Increased sensitivity to the stimulant effects of morphine conferred by anti-adhesive glycoprotein SPARC in amygdala

SPARC and GluA1-Containing AMPA Receptors Promote Neuronal Health Following CNS Injury

The proper formation and maintenance of functional synapses in the central nervous system (CNS) requires communication between neurons and astrocytes and the ability of astrocytes to release neuromodulatory molecules. Previously, we described a novel role for the astrocyte-secreted matricellular protein SPARC (Secreted Protein, Acidic and Rich in Cysteine) in regulating α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) and plasticity at developing synapses. SPARC is highly expressed by astrocytes and microglia during CNS development but its level is reduced in adulthood. Interestingly, SPARC has been shown to be upregulated in CNS injury and disease. However, the role of SPARC upregulation in these contexts is not fully understood. In this study, we investigated the effect of chronic SPARC administration on glutamate receptors on mature hippocampal neuron cultures and following CNS injury. We found that SPARC treatment increased the number of GluA1-containing AMPARs at synapses and enhanced synaptic function. Furthermore, we determined that the increase in synaptic strength induced by SPARC could be inhibited by Philanthotoxin-433, a blocker of homomeric GluA1-containing AMPARs. We then investigated the effect of SPARC treatment on neuronal health in an injury context where SPARC expression is upregulated. We found that SPARC levels are increased in astrocytes and microglia following middle cerebral artery occlusion (MCAO) in vivo and oxygen-glucose deprivation (OGD) in vitro. Remarkably, chronic pre-treatment with SPARC prevented OGD-induced loss of synaptic GluA1. Furthermore, SPARC treatment reduced neuronal death through Philanthotoxin-433 sensitive GluA1 receptors. Taken together, this study suggests a novel role for SPARC and GluA1 in promoting neuronal health and recovery following CNS damage.

Pentylenetetrazol modulates redox system by inducing addicsin translocation from endoplasmic reticulum to plasma membrane in NG108-15 cells

Addicsin (Arl6ip5) is a multifunctional physiological and pathophysiological regulator that exerts its effects by readily forming homo- and hetero-complexes with various functional factors. In particular, addicsin acts as a negative modulator of neural glutamate transporter excitatory amino acid carrier 1 (EAAC1) and participates in the regulation of intracellular glutathione (GSH) content by negatively modulating EAAC1-mediated cysteine and glutamate uptake. Addicsin is considered to play a crucial role in the onset of neurodegenerative diseases including epilepsy. However, the molecular dynamics of addicsin remains largely unknown. Here, we report the dynamics of addicsin in NG108-15 cells upon exposure to pentylenetetrazol (PTZ), a representative epileptogenic agent acting on the gamma-Aminobutyric acid A (GABA_A) receptor. Fluorescent immunostaining analysis demonstrated that addicsin drastically changed its localization from the endoplasmic reticulum (ER) to the plasma membrane within 1 h of PTZ exposure in a dose-dependent manner. Moreover, addicsin was co-localized with the plasma membrane markers EAAC1 and Na⁺/K⁺ ATPase alpha-3 upon PTZ stimulation. This translocation was significantly inhibited by a non-competitive GABA_A receptor antagonist, picrotoxin, but not by a competitive GABA_A receptor antagonist, bicuculline. Furthermore, lactate dehydrogenase (LDH) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay showed that PTZ-induced addicsin translocation was accompanied by a decrease of radical-scavenging activity and an increase of cytotoxicity in a PTZ dose-dependent manner. These findings suggest that PTZ induces the translocation of addicsin from the ER to the plasma membrane and modulates the redox system by regulating EAAC1-mediated GSH synthesis, which leads to the activation of cell death signaling.

