Receptor Subunit mRNA Expression Research Articles

Ionotropic glutamate receptor binding and subunit mRNA expression in thalamic nuclei in schizophrenia.

Both thalamic and glutamatergic dysfunction have been implicated in the pathophysiology of schizophrenia. The authors examined ionotropic glutamate receptor expression in postmortem samples from patients with schizophrenia and comparison subjects, using the hypothesis that glutamate receptor expression differs in limbic nuclei of the thalamus in schizophrenia. N-Methyl-D-aspartate (NMDA), AMPA, and kainate receptor expression was determined in six thalamic nuclei from 12 subjects with DSM-III-R diagnoses of schizophrenia and eight psychiatrically normal individuals. The authors used in situ hybridization to determine NMDAR1, NMDAR2A-NMDAR2D, gluR1-gluR7, KA1, and KA2 subunit mRNA levels and receptor autoradiography to determine binding to glutamate binding sites of the three receptor subtypes and to the glycine, polyamine, and ion channel binding sites of the NMDA receptor. Glutamate receptor expression was lower at both transcriptional (NMDAR1, NMDAR2B, NMDAR2C, gluR1, gluR3, and KA2 subunit mRNAs) and posttranscriptional ([(3)H]ifenprodil and [(3)H]MDL105,519 binding to polyamine and glycine sites of the NMDA receptor) levels in the thalamus in patients with schizophrenia than in comparison subjects, but differences were most prominent in nuclei with reciprocal projections to limbic regions. Abnormalities in NMDA, AMPA, and kainate receptor expression in limbic thalamus are suggestive of the NMDA receptor hypoactivity hypothesis of schizophrenia and are consistent with diminished glutamatergic activity in the thalamus in schizophrenia. Alternatively, these results could suggest abnormal glutamatergic innervation in afferent and/or efferent regions, which are limbic structures that have been implicated in this illness. These results may provide a neurochemical anatomical substrate for antipsychotic therapies targeting ionotropic glutamate receptors.

Laminar Shear Stress Upregulates Integrin Expression

Laminar shear stress exerts important effects on endothelial cell (EC) function and inhibits apoptosis of ECs induced by various stimuli. The mechanism by which hemodynamic forces, such as shear stress, are transduced into cellular signaling is still not known. Located at the cell surface, integrins, which are required for cell adhesion and cell survival, are potential mechanotransducers. Therefore, we investigated the effect of shear stress on integrin expression in ECs. Shear stress time-dependently increased the mRNA expression of the fibronectin receptor subunits alpha(5) and beta(1) with a maximum at 6 hours (283+/-41% and 215+/-27% of control, respectively). In addition, the protein levels of the fibronectin receptor subunits alpha(5) and beta(1) were enhanced with a maximum at 12 hours of shear stress exposure (343+/-53% and 212+/-38% of control, respectively). The shear stress-induced upregulation of integrins is independent of nitric oxide. Furthermore, we confirmed the enhanced functional activity of alpha(5)beta(1) integrin expression by FACS analysis. As a functional consequence, human umbilical vein ECs, which were preexposed to shear stress, revealed a significantly increased attachment (178+/-10% of static controls) and a more pronounced extracellular signal-regulated kinase 1 and 2 activation in response to cell attachment. Finally, we demonstrated that shear stress requires RGD-sensitive integrins to mediate its antiapoptotic effect. Taken together, these results define a novel mechanism by which shear stress may exert its atheroprotective effects via upregulation of integrins to support EC adhesion and survival.

