Intracerebroventricular administration of conjugated linoleic acid (CLA) inhibits food intake by decreasing gene expression of NPY and AgRP

Dietary conjugated linoleic acid (CLA) has been investigated for its beneficial effects on disease prevention and treatment, and now obesity is one of the most perspective researching highlights. In a variety of experimental models, the results of studies on the effects of CLA on food intakes are somewhat inconsistent. Our experiment was conducted to extend these observations to hypothalamus and other regions within the central nervous system so that the mechanism of the actions of CLA might be more easily elucidated. In the experiment, a permanent cannula was inserted into the lateral ventricle of each rat. For the experiment, animals received intracerebroventricular injections of either 150 nmol (n = 16) CLA, or LA as non-conjugated control, or normal saline as vehicle. Hypothalamus and blood samples were collected at the 2nd, 4th, 8th, and 14th day. The results show that CLA in cerebral ventricle can inhibit food intake of experimented rats and this inhibition is related with the decreased expression of neuropeptides Y (NPY) and agouti-related protein (AgRP). The circulating leptin level was also increased by this tentative treatment (2.94 ± 0.71 versus 1.18 ± 0.18 ng/ml). However, the glucose metabolism was not affected by ICV CLA. It is concluded that CLA in brain can inhibit the appetite of rats through the mechanism of decreasing the expression of NPY and AgRP.     

Intracerebroventricular administration of octopamine stimulates food intake of chicks through alpha(2)-adrenoceptor

Octopamine, known to be an important neurotransmitter in invertebrates, has been noted to have several similarities to noradrenaline (NA) in mammals. The present study was done to elucidate whether central injection of octopamine enhances the feeding behavior of chicks and to investigate the interaction of octopamine with both alpha(1)- and alpha(2)-adrenoceptors. We found that the intracerebroventricular injection of octopamine significantly stimulated food intake of neonatal chicks during 30 min postinjection, but not thereafter. Moreover, this octopamine-induced eating response was attenuated by the alpha(2)-antagonist yohimbine, but not by the alpha(1)-antagonist prazosin. These results suggest that the action of octopamine on the feeding behavior of the neonatal chick is similar to that of NA, since octopamine regulates food intake through the alpha(2)-adrenoceptor.     

Intracerebroventricular administration of nocistatin reduces inflammatory hyperalgesia in rats.

Nocistatin is a biologically active peptide derived from prepronociceptin, and its intrathecal administration has been reported to reduce nociceptin- or prostaglandin E2-induced hyperalgesia and allodynia in mice. In this study, we investigated the effects of intracerebroventricular (i.c.v.) administration of nocistatin on the inflammatory hyperalgesia induced by hindlimb intraplantar injection of carrageenan/kaolin in the rat paw-pressure test. Intracerebroventricular administration of nocistatin (0.5-50 pmol/rat) dose-dependently reduced carrageenan/kaolin-induced hyperalgesia, which peaked at 15-30 m. However, i.c.v. administration of nocistatin (50 pmol/rat) had no effect on the nociceptive threshold of non-inflamed rats. These results indicate that nocistatin has anti-hyperalgesic effects on the inflammatory hyperalgesia induced by carrageenan/kaolin at the supraspinal level.     

Hyaluronan stimulates chondrogenic gene expression in human meniscus cells

Purpose/Aim of the Study: Inner meniscus cells have a chondrocytic phenotype, whereas outer meniscus cells have a fibroblastic phenotype. In this study, we examined the effect of hyaluronan on chondrocytic gene expression in human meniscus cells. Materials and Methods: Human meniscus cells were prepared from macroscopically intact lateral meniscus. Inner and outer meniscus cells were obtained from the inner and outer halves of the meniscus. The cells were stimulated with hyaluronan diluted in Dulbecco’s modified Eagle’s medium without serum to the desired concentration (0, 10, 100, and 1000 μg/mL) for 2–7 days. Cellular proliferation, migration, and polymerase chain reaction analyses were performed for the inner and outer cells separately. Meniscal samples perforated by a 2 mm diameter punch were maintained for 3 weeks in hyaluronan-supplemented medium and evaluated by histological analyses. Results: Hyaluronan increased the proliferation and migration of both meniscus cell types. Moreover, cellular counts at the surface of both meniscal tissue perforations were increased by hyaluronan treatments. In addition, hyaluronan stimulated α1(II) collagen expression in inner meniscus cells. Accumulation of type II collagen at the perforated surface of both meniscal samples was induced by hyaluronan treatment. Hyaluronan did not induce type I collagen accumulation around the injured site of the meniscus. Conclusion: Hyaluronan stimulated the proliferation and migration of meniscus cells. Our results suggest that hyaluronan may promote the healing potential of meniscus cells in damaged meniscal tissues.     