Effect of ASF (a Compound of Traditional Chinese Medicine) on Behavioral Sensitization Induced by Ethanol and Conditioned Place Preference in Mice

ASF composed by semen and epimedium herbal is a traditional plant compound that is widely used in the treatment of insomnia. Studies have shown that saponins and flavonoids contained in semen can significantly decrease the content of excitatory neurotransmitter Glu in mice. And the total flavone of YinYangHuo can increase the release of GABA in the anterior periventricular system of rat and increase the affinity of GABA for the receptors GABAA. It can be inferred that their synergism may have effect on the neurotransmitter that causes behavioral sensitization and conditioned place preference in experimental animals and affects their drinking behaviors, which is the starting point of this research. The present study found that ASF can inhibit development and expression of behavioral sensitization induced by ethanol and the development of CPP in mice. We demonstrate the inhibition of ASF on behavioral sensitization partly due to its effect on the mesolimbic neurotransmitter system, including decreasing level of DA and Glu and increasing the content of GABA. It suggested that the ASF may have pharmacological effects in the treatment of alcohol addiction.

Astrocytes control glutamate receptor levels at developing synapses through SPARC-beta-integrin interactions

Neurons recruit numerous mechanisms to facilitate the development of synaptic connections. However, little is known about activity-dependent mechanisms that control the timing and fidelity of this process. Here we describe a novel pathway used by neurons to regulate glutamate receptors at maturing central synapses. This pathway relies on communication between neurons and astrocytes and the ability of astrocytes to release the factor SPARC (secreted protein, acidic and rich in cysteine). SPARC expression is dynamically regulated and plays a critical role in determining the level of synaptic AMPARs. SPARC ablation in mice increases excitatory synapse function, causes an abnormal accumulation of surface AMPARs at synapses, and impairs synaptic plasticity during development. We further demonstrate that SPARC inhibits the properties of neuronal β3-integrin complexes, which are intimately coupled to AMPAR stabilization at synapses. Thus neuron-glial signals control glutamate receptor levels at developing synapses to enable activity-driven modifications of synaptic strength.

Inactivation of SPARC enhances high-fat diet-induced obesity in mice

Secreted protein, acidic and rich in cysteine (SPARC), a matricellular protein, modulates extracellular matrix assembly and turnover in many physiological processes. SPARC-null mice exhibit an increased accumulation of adipose tissue. To distinguish between the functions of SPARC in adipogenesis during development and adulthood, we studied wild-type (WT) and SPARC-null mice maintained on a normal (low-fat) or high-fat (HF) diet. On an HF diet, SPARC-null mice exhibited significantly greater weight gain, in comparison to their WT counterparts, and had an enhanced cortical bone area that was likely due to increased mechanical loading. Diet-induced obesity (DIO) was also associated with an increase in vertebral trabecular bone in WT mice, but a significant change in this parameter was not observed in SPARC-null animals. We show that SPARC inhibits mitotic clonal expansion of preadipocytes at an early stage of adipogenesis. Moreover, there were substantially diminished levels of type I collagen in SPARC-null adipose tissue, as well as a reduction in the number of cross-linked, mature collagen fibers. In the absence of SPARC, mice show enhanced DIO. In adult animals, SPARC functions in the production and remodeling of adipose tissue, as well as in the regulation of preadipocyte differentiation.

Identification of astrocyte-derived immune suppressor factor that induces apoptosis of autoreactive T cells

In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, apoptosis of T cells is mainly seen at inflammation sites of the central nervous system (CNS). Cumulative data suggests that astrocytes might render T cells susceptible to induction of apoptotic cell death. We observed that apoptotic cell death of proteolipid protein (PLP)-reactive T cells was induced by an interferon (IFN)-γ-treated astrocyte cell line. In this study, we have identified and cloned the genes derived from the IFN-γ-treated astrocyte cell line that induce apoptosis of autoreactive T cells. We created subtraction cDNA libraries from the IFN-γ-treated astrocyte cell line and obtained 100 positive clones. After screening of subtracted cDNAs, we found two candidate genes that induced apoptosis of the PLP-reactive T cell line. The first is a previously unknown gene of 726 base pairs that we named astrocyte-derived immune suppressor factor (AdIF). It contained an open reading frame encoding a polypeptide of 228 amino acids. The second was SPARC/osteonectin, a multifunctional glycoprotein secreted in the extracellular matrix. AdIF protein was found at the inflammatory sites of the EAE brain, and bound to the surface of CD4(+) T cells. Purified recombinant AdIF protein inhibited the proliferation of activated PLP-reactive CD4(+) T cells and induced their apoptosis in vitro. Intravenous administration of recombinant AdIF protein to mice with in which acute EAE was induced prevented the incidence of EAE and suppressed the symptoms. The newly discovered molecule AdIF may render auto-reactive T cells susceptible to the induction of apoptotic cell death and could potentially be a new therapeutic agent for multiple sclerosis.

