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M Rattray

Publications and source records attributed to M Rattray.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of hypophysectomy and growth hormone administration on the mRNA levels of collagen I, III and insulin-like growth factor-I in rat skeletal muscle.

The effect of short-term treatment of normal or hypophysectomized rats with biosynthetic growth hormone (GH) was studied in extensor digitorum longus and soleus muscles. In situ hybridization revealed that in normal rats, mRNA for collagen I, collagen III and insulin-like growth factor-I (IGF-I) are expressed by fibroblasts between the muscle fibre areas and that the specificity of this location was not altered by GH administration. Hypophysectomy appeared to cause a decrease in IGF-I and decreased collagen I and III gene expression (P < 0.001, P < 0.001, respectively). GH administration seemed to increase IGF-I mRNA levels in all the animals studied. Quantitative image analysis that GH administration to hypophysectomized rats caused an increase in collagen I gene expression after 2 days (P < 0.05) and an increase in collagen III gene expression after 4 days (P < 0.05). The results indicate that the fibroblast cells are an important target for the action of GH on skeletal muscle and that the fibroblasts respond to GH by increases in the expression of mRNA for collagen I and collagen III.

Animals↗
PubMed1997

Nerve growth factor treatment increases brain-derived neurotrophic factor selectively in TrkA-expressing dorsal root ganglion cells and in their central terminations within the spinal cord.

Using immunocytochemistry and in situ hybridization, we have examined the expression of brain-derived neurotrophic factor (BDNF) and of neurotrophin receptors in dorsal root ganglion cells. In the adult rat, BDNF mRNA and protein were found mainly in the subpopulation of cells that express the nerve growth factor (NGF) receptor trkA and the neuropeptide calcitonin gene-related peptide (CGRP). NGF increased BDNF within the trkA/CGRP cells to the extent that almost 90% of trkA cells contained BDNF mRNA after intrathecal NGF treatment, and 80-90% of BDNF-expressing cells contained trkA. Non-trkA cells that expressed BDNF included some trkC cells and some small cells that labeled with the lectin Griffonia simplicifolia IB4, a marker for cells that do not express trks. However, very few trkB cells expressed either BDNF mRNA or protein, and NGF did not increase BDNF expression in non-trkA cells. BDNF protein was anterogradely transported both peripherally and centrally. The central transport resulted in BDNF immunoreactivity in CGRP containing terminal arbors in the dorsal horn of the spinal cord, and this immunoreactivity was increased by NGF treatment. Electron microscopic analysis revealed that the BDNF immunoreactivity was present in finely myelinated and unmyelinated axons and in axon terminals, where it was most concentrated over dense-cored vesicles. Our data do not support an autocrine or paracrine role for BDNF within normal dorsal root ganglia, but indicate that BDNF may act as an anterograde trophic messenger. NGF levels in the periphery could influence dorsal horn neurons via release of BDNF from primary afferents.

Afferent Pathways↗
PubMed1997

Expression of GABA transporter mRNAs in the developing and adult rat optic nerve.

There is electrophysiological evidence of a functional role for gamma-aminobutyric acid (GABA) and GABA transporters (GATs) in the neonatal rat optic nerve, and that they are down-regulated during development. The results of the present study demonstrate directly by reverse transcription-polymerase chain reaction (RT-PCR) that the mRNAs encoding for GAT-1, -2 and -3 are expressed in the optic nerves of both neonatal (5 day old) and adult rats. The results support a role for GABA in the developing rat optic nerve, a typical white matter tract which contains axons and glia, but neither neuronal cell bodies nor synapses. Significantly, the persistence of GAT mRNAs suggests an enduring function for both GABA and glial uptake mechanisms in the adult optic nerve.

Animals↗
PubMed1997

Selective up-regulation of protein kinase C epsilon in granule cells after kainic acid-induced seizures in rat.