Chronic Ethanol Consumption Alters Recovery of Spontaneously Active Medial Septal/Diagonal Band of Broca Neurons From GABA‐Microiontophoresis

Acute ethanol administration increases GABA-mediated inhibition in a variety of cerebral cortical preparations. Furthermore, chronic ethanol administration blunts ethanol-induced increases in GABA-mediated inhibition and alters GABA A receptor subunit mRNA and peptide expression in the cerebral cortex. The sedative hypnotic effects of ethanol are believed to be modulated by GABA-induced inhibition in medial septum/diagonal band of Broca (MS/DB) neurons, a brain region where acute ethanol administration increases GABA-mediated inhibition of spontaneously active neurons. Chronic ethanol administration produces tolerance to the sedative effects of ethanol. However, it is unknown if chronic ethanol consumption produces alterations in GABA-mediated inhibition in the MS/DB in a manner similar to that found in the cerebral cortex. Animals either consumed ethanol chronically for 14 days via a liquid diet or were pair-fed an equicaloric dextrose-containing control diet. Spontaneously active MS/DB neurons were recorded using multibarrel glass micropipettes while the effect of GABA-microiontophoresis was investigated. The total amount of GABA-mediated inhibition at four ejection currents was analyzed, as was the recovery to spontaneous neural firing rates following GABA inhibition. In a separate group of animals, the medial septum was microdissected, and the relative expression of GABA A receptor alpha1 and alpha4 subunit peptide were analyzed via Western blot analysis. Chronic ethanol consumption altered recovery of spontaneous neural activity of MS/DB neurons following GABA-microiontophoresis compared to premicroiontophoresis levels. Specifically, the recovery of spontaneous neural activity of MS/DB neurons recorded from animals that chronically consumed ethanol was slower following GABA-microiontophoresis compared to neurons recorded from control animals. This effect was temporary and reversible. Furthermore, the alteration in recovery of spontaneous neural activity was not due to changes in the total amount of inhibition produced by GABA. Finally, there was no significant change in GABA A receptor alpha1 and alpha4 subunit peptide levels in the MS/DB. Chronic ethanol consumption alters the frequency of spontaneous MS/DB neural activity following GABA microiontophoresis compared to premicroiontophoresis levels. These data suggest that the kinetics of GABA A receptors in the MS/DB are altered by chronic ethanol consumption independent of changes in the total amount of inhibition or alterations in GABA A receptor alpha1 and alpha4 subunit peptide expression.

Chronic Ethanol Consumption Alters Recovery of Spontaneously Active Medial Septal/Diagonal Band of Broca Neurons From GABA-Microiontophoresis

Background: Acute ethanol administration increases GABA-mediated inhibition in a variety of cerebral cortical preparations. Furthermore, chronic ethanol administration blunts ethanol-induced increases in GABA-mediated inhibition and alters GABAA receptor subunit mRNA and peptide expression in the cerebral cortex. The sedative hypnotic effects of ethanol are believed to be modulated by GABA-induced inhibition in medial septum/diagonal band of Broca (MS/DB) neurons, a brain region where acute ethanol administration increases GABA-mediated inhibition of spontaneously active neurons. Chronic ethanol administration produces tolerance to the sedative effects of ethanol. However, it is unknown if chronic ethanol consumption produces alterations in GABA-mediated inhibition in the MS/DB in a manner similar to that found in the cerebral cortex. Methods: Animals either consumed ethanol chronically for 14 days via a liquid diet or were pair-fed an equicaloric dextrose-containing control diet. Spontaneously active MS/DB neurons were recorded using multibarrel glass micropipettes while the effect of GABA-microiontophoresis was investigated. The total amount of GABA-mediated inhibition at four ejection currents was analyzed, as was the recovery to spontaneous neural firing rates following GABA inhibition. In a separate group of animals, the medial septum was microdissected, and the relative expression of GABAA receptor α1 and α4 subunit peptide were analyzed via Western blot analysis. Results: Chronic ethanol consumption altered recovery of spontaneous neural activity of MS/DB neurons following GABA-microiontophoresis compared to premicroiontophoresis levels. Specifically, the recovery of spontaneous neural activity of MS/DB neurons recorded from animals that chronically consumed ethanol was slower following GABA-microiontophoresis compared to neurons recorded from control animals. This effect was temporary and reversible. Furthermore, the alteration in recovery of spontaneous neural activity was not due to changes in the total amount of inhibition produced by GABA. Finally, there was no significant change in GABAA receptor α1 and α4 subunit peptide levels in the MS/DB. Conclusions: Chronic ethanol consumption alters the frequency of spontaneous MS/DB neural activity following GABA microiontophoresis compared to premicroiontophoresis levels. These data suggest that the kinetics of GABAA receptors in the MS/DB are altered by chronic ethanol consumption independent of changes in the total amount of inhibition or alterations in GABAA receptor α1 and α4 subunit peptide expression.

Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures.

Using organotypic slice cultures of hippocampus and cortex-striatum from newborn to 7 day old rats, we are currently studying the excitotoxic effects of kainic acid (KA), AMPA and NMDA and the neuroprotective effects of glutamate receptor blockers, like NBQX. For detection and quantitation of the induced neurodegeneration, we have developed standardized protocols, including--a) densitometric measurements of the cellular uptake of propidium iodide (PI), --b) histological staining by Flouro-Jade, --c) lactate dehydrogenase (LDH) release to the culture medium, --d) immunostaining for microtubulin-associated protein 2, and --e) general and specific neuronal and glial cell stains. The results show good correlation between the different markers, and are in accordance with results obtained in vivo. Examples presented in this review will focus on the use of PI uptake to monitor the excitotoxic effects of --a) KA and AMPA (and NMDA) in hippocampal slice cultures, and --b) KA and AMPA in corticostriatal slice cocultures, with demonstration of differentiated neuroprotective effects of NBQX in relation to cortex and striatum and KA and AMPA. A second set of studies include modulation of hippocampal KA-induced excitotoxicity and KA-glutamate receptor subunit mRNA expression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardized procedures for quantitation of cell damage and receptor subunit changes is of great potential use for studies of excitotoxic, glutamate receptor-induced neuronal cell death, receptor modulation and related neuroprotection.

Maternal care, hippocampal synaptogenesis and cognitive development in rats.

We report that variations in maternal care in the rat promote hippocampal synaptogenesis and spatial learning and memory through systems known to mediate experience-dependent neural development. Thus, the offspring of mothers that show high levels of pup licking and grooming and arched-back nursing showed increased expression of NMDA receptor subunit and brain-derived neurotrophic factor (BDNF) mRNA, increased cholinergic innervation of the hippocampus and enhanced spatial learning and memory. A cross-fostering study provided evidence for a direct relationship between maternal behavior and hippocampal development, although not all neonates were equally sensitive to variations in maternal care.

Regional variations in the effects of chronic ethanol administration on GABA A receptor expression: potential mechanisms

Gamma-aminobutyric acid type A (GABA A) receptors in brain adapt to chronic ethanol exposure via changes in receptor function and subunit expression. The present review summarizes currently available data regarding changes in GABA A receptor subunit mRNA and peptide expression. Data are presented from various different brain regions and the variations between specific brain regions used to draw conclusions about mechanisms that may underlie GABA A receptor adaptations during chronic ethanol exposure. In the whole cerebral cortex, chronic ethanol exposure leads to a reduction of GABA A receptor α1 subunit mRNA and peptide levels and a near equivalent increase in α4 subunit mRNA and peptide levels. This observation is the primary support for the hypothesis that altered receptor composition is a mechanism for GABA A receptor adaptation produced by chronic ethanol exposure. However, other brain regions do not display similar patterns of subunit changes. Moreover, subregions within cortex (prefrontal, cingulate, parietal, motor, and piriform) exhibit patterns of changes in subunit expression that differ from whole cortex. Therefore, regional differences in GABA A receptor subunit expression are evident following chronic ethanol administration, thus suggesting that multiple mechanisms contribute to the regulation of GABA A receptor expression. These mechanisms may include the involvement of other neurotransmitter systems, endogenous steroids and second or third messenger cross-talk.

Ginsenoside Rc and Rg1 differentially modulate NMDA receptor subunit mRNA levels after intracerebroventricular infusion in rats.