Genes associated with alcohol abuse and tobacco smoking in the human nucleus accumbens and ventral tegmental area

BACKGROUND

The incidence of alcohol and tobacco co-abuse is as high as 80%. The molecular mechanism underlying this comorbidity is virtually unknown, but interactions between these drugs have important implications for the development of and recovery from drug dependence.

METHODS

We investigated the effects of chronic tobacco and alcohol abuse and the interaction of the 2 behaviors on global gene expression in the human nucleus accumbens using cDNA microarrays and 20 alcoholic and control cases, with and without smoking comorbidity. Changes in gene expression were established by factorial ANOVA. Unsupervised hierarchical clustering was utilized to probe the strength of the data sets. Applying real-time PCR differential expression of candidate genes was confirmed in the nucleus accumbens and explored further in a second core region of the mesolimbic system, the ventral tegmental area.

RESULTS

Subjecting the data sets derived from microarray gene expression screening to unsupervised hierarchical clustering tied the cases into distinct groups. When considering all alcohol-responsive genes, alcoholics were separated from nonalcoholics with the exception of 1 control case. All smokers were distinguished from nonsmokers based on similarity in expression of smoking-sensitive genes. In the nucleus accumbens, alcohol-responsive genes were associated with transcription, lipid metabolism, and signaling. Smoking-sensitive genes were predominantly assigned to functional groups concerned with RNA processing and the endoplasmic reticulum. Both drugs influenced the expression of genes involved in matrix remodeling, proliferation, and cell morphogenesis. Additionally, a gene set encoding proteins involved in the canonical pathway "regulation of the actin cytoskeleton" was induced in response to alcohol and tobacco co-abuse and included. Alcohol abuse elevated the expression of candidate genes in this pathway in the nucleus accumbens and ventral tegmental area, while smoking comorbidity blunted this induction in the ventral tegmental area.

CONCLUSIONS

The region-specific modulation of alcohol-sensitive gene expression by smoking may have important consequences for alcohol-induced aberrations within the mesolimbic dopaminergic system.

Differential expression patterns of occ1-related genes in adult monkey visual cortex

We have previously revealed that occ1 is preferentially expressed in the primary visual area (V1) of the monkey neocortex. In our attempt to identify more area-selective genes in the macaque neocortex, we found that testican-1, an occ1-related gene, and its family members also exhibit characteristic expression patterns along the visual pathway. The expression levels of testican-1 and testican-2 mRNAs as well as that of occ1 mRNA start of high in V1, progressively decrease along the ventral visual pathway, and end of low in the temporal areas. Complementary to them, the neuronal expression of SPARC mRNA is abundant in the association areas and scarce in V1. Whereas occ1, testican-1, and testican-2 mRNAs are preferentially distributed in thalamorecipient layers including “blobs,” SPARC mRNA expression avoids these layers. Neither SC1 nor testican-3 mRNA expression is selective to particular areas, but SC1 mRNA is abundantly observed in blobs. The expressions of occ1, testican-1, testican-2, and SC1 mRNA were downregulated after monocular tetrodotoxin injection. These results resonate with previous works on chemical and functional gradients along the primate occipitotemporal visual pathway and raise the possibility that these gradients and functional architecture may be related to the visual activity–dependent expression of these extracellular matrix glycoproteins.

