subtype in ET(B)-/- knockout animals. Our second aim was to test whether deletion of ET(B) receptors, which is associated with elevated plasma levels of ET-1, would also reduce ET(A) expression in the periphery. In longitudinal sections from wild-type mice, the highest densities of ET(A) receptors localized to major organs including the ventricle of the heart, lung, and liver parenchyma. High densities of ET(A) receptors were detected in the smooth muscle layer of the vasculature such as intrarenal vessels as well as the smooth muscle layer and epithelial cells of the gastrointestinal tract. In these tissues, the ET(A) subtype was more abundant, representing between 60% and 100% of the ET receptors. ET(B) receptors predominated in the medulla of kidney, with high densities also localizing to glomeruli within the cortex and to the sinusoids from the liver. Lower densities of ET(B) receptors were also present in the lung, heart, liver, and the smooth muscle layer of the gastrointestinal tract. In ET(B)-/- knockout mice, ET(B) receptors were not detected as expected by either ligand binding or immunocytochemistry. The pattern of ET(A) receptor distribution in the ET(B)-/- knockout mice was similar to the controls, but the density of ET(A) receptors was significantly reduced in the lung by 39%. Diminished responses to the endogenous agonist after repeated stimulation are an important feature of G-protein signaling, preventing potential damage to the overstimulated cell, and it is likely that downregulation occurs in response to higher circulating levels of ET-1.

Animals↗