Biomedical subjects

P C Emson

Publications and source records attributed to P C Emson.

At least 19 recordsLinked to original sources

PubMed1992

Differential expression of growth-associated protein (GAP-43) mRNA in rat primary sensory neurons after peripheral nerve lesion: a non-radioactive in situ hybridisation study.

An alkaline phosphatase-labelled anti-sense oligodeoxynucleotide probe specific for growth-associated protein messenger RNA (GAP-43 mRNA) was used for non-radioactive in situ hybridisation histochemistry to follow relative changes in GAP-43 mRNA content in lumbar primary sensory neurons (L4-6) after unilateral ligation of the sciatic nerve. In normal dorsal root ganglia (DRG) 16% of neurons expressed GAP-43 mRNA, and these cells belonged to a sub-group of intermediate-sized (32-50 microns diameter) and large (> 50 microns) neurons. The hybridisation signal detected in these cells was weak to moderate. One day after nerve ligature a significant increase in the number of GAP-43 mRNA expressing neurons in the ipsilateral DRG was detected involving particularly the very small (12-20 microns) cells, and small cell population (20-32 microns), though the hybridisation signal was less pronounced in this latter cell group. A significant increase in the cellular content of GAP-43 mRNA was detected in both cell groups when compared to the normal DRG by 2 days after the lesion. At later times (4, 7, and 10 days postinjury) the intermediate-sized and large cell subpopulations also showed an increase in the number of GAP-43 mRNA positive neurons, followed by a significant rise in their content of GAP-43 mRNA. However, they did not reach the same intensity of hybridisation signal as seen in the small and very small neurons. All DRG neurons showed a maximum of GAP-43 mRNA expression by 10 days postsurgery. At longer times there was a slight decrease in the content of GAP-43 mRNA towards 14 days postinjury, but mRNA levels remained elevated up to 28 days after nerve ligature, the longest time point examined in this study. The different onset and levels of GAP-43 gene expression in the rat primary sensory neurons after lesion of their peripheral branch axons further characterize the different subclasses of these cells and may reflect their different involvement in the plastic changes following peripheral nerve injury.

Alkaline Phosphatase↗

PubMed1992

c-fos may code for a common transcription factor within the hypothalamic neural circuits involved in osmoregulation.

Conscious rats were given an intraperitoneal (i.p.) injection of isotonic or hypertonic saline, and killed 10-240 min later. In the hypothalamus of hypertonic saline-injected rats, c-fos-mRNA positive cells were mainly restricted to the supraoptic and paraventricular nuclei and to structures associated with the lamina terminalis of the third ventricle, including in particular the subfornical organ, the organum vasculosum of the lamina terminalis (OVLT) and the median preoptic nucleus. These structures comprise the proposed anterior hypothalamic 'osmoreceptor complex' for regulation of vasopressin release. The time course of the appearance and disappearance of c-fos mRNA signals was similar in all regions. Thus c-fos protein (Fos) may be a common transcription factor in the hypothalamic neural circuits involved in osmoregulation.

Animals↗

PubMed1992

Compartmental distribution of cytochrome oxidase in the striatum of the rat.

Endogenous cytochrome oxidase activity was investigated in the adult rat striatum at the light microscope level to see if it was distributed in accordance with the established striatal patch/matrix compartmentalisation. Striatal sections stained to visualise cytochrome oxidase activity were compared with serial sections stained to visualise tyrosine hydroxylase and calbindinD28k-like immunoreactivity, established markers of the matrix compartment. The distribution of endogenous cytochrome oxidase activity was found to coincide with the immunocytochemical staining pattern seen for tyrosine hydroxylase and calbindinD28k whereby areas of intense tyrosine hydroxylase and calbindinD28k-like immunoreactivity (termed the matrix) corresponded to areas of intense cytochrome oxidase activity. Conversely, areas of less intense tyrosine hydroxylase and calbindinD28k-like immunoreactivity (termed patches) corresponded to areas of low cytochrome oxidase activity. In addition, the distribution of two other oxidative enzymes involved in the regulation of mitochondrial respiration, succinic dehydrogenase and NADH-diaphorase, was examined in the striatum and substantia nigra by using histochemical techniques. Both NADH-diaphorase and succinic dehydrogenase histochemistry showed an uneven pattern of neuropil staining in the striatum. In the substantia nigra a few intensely stained cell bodies were seen in the dorsal-lateral tip of the pars reticulata with both histochemical techniques. By using an anti-cytochrome oxidase antibody an abundance of immunoreactive cell bodies and processes were seen in the substantia nigra, particularly in the dorso-medial rim and dorsal tip of the pars reticulata. The substantia nigra pars lateralis contained many intensely stained cytochrome oxidase-like immunoreactive cell bodies and processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Increase in galanin gene expression in locus coeruleus neurones of the rat following reserpine treatment.