SPARC is expressed by macroglia and microglia in the developing and mature nervous system

SPARC (secreted protein, acidic and rich in cysteine) is a matricellular protein that is highly expressed during development, tissue remodeling, and repair. SPARC produced by olfactory ensheathing cells (OECs) can promote axon sprouting in vitro and in vivo. Here, we show that in the developing nervous system of the mouse, SPARC is expressed by radial glia, blood vessels, and other pial-derived structures during embryogenesis and postnatal development. The rostral migratory stream contains SPARC that becomes progressively restricted to the SVZ in adulthood. In the adult CNS, SPARC is enriched in specialized radial glial derivatives (Müller and Bergmann glia), microglia, and brainstem astrocytes. The peripheral glia, Schwann cells, and OECs express SPARC throughout development and in maturity, although it appears to be down-regulated with maturation. These data suggest that SPARC may be expressed by glia in a spatiotemporal manner consistent with a role in cell migration, neurogenesis, synaptic plasticity, and angiogenesis.

Pseudoginsenoside-F11 decreases morphine-induced behavioral sensitization and extracellular glutamate levels in the medial prefrontal cortex in mice

Morphine produces a variety of behavioral and biochemical changes related to its abuse. Our previous studies showed that Pseudoginsenoside-F11 (PF11), an ocotillol-type saponin existing in American ginseng, can antagonize pharmacological effects of morphine. To further investigate the effects of PF11 on morphine abuse and the underlying mechanisms, we tested the effects of PF11 on morphine-induced development of behavioral sensitization and alterations in glutamate levels in the medial prefrontal cortex (mPFC) in freely moving mice by using in vivo microdialysis. As the results shown, PF11 antagonized the development of behavioral sensitization and decrease of glutamate in the mPFC induced by morphine. Therefore, these findings suggest that PF11 may block the development of morphine-induced behavioral sensitization via its effect, at least partially, on the glutamatergic system in the mPFC.

The proteomic analysis of mouse choroid plexus secretome reveals a high protein secretion capacity of choroidal epithelial cells

Choroid plexuses (CP) are involved in multiple functions related to their unique architecture and localization at the interface between the blood and cerebrospinal fluid compartments. These include the release by choroidal epithelial cells (CEC) of biologically active molecules, such as polypeptides, which are distributed globally to the brain. Here, we have used a proteomic approach to get an unbiased overview of the proteins that are secreted by primary cultures enriched in epithelial cells from mice CP. We identified a total of 43 proteins secreted through the classical vesicular pathway in CEC -conditioned medium. They include transport proteins, collagen subunits and other cell matrix proteins, proteases, protease inhibitors and neurotrophic factors. Treating CEC cultures with lipopolysaccharide, increased the secretion of four protein species and induced the release of two additional proteins. Our study also reveals a higher protein secretion capacity of CECs compared with other CP cells or cultured astrocytes. In conclusion, this study provides for the first time the characterization of the major proteins that are secreted by CECs. These proteins may play a critical role in neuronal growth, differentiation and function as well as in brain pathologies.

Candidate genes, pathways and mechanisms for alcoholism: an expanded convergent functional genomics approach

We describe a comprehensive translational approach for identifying candidate genes for alcoholism. The approach relies on the cross-matching of animal model brain gene expression data with human genetic linkage data, as well as human tissue data and biological roles data, an approach termed convergent functional genomics. An analysis of three animal model paradigms, based on inbred alcohol-preferring (iP) and alcohol-non-preferring (iNP) rats, and their response to treatments with alcohol, was used. A comprehensive analysis of microarray gene expression data from five key brain regions (frontal cortex, amygdala, caudate-putamen, nucleus accumbens and hippocampus) was carried out. The Bayesian-like integration of multiple independent lines of evidence, each by itself lacking sufficient discriminatory power, led to the identification of high probability candidate genes, pathways and mechanisms for alcoholism. These data reveal that alcohol has pleiotropic effects on multiple systems, which may explain the diverse neuropsychiatric and medical pathology in alcoholism. Some of the pathways identified suggest avenues for pharmacotherapy of alcoholism with existing agents, such as angiotensin-converting enzyme (ACE) inhibitors. Experiments we carried out in alcohol-preferring rats with an ACE inhibitor show a marked modulation of alcohol intake. Other pathways are new potential targets for drug development. The emergent overall picture is that physical and physiological robustness may permit alcohol-preferring individuals to withstand the aversive effects of alcohol. In conjunction with a higher reactivity to its rewarding effects, they may able to ingest enough of this nonspecific drug for a strong hedonic and addictive effect to occur.