We investigated the influence of centrally administered ginsenoside on the regulation of mRNA levels of the family of NMDA receptor subtypes (NR1, NR2A, NR2B, NR2C) by in situ hybridization histochemistry in the rat brain. The ginsenosides Rc and Rg1, the major components of ginseng saponin, differentially modulate NMDA receptor subunit mRNA levels in rat brain following prolonged i.c.v.-infusion. Ginsenosides Rc or Rg1 (10 microg/10 microl/hr for 7 days) was infused through preimplanted cannulae connected to osmotic mini-pumps. The level of NR1 mRNA is significantly increased in temporal cortex, caudate putamen, hippocampus, and granule layer of cerebellum in Rg1-infused rats as compared to control group. The level of NR2A mRNA is elevated in the frontal cortex. In contrast, it was decreased in CAI area of hippocampus in Rg1-infused rats. However, there was no significant change of NR1 and NR2A mRNA levels in Rc-infused rats. The level of NR2B mRNA is elevated in cortex, caudate putamen, and thalamus in both Rc- and Rg-infused rats. In contrast, NR2B level is decreased in CA3 in Rg1-infused rats. The level of NR2C mRNA is increased in the granule layer of cerebellum in only Rg1 but not Rc infused rats. These results show that structure difference of ginsenoside may diversely affect the modulation of expression of NMDA receptor subunit mRNA after infusion into cerebroventricle in rats.

Fluorescence imaging of GABA A receptor-mediated intracellular [Cl −] in P19-N cells reveals unique pharmacological properties

This study describes the pharmacological properties of GABA A receptors expressed in P19-N cells using fluorescence imaging of intracellular chloride with 6-methoxy- N-ethylquinolinium iodide (MEQ). We show that application of the GABA agonist, muscimol (10–200 μM), produces time- and concentration-dependent increases in intracellular [Cl −] that are blocked by bicuculline. Diazepam (10 μM) and pentobarbital (1 mM) potentiate muscimol-stimulation. These receptors exhibit novel pharmacological properties. The neurosteroid, 3α-hydroxy-5α-pregnane-20-one (1–10 μM) exhibited weak potency in enhancement of muscimol-stimulation. Ethanol (50 and 100 mM) exhibited high efficacy on muscimol responses, a 4- to 5-fold potentiation, respectively, of muscimol (10 μM) alone. GABA and muscimol allosterically modulated specific binding of [ 3 H ]flunitrazepam to differentiated P19 cells. Modulation of GABA A receptor mediated increases in intracellular [Cl −] demonstrated stability in response magnitude from 7 to 15 days following removal of retinoic acid. In concert, GABA A receptor subunit mRNA and protein expression patterns in these neuron-like cells were stable over the same period. Using RT-PCR we determined that differentiated P19 cells lack γ1, γ2L, α6 and δ subunit mRNAs while expressing α1, α2, α3, α4, α5, β1, β2, β3, γ2S and γ3. Furthermore, subunit specific antibody immunocytochemical labeling of cells with a neuronal morphology indicated the presence of α1, α2, α4, and γ2 subunits (the only subunits tested). Therefore, P19-N cells should prove useful to researchers in need of a model cell culture system in which to study function and regulation of neuronal GABA A receptors.

Chronic ethanol exposure and withdrawal influence NMDA receptor subunit and splice variant mRNA expression in the rat cerebral cortex

Chronic ethanol exposure and subsequent withdrawal are known to change NMDA receptor activity. This study examined the effects of chronic ethanol administration and withdrawal on the expression of several NMDA receptor subunit and splice variant mRNAs in the rat cerebral cortex. Ethanol dependence was induced by ethanol vapour exposure. To delineate between seizure-induced changes in expression during withdrawal and those due to withdrawal per se, another group of naive rats was treated with pentylenetetrazol (PTZ) injection (30 mg/kg, i.p.). RNA samples from the cortices of chronically treated and withdrawing animals were compared to those from pairfed controls. Changes in NMDA receptor mRNA expression were determined using ribonuclease protection assays targetting the NR2A, -2B, -2C and NR1-pan subunits as well as the three alternatively spliced NR1 inserts (NR1-pan describes all the known NR1 splice variants generated from the 5′ insert and the two 3′ inserts). The ratio of NR1 mRNA incorporating the 5′ insert vs. that lacking it was decreased during ethanol exposure and up to 48 h after withdrawal. NR2B mRNA expression was elevated during exposure, but returned to control levels 18 h after withdrawal. Levels of NR2A, NR2C, NR1-pan and both 3′ NR1 insert mRNAs from the ethanol-treated groups did not alter compared with the pair-fed control group. No changes in the level of any NMDA receptor subunit mRNA was detected in the PTZ-treated animals. These data support the hypothesis that changes in NMDA receptor subunit composition may underlie a neuronal adaptation to the chronic ethanol-inhibition and may therefore be important in the precipitation of withdrawal hyperactivity.