Kainate-induced seizure activity causes persistent changes in the hippocampus that include synaptic reorganization and functional changes in the mossy fibers. Using in situ hybridization histochemistry, the expression of PKC alpha, PKC beta, PKC gamma, PKC delta and PKC epsilon mRNAs was investigated in the hippocampus of adult rats following seizures induced by a s.c. injection of kainic acid. In CA1 and CA3, we found a significant decrease in PKC gamma mRNA 1 day after kainic acid which persisted for a 2nd day in CA1. None of the other PKC isoform mRNAs were altered in CA1 or CA3. In granule cells, a significant up-regulation specific to PKC epsilon mRNA was observed. One week after kainic acid administration, a marked increase in PKC epsilon immunoreactivity was found that persisted 2 months after kainic acid administration. PKC epsilon immunoreactivity was found associated with mossy fibers projecting to the hilus of the dentate gyrus and to the stratum lucidum of the CA3 field and presumably with the newly sprouted mossy fibers projecting to the supragranular layer. These data provide the first evidence for a long-lasting increase of the PKC epsilon in the axons of granule cells caused by kainate-induced seizures and suggest that PKC epsilon may be involved in the functional and/or structural modifications of granule cells that occur after limbic seizures.

Amygdala↗
PubMed1997

TrkA immunoreactive neurones in the rat spinal cord.

We report the presence in rat spinal cord of a novel neuronal system expressing tyrosine kinase receptor (trkA), the high affinity receptor for nerve growth factor (NGF). TrkA immunoreactive cell bodies were observed in the intermediate grey matter of the spinal cord and were classified into three main groups: central canal cells located dorsolateral to the aqueduct, partition cells located between lamina X, and the lateral border of the intermediate grey, and a morphologically heterogeneous group which included large cells located near the lateral border. In situ hybridization confirmed that cells in all these areas express trkA mRNA. Combined immunofluorescence and retrograde Fluoro-Gold labelling was used to further characterise the projections and neurotransmitter profile of the trkA cells. Although often located in the vicinity of preganglionic cell groups, trkA immunoreactive cells are not themselves preganglionic. Rather, the central canal and partition cells belong to a neurochemically complex cholinergic propriospinal system. Many partition cells coexpress trkA, choline acetyltransferase (ChAT), the low affinity neurotrophin receptor, p75, and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). In contrast, trkA immunoreactive central canal cells express ChAT, but do not express p75 and only a subpopulation express NADPH-d. The large trkA immunoreactive cells located on the lateral border do not express ChAT. TrkA immunoreactive fibres were also present and were located in the dorsal horn, in the dorsal columns, and in a bundle ventral to the aqueduct. However, double labelling revealed that the trkA immunoreactive fibres are not intrinsic but are primary afferent in origin and coexpress p75. The location of this novel trkA neuronal system is consistent with it having a role in the segmental integration of autonomic outflow. NGF could affect this system by modulating neuronal phenotype and/or synaptic efficacy.

Animals↗
PubMed1997

Identification of 5-hydroxytryptamine receptors positively coupled to adenylyl cyclase in rat cultured astrocytes.

