Biomedical subjects

P J Isackson

Publications and source records attributed to P J Isackson.

At least 37 records · Page 2Linked to original sources

PubMed1996

A metabotropic glutamate receptor agonist regulates neurotrophin messenger RNA in rat forebrain.

We have examined the role of metabotropic glutamate receptor activation in regulating neurotrophin messenger RNA levels in the brain with the use of the selective agonist (1S,3R)-1-aminocy-clopentane-1,3-dicarboxylic acid. Intracerebroventricular injection of (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid into adult adult rats resulted in increased expression of nerve growth factor and brain-derived neurotrophic factor messenger RNA in the hippocampal and pyriform cortex and decreased levels of neurotrophin-3 messenger RNA in the hippocampal dentate gyrus granule cell layer. C-fos messenger RNA levels were also increased throughout hippocampal and cortical subfields following (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid administration. (1S,3R)-1-Aminocyclopentane-1,3-dicarboxylic acid-induced changes in messenger RNA levels occurred without behavioral seizures, yet these changes were similar in magnitude and time course to early changes in neurotrophin and c-fos messenger RNA levels observed following recurrent limbic seizures. In contrast quisqualate, a potent agonist of metabotropic as well as ionotropic kainate/alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors, was only capable of inducing increased expression of brain-derived neurotrophic factor messenger RNA at doses which produced recurrent motor seizures, and both effects were completely inhibited by the non-N-methyl-D-aspartate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Neurotrophin messenger RNA changes induced by (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid were also partially susceptible to 6-cyano-7-nitroquinoxaline-2,3-dione antagonism, as well as the specific N-methyl-D-aspartate receptor antagonist (+)-5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)-cyclohepten-5,10- iminedizoleipine. These results suggest that (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-sensitive metabotropic glutamate receptors can dramatically increase the expression of neurotrophin and c-fos messenger RNAs in rat forebrain without producing significant behavioral trauma and that these influences may involve ionotropic glutamate receptors in certain brain regions.

Animals↗

PubMed1995

Induction of nerve growth factor and basic fibroblast growth factor mRNA following clenbuterol: contrasting anatomical and cellular localization.

RNase protection assay and in situ hybridization were used to analyze the temporal and cellular changes in nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) mRNA content evoked by the lipophilic beta-adrenergic receptor agonist clenbuterol in adult rat brain. Clenbuterol elicited a threefold increase in NGF mRNA expression which was limited to the cerebral cortex. This increase was maximal at 5 h, still evident by 10 h, and declined to control levels by 24 h. By 10 h NGF protein was also increased. Elevated NGF mRNA hybridization following clenbuterol was localized in the superficial cortical layers II and III in large Nissl-pale cells, suggesting that NGF mRNA induction occurs in neurons. In the same animals, clenbuterol induced a twofold increase in the levels of bFGF mRNA in cerebral cortex and hippocampus. This increase was localized primarily in glial cells as demonstrated by bFGF mRNA hybridization over all cortical regions and by labeling of the stratum lacunosum moleculare of the hippocampus. Our results suggest that enhanced noradrenergic tone regulates expression of these two trophic factors by different synaptic mechanisms and suggest that neurotransmitter(s) can coordinate trophic influences on different cell populations.

Animals↗

PubMed1995

Decreased expression of the alpha subunit of Ca2+/ calmodulin-dependent protein kinase type II mRNA in the adult rat CNS following recurrent limbic seizures.