Intracerebroventricular injection of orexin-A stimulates monoamine metabolism but not HPA axis in neonatal chicks

We investigated the effects of intracerebroventricular (ICV) injection of orexin-A on plasma corticosterone (CORT) concentration and brain monoamine metabolism to clarify the mechanism by which ICV orexin-A induced arousal in chicks. In Experiment 1, plasma CORT concentrations were measured as an indicator of hypothalamic-pituitary-adrenal (HPA) axis activity. There was no significant difference in CORT concentration between the control and orexin-A administered groups. In Experiment 2, the concentrations of monoamines (norepinephrine, dopamine and serotonin), their metabolites, and their metabolic turnover rates in the telencephalon, mesencephalon, and diencephalon were investigated. All metabolic turnover rates studied were increased at all brain sites after ICV orexin-A injection. In conclusion, the HPA axis does not appear to be involved in arousal-inducing mechanisms of orexin-A in neonatal chicks; however, several monoaminergic systems do.     

Human NPY promoter variation rs16147:T>C as a moderator of prefrontal NPY gene expression and negative affect

Studies in humans and animals suggest a role for NPY in the mediation of behavioral stress responses. Here, we examined whether the NPY promoter variant rs16147:T>C is functional for expression of NPY in a brain region relevant for behavioral control, anxiety and depression, the anterior cingulate cortex. In silico analysis of DNA structural profile changes produced by rs16147 variation suggests allelic differences in protein binding at the rs16147 site. This was confirmed by electrophoretic mobility shift assay, demonstrating that the rs16147 C‐allele has strongly reduced affinity for a yet unknown factor compared to the T‐allele. Analyzing 107 human post‐mortem brain samples we show that allelic variation at rs16147 contributes to regulation of NPY mRNA and peptide levels in this region. Specifically, the C‐allele leads to increased gene expression. In agreement with the molecular findings, rs16147:T>C is associated with anxiety and depressive symptoms in 314 young adults via a gene x environment interaction with early childhood adversity, replicating the recent finding of rs16147‐C as a risk factor for stress related psychopathology. Our results show the importance of rs16147:T>C for regulation of NPY gene expression and brain function. © 2010 Wiley‐Liss, Inc.     

侧脑室注射肾上腺髓质素激活去缓冲神经大鼠最后区神经元

目的观察侧脑室注射肾上腺髓质素(AM)对去缓冲神经大鼠最后区神经元自发放电和Fos蛋白表达的影响。方法应用细胞外记录的电生理学方法,观察雄性SD大鼠神经元自发放电活动;用免疫组化方法检测Fos蛋白的表达。结果侧脑室注射AM(1,3nmol/kg)诱发最后区出现大量Fos样免疫阳性神经元(Fos-LI),最后区神经元自发放电频率明显增加;降钙素基因相关肽受体拮抗剂CGRP8-37(30nmol/kg)可明显减弱AM的效应。结论AM对最后区神经元有直接兴奋作用,降钙素基因相关肽受体介导这一效应。     

Intracerebroventricular administration of chicken motilin does not induce hyperphagia in meat-type chicks

The effect of chicken motilin on food intake was investigated in meat-type chicks under ad libitum feeding, refeeding, and fasting conditions. We found that the intracerebroventricular injection of chicken motilin (0.1 and 0.2 microg) tended to increase food intake under ad libitum feeding and refeeding conditions at 60 min postinjection, but the differences were not significant (P>.05). On the other hand, central administration of chicken motilin (0.2 and 0.4 microg) showed a tendency to suppress feeding of fasted chicks as well as the result of high dose (5.0 microg) under ad libitum feeding conditions. Therefore, the results presented here suggest that central motilin alone does not induce hyperphagia in meat-type chicks.     