1. 5-Hydroxytryptamine (5-HT) elicited a dose-dependent stimulation of intracellular adenosine 3': 5'-cyclic monophosphate (cyclic AMP) accumulation in cultured astrocytes derived from neonatal rat (Sprague Dawley) thalamic/hypothalamic area with a potency (pEC50) of 6.68 +/- 0.08 (mean +/- s.e. mean). 2. In order to characterize the 5-HT receptor responsible for the cyclic AMP accumulation the effects of a variety of compounds were investigated on basal cyclic AMP levels (agonists) and 5-carboxamidotryptamine (5-CT) stimulated cyclic AMP levels (antagonists). The rank order of potency for the agonists investigated was 5-CT (pEC50 = 7.81 +/- 0.09) > 5-methoxytryptamine (5-MeOT) (pEC50 = 6.86 +/- 0.36) > 5-HT (pEC50 = 6.68 +/- 0.08). The following compounds, at concentrations up to 10 microM, did not affect basal cyclic AMP levels 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), cisapride, sumatriptan, DOI and RU 24969. The rank order of potency of antagonists was methiothepin (pKi = 7.98 +/- 0.25) > mesulergine (pKi = 7.58 +/- 0.18) > ritanserin (pKi = 7.20 +/- 0.24) > clozapine (pKi = 7.03 +/- 0.19) > mianserin (pKi = 6.41 +/- 0.19). The following compounds, at concentrations up to 10 microM, were inactive: ketanserin, WAY100635, GR127935. This pharmacological profile is consistent with that of 5-HT7 receptor subtype-mediated effects. 3. The cultured astrocytes exhibited regional heterogeneity in the magnitude of cyclic AMP accumulation (Emax). Cells cultured from the thalamic/hypothalamic area had significantly higher Emax values (588 +/- 75% and 572 +/- 63% of basal levels for 5-CT and 5-HT, respectively) compared to brainstem (274 +/- 51% and 318 +/- 46%, respectively) and colliculus astrocytes (244 +/- 15% and 301 +/- 24%, respectively). No significant differences in pEC50 (for either 5-HT or 5-CT) values were observed. 4. Reverse transcriptase-polymerase chain reaction (RT-PCR) with primers specific for the 5-HT7 receptor confirmed expression of messenger RNA for this receptor subtype by the cultured astrocytes derived from all regions investigated. Primers specific for the 5-HT6 receptor also amplified a cDNA fragment from the same samples. 5. From these findings, we conclude that astrocytes cultured from a number of brain regions express functional 5-HT receptors positively coupled to adenylyl cyclase and that the level of receptor expression or the efficiency of receptor coupling is regionally-dependent. The pharmacological profile of the receptor on thalamic/hypothalamic astrocytes suggests that the 5-HT7 receptor is the dominant receptor that is functionally expressed even though astrocyte cultures have the capacity to express both 5-HT6 and 5-HT7 receptor messenger RNA.

Adenylyl Cyclases↗
PubMed1996

Altered expression of group I metabotropic glutamate receptors in the hippocampus of amygdala-kindled rats.

Kindling is a well documented model of acquired focal epilepsy and synaptic plasticity in the nervous system. Previous biochemical studies have indicated an increase in mGluR-mediated phosphoinositide hydrolysis in the amygdala or hippocampus of fully kindled animals. In this study we have used in situ hybridisation techniques to examine the mRNA expression of group I metabotropic glutamate receptors (mGluR1 and mGluR5 both linked to phosphoinositide hydrolysis) in the hippocampus of amygdala-kindled animals sacrificed 24 h, 7 days or 28 days following the last electrically evoked stage 5 seizure, and in implanted non-stimulated control rats. Results indicate an initial up-regulation in mGluR1 mRNA (expressed as percentage of control) bilaterally in the DG (35-40%) and CA3 (16-48%), and unilaterally in CA4 (12%) in the 24 h post-kindled group. In kindled animals studied 7 days after the last seizure, these changes were either reduced or had returned to control levels. By 28 days mGluR1 mRNA levels had returned to control levels, with only a persistent increase in expression unilaterally in the DG (14%). In contrast, an initial down-regulation in mGluR5 mRNA was observed bilaterally in CA4 (-45 and -25%) and CA1 (-46 and -45%), and unilaterally in DG and CA3 (-27 and -42% respectively) 24 h after the last kindled seizure. In the 7 and 28 day kindled groups significant alterations in expression of mGluR5 mRNA were still apparent. These data show that the mRNAs for mGluR1 and mGluR5 are differentially regulated by kindling, indicating that the expression of each of these receptors is under independent regulatory control. These perturbations in mRNA expression may contribute to kindling epileptogenesis but are unlikely to account for the maintenance of the kindled state.

Amygdala↗
PubMed1996

Circadian changes of glutamate decarboxylase 65 and 67 mRNA in the rat suprachiasmatic nuclei.