Expression of the α3 nicotinic receptor subunit mRNA in aging and Alzheimer's disease

Changes in the number of high-affinity nicotine binding sites have been widely reported in specific regions of the human brain during aging and in degenerative neurological diseases associated with aging, such as Alzheimer's disease. Nicotinic receptors are highly diverse and a description of the molecular subtypes affected in such conditions has not been achieved to date. To investigate the status of the α3 subunit-containing subtypes in such conditions, we assessed by in situ hybridisation the α3 mRNA density in the hippocampus, entorhinal cortex and thalamus of Alzheimer's patients and age-matched controls. No significant difference in the expression of the α3 mRNA, either qualitative or quantitative, was found between Alzheimer's individuals and controls in any of the analysed areas. This result suggests that the nicotine binding changes occurring in these areas in Alzheimer's patients are not correlated to a variation of the α3 mRNA in the same regions. Nevertheless, a negative correlation between the α3 mRNA density and the age was observed in the entorhinal cortex of both the Alzheimer's and the normal subjects, suggesting a potentially extensive decay of the α3-expressing neurons or loss of α3-containing receptors in intact neurons of the entorhinal cortex in the late elderly.

Effects of NO on ionic channels

Abnormalities in glutamate neurotransmission are thought to be among the major contributing factors to the pathophysiology of schizophrenia. Although schizophrenia has been regarded mostly as a disorder of higher cortical function, the cortex and thalamus work as a functional unit. Existing data regarding alterations of glutamate receptor subunit expression in the thalamus in schizophrenia remain equivocal. This postmortem study examined mRNA expression of ionotropic glutamate receptor (iGluR) subunits and PSD95 in 5 precisely defined and dissected thalamic subdivisions (medial and lateral sectors of the mediodorsal nucleus; and the ventral lateral posterior, ventral posterior, and centromedian nuclei) of persons with schizophrenia and matched controls using quantitative PCR with normalization to multiple endogenous controls. Among 15 genes examined (NR1 and NR2A-D subunits of the NMDA receptor; GluR1-4 subunits of the AMPA receptor; GluR5-7 and KA1-2 subunits of the kainate receptor; PSD95), all but two (GluR4 and KA1) were expressed at quantifiable levels. Differences in iGluR gene expression were seen between different thalamic nuclei but not between diagnostic groups. The relative abundance of transcripts was: NR1≫NR2A>NR2B>NR2D>NR2C for NMDA, GluR2>GluR1>GluR3 for AMPA, and KA2>GluR5>GluR7>GluR6 for kainate receptors. The expression of PSD95 correlated with the expression of NR1, NR2A, NR2B, NR2D and GluR6 in all nuclei. These results provide detailed and quantitative information on iGluR subunit expression in multiple nuclei of the human thalamus but suggest that alterations in their expression are not a prominent feature of schizophrenia.

AMPA Receptor Binding and Subunit mRNA Expression in Prefrontal Cortex and Striatum of Elderly Schizophrenics

AMPA Receptor Binding and Subunit mRNA Expression in Prefrontal Cortex and Striatum of Elderly Schizophrenics

AMPA receptor binding and subunit mRNA expression in prefrontal cortex and striatum of elderly schizophrenics.