Endotoxin stimulates expression of the murine urokinase receptor gene in vivo.

The regulation of urokinase receptor (u-PAR) gene expression during endotoxemia was studied in vivo with a murine model system. Northern blot analysis demonstrated relatively high levels of u-PAR mRNA in mouse placenta, with intermediate levels in lung and spleen and very low levels in heart and kidney. No u-PAR mRNA could be detected in liver, gut, thymus, brain, or skeletal muscle. Intraperitoneal injection of endotoxin (lipopolysaccharide) increased the steady-state levels of u-PAR mRNA in most tissues examined. The greatest induction (sevenfold) was observed in the lung at 1 hour after injection. The cellular localization of u-PAR mRNA was assessed by in situ hybridization. In control mice, u-PAR mRNA was detected primarily in alveolar macrophages of the lung and lymphocytes of the spleen and thymus, although a specific signal was also present in other cell types. In general, endothelial cells lacked detectable u-PAR mRNA. The induction of u-PAR mRNA by lipopolysaccharide was apparent within 30 minutes and was localized to tissue macrophages, lymphocytes, and endothelial cells lining arteries and veins. At later times (1 to 3 hours), specialized epithelial cells present in gastrointestinal tract, bile ducts, and uterus were also positive for u-PAR mRNA. Induction of u-PAR in vivo by lipopolysaccharide may facilitate the extravasation and migration of leukocytes during inflammation.     

Upregulation of the pro-opiomelanocortin gene in motoneurones after acrylamide administration in mice

Immunocytochemistry was used to demonstrate the presence of beta-endorphin and alpha-MSH, and in situ hybridisation was used to study the presence of pro-opiomelanocortin (POMC) mRNA, in spinal motoneurones, up to 8 days following the administration of a single dose of acrylamide in mice. The proportions of POMC-mRNA positive neurones, beta-endorphin-immunoreactive neurones and alpha-MSH-immunoreactive neurones were significantly increased in the treated animals compared to controls. It seems likely that upregulation of the POMC gene precedes acrylamide-induced neuropathy.     

Central administration of motilin stimulates feeding in rats

Peripheral administration of motilin has been found to stimulate feeding behavior in rats. Since motilin immunoreactivity has been found in discrete brain sites, we tested the effect of motilin administered intracerebroventricularly on feeding in rats. Injection of 1 microgram of motilin significantly increased food consumption at 2 hours, 22 hours, and at 24 hours in animals tested either at or 2 hr prior to lights out. Motilin also significantly increased food consumption in animals maintained under continuous lights-on at 2 hours (488% of control), 22 hours (128% of control), and at 24 hours (140% of control).     

缺血性鼠脑中的IL-6基因表达

IL-6是一多效应的细胞因子,在宿主的防卫和急性炎症反应中起重要的作用[1]。它的表达异常和失调与多种疾病发病有关,如肿瘤、Alzheimer’s病、不同类型的脑损害。为探讨IL-6与缺血性脑损害的关系,我们用PT-PCR方法对缺血性鼠脑不同部位IL-6mRNA表达进行了研究,报道如下:1材料和方法1.1动物模型研制ICR小鼠18只,每组6只,雌雄各半,重45～50g。用线栓法研制成右侧大脑中动脉栓塞模型[2],即25%戊拉坦1000mg/kg,IP麻醉。手术显微镜下,颈部正中切开,分离右颈总动脉,用5～0号进口尼龙线约10～12mm长,头端涂用cilicon,插入颈内动脉抵大脑中…     

Intracerebroventricular administration of an endothelin ETB receptor agonist increases expression of tissue inhibitor of matrix metalloproteinase-1 and -3 in rat brain