Changes in galanin mRNA content in locus coeruleus neurones of the rat were studied after reserpine treatment (10 mg/kg s.c.) using an in situ hybridization technique and an alkaline phosphatase labelled oligodeoxynucleotide probe. An increase in galanin mRNA content in locus coeruleus neurones was detected as early as 3 h after reserpine treatment when compared to vehicle injected rats. A maximal increase in mRNA content was detected at 3 days after reserpine treatment. This transient increase in galanin mRNA content had subsided by post treatment day 20. The response of locus coeruleus neurones to the single reserpine injection was heterogeneous; cells in the dorsal portion of the nucleus exhibiting a greater response than ventrally located cells.

Animals↗

PubMed1992

Pertussis toxin administration increases the expression of proneurotensin and preproenkephalin A mRNAs in rat striatum.

The effect of a unilateral intrastriatal microinjection of pertussis toxin on the expression of proneurotensin and preproenkephalin A mRNAs in the adult rat neostriatum was investigated using a technique of non-radioactive in situ hybridization. Control sham microinjected animals received an equal volume of vehicle only and were processed in parallel with the pertussis toxin-treated rats. All rats were allowed to recover from the stereotaxic surgery for 22 h before being killed and their brains rapidly removed and processed for in situ hybridization using alkaline phosphatase-labelled oligonucleotide probes. In comparison to sham microinjected rats, a single intrastriatal microinjection of pertussis toxin (1 microgram) resulted in a significant increase in the amount of both proneurotensin and preproenkephalin A mRNAs in the ipsilateral neostriatum. For proneurotensin mRNA, this increase was reflected by a substantial increase in the number of mRNA-containing cells detected. Proneurotensin mRNA-containing cells detected in the nucleus accumbens appeared to be unaffected by the intrastriatal pertussis toxin microinjection. In contrast, the significant increase in preproenkephalin A mRNA, when compared to the contralateral uninjected striatum and the ipsilateral striatum of control sham injected rats, was reflected by an increase in the cellular amount of preproenkephalin A mRNA and not by an increase in the number of mRNA-containing cells detected. These results demonstrate that the expression of both proneurotensin mRNA and preproenkephalin A mRNA in the adult rat striatum are rapidly increased in vivo by an intrastriatal microinjection of pertussis toxin.

Animals↗

PubMed1992

Morphology of intracellularly stained spiny neurons in rat striatal grafts.

Two to six months after implantation of fetal striatal primordia into the kainic acid-lesioned neostriatum of adult rats, spiny neurons in the grafts were stained intracellularly with biocytin. To determine whether the spiny neurons in the grafts differentiate morphologically as in the host neostriatum, the intracellularly stained spiny neurons in the grafts were studied with light and electron microscopy and compared with that of spiny neurons in the host neostriatum. The spiny neurons in the grafts had ovoid or polygonal cell bodies with dendrites radiating in all directions. The somata were smooth and the dendrites, except for their most proximal portions, were rich in spines. All these features resembled the appearance of spiny neurons in the intact neostriatum. However, quantitative studies showed that the somata of spiny neurons in the grafts were larger than those in the host neostriatum (projected cross-sectional areas of 230 +/- 64.6 microns 2 in the grafts and 158 +/- 28.9 microns 2 in the host) and the spine density of graft neurons was lower than that of host neurons. Cells near the border of the grafts had dendrites extending both into the graft and into the host neostriatum. In these cells, the dendrites in the grafts had fewer spines than the dendrites in the host tissue. The axons of spiny neurons in the grafts had very large and dense intrastriatal collateral arborizations, which occupied a much larger volume than that of the dendritic domain of the parent cells. The local axonal arborizations of each of these cells filled almost the entire graft. In some cells, axonal branches were traced outside the grafts and were seen to enter the internal capsule fascicles. Unlike spiny neurons in the normal adult neostriatum, the spiny cells of the graft could have nuclear indentations. With this exception, the ultrastructural features of spiny neurons in the grafts were very similar to those in the hosts. Many unlabeled boutons made synapses on identified spiny neurons in the grafts. Terminals with small round vesicles made synaptic contacts on dendritic shafts and dendritic spines, while terminals with flattened or pleomorphic vesicles contacted somata, dendrites, and dendritic spines. Labeled axon collaterals of graft neurons made symmetrical synapses on somata, dendrites and spines in the grafts and in the host neostriatum. In the grafts, more than 60% of the axon terminals contacted dendritic shafts. The proportion of axosomatic and axospinous synapses varied substantially from cell to cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Stable transfection of calbindin-D28k into the GH3 cell line alters calcium currents and intracellular calcium homeostasis.