Calcium/calmodulin-dependent protein kinase type II (CamKII) is a ubiquitous brain enzyme implicated in a wide variety of neuronal processes. Understanding CamKII has become increasingly complicated with the recent identification of multiple gene transcripts coding for separate subunits. Previous studies have shown that mRNA for the alpha subunit of CamKII can be increased by reduction of afferent input. In this study we have examined the regulation of alpha CamKII mRNA following increased activity due to seizures. Using in situ hybridization with a cRNA probe against the rat alpha CamKII sequence we found reduced levels of hybridization following limbic seizures induced by lesions of the hilus of the dentate gyrus. Hybridization was most dramatically reduced in the granule cells of the dentate gyrus and the pyramidal cells of hippocampal region CA1. There were also significant reductions in hybridization in the superficial layers of neocortex and piriform cortex. In each of these region hybridization was decreased in the molecular layers which is consistent with the reported dendritic localization of alpha CamKII mRNA. All changes in mRNA content were transient, with maximal reductions at 24 h following lesion placement and a return to control levels by 96 h. These findings demonstrate the negative regulation of alpha CamKII mRNA by seizure activity and raise the possibility that synthesis of this kinase may be regulated by normal physiological activity.

Animals↗

PubMed1995

Trophic factor response to neuronal stimuli or injury.

Neurotrophic factors are produced by CNS neurons, and have both paracrine and autocrine activities. In nerve cells, expression of neurotrophic factors is regulated by physiological afferent activity, which implies that these factors play a role in activity-dependent plasticity and survival. Neurotrophic factor levels are also altered following injury, which suggests that they play a part in the neurodegenerative response and synaptic reorganization as well. Recent studies have examined extensively the regulation and functional roles of the neurotrophin family, and have also identified other neurotrophic factors present in brain that are regulated by different, as well as similar mechanisms.

Animals↗

PubMed1994

Dopaminergic neurons in rat ventral midbrain express brain-derived neurotrophic factor and neurotrophin-3 mRNAs.

Studies of the trophic activities of brain-derived neurotrophic factor and neurotrophin-3 indicate that both molecules support the survival of a number of different embryonic cell types in culture. We have shown that mRNAs for brain-derived neurotrophic factor and neurotrophin-3 are localized to specific ventral mesencephalic regions containing dopaminergic cell bodies, including the substantia nigra and ventral tegmental area. In the present study, in situ hybridization with 35S-labeled cRNA probes for the neurotrophin mRNAs was combined with neurotoxin lesions or with immunocytochemistry for the catecholamine-synthesizing enzyme tyrosine hydroxylase to determine whether the dopaminergic neurons, themselves, synthesize the neurotrophins in adult rat midbrain. Following unilateral destruction of the midbrain dopamine cells with 6-hydroxydopamine, a substantial, but incomplete, depletion of brain-derived neurotrophic factor and neurotrophin-3 mRNA-containing cells was observed in the ipsilateral substantia nigra pars compacta and ventral tegmental area. In other rats, combined in situ hybridization and tyrosine hydroxylase immunocytochemistry demonstrated that the vast majority of the neurotrophin mRNA-containing neurons in the substantia nigra and ventral tegmental area were tyrosine hydroxylase immunoreactive. Of the total population of tyrosine hydroxylase-positive cells, double-labeled neurons constituted 25-50% in the ventral tegmental area and 10-30% in the substantia nigra pars compacta, with the proportion being greater in medial pars compacta. In addition, tyrosine hydroxylase/neurotrophin mRNA coexistence was observed in neurons in other mesencephalic regions including the retrorubral field, interfascicular nucleus, rostral and central linear nuclei, dorsal raphe nucleus, and supramammillary region. The present results demonstrate brain-derived neurotrophic factor and neurotrophin-3 expression by adult midbrain dopamine neurons and support the suggestion that these neurotrophins influence dopamine neurons via autocrine or paracrine mechanisms. These data raise the additional possibility that inappropriate expression of the neurotrophins by dopaminergic neurons could contribute to the neuropathology of disease states such as Parkinson's disease and schizophrenia.

Animals↗

PubMed1994

Seizure-induced increases in NGF mRNA exhibit different time courses across forebrain regions and are biphasic in hippocampus.