Production of tissue inhibitors of matrix metalloproteinases (TIMPs), a family of secreted proteins with inhibitory actions on matrix metalloproteinases (MMPs), is up-regulated following nerve injuries and is suggested to have protective effects against MMP-mediated tissue damages. To clarify the extracellular signals involved in TIMP production in the brain, the effects of endothelins (ETs), a family of vasoconstricting peptides, were examined. I.c.v. administration of 500 pmol/day Ala(1,3,11,15)-ET-1, an ET(B) receptor agonist, increased the level of TIMP-1 mRNA in rat hippocampus, caudate-putamen and cerebrum. Ala(1,3,11,15)-ET-1 increased the level of TIMP-3 mRNA in the cerebrum, but not in the hippocampus or caudate-putamen. TIMP-2 mRNA was not affected in these brain regions. Ala(1,3,11,15)-ET-1 also stimulated the production of TIMP-1 and TIMP-3 proteins in the cerebrum. Immunohistochemical observations in the hippocampi of Ala(1,3,11,15)-ET-1-infused rats showed that NeuN-positive neurons and glial fibrillary acidic protein-positive astrocytes were immunoreactive for TIMP-1. In the cerebrum, astrocytes had TIMP-1 and TIMP3 reactivity, but neurons did not. In rat cultured astrocytes, both 100 nM Ala(1,3,11,15)-ET-1 and ET-1 increased the mRNA levels and protein release of TIMP-1 and TIMP-3 mRNAs. The effects of ET-1 on astrocytic TIMP-1 and TIMP-3 mRNAs were inhibited by BQ788, an ET(B) antagonist. These findings indicate that activation of brain ET(B) receptors causes production of TIMP-1 and TIMP-3, and suggest the involvement of astrocytes in ET-induced TIMP production.     

Intracerebroventricular administration of corticotropin-releasing factor antagonist attenuates arousal response accompanied by yawning behavior in rats

We have reported that an arousal response accompanied by yawning behavior can be evoked by electrical and chemical stimulation of the hypothalamic paraventricular nucleus (PVN) in rats, although the mechanism responsible for the arousal response accompanied by yawning evoked by PVN stimulation is still unknown. In the present study, we examined the involvement of corticotropin-releasing factor (CRF) in the arousal response during yawning induced by electrical stimulation of the PVN in anesthetized, spontaneous breathing rats using intracerebroventricular (icv) injection of alpha-helical CRF, a CRF antagonist (4.2 microg, lateral ventricle). The electrocorticogram (ECoG) was recorded to evaluate arousal responses during yawning. Fast Fourier transform was used to obtain the power spectrum in delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-20 Hz) bands. We also recorded the intercostal electromyogram as an index of inspiratory activity and blood pressure (BP) as an index of autonomic function to evaluate yawning response. PVN stimulation induced significant increases in relative powers of theta, alpha, and beta bands, but not delta band, concurrent with yawning events regardless of icv injection, though the relative powers after icv injection of alpha-helical CRF were significantly lower than those after saline injection. These findings suggest that CRF neurons in the PVN are primarily responsible for the arousal response accompanied by yawning behavior.     

Intracerebroventricular administration of anti-endothelin-1 IgG selectively upregulates endothelin-A and kappa opioid receptors

Endothelin (ET) type A receptor antagonists enhance morphine-induced antinociception and restore morphine analgesia in morphine tolerant rats [Peptides 23 (2002) 1837; Peptides 24 (2003) 553]. These studies suggest that the central ET and opioid systems functionally interact. To explore this idea further, we determined the effect of i.c.v. administration of anti-ET-1 IgG (rabbit) on brain opioid receptor and ET receptor expression. Three days after implanting cannula into the lateral ventricle, male Sprague-Dawley rats were administered 10 microl (i.c.v.) of either control rabbit IgG (2.5 microg/microl) or anti-ET IgG (2.5 microg/microl) on day 1, day 3, and day 5. On day 6, animals were killed and the caudate and hippocampus collected. Anti-ET IgG had no significant effect on expression, measured by Western blots, of mu, delta or ET-B receptors, but increased kappa opioid (59%) and ET-A (33%) receptor protein expression in the caudate. [35S]-GTP-gamma-S binding assays demonstrated that anti-ET IgG decreased [D-Ala2-MePhe4, Gly-ol5]enkephalin efficacy, but not potency in the caudate. Control experiments showed that there was no detectable rabbit IgG in caudate and hippocampal samples. These results suggest that ET in the CSF negatively regulates kappa opioid and ET-A receptors in certain brain regions. These findings support the hypothesis that CSF neuropeptides have regulatory effects and further demonstrate a link between ET and the opioid receptor system.     