Gaba has been implicated in the regulation of the circadian clock within the suprachiasmatic nuclei (SCN). In the present study in situ hybridization histochemistry was used to assess expression of mRNA for the two isoforms of the enzyme governing GABA synthesis, glutamic acid decarboxylase (GAD) 65 and 67, within the rat SCN during a 24 h cycle in constant darkness. GAD 65 mRNA exhibited a monophasic rhythm, with a peak at the beginning of the subjective day and a nadir early in the subjective night. In contrast, there was a biphasic variation in GAD 67 expression, with peaks at the beginning of the subjective day and early in the subjective night. No significant variation in the mRNAs for GAD 65 or GAD 67 was observed in the cingulate cortex. These results suggest that the clock intrinsic to the SCN controls the expression of the mRNAs encoding GAD 65 and GAD 67 in both a coordinated and a differential manner.

Animals↗
PubMed1996

Circadian variation of EAAC1 glutamate transporter messenger RNA in the rat suprachiasmatic nuclei.

Using in situ hybridization, we examined temporal changes of the EAAC1 glutamate transporter mRNA within the suprachiasmatic nuclei (SCN) of rats in constant darkness. Film autoradiographs showed that the SCN and supraoptic nuclei (SON) contained a marked density of hybridization signal. Analysis of silver grains per cell in emulsion-dipped sections indicated that cellular expression of EAAC1 mRNA in the SCN was elevated during the latter part of the subjective night and at the beginning of the subjective day, with a peak at circadian time 23.1 as determined by cosinor analysis. The times at which EAAC1 mRNA is highest correspond to the time points at which extracellular glutamate, a neurotransmitter that putatively mediates photic entrainment, has been reported to be low within the SCN. The presence of EAAC1 mRNA in the SCN and SON may partially explain the resistance of these nuclei to glutamate receptor-mediated excitotoxins; furthermore, the raised level preceding subjective dawn in the SCN may ensure sub-toxic levels of extracellular glutamate at the onset of photic stimulation during the LD cycle. In contrast, cellular expression of EAAC1 mRNA in the cingulate cortex and reticular thalamus remained constant at all time points studied. These results suggest that there is circadian control of the EAAC1 mRNA by the clock intrinsic to the SCN.

Amino Acid Transport System X-AG↗
PubMed1996

p-Chlorphenylalanine changes serotonin transporter mRNA levels and expression of the gene product.

After a single intraperitoneal injection of the irreversible tryptophan hydroxylase inhibitor p-chlorophenylalanine (PCPA; 300 mg/kg), there was a rapid down-regulation of serotonin (5-HT) transporter mRNA levels in cell bodies. This change was significant at 1 and 2 days after PCPA administration within the ventromedial but not the dorsomedial portion of the dorsal raphe nucleus. Seven days after PCPA treatment, 5-HT transporter mRNA levels were significantly elevated compared with controls in both regions of the dorsal raphe nucleus. PCPA administration produced no change in the [3H]citalopram binding and synaptosomal [3H]5-HT uptake in terminal regions at 2 and 7 days after treatment but significantly reduced both these parameters by approximately 20% in the hippocampus and in cerebral cortex 14 days after PCPA administration. The striatum showed a lower sensitivity to this effect. No significant changes were observed in the levels of [3H]citalopram binding to 5-HT cell bodies in the dorsal raphe nucleus. In the same animals used for 5-HT transporter mRNA level measurements, levels of tryptophan hydroxylase mRNA in neurons of the ventromedial and dorsomedial portions of the dorsal raphe nucleus were increased 2 days after PCPA administration and fell to control levels 7 days after injection in the ventromedial region but not in the dorsomedial portion of the dorsal raphe nucleus, where they remained significantly higher than controls. Altogether, these results show that changes in 5-HT transporter mRNA are not temporally related to changes in 5-HT transporter protein levels. In addition, our results suggest that the 5-HT transporter and tryptophan hydroxylase genes are regulated by different mechanisms. We also provide further evidence that dorsal raphe 5-HT neurons are differentially regulated by drugs, depending on their location.

Animals↗
PubMed1995

Growth hormone increases IGF-I, collagen I and collagen III gene expression in dwarf rat skeletal muscle.