Previous work demonstrating the presence and differential distribution of Ca(2+)-binding proteins in the CNS has led to the proposal that cytosolic proteins, such as calbindin-D28k (CB), may play a pivotal role in neurons. We have used a retrovirus containing the full-length cDNA for CB to transfect the pituitary tumor cell line GH3, to generate CB-expressing GH3 cells and to investigate whether ionic channel activities as well as the concentration of intracellular free Ca2+ ([Ca2+]i) homeostasis could be altered by the presence of this Ca(2+)-binding protein. We show that CB-transfected GH3 cells exhibited lower Ca2+ entry through voltage-dependent Ca2+ channels and were better able to reduce [Ca2+]i transients evoked by voltage depolarizations than the wild-type parent cell line. These observations provide a mechanism by which CB may protect tissues against Ca(2+)-mediated excitotoxicity.

Animals↗

PubMed1991

Localization of calpain immunoreactivity in senile plaques and in neurones undergoing neurofibrillary degeneration in Alzheimer's disease.

An antibody raised against the calcium activated neutral protease (calpain) was used to investigate the possible involvement of this enzyme in the formation of plaques and tangles in Alzheimer-type dementia (ATD) brain. Our results revealed the presence of a number of strongly stained calpain positive neurones in the normal human cerebral cortex and a loss of calpain positive cells in ATD brain. Furthermore, double staining experiments revealed that calpain immunoreactivity was present in cells undergoing tangle formation, and was also present in senile plaques. These data suggest that activation of calpain may be an important factor in the abnormal proteolysis underlying the accumulation of plaques and tangles in ATD.

Aged↗

PubMed1991

Production and characterization of an anti-peptide antibody specific for the growth-associated protein, GAP-43.

In an attempt to raise specific anti-GAP-43 antibodies, a C-terminal tetradecapeptide was synthesized based on the predicted rat GAP-43 amino acid sequence using the F-moc polyamide solid phase procedure. The synthesized carboxy-terminal peptide was purified by reverse phase HPLC, conjugated to bovine serum albumin (BSA) and used as an immunogen. Polyclonal antipeptide antibodies raised in rabbits were affinity purified and their specificity for GAP-43 tested by Western blotting. Brain and spinal cord homogenates and GAP-43 enriched synaptosomal membrane fractions were analysed either by SDS-PAGE or reverse phase HPLC. The anti-GAP-43 antibodies detected a major immunoreactive band at 43 kDa (B-50), and a minor immunoreactive band at 38 kDa (B-60) together with an additional protein-band at 68 kDa, which was related to the peptide carrier, BSA. Immunohistochemical studies using these carboxy-terminal antipeptide antibodies revealed a widespread distribution of GAP-43 immunoreactivity throughout the adult rat brain and spinal cord, in a pattern generally consistent with earlier histochemical studies. It is concluded that the C-terminal GAP-43 specific tetradecapeptide is a potent immunogen and provides a convenient tool for the production of sequence specific anti-GAP-43 antibodies.

Aging↗

PubMed1991

Demonstration of neurofibrillary tangles in parvalbumin-immunoreactive interneurones in the cerebral cortex of Alzheimer-type dementia brain.

The pathological changes occurring in a population of parvalbumin-like immunoreactive cerebral cortical interneurones in postmortem Alzheimer-type dementia brain tissue were determined by double staining cerebral cortical sections for parvalbumin, tau and/or calpain-like immunoreactivities. By counting the number of double immunostained cells it was determined that 4% parvalbumin and 25% of calpain-like immunoreactive cells showed evidence of tau-like immunoreactivity, indicative of neurofibrillary tangles. These results suggest that cerebral cortical parvalbumin-like immunoreactive neurones are relatively resistant to the pathological changes underlying the formation of neurofibrillary tangles associated with Alzheimer-type dementia.

Alzheimer Disease↗

PubMed1991

Transient expression of neurotensin mRNA in the mitral cells of rat olfactory bulb during development.