In the present study, in situ hybridization and S1 nuclease protection analyses were used to evaluate the temporal and spatial parameters of changes in nerve growth factor (NGF) mRNA expression in rat forebrain following hilus lesion-induced recurrent limbic seizures. Seizure-induced increases in NGF mRNA levels were widespread with differences in the temporal parameters of change between brain areas. There were two distinct increases in NGF cRNA hybridization in dentate gyrus stratum granulosum. Hybridization was increased several-fold by 6 h after a seizure-producing hilus lesion (HL), declined to below control values by 12 h post-HL, and then increased again by 24 h post-HL, or 12 h after the termination of seizures. This biphasic increase was corroborated by S1 nuclease protection analysis. In entorhinal cortex, cingulate cortex and neocortex NGF cRNA hybridization was markedly increased first in layers II/III by 6-12 h post-HL and progressed to layers V/VI by 24 h post-HL. Striking increases in NGF mRNA were detected in the majority of amygdaloid nuclei beginning with the cortical nuclei by 12 h postlesion and extending into the more deeply placed nuclei by 24 h postlesion. Labeling was increased in sparsely distributed neurons in the caudate putamen, ventral pallidum, and tenia tecta at 24 h post-HL. In all areas, hybridization declined to control values by 48-96 h post-HL. NGF expression was not changed in some forebrain regions which normally contain NGF mRNA including the diagonal bands of Broca and select thalamic nuclei. These data demonstrate that seizures stimulate NGF expression in many different types of neurons. Moreover, regional differences in the time courses of induction suggest that distinct regulatory mechanisms subserve activity-dependent changes in NGF mRNA expression in different neuronal populations.

Animals↗

PubMed1994

Cellular localization of NGF and NT-3 mRNAs in postnatal rat forebrain.

The presence of transiently elevated levels of mRNA for nerve growth factor (NGF) and neurotrophin-3 (NT-3) in postnatal development of several brain areas suggests that these factors may be expressed by a greater number of cell types in the immature than in the adult brain. To evaluate this possibility, in situ hybridization was used to determine the cellular localization of NGF mRNA and NT-3 mRNA in hippocampus, cingulate cortex, posterolateral neocortex, thalamus, and cerebellum of postnatal rat. In areas expressing both neurotrophins (i.e., hippocampus, cingulate cortex, and anteroventral thalamus), NT-3 mRNA was detected at earlier ages than NGF mRNA. Patterns of hybridization in hippocampus and cerebellum indicate that NT-3 is expressed by neurons soon after leaving the mitotic cycle whereas NGF expression is a feature of more mature neurons. The exception to this pattern was NGF expression in the lateral geniculate nuclei which was present by Postnatal Day 1 and retained in the adult. Both neurotrophins were transiently expressed in several brain areas. The loss of expression with age was most striking in thalamus with transient expression of NT-3 mRNA by the majority of dorsal thalamic relay nuclei and of NGF mRNA by fewer nuclei including the posterior, anteroventral, ventrolateral, and ventromedial nuclei. NT-3 expression also was transient in caudal cingulate/retrosplenial cortex, hippocampal CA3 stratum pyramidale, and the granule cells of archicerebellum. In early postnatal cingulate and retrosplenial cortices there were reciprocal rostrocaudal gradients of NGF and NT-3 expression. These results suggest both distinct and overlapping functions for NT-3 and NGF in early developmental processes including involvement of NT-3 in cerebellar development and of NGF in the development and maintenance of visual afferents to thalamus. Patterns of neurotrophin expression in medial limbic cortex may establish trophic gradients which influence the topography of thalamic innervation.

Aging↗

PubMed1994

Seizures increase basic fibroblast growth factor mRNA in adult rat forebrain neurons and glia.