Expression profile of addicsin/GTRAP3-18 mRNA in mouse brain

Addicsin is a murine homologue of rat glutamate-transporter-associated protein 3-18 (GTRAP3-18), a putative modulator of neural glutamate-transporter excitatory amino acid carrier 1 (EAAC1). The other molecular functions of addicsin, however, remain largely unknown. We analyzed here the regional and cellular distribution of addicsin transcript in the mature brain using in situ hybridization analysis, and examined the sequential addicsin mRNA expression levels in the developing brain using Northern blot analysis. In the mature brain, we found addicsin mRNA to be ubiquitously expressed in neuron-like cells, but not glial cells, in various brain regions including the olfactory bulbs, hippocampus and cerebral cortex. In the hippocampus, addicsin mRNA was expressed in the neuron-like cells of the CA1-CA3 pyramidal cell layer and the interneuron-like cells of the stratum oriens, stratum radiatum and stratum lacunosum-moleculare. Addicsin transcripts were also extremely abundant in trigeminal neurons such as the principal trigeminal nucleus, mesencephalic trigeminal nucleus and motor trigeminal nucleus. Our evidence suggests that addicsin mRNA is chiefly expressed in the excitatory and inhibitory neurons, and that addicsin may participate in the functional expression of the somatic sensory system by modulation of EAAC1-mediated glutamate transport. Northern blot analysis revealed that addicsin mRNA levels increased with maturation, reaching their maximum level at postnatal day 5 (P5), then significantly declined by about 50% until P14, suggesting that addicsin may contribute to embryogenesis and synaptogenesis in the developing brain. Thus, addicsin may participate in multiple physiological functions in the developing and mature brain.

Entorhinal deafferentation induces upregulation of SPARC in the mouse hippocampus

SPARC is a matricellular protein that modulates cell-cell and cell-matrix interactions by virtue of its antiproliferative and counteradhesive properties. Here, we report the denervation-induced upregulation of SPARC mRNA and protein in the mouse hippocampus following transections of the entorhinal afferents. Northern blot analysis showed that SPARC mRNA was upregulated in a transient manner in the deafferented mouse hippocampus. In situ hybridization and immunohistochemistry confirmed the temporal upregulation of both SPARC mRNA and protein specifically in the denervated areas, which initiated at 7 days postlesion, reached the maximum at 15 as well as 30 days postlesion, and subsided towards normal levels by 60 days postlesion. Double labeling by either a combination of in situ hybridization for SPARC mRNA with immunohistochemistry for glial fibrillary acidic protein or double immunofluorescence staining for both proteins in the hippocampus revealed that SPARC-expressing cells are reactive astrocytes. In respect to the spatiotemporal alterations of SPARC expression in the denervated hippocampus, we suggest that SPARC may be involved in modulation of the denervation-induced plasticity processes such as glial cell proliferation, axonal sprouting and subsequent synaptogenesis in the hippocampus following entorhinal deafferentation.

Osteonectin is a Schwann cell-secreted factor that promotes retinal ganglion cell survival and process outgrowth

We have investigated the factors made by Schwann cells (SCs) that stimulate survival and neurite outgrowth from postnatal rat retinal ganglion cells (RGCs). These effects are preserved under K252a blockade of the Trk family of neurotrophin receptors and are not fully mimicked by the action of a number of known trophic factors. To identify novel factors responsible for this regenerative activity, we have used a radiolabelling assay. Proteins made by SCs were labelled radioactively and then fed to purified RGCs. The proteins taken up by the RGCs were then isolated and further characterized. Using this assay we have identified a major 40 kDa factor taken up by RGCs, which was microsequenced and shown to be the matricellular protein osteonectin (ON). Using an in vitro assay of purified RGCs we show that ON promotes both survival and neurite outgrowth. We conclude that ON has a potential new role in promoting CNS repair.