The dopamine hypothesis of schizophrenia has recently evolved into a model of dysfunctional integration between cortical and subcortical dopaminergic activity. Anatomical data suggest that regional alterations in dopaminergic activity may be linked by means of the rich glutamatergic innervation of the striatum by corticostriatal projections, suggesting a potential role for glutamatergic dysfunction in schizophrenia. Although pharmacological data have implicated the NMDA subtype of glutamate receptor in this illness, disturbance in AMPA receptor expression could potentially lead to the NMDA receptor hypoactivity hypothesized in schizophrenia. To address this possibility, we examined AMPA receptor binding and subunit mRNA levels in prefrontal cortex and striatum of schizophrenics and matched controls. There were no significant differences in AMPA receptor binding or subunit mRNA levels in either prefrontal cortical or striatal regions of schizophrenics. Furthermore, AMPA receptor expression did not seem to be regulated by chronic antipsychotic drug exposure, when neuroleptic treated and drug-free schizophrenics were analyzed separately. These data do not support a role for altered AMPA receptor expression in cortex and striatum in schizophrenia.

Expression of NMDA receptor subunit mRNA after MK-801 treatment in neonatal rats

Although NMDA receptor antagonists are neuroprotective when delivered in conjunction with NMDA, supersensitivity to NMDA-mediated injury follows dizocilpine (MK-801) administration in neonatal rats. An increase in NMDA-sensitive [ 3 H ]-glutamate binding accompanies the increase in vulnerability to excitotoxic injury. The present study tests the hypothesis that MK-801 may alter gene expression for the NMDA receptor subunits. Quantitative in situ hybridization histochemistry was used to evaluate the expression of NMDA receptor subunits NR1 and NR2A-D in neonatal rats, 2 to 4 h after treatment with MK-801. Increased mRNA for multiple NMDA receptor subunits was observed in cerebral cortex, striatum and hippocampus. The percent increase in NR2A mRNA was larger than the percent change in NR1, NR2B or NR2D. A small increase in mRNA for the metabotropic glutamate receptor mGluR5 was also observed after MK-801 treatment. These results indicate that gene expression for NMDA receptor subunits in the developing brain is rapidly altered after antagonist exposure. Increased expression of excitatory amino acid receptor subunit mRNA may contribute to the enhanced vulnerability to excitotoxic injury that has been observed after MK-801 treatment.

GABA receptor subunit mRNA expression in brain of conflict, yoked control and control rats

Animal conflict models have been used for years as a preclinical screen for predicting anxiolytic therapeutic efficacy. Anxiolytics, including benzodiazepines, increase punished responding. This suggests that the punished behavior may be mediated by the GABA receptor. To evaluate this hypothesis, we performed in situ hybridization histochemistry studies of GABA receptor subunits ( α1– α4) and synthetic enzymes glutamic acid decarboxylase (GAD 65 and GAD 67) in four groups of rats: conflict (punishment), yoked controls (rats shocked without conflict training history), fixed interval only controls (rats that worked for food but were not shocked) and untreated controls. With conflict behavioral training, bilateral reduction of mRNA for the GABA A α1 subunit was seen relative to controls in the cortex, thalamus and hippocampus. In contrast, alteration of α2 mRNA levels appeared only in the yoked control group, with increased levels seen in the thalamus and cortex and decreased levels in the hippocampus. There were no differences in the α2 mRNA level between the control and the conflict behavioral trained animals. Further, no significant differences were found between groups in the mRNA levels for the α3 subunit, α4 subunit, GAD 65, and GAD 67. These results suggest that the behaviors related to conflict and uncontrollable aversive stimuli (yoked control group) are accompanied and perhaps mediated by selective changes in the GABA A α1 or α2 subunits, respectively. These findings highlight the potential usefulness of the conflict model as a means of elucidating the biological underpinnings of anxiety disorder.

Prenatal Cocaine Exposure Does Not Affect Selected GABAA Receptor Subunit mRNA Expression in Rabbit Visual Cortexa