The distribution of basic fibroblast growth factor (bFGF) mRNA in normal rat forebrain, and the influence of recurrent seizure activity on the expression of this mRNA, was evaluated using in situ hybridization and S1 nuclease protection techniques. In the untreated adult rat, hybridization of 35S-labeled bFGF cRNA densely labeled neurons in a few discrete areas including the tenia tecta, indusium gresium, and hippocampal stratum pyramidale of regions CA2 and rostromedial CA1. Neurons in the prosubiculum and rostromedial dentate gyrus stratum granulosum were lightly labeled. In addition, a diffuse distribution of autoradiographic labeling in areas such as the hippocampal molecular layers, olfactory cortical layer I, and the olfactory nerve layer was suggestive of localization in glial cells. Platinum wire hilar lesions, which did not induce seizures, increased cRNA hybridization in glial cells in primary and secondary areas of degeneration in the ipsilateral hemisphere only; hybridization was not noticeably increased in neurons in these lesion-control rats. Focal stainless-steel wire hilar lesions, which caused recurrent seizures 2-10 h postlesion, induced bilaterally distributed increases in cRNA hybridization in hippocampus, neocortex, olfactory cortex, amygdala, and septum. These seizure-dependent increases in hybridization were evident 6 h postlesion, were maximal from 12 to 24 h postlesion, and declined to near control levels by 4 days. In most regions the elevated hybridization appeared to be associated primarily with astroglia but in experimental seizure rats sacrificed 12 and 24 h postlesion hybridization was also markedly increased in the dentate gyrus granule cells and olfactory cortical neurons. These results demonstrate that recurrent seizures increase bFGF mRNA expression by both forebrain neurons and glia and implicate bFGF in the coordination of other changes in the biosynthetic activities of forebrain neurons that occur after seizures.

Animals↗

PubMed1994

Differential regulation of brain-derived neurotrophic factor and type II calcium/calmodulin-dependent protein kinase messenger RNA expression in Alzheimer's disease.

The relative levels of messenger RNA for brain-derived neurotrophic factor and the alpha subunit of calcium/calmodulin-dependent protein kinase type II were examined in hippocampal sections from Alzheimer's diseased and age matched non-diseased brains by in situ hybridization histochemistry. Consistent with previous reports in monkey and rodent, calcium/calmodulin-dependent protein kinase II messenger RNA was prevalent throughout the dentate gyrus, all the principal hippocampal subfields, and adjacent cortical regions. A distribution consistent with the dendritic localization of calcium/calmodulin-dependent protein kinase II was also observed. In contrast, brain-derived neurotrophic factor messenger RNA levels were much lower than calcium/calmodulin-dependent protein kinase II messenger RNA levels and were less widely distributed. Within the hippocampus of Alzheimer's diseased brains, levels of calcium/calmodulin-dependent protein kinase II messenger RNA were increased and levels of brain-derived neurotrophic factor messenger RNA were decreased in comparison with matched controls. These changes were consistently seen in four out of six cases processed for both messenger RNA species and ranged from 150-300% relative to non-diseased brain tissue for calcium/calmodulin-dependent protein kinase II and 20-70% for brain-derived neurotrophic factor. These results suggest that within the Alzheimer's hippocampus an altered program of gene expression is occurring leading to aberrant levels of both calcium/calmodulin-dependent protein kinase II and brain-derived neurotrophic factor messenger RNA. Previous studies of the activity-dependent regulation of these messenger RNA species suggest these results are consistent with a decrease in afferent activity within the Alzheimer's hippocampus.

Aged↗

PubMed1994

Lamina-specific expression and activity-dependent regulation of seven GABAA receptor subunit mRNAs in monkey visual cortex.