The effect of short-term treatment with biosynthetic growth hormone (GH) of male dwarf rats was studied in EDL and soleus muscles. In situ hybridisation revealed that in the untreated dwarf rat collagen I, collagen III and insulin-like growth factor-I (IGF-I) mRNA is mainly expressed by fibroblasts between the muscle fibre areas. Quantitative image analysis showed that, 8 h after a single GH injection, the level of mRNA for all three genes increased compared to the untreated dwarf animal. IGF-I mRNA levels were similar in normals and untreated dwarf rats but significantly increased 8 h after a single GH injection in EDL (P < 0.01) and soleus (P < 0.001). In untreated dwarf rats, collagen I and III gene expression was significantly less than in normal animals (P < 0.001). Collagen III gene expression also increased significantly 8 h after a single GH injection, in both muscles (P < 0.01). Collagen I gene expression showed significant increases 8 and 24 h after GH treatment in EDL (P < 0.01), although the increases seen in soleus did not reach significance. The effects of multiple GH injections (one, two or four) did not appear to be additive. The results of the time course studies are consistent with an intermediary role for IGF-I in the production of collagen in muscle.

Animals↗
PubMed1995

Analysis of the neuronal promoter of the rat aromatic L-amino acid decarboxylase gene.

The rat aromatic L-amino acid decarboxylase (AADC) gene contains alternative promoters directing expression of neuronal and nonneuronal mRNAs that differ only in their 5' untranslated regions (UTRs). We have analyzed the expression of the neuronal promoter of the AADC gene in cells synthesizing catecholamines and serotonin, as well as in non-AADC-expressing cells. We demonstrate the use of the neuronal-specific UTR in individual dopamine-, norepinephrine-, and serotonin-containing neurons. Transfection analyses show that the rat AADC neuronal promoter, containing 2,400 bp upstream of the transcription start site and including the 68-bp untranslated exon 2, can activate transcription from a reporter gene in both catecholaminergic and serotonergic cell lines. These analyses identified several positive and negative cis-active elements within this region. Unexpectedly, we observed that this promoter, when removed from its native context within the AADC gene, can also direct expression of a reporter gene in cells that do not normally express AADC mRNA. These results suggest that tissue-specific expression of the neuronal promoter may not be controlled by cis-active elements within the first 2,400 bp of the promoter. Additional information may be required to restrict neuronal promoter expression to appropriate cell types. This regulatory information could reside elsewhere within the promoter, within introns, or may be provided by interactions between the two AADC promoters.

Animals↗
PubMed1994

Distribution of messenger RNAs encoding enkephalin, substance P, somatostatin, galanin, vasoactive intestinal polypeptide, neuropeptide Y, and calcitonin gene-related peptide in the midbrain periaqueductal grey in the rat.

The midbrain periaqueductal grey matter (PAG) has numerous functional roles that include mediating nociceptive inhibition and integrating behavioural and physiological responses to potentially threatening or stressful stimuli. Underlying these behaviours is the diverse interconnectivity of this region, and it is possible that neurochemical subdivisions within the PAG reflect the functional properties of the different PAG regions. In this study, using in situ hybridization, we have investigated the distribution in the rat PAG of the messenger ribonucleic acids (mRNAs) encoding seven neuropeptides: enkephalin (ENK), substance P (SP), somatostatin (SST), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP). Each peptide mRNA had a distinct topographical distribution in the PAG. Preproenkephalin A (ENK) mRNA-expressing cells were found at all levels of the PAG in three distinct longitudinal columns. Preprotachykinin A (SP)-expressing cells were found at all levels of the PAG, principally in the Edinger-Westphal nucleus and the lateral and dorsal PAG. There was a column of neurons producing mRNA-encoding somatostatin that extended along the rostrocaudal extent of the ventrolateral PAG; there were also labelled cells in the dorsal and dorsolateral subdivisions at some levels of the PAG. Galanin mRNA-producing neurones were limited to the dorsal raphe nucleus and to a second population in the ventral border of the aqueduct. VIP mRNA-producing neurones were found in very localized regions of the PAG, including the cell-sparse region immediately ventral to the aqueduct and the ventral part of the dorsal raphe nucleus. NPY mRNA-producing neurones were localized mainly in some cells of the Edinger-Westphal nucleus and dorsal raphe nucleus. CGRP mRNA-expressing neurons were limited to the oculomotor and trochlear nucleus. The results showed a topographical distribution of neuropeptides over the rostrocaudal extent of the PAG that is compatible with the emerging theory that the anatomical and functional specificity of the PAG is expressed in the form of longitudinally arranged neuronal columns that extend for varying distances along the rostrocaudal axis of the midbrain PAG.