Annals of the New York Academy of SciencesVolume 846, Issue 1 p. 371-374 Prenatal Cocaine Exposure Does Not Affect Selected GABAA Receptor Subunit mRNA Expression in Rabbit Visual Cortexa JED S. SHUMSKY, Corresponding Author JED S. SHUMSKY Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorYUNXING WU, Corresponding Author YUNXING WU Department of Psychiatry, Allegheny University of the Health Sciences, 320 East North Avenue, Pittsburgh, Pennsylvania 15212, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorE. HAZEL MURPHY, Corresponding Author E. HAZEL MURPHY Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorJONATHAN NISSANOV, Corresponding Author JONATHAN NISSANOV Imaging and Computer Vision Center, Drexel University, 32nd and Chestnut St., Philadelphia, Pennsylvania 19104, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorDENNIS R. GRAYSON, Corresponding Author DENNIS R. GRAYSON Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Department of Psychiatry, Allegheny University of the Health Sciences, 320 East North Avenue, Pittsburgh, Pennsylvania 15212, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this author JED S. SHUMSKY, Corresponding Author JED S. SHUMSKY Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorYUNXING WU, Corresponding Author YUNXING WU Department of Psychiatry, Allegheny University of the Health Sciences, 320 East North Avenue, Pittsburgh, Pennsylvania 15212, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorE. HAZEL MURPHY, Corresponding Author E. HAZEL MURPHY Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorJONATHAN NISSANOV, Corresponding Author JONATHAN NISSANOV Imaging and Computer Vision Center, Drexel University, 32nd and Chestnut St., Philadelphia, Pennsylvania 19104, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this authorDENNIS R. GRAYSON, Corresponding Author DENNIS R. GRAYSON Department of Neurobiology and Anatomy, MCP ◆ Hahnemann University School of Medicine, Allegheny University of the Health Sciences, 3200 Henry Avenue, Philadelphia, Pennsylvania 19129, USA Department of Psychiatry, Allegheny University of the Health Sciences, 320 East North Avenue, Pittsburgh, Pennsylvania 15212, USA Phone, 215/842-4641 or 4640; fax, 215/843-9082; e-mail: [email protected] or [email protected] Phone, 412/359-4814; fax, 412/359-4364; e-mail: [email protected] or [email protected] Phone, 215/895-1381; fax, 215/895-4987; e-mail: [email protected]Search for more papers by this author First published: 07 February 2006 https://doi.org/10.1111/j.1749-6632.1998.tb09758.xCitations: 2 a This work was supported by P01DA06871 (E.H.M.), K04NS01647 (D.R.G.), and P41RR01638 (J.N.). Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume846, Issue1COCAINE: EFFECTS ON THE DEVELOPING BRAINJune 1998Pages 371-374 RelatedInformation

6-hydroxydopamine lesion of rat nigrostriatal dopaminergic neurons differentially affects nicotinic acetylcholine receptor subunit mRNA expression.

Nicotinic acetylcholine receptor (nAChR) subunit mRNA expression in the rat substantia nigra (SN) was assayed by semiquantitative RT-PCR following 6-hydroxydopamine (6-OHDA) lesion of nigrostriatal dopaminergic neurons. Six months after unilateral injection of 6-OHDA or saline into the SN, total RNA was isolated from ipsilateral and contralateral tissue samples. RT-PCR amplifications were performed with template titration using primers specific for sequences encoding 1. nAChR alpha 2-alpha 7 and beta 2-beta 4 subunits 2. Glutamic acid decarboxylase 3. Glyceraldehyde 3-phosphate dehydrogenase for normalization of template mass. PCR products specific for alpha 3, alpha 4, alpha 5, alpha 6, alpha 7, beta 2, beta 3, and glutamic acid decarboxylase were detected in the reactions containing SN RNA. This is the first evidence that alpha 7 may be expressed in the SN. alpha 2 and beta 4 PCR products were not detected in SN reactions, although they were observed in hippocampus and thalamus control reactions. A comparison of ipsilateral and contralateral SN RT-PCR reaction products showed substantial decreases in alpha 5, alpha 6, and beta 3 product yields following 6-OHDA, but not sham treatment. Neither the SN of sham-lesioned rats nor the thalamus of 6-OHDA-lesioned rats yielded similar results, indicating that the effects observed in 6-OHDA-treated SN were not caused by local mechanical damage or a nonspecific response, respectively. Effects of 6-OHDA treatment on alpha 3, alpha 4, alpha 7, beta 2, or glutamic acid decarboxylase product yields from SN samples were small or undetectable. The results suggest that alpha 5, alpha 6, and beta 3 subunit-encoding mRNAs are expressed at substantially higher levels in dopaminergic than in nondopaminergic cell bodies in the SN.