Seven monkey-specific GABAA receptor subunit cDNAs were isolated and cloned; radioactive cDNA and cRNA probes derived from them were used for Northern blot analysis and in situ hybridization histochemistry of the primary visual cortex (area 17), with comparative observations on other cortical areas. cDNAs corresponding to alpha 1, alpha 2, alpha 4, alpha 5, beta 1, beta 2, and gamma 2 GABAA receptor subunits were isolated and had sequences unique to the monkey but recognized mRNAs of distinct molecular weights consistent with those reported in other species. mRNAs for the alpha 1, beta 2, and gamma 2 subunits were expressed at much higher levels in area 17 than in motor, somatosensory, or temporal association cortex, possibly reflecting the greater density of GABA cells and synapses in area 17. In areas 17 and 18, each of the seven subunit mRNAs showed individually distinct patterns of laminar distribution. alpha 1, beta 2, and gamma 2 subunit mRNAs, which are thought to form the basis of receptors with the full range of classical GABAA receptor properties in the adult, were particularly enriched in layers II-III, IVC, and VI of area 17, following patterns of receptor distribution previously demonstrated by radioligand binding and immunocytochemistry. alpha 2, alpha 4, alpha 5, and beta 1 transcripts had quite different localization patterns that did not match the antoradiographic or immunocytochemical receptor localization patterns. alpha 2 and alpha 5 subunit mRNAs, which are thought to be the subunits mainly expressed in development, were enriched in layer VI and the underlying white matter, possibly reflecting the involvement of receptors formed from alpha 2 and alpha 5 polypeptides in trophic interactions in the cortical subplate zone during development of the cerebral cortex. Following 8-21 d periods of monocular deprivation induced by intravitreal injection of TTX, levels of alpha 1, beta 2, and gamma 2 subunit mRNAs were substantially reduced in deprived ocular dominance columns of layer IVC in area 17. The effect was greatest for the alpha 1 subunit; for both alpha 1 and gamma 2 subunit mRNAs, it extended into deprived rows of cytochrome oxidase-identified periodicities in other layers. Apart from the alpha 5 subunit mRNA, which showed reduced levels in layer VI, the other subunit mRNAs were unaffected by monocular deprivation. These results demonstrate the heterogeneity of GABAA receptor subunit expression in a complex, multilaminar cortical area. They suggest that receptors with different functional properties may be assembled from different combinations of subunit polypeptides in different layers and show that subunit expression is differentially regulated under activity-dependent conditions.

Animals↗

PubMed1993

Nerve growth factor mRNA is expressed by GABAergic neurons in rat hippocampus.

Isotopic and colorimetric in situ hybridization techniques were combined to determine if nerve growth factor (NGF) mRNA is colocalized with mRNA for the GABA biosynthetic enzyme glutamic acid decarboxylase (GAD) in adult rat hippocampus. Quantification of neurons labeled with both 35S-labeled GAD67 mRNA and digoxigenin-labeled NGF cRNA determined that of the NGF cRNA-labeled neurons, 97% within regions CA3-CA1, and 88% within the hilus, were also labeled with GAD67 cRNA. Overall, 47% of the total population of GAD67 cRNA labeled cells were NGF cRNA positive. The greater portion of stratum granulosum was lightly labeled by the NGF cRNA alone. The results indicate that, excepting stratum granulosum, NGF is predominantly synthesized by GABAergic neurons in rat hippocampus.

Animals↗

PubMed1993

Synthetic chimeras of mouse growth factor-associated glandular kallikreins. I. Kinetic properties.

A series of six chimeric proteins, composed of fragments corresponding to either one or the other of the growth factor-associated mouse glandular kallikreins-epidermal growth factor binding protein (EGF-BP) and the gamma-subunit of nerve growth factor (gamma-NGF)--were expressed in Escherichia coli and isolated, and their kinetic properties were characterized. The assembly of these synthetic proteases involved the substitution of regions of the proteins containing four specific surface loops that have been postulated to influence both kinetic specificity and the formation of growth factor complexes. The substrates utilized in the kinetic characterization of these chimeric kallikreins were tripeptide nitroanilides representing carboxyl termini of both the EGF and beta-NGF mature hormones, putative processing sites for these kallikreins in the precursors. Characterization of these hybrid enzymes demonstrates that Km and kcat kinetic constants may be independently affected by the regions utilized in construction of these chimeric kallikreins. Specifically, loop 1, located in the amino terminal region (Bode, W., et al., J. Mol. Biol. 164, 237-282, 1983), in gamma-NGF enhanced the kcat for substrates containing threonine in the P2 position, as is the case during the processing of the carboxy terminus of the beta-NGF precursor. Also, the central regions of the kallikreins containing loop 2 and the kallikrein loop dictated the generally inverted Km and kcat kinetic constants observed between EGF-BP and gamma-NGF. Finally, in gamma-NGF the autolysis loop, found in the carboxyl terminal region, functions to lower the Km kinetic constant for a variety of substrates. The results allow previously characterized kinetic differences between EGF-BP and gamma-NGF to be interpreted in terms of specific regions of the proteins and identify a subset of amino acid positions responsible for these functional characteristics.