Animals↗
PubMed1994

Chronic D-fenfluramine decreases serotonin transporter messenger RNA expression in dorsal raphe nucleus.

In situ hybridization was used to measure the effects of chronic fenfluramine administration on serotonin transporter messenger RNA expression in cells of the dorsal raphe nucleus complex. Fenfluramine produced a significant, but transient, down-regulation of serotonin transporter mRNA in cells which lie in the ventral portion of the dorsal raphe nucleus, but not in the dorsal part of the dorsal raphe nucleus. Our findings suggest that cells which lie in the ventral part of the dorsal raphe nucleus are more sensitive to the effects of chronic fenfluramine administration, but that fenfluramine does not cause long-term changes in gene expression in serotonin cell bodies.

Animals↗
PubMed1994

Changes in CCK mRNA in hippocampal neurones following fimbria fornix transection.

Preprocholecystokinin (CCK) mRNA expression was measured in a subset of hippocampal interneurones after transection of afferent septohippocampal fibres in the fimbria fornix. Two weeks after the lesions were made, CCK mRNA levels were significantly lower in these neurones on the side ipsilateral to the lesion compared with equivalent neurones on the unlesioned side. These findings suggest that axotomizing lesions can change gene expression in denervated target cells, and that CCK mRNA levels in hippocampal interneurones may be modulated by afferent septohippocampal input.

Afferent Pathways↗
PubMed1994

Serotonin and NADPH-diaphorase in the dorsal raphe nucleus of the adult rat.

NADPH-diaphorase histochemistry, employed as a marker for nitric oxide synthase (NOS), was combined with serotonin (5-HT) immunofluorescence to investigate the relationship between NOS and 5-HT in the rat dorsal raphe nucleus. Many NADPH-diaphorase labelled cells and varicose axons were observed in the nucleus. Coexistence between NADPH-diaphorase and 5-HT occurs in cells of the dorsomedial and ventromedial subgroups but not in the lateral subgroups. Coexistence was not observed in axons, but NADPH-diaphorase labelled axons contact 5-HT/NADPH-diaphorase containing cell bodies. These findings have implications for the role of nitric oxide in 5-HT pathways and for the mechanism of action of 5-HT neurotoxins.

Amino Acid Oxidoreductases↗
PubMed1994

Repeated administration of MDMA down-regulates preprocholecystokinin mRNA expression but not tyrosine hydroxylase mRNA expression in neurones of the rat substantia nigra.

The effect of repeated administration of 3,4-methylenedioxymethamphetamine (MDMA) on the expression of tyrosine hydroxylase and preprocholecystokinin (CCK) messenger RNAs in substantia nigra was examined by in situ hybridisation histochemistry. Sections hybridised with 35S-labelled oligonucleotides were subjected to computerised image analysis to determine the density of silver grains above positively labelled cells as an index of steady state mRNA levels. In the substantia nigra pars compacta, CCK mRNA levels were significantly reduced in drug-treated animals 24 h and at 2 weeks after the last dose of MDMA (10 mg/kg i.p., twice daily for 4 days). In the same animals, MDMA caused no change in the level of tyrosine hydroxylase mRNA in this brain region. The results show that MDMA can produce changes in dopamine neurones. Furthermore, since tyrosine hydroxylase and cholecystokinin are co-expressed in substantia nigra pars compacta, these results suggest that the expression of the tyrosine hydroxylase and CCK genes are regulated independently.

Animals↗