Valproate prevents the induction, but not the expression of morphine sensitization in mice

Repetitive exposure to opioids elicits sensitization to its locomotor stimulating effects. Several lines of evidence have shown that the central GABAergic system is involved in behavioral sensitization induced by morphine. Valproate, a clinically widely used anticonvulsant and mood stabilizer, can mainly inhibit gamma-aminobutyric acid (GABA) transaminase and activate glutamic acid decarboxylase, which result in decrease in the degradation and increase in the synthesis of GABA, and then the elevation of extracellular GABA in the central nervous system. However, the effects of valproate on behavioral sensitization to morphine have not been documented. Herein, we investigated the effects of valproate on the induction and the expression of behavioral sensitization to morphine. Mice treated daily for 7 days with 10 mg/kg morphine and challenged with the same dose after 7 days of washout showed increased locomotor activity. Co-administration of valproate (37.5, 75, 150 mg/kg, intraperitoneal (i.p.)), at doses that did not affect the spontaneous activity, 30 min prior to morphine dose-dependently inhibited the induction of morphine sensitization. However, neither single nor multiple administration (37.5, 75, 150 mg/kg x 7 injections) of valproate had any effect on the expression of morphine sensitization once it developed. Our results indicated that GABA plays an important role in the induction, but not in the expression of morphine sensitization in mice.

Brain region-specific mechanisms for acute morphine-induced mitogen-activated protein kinase modulation and distinct patterns of activation during analgesic tolerance and locomotor sensitization

Opioid-receptor activation in cell lines results in phosphorylation of p42/44 mitogen-activated protein kinase (MAPK), which contributes to agonist-induced desensitization of adenylate cyclase signaling. In this study, morphine-induced MAPK modulation was examined in the mouse brain using antibodies against phosphorylated MAPK. Thirty minutes after systemic morphine, MAPK modulation was observed in brain areas associated with analgesia and reward. Activation of MAPK was increased in the anterior cingulate (Acc), somato-sensory and association cortices, and locus ceruleus (LC). In contrast, MAPK activation was decreased in the nucleus accumbens and central amygdala (CeA). Double-label confocal microscopy revealed that morphine-induced MAPK modulation occurred predominantly in cells not expressing mu-opioid receptors, with the exception of the LC. Furthermore, the NMDA receptor antagonist 3,3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonate blocked morphine-induced MAPK modulation in several cortical areas including the Acc. We then examined morphine-induced MAPK modulation during expression of either analgesic tolerance or locomotor sensitization, which were differentiated by two repeated morphine regimens. Analgesic tolerance was accompanied by tolerance to morphine-induced MAPK modulation in all of the brain areas examined except the CeA. Locomotor sensitization resulted in sensitization to morphine-induced MAPK activation in the posterior basolateral amygdala. Additionally, a pronounced instatement of morphine-induced MAPK activation was observed in CA3 hippocampal processes. This instatement was observed during expression of tolerance; however, it was not significant during sensitization. In summary, these results provide distinct, region-specific mechanisms for morphine-induced MAPK modulation in the mouse brain and give insight into the brain circuitry involved in acute and adaptive opioid behaviors.

L-type Ca(2+) channel blockers inhibit the development but not the expression of sensitization to morphine in mice

The relationship between opioid actions and L-type Ca(2+) channel blockers has been well documented. However, there is no report relevant to L-type Ca(2+) channel blockers and morphine sensitization, which is suggested to be an analog of behaviors that are characteristic of drug addiction. We now studied systematically the effects of three L-type Ca(2+) channel blockers, nimodipine, nifedipine and verapamil, on morphine-induced locomotor activity, the development and the expression of sensitization to morphine. The results showed that both nimodipine and verapamil attenuated, while nifedipine had only a tendency to decrease morphine-induced locomotor activity. All three drugs inhibited the development of sensitization to morphine. However, none of them showed any effects on the expression of morphine sensitization. These results indicate that blocking L-type Ca(2+) channel attenuates the locomotor-stimulating effects of morphine and inhibits the development but not the expression of morphine sensitization.