Amino Acid Sequence↗

PubMed1993

Synthetic chimeras of mouse growth factor-associated glandular kallikreins. II. Growth factor binding properties.

Six chimeric constructs of the sequentially similar growth factor-associated kallikreins-epidermal growth factor binding protein (EGF-BP) and the gamma-subunit of nerve growth factor (gamma-NGF)--have been expressed, and their ability to generate complexes with epidermal growth factor (EGF) and beta-NGF, analogous to the high molecular weight forms (7S NGF and HMW-EGF) found in the mouse submaxillary gland, evaluated. The chimeras are distinguished by the interchange of three regions composing the amino, middle, and carboxyl terminal regions that encompass four surface loops possibly involved in specific growth factor interactions. Native beta-NGF (along with native alpha-NGF) formed complexes indistinguishable from naturally occurring 7S NGF, characterized by an alpha 2 beta gamma 2 structure (where beta-NGF is itself a dimer), with recombinant (r) gamma-NGF and with a chimera in which the amino terminal region from EGF-BP was substituted. Two other chimeras containing either the middle or carboxyl terminal regions of gamma-NGF showed weaker ability to form 7S complexes. Thus, all chimeras containing two segments from gamma-NGF retained at least some ability to form the 7S complex. rEGF-BP reacted weakly with EGF, but the chimera composed of the amino and middle segments of EGF-BP and the carboxyl terminal segment of gamma-NGF formed a nativelike HMW-EGF complex. None of the other chimeras appeared to bind EGF. These results identify amino acid positions within each kallikrein that participate in strong growth factor interactions and demonstrate that, outside of active site contacts, different regions of the kallikreins are involved in the binding of EGF and beta-NGF, respectively.

Amino Acid Sequence↗

PubMed1993

In situ hybridization localization of choline acetyltransferase mRNA in adult rat brain and spinal cord.

The cellular distribution of choline acetyltransferase (ChAT) mRNA within the adult rat central nervous system was evaluated using in situ hybridization. In forebrain, hybridization of a 35S-labeled rat ChAT cRNA densely labeled neurons in the well-characterized basal forebrain cholinergic system including the medial septal nucleus, diagonal bands of Broca, nucleus basalis of Meynert and substantia innominata, as well as in the striatum, ventral pallidum, and olfactory tubercle. A small number of lightly labeled neurons were distributed throughout neocortex, primarily in superficial layers. No cellular labeling was detected in hippocampus. In the diencephalon, dense hybridization labeled neurons in the ventral aspect of the medial habenular nucleus whereas cells in the lateral hypothalamic area and supramammillary region were more lightly labeled. Hybridization was most dense in neurons of the motor and autonomic cranial nerve nuclei including the oculomotor, Edinger-Westphal, and trochlear nuclei of the midbrain, the abducens, superior salivatory, trigeminal, facial and accessory facial nuclei of the pons, and the hypoglossal, vagus, and solitary nuclei and nucleus ambiguous of the medulla. In addition, numerous cells in the pedunculopontine and laterodorsal tegmental nuclei, the ventral nucleus of the lateral lemniscus, the medial and lateral divisions of the parabrachial nucleus, and the medial and lateral superior olive were labeled. Occasional labeled neurons were distributed in the giantocellular, intermediate, and parvocellular reticular nuclei, and the raphe magnus nucleus. In the medulla, light to moderately densely labeled cells were scattered in the nucleus of Probst's bundle, the medial vestibular nucleus, the lateral reticular nucleus, and the raphe obscurus nucleus. In spinal cord, the cRNA densely labeled motor neurons of the ventral horn, and cells in the intermediolateral column, surrounding the central canal, and in the spinal accessory nucleus. These results are in good agreement with reports of the immunohistochemical localization of ChAT and provide further evidence that cholinergic neurons are present within neocortex but not hippocampus.