The transient expression of neurotensin mRNA in the mitral cells of the rat olfactory bulb was demonstrated during the perinatal period using non-radioactive in situ hybridization in which an alkaline phosphatase labelled oligodeoxynucleotide probe was used. The relative cellular content of neurotensin mRNA signal was measured by use of a microdensitometer. Neurotensin mRNA positive cells were observed in the primordium of mitral cells on embryonic day 14 and their mRNA content increased gradually up to the day of birth. During the first postnatal week, the strength of their neurotensin mRNA signal decreased dramatically, and continued to decrease until in the adult olfactory bulb neurotensin mRNA was no longer detectable. This decrease of the neurotensin mRNA content coincided with a parallel decrease of neurotensin immunoreactivity observed in the lateral olfactory tract.

Animals↗

PubMed1991

The calcium binding protein calbindin-D 28K reveals subpopulations of projection and interneurons in the cat superior colliculus.

The calcium binding protein calbindin-D 28K (CaBP) has been localized in the cat superior colliculus (SC). Four important features of SC organization have been revealed by using CaBP immunocytochemistry. 1) CaBP neurons formed three laminar tiers in SC, one within the upper one half of the superficial gray layer (SGL), the second bridging the deep optic (OL) and intermediate gray layers (IGL), and the third within the deep gray layer (DGL). 2) CaBP labeled several classes of interneuron in SC. In the upper CaBP tier, the labeled neurons were all small, but they varied in morphology and included horizontal, pyriform, and stellate neurons. A unique class of interneuron was labeled by anti-CaBP in the OL-IGL tier. This cell was stellate-like with highly varicose dendrites and broad dendritic trees. Other labeled neurons in the intermediate and deep tiers included nonvaricose stellate neurons and rare large neurons in the DGL. 3) A few anti-CaBP neurons were projection neurons. Virtually no CaBP neurons were retrogradely labeled after injections of HRP into the predorsal bundle and dorsolateral midbrain tegmentum or into the lateral posterior nucleus. However, 2.4% of anti-CaBP neurons were retrogradely labeled after HRP injections into the dorsal and ventral lateral geniculate nuclei. These represented 14.7% of all neurons projecting to the LGN complex. 4) A small percentage of CaBP neurons co-localized GABA. A two-chromagen double-labeling technique showed that about 4.0% of labeled neurons were labeled by both antibodies. In summary, antibodies to CaBP densely labeled subpopulations of neurons in the cat SC, most of which were interneurons, some of which projected to the LGN, and a few of which co-localized GABA.

Animals↗

PubMed1991

The transient appearance of proneurotensin mRNA in the rat hypoglossal nucleus during development.

Using a sensitive non-radioactive in situ hybridization technique utilizing alkaline phosphatase labelled oligodeoxynucleotide neurotensin probe we have observed the transient expression of neurotensin mRNA in the rat hypoglossal nucleus. Neurotensin mRNA containing cells were first observed on embryonic day 14 in the primodium of the hypoglossal nucleus. The intensity of the mRNA signal increased during the perinatal period until a maximum signal was observed at birth. After this time, the intensity of the neurotensin mRNA signal decreased dramatically during the first postnatal week. Subsequently the mRNA signal decreased gradually during maturation until only a very weak signal was detected in the adult. The visualization of neurotensin mRNA containing cells in the hypoglossal nucleus has not previously been reported. The transient expression of NT mRNA containing cells prior to birth may suggest that neurotensin has a role in the development of this nucleus.

Aging↗

PubMed1991

Restoration of thalamostriatal projections in rat neostriatal grafts: an electron microscopic analysis.

The thalamostriatal projections to rat neostriatal grafts were studied by using the Phaseolus vulgaris-leucoagglutinin (PHA-L) axonal tracing technique. Two to 6 months after implantation of striatal primordia into adult neostriata, PHA-L was injected into two different portions of the intralaminar nuclear complex of the thalamus. In the host neostriatum, labeled fibers from the parafascicular nucleus (PF) arborized in a large region in the neostriatum, but avoided small patchlike areas. Most of the fibers from PF had irregular curved trajectories with short side branches that formed boutons. Labeled fibers from the centromedial and paracentral nuclei (CeM-PC) projected to a similarly large area within the neostriatum but did not show any nonuniformity. CeM-PC axons had relatively straight trajectories and formed boutons en passant. Both sets of thalamostriatal projection fibers were found in the grafts. Some of the labeled fibers in the grafts formed dense, focal arborizations. Compared to the host neostriatum, the distribution of postsynaptic elements in the grafts was altered dramatically. In the host neostriatum, 89% of the terminals from PF terminated onto dendritic shafts; 93% of the CeM-PC terminals contacted dendritic spines. However, only 47% of the PF terminals in the grafts contacted dendritic shafts; 53% of them terminated on dendritic spines. In grafts, 81% of the terminals from CeM-PC region contacted dendritic spines; 19% of them made synapses on dendritic shafts. The shift of postsynaptic elements in the grafts suggests a loss of pathway specificity in the induction of dendritic spines on neostriatal neurons in grafts.