Identification of addicsin/GTRAP3-18 as a chronic morphine-augmented gene in amygdala

Using subtractive cloning, we identified a 1.4 kb mRNA that was ubiquitously expressed in various tissues; this mRNA was highly up-regulated in amygdala nuclei in mice when morphine was repeatedly administered but not when an opiate-receptor antagonist was co-administered. The mRNA encodes a 23 kDa protein, designated 'addicsin'. This contains two putative PKC-phosphorylation motifs and several hydrophobic regions, and was recovered in a soluble protein fraction of brain lysate. Its primary structure showed 98% identity with that of rat glutamate-transporter-associated protein 3-18 (GTRAP3-18), a putative modulator of neural glutamate-transporter EAAC1. Up-regulation of addicsin expression by morphine may affect glutamate uptake in the amygdala, causing mice to develop morphine tolerance and dependence.

Expression of tenascin-C long isoforms is induced in the hypothalamus by FGF-1

Fibroblast growth factor (FGF)-1 modulates various brain functions, such as the hypothalamic control of feeding. In the rat, we examined the effect of intracerebroventricularly infused FGF-1 on the hypothalamic expression of tenascin-C, a selective mediator of neuron-glial interaction. In situ hybridization revealed little tenascin-C mRNA expression in control brains, but greatly increased expression in ependymal cells around the third ventricle in the FGF-1-infused rats. Reverse transcription-linked PCR analysis of hypothalamic mRNA revealed an FGF-1-induced expression not of the shortest isoform of tenascin-C, but of the long isoforms (with additional fibronectin type III-domain insertions). Quantitative analysis by real time PCR revealed that this induction was transient and dose-dependent. Specific modulation of hypothalamic neuron-glial interactions by tenascin-C may mediate FGF-1-induced feeding suppression.

Endogenous opiates: 2000

This paper is the twenty-third installment of the annual review of research concerning the opiate system. It summarizes papers published during 2000 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunological responses.

[Microinfusion experiment for mice and its application to pharmacological studies]

It is urgently necessary to clarify functions of uncharacterized proteins. To understand life processes, we must investigate the functions and networks of proteins expressed from genomic DNA. In the near future, microinfusion experiments will become a more important method for analyzing uncharacterized function of proteins in vivo. Here we provide a practical manual for performing microinfusion experiments in mice. We also describe our experiment in which we performed a single injection of morphine following Secreted Protein Acidic and Rich in Cysteine (SPARC) infusion into the basolateral amygdala of previously uninjected mice and found markedly enhanced locomotor activity. We discuss the utility of microinfusion experiments in mice.

Gene expression following acute morphine administration

The long-term response to neurotropic drugs depends on drug-induced neuroplasticity and underlying changes in gene expression. However, alterations in neuronal gene expression can be observed even following single injection. To investigate the extent of these changes, gene expression in the medial striatum and lumbar part of the spinal cord was monitored by cDNA microarray following single injection of morphine. Using robust and resistant linear regression (MM-estimator) with simultaneous prediction confidence intervals, we detected differentially expressed genes. By combining the results with cluster analysis, we have found that a single morphine injection alters expression of two major groups of genes, for proteins involved in mitochondrial respiration and for cytoskeleton-related proteins. RNAs for these proteins were mostly downregulated both in the medial striatum and in lumbar part of the spinal cord. These transitory changes were prevented by coadministration of the opioid antagonist naloxone. Data indicate that microarray analysis by itself is useful in describing the effect of well-known substances on the nervous system and provides sufficient information to propose a potentially novel pathway mediating its activity.