Animals↗

PubMed1993

Identification of a polymorphism in the human neurotensin receptor gene.

A complementary DNA (cDNA) clone encoding the neurotensin receptor was isolated from a human substantia nigra cDNA library. The deduced amino acid sequence of this clone was almost identical to that of a cDNA for this receptor cloned from a previously described HT29 human colonic adenocarcinoma cell line. We found three base changes between the previously reported HT29 cDNA clone and the current cDNA clone. We investigated these changes by using polymerase chain reactions to amplify these areas from various human samples. One of the differences, which resulted in an amino acid change at AA194 (a leucine in the HT29 sequence was a phenylalanine in the current sequence), was found in some, but not in all, human samples. This finding represents genetic variability in human neurotensin receptors, the first such report for a peptide receptor. Both of these receptors, however, when expressed separately in transfected cell lines, had similar affinities for neurotensin and some related peptides.

Amino Acid Sequence↗

PubMed1993

Haloperidol but not clozapine increases neurotensin receptor mRNA levels in rat substantia nigra.

We examined the effects of chronic (2 weeks) treatment with a typical neuroleptic, haloperidol (1 mg/kg, s.c.), and an atypical neuroleptic, clozapine (20 mg/kg, s.c.), on neurotensin receptor (NTR) mRNA levels by in situ hybridization histochemistry. Quantitative OD analysis showed haloperidol-induced NTR mRNA levels in the substantia nigra/ventral tegmental area (SN/VTA) 110% over control levels (significant difference from the control, p < 0.05). In contrast, the same analysis applied to the sections from clozapine-treated animals showed no significant change in NTR mRNA levels compared with matched control sections (p > 0.05). Thus, chronic treatment with haloperidol but not clozapine resulted in elevated levels of NTR mRNA within the SN/VTA. These results suggest that the high incidence of extrapyramidal side effects of typical neuroleptics could result from changes in NTR expression in the SN/VTA.

Animals↗

PubMed1993

Coexpression of mRNAs for NGF, BDNF, and NT-3 in the cardiovascular system of the pre- and postnatal rat.

The expression of NGF, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) mRNAs was examined in whole rat embryos and in the heart and great vessels of postnatal and adult rats, using in situ hybridization of cRNA probes. The patterns of expression were correlated with innervation patterns as revealed by immunostaining for neural cell adhesion molecule (NCAM) and with the HNK-1 antibody, which demonstrates derivatives of the neural crest. The patterns of neurotrophin mRNA localization were different from those of mRNAs for the low-molecular-weight NGF receptor. Hybridization indicating the presence of mRNAs for all three neurotrophins is particularly prominent within the tunica media of the aorta, pulmonary, and other major elastic arteries of the thorax and abdomen and is first observed on embryonic day 13 (E13) when innervation is being established and rises to maximum by E15. In the fetus, there is little or no detectable expression in the CNS or PNS. NT-3 expression in the vessels is relatively constant and high from embryonic to adult stages, while levels of BDNF increase and those of NGF decrease over the same time course. During the fetal period, hybridization in the heart is absent. In the postnatal period, additional label becomes detectable in the coronary arteries but not in the walls of the atria or ventricles, other than at the base of the aorta and pulmonary trunk.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1992

Developmental expression of brain derived neurotrophic factor mRNA by neurons of fetal and adult monkey prefrontal cortex.

In situ hybridization histochemistry with labeled cRNA probes complementary to monkey brain derived neurotrophic factor (BDNF) mRNAs has been used to study the cellular localization and expression of this neurotrophin in the prefrontal cerebral cortex of fetal and adult monkeys. Expression could not be detected in prefrontal cortex before the 121st fetal day. Thereafter, in fetal life and in adulthood BDNF mRNA could be detected primarily in large, putative pyramidal cells of layers III and VI throughout the prefrontal cortex. The temporal course and cellular localization of BDNF expression suggests its association with the development and stabilization of specific connections in regions of cortex that display marked functional plasticity.

Aging↗