Intracerebroventricular administration of substance P increases dopamine content in the brain of 6-hydroxydopamine-lesioned rats

The interactions existing between substance P- and dopamine-positive neurons, notably in the basal ganglia, suggest that substance P may have therapeutic use in treatment of Parkinson's disease characterized by impaired dopaminergic transmission. The effects of intracerebroventricularly administered substance P were tested on the levels of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex of 6-hydroxydopamine-lesioned rats. Intracerebroventricular injection of 6-hydroxydopamine decreased the levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the brain structures under investigation. Administration of substance P in low dose (0.35 nmol/kg) had no effect on the 6-hydroxydopamine-induced reduction of the dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid contents in the brain. However, treatment with substance P in higher dose (3.5 nmol/kg) increased the concentrations of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex relative to saline-treated group. Additionally, 6-hydroxydopamine lesions significantly increased 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum and nucleus accumbens. Substance P (3.5 nmol/kg) partially reversed lesion-induced increases in 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum, but did not alter these ratios in nucleus accumbens. To test whether substance P fragmentation is responsible for this phenomenon, substance P_5–11, which is one of the main substance P fragments in rat CNS, was administered in equimolar dose. Substance P_5–11 was found to have no effect on the content of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum and nucleus accumbens. In the frontal cortex, substance P_5–11 produced decreases in dopamine levels and increases in homovanillic acid/dopamine ratio.The results of this study suggest that substance P helps to restore dopamine deficit in the brain in an animal model of Parkinson's disease, with the positive effects being more prominent on the nigrostriatal than on the mesocorticolimbic dopaminergic system, but substance P_5–11 is not responsible for this effect.     

Allelic variation in the NPY gene in 14 Indian populations

NPY is a 36-aminoacid peptide expressed in several areas of the nervous system. Neuropeptide Y (NPY) receptors represent a widely diffused system that is involved in the regulation of multiple biological functions. The human NPY gene is located in chromosome 7. The functional significance of coding Leu7Pro polymorphism in the signal peptide of preproNPY is known. Six hundred and fifty four individuals of 14 ethnic Indian populations were screened for three mutations in the NPY gene, including Leu7Pro. We found that the Pro7 frequencies among the studied populations were much higher than in previous studies from other parts of the world. The highest allele frequency of Pro7 was detected in the Kota population in the Nilgiri Hill region of south India, and this may reflect a founder event in the past or genetic drift. All populations followed the Hardy–Weinberg equilibrium for the assayed markers. A total of five haplotypes were observed, only two of which were found to occur with a high frequency in all populations. No linkage disequilibrium (LD) was observed across the tested alleles in any population with the exception of Leu7Pro and Ser50Ser in the Badaga population (χ ² = 13.969; p = 0.0001).     

Intracerebroventricular administration of substance P increases dopamine content in the brain of 6-hydroxydopamine-lesioned rats

The interactions existing between substance P- and dopamine-positive neurons, notably in the basal ganglia, suggest that substance P may have therapeutic use in treatment of Parkinson's disease characterized by impaired dopaminergic transmission. The effects of intracerebroventricularly administered substance P were tested on the levels of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex of 6-hydroxydopamine-lesioned rats. Intracerebroventricular injection of 6-hydroxydopamine decreased the levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the brain structures under investigation. Administration of substance P in low dose (0.35 nmol/kg) had no effect on the 6-hydroxydopamine-induced reduction of the dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid contents in the brain. However, treatment with substance P in higher dose (3.5 nmol/kg) increased the concentrations of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex relative to saline-treated group. Additionally, 6-hydroxydopamine lesions significantly increased 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum and nucleus accumbens. Substance P (3.5 nmol/kg) partially reversed lesion-induced increases in 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum, but did not alter these ratios in nucleus accumbens. To test whether substance P fragmentation is responsible for this phenomenon, substance P(5-11), which is one of the main substance P fragments in rat CNS, was administered in equimolar dose. Substance P(5-11) was found to have no effect on the content of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum and nucleus accumbens. In the frontal cortex, substance P(5-11) produced decreases in dopamine levels and increases in homovanillic acid/dopamine ratio. The results of this study suggest that substance P helps to restore dopamine deficit in the brain in an animal model of Parkinson's disease, with the positive effects being more prominent on the nigrostriatal than on the mesocorticolimbic dopaminergic system, but substance P(5-11) is not responsible for this effect.