Hippocampal NMDA receptor mRNA undergoes subunit specific changes during developmental lead exposure

The N-methyl- d-aspartate (NMDA) receptor has shown to play an important role in the cognitive deficits associated with developmental lead (Pb) exposure. In this study, we examined the effects of low-level Pb exposure on NMDA receptor subunit gene expression in the developing rat brain. The pattern of NR1, NR2A, NR2B, and NR2C subunit mRNA in situ hybridization was consistent with previous studies. Brain levels of NR1 and NR2A mRNAs were lowest shortly after birth, increasing to reach peak levels by 14 or 21 days of age and subsequently decreasing at 28 days of age. NR2B mRNA levels were highest during early development and decreased as the animals aged. NR2C subunit mRNA was restricted to the cerebellum and a signal was not detectable until the second week of life. Lead exposure resulted in significant and opposite effects in NR1 and NR2A subunit mRNA expression with no changes in NR2B or NR2C subunit expression. The Pb-induced changes in NR1 and NR2A subunit mRNA were mainly present in the hippocampus. Hippocampal NR1 mRNA levels were significantly increased in the CA1 (15.3%) and CA4 (26.8%) pyramidal cells from 14-day-old Pb-exposed rats. At 21 days of age, only the NR1 mRNA at the CA4 subfield remained significantly elevated (10.3%). Lead exposure caused reductions of NR2A mRNA levels (11.9–19.3%) in the pyramidal and granule cell layers of the hippocampus at 14 and 21 days of age. NR1 mRNA levels were also significantly increased (14.0%) in the cerebellum of 28-day-old rats with no change in NR2A mRNA at any age. No significant changes in subunit mRNA levels were present in cortical or subcortical regions at any age. The Pb-induced changes in hippocampal NMDA receptor subunit mRNA expression measured in the present study may lead to modifications in receptor levels or subtypes and alter the development of defined neuronal connections which require NMDA receptor activation.

Developmental expression of GABA(A) receptor subunit mRNAs in individual hippocampal neurons in vitro and in vivo.

The GABA(A) receptor is a heterooligomeric protein complex composed of multiple receptor subunits. Developmental changes in the pattern of expression of 11 GABA(A) receptor subunits in individual rat embryonic hippocampal neurons on days 1-21 in culture and acutely dissociated hippocampal neurons from postnatal day (PND) 5 rat pups were investigated using the technique of single-cell mRNA amplification. We demonstrate that multiple GABA(A) receptor subunits are expressed within individual hippocampal neurons, with most cells simultaneously expressing alpha1, alpha2, alpha5, beta1, and gamma2 mRNAs. Further, relative expression of several GABA(A) receptor subunit mRNAs changes significantly in embryonic hippocampal neurons during in vitro development, with the relative abundance (compared with beta-actin) of alpha1, alpha5, and gamma2 mRNAs increasing 2.3-, 2.7-, and 3.8-fold, respectively, from days 1 to 14, and beta1 increasing 5-fold from days 1 to 21. In situ hybridization with antisense digoxigenin-labeled alpha1, beta1, and gamma2 RNA probes demonstrates a similar increase in expression of subunit mRNAs as embryonic hippocampal neurons mature in vitro. Relative abundances of alpha1, beta1, and gamma2 subunit mRNAs in acutely dissociated PND 5 hippocampal neurons are also significantly greater than in embryonic day 17 neurons on day 1 in vitro and exceed the peak values seen in cultured neurons on days 14-21, suggesting that GABA(A) receptor subunit mRNA expression within individual hippocampal neurons follows a similar, if somewhat delayed, developmental pattern in vitro compared with in vivo. These findings suggest that embryonic hippocampal neuronal culture provides a useful model in which to study the developmental regulation of GABA(A) receptor expression and that developmental changes in GABA(A) receptor subunit expression may underlie some of the differences in functional properties of GABA(A) receptors in neonatal and mature hippocampal neurons.