Animals↗

PubMed1991

Further studies on galanin-, substance P-, and CGRP-like immunoreactivities in primary sensory neurons and spinal cord: effects of dorsal rhizotomies and sciatic nerve lesions.

The peptides galanin (GAL), substance P (SP), and calcitonin gene-related peptide (CGRP) were analyzed with immunohistochemistry and radioimmunoassay in the spinal cord, dorsal root ganglia, dorsal roots, and sciatic nerve of normal rats and rats subjected to several experimental procedures, including ligation, crush, and/or sectioning of nerves. The results show that peripheral nerve transection induces a dramatic increase in GAL content both in dorsal roots and sciatic nerve, demonstrating that this lesion causes an increased out-transport of the newly synthesized peptide both into the central and peripheral branches of the primary sensory neurons. In contrast evidence was obtained for decreased out-transport of SP and CGRP. The functional significance of these findings remains to be analyzed.

Animals↗

PubMed1991

Differential effects of acute dopaminergic D1 and D2 receptor antagonists on proneurotensin mRNA expression in rat striatum.

The effect of acute dopamine (DA) antagonist treatment on neuronal proneurotensin (NT) mRNA was investigated in the rat striatum using a technique of non-radioactive in situ hybridisation. Adult Wistar rats were given a single intraperitoneal injection of either raclopride (D2 antagonist), SCH 23390 (D1 antagonist) or its inactive isomer SCH 23388 and left to survive for 3 h. Their brains were rapidly removed and striatal sections processed for in situ hybridisation using an alkaline phosphatase (AP) labelled oligonucleotide specific for NT mRNA. Blockade of the DA D2 receptors by a single injection of raclopride resulted in an increase in the number of NT mRNA containing cells in the dorsal lateral rim of the striatum adjacent to the corpus callosum. In contrast, no such increase was observed following blockade of the DA D1 receptors with SCH 23390. These findings demonstrate that NT mRNA expression is differentially regulated in the adult rat striatum by selective D1 and D2 antagonists.

Animals↗

PubMed1991

Colchicine-induced expression of proneurotensin mRNA in rat striatum and hypothalamus.

The effect of colchicine treatment on proneurotensin mRNA expression was examined using a sensitive non-radioactive in situ hybridization histochemistry technique with an enzyme-labelled antisense oligonucleotide probe. Intraventricular injection of colchicine rapidly induced strong neurotensin mRNA expression in a number of neurons in the dorsomedial part of the caudate putamen, and in the paraventricular, and arcuate nuclei while an induction of neurotensin mRNA was not observed in vehicle (saline)-injected animals. Neurotensin mRNA was not induced significantly in other periventricular areas such as the medial preoptic area or the lateral septum. These results indicate that colchicine can itself rapidly induce neurotensin mRNA expression and that this induction is specific to certain cell populations in the vicinity of the ventricles. These results demonstrate that colchicine should be used with caution in immunohistochemical studies demonstrating the normal distribution of peptide immunoreactivity or mRNA.

Animals↗

PubMed1991

Co-expression of cholecystokinin mRNA and tyrosine hydroxylase mRNA in populations of rat substantia nigra cells; a study using a combined radioactive and non-radioactive in situ hybridization procedure.

Improvements in the sensitivity of non-radioactive in situ hybridization histochemistry methods for detection of mRNA now make it feasible to combine the use of non-radioactive and radioactive in situ methods to visualize two mRNAs on the same tissue section. The method reported here allows the simultaneous detection of two mRNAs in one cell and therefore is ideally suited to the studies of co-expression. Here we demonstrate the co-expression of tyrosine hydroxylase (TH) mRNA and cholecystokinin (CCK) mRNA in the ventral mesencephalic dopaminergic neurones of the rat. The distribution of dopaminergic neurones containing both TH and CCK transcripts suggests, on the basis of earlier anatomical studies that these CCK/TH-containing doubled-labelled cells project mainly to the striatal matrix. Dopamine neurones believed to project to the patch compartment did not contain CCK mRNA.

Animals↗