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Biomedical subjects

W J Freed

Publications and source records attributed to W J Freed.

At least 73 records · Page 4Linked to original sources
PubMed1990

Cell adhesion molecules (CAMs) in adrenal medulla in situ and in vitro: enhancement of chromaffin cell L1/Ng-CAM expression by NGF.

We have studied the expression of the cell adhesion molecules (CAMs) L1/Ng-CAM, N-CAM, J1/tenascin, and myelin-associated glycoprotein and their common carbohydrate L2/HNK-1 epitope in normal rat adrenal gland sections as well as in adrenal medulla cell culture with and without NGF stimulation. In situ L1/Ng-CAM was observed on the surface of some but not all chromaffin cell clusters, including their closely associated extracellular matrix (ECM). N-CAM immunoreactivity was present on all chromaffin cells and ECM. The ECM of whole medullas also expressed J1/tenascin molecules. In long-term cultures, nerve growth factor (NGF) stimulation enhanced L1/Ng-CAM, N-CAM, and Thy 1.1 immunolabeling on chromaffin cells and their processes. Process outgrowth was greater from chromaffin cell clusters containing S-100 positive Schwann cells as compared to dispersed single chromaffin cells. When long bundles of chromaffin cell fibers were present, S-100, L1/Ng-CAM, and N-CAM positive Schwann cells were always found and were grouped in distinct clusters in the intervals between the chromaffin cells. In some areas, however, after NGF stimulation some chromaffin cell process development occurred despite an apparent lack of close contact with Schwann cells. NGF-activated chromaffin cells also demonstrated neurofilament- and vimentin-like-immunoreactive filaments within cell bodies and their processes. Chromaffin cells were usually found on a layer of N-CAM and fibronectin positive fibroblasts, and often were associated with laminin-immunoreactive material. These data suggest a possible role of N-CAM and L1/Ng-CAM as well as ECM laminin in process outgrowth from chromaffin cells.

Adrenal Medulla↗
PubMed1990

Cell adhesion molecules in adrenal medulla grafts: enhancement of chromaffin cell L1/Ng-CAM expression and reorganization of extracellular matrix following transplantation.

Intracerebral adrenal medulla grafts have been used in human patients as an experimental treatment for Parkinson's disease, based on studies in animal models of this disorder. However, alterations in chromaffin cell properties after transplantation and the factors controlling graft survival are poorly understood. Since cell adhesion molecules (CAMs) are involved in regeneration and development of neural tissue in vivo and in vitro, the present study was undertaken to determine the expression of CAMs in adrenal medulla isografts. Fragments of rat adrenal medulla were implanted into the right lateral ventricle. The majority of grafts survived quite well, for up to 2 months (the longest studied period). The implanted chromaffin cells did not develop extensive processes. The cells retained tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) immunoreactivity, while phenylethanolamine N-methyltransferase (PNMT) expression was decreased. Surviving transplanted chromaffin cells showed enhancement and spreading of surface L1/Ng-CAM expression as compared to normal chromaffin cells in adrenal medulla. The implanted chromaffin cells demonstrated only partial conversion to neuronal phenotypes. These chromaffin cells did not develop extensive processes, but showed an enhancement of L1/Ng-CAM expression. Surviving chromaffin cells were accompanied by reorganization of their closely associated extracellular matrix (ECM). As compared to normal in situ adrenal medulla, graft ECM demonstrated a substantial increase of L1/Ng-CAM and laminin immunoreactivities and a distinct decrease in J1/tenascin expression. Some adrenal medulla grafts degenerated, particularly when misplaced within the host brain parenchyma. In these cases the grafts showed fragmentation of ECM and gradual disappearance of CAMs. These results suggest that surviving adrenal medulla grafts exhibit increased synthesis of certain CAMs by chromaffin cells, which may be involved in interactions between chromaffin cells and the surrounding ECM. It is speculated that both surviving and degenerating adrenal medulla grafts could provide CAMs and ECM components including laminin to host brain and this way contribute to functional effects of grafts.

Adrenal Medulla↗
PubMed1990

A slight anticonvulsant effect of CNQX and DNQX as measured by homocysteine- and quisqualate-induced seizures.

CNQX and DNQX are compounds that have recently been reported to show potent non-NMDA excitatory amino acid receptor antagonist activity. Effects of these compounds on seizures induced by homocysteine thiolactone and quisqualic acid were studied in order to examine the pharmacological properties of these compounds. In a dosage of 1.16 micrograms intracerebroventricularly (ICV), CNQX prolonged the latency to the onset of quisqualate-, but not homocysteine-induced seizures. DNQX was not effective when given either ICV or systemically, although a 3.78 micrograms dose of DNQX given ICV markedly increased the variability in latency to seizure onset, suggesting a combination of pro- and anticonvulsant effects. Higher dosages of both CNQX and DNQX induced seizure-like activity after ICV injection. These data confirm that CNQX has pharmacological effects corresponding to its effects on cellular responses to quisqualate and kainate agonists, but these effects are weak and may limit its usefulness as a pharmacological tool.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1990

Prenatal exposure to ethanol causes a delay in the developmental expression of neurofilament epitopes in cerebellum.

The expression of nonphosphorylated neurofilaments (nPNFs) and phosphorylated neurofilaments (PNFs) was examined in cerebella during development of C57/Bl/6J mice prenatally exposed to ethanol. The length of nPNF immunoreactive portions of primary and secondary dendrites of Purkinje neurons was reduced during early postnatal developmental stages. This difference disappeared by 2 months of age. These results indicate a delay in the maturation of nPNFs in Purkinje neurons of ethanol-exposed mice. There also appeared to be some underdevelopment of basket cell axons in terms of PNF expression, during early postnatal stages, as compared to normal control litters. These findings may reflect a general delay in neuronal maturation after ethanol exposure. Prenatal exposure to ethanol may, therefore, have profound effects on developmental events occurring during early postnatal life. We could not, however, exclude the possibility that the disturbances in neurofilament expression were due to malnutrition in the alcohol-treated animals.

Animals↗
PubMed1990

Adrenal medulla graft induced recovery of function in an animal model of Parkinson's disease: possible mechanisms of action.

Following unilateral dopamine (DA) denervation of the striatum in animals, there is an asymmetry in the striatal DA system. Animals with such denervations will rotate vigorously when given dopaminergic drugs. Adrenal medulla grafts placed in the lateral ventricle adjacent to a DA-denervated striatum decrease rotational behaviour induced by DA receptor agonists or DA-releasing agents. This discussion reviews research on the use of adrenal medulla grafts to reverse behavioural deficits following DA-denervation of the striatum. Results from basic animal research and from the application of the procedure to patients with Parkinson's disease suggests that at least three different fundamental processes may mediate the functional effects of adrenal medulla grafts: (a) Adrenal medulla grafts may induce changes in the blood-brain barrier; (b) adrenal medulla grafts may induce an increase in serum DA; and (c) adrenal medulla grafts may have a trophic effect on the host brain. Hypotheses are proposed to explain the behavioural effects of adrenal medulla grafts in light of the processes that are thought to mediate their effects.

Adrenal Medulla↗
PubMed1989

Expression of cell adhesion molecules from the L2/HNK-1 family in cerebellar isografts in mice.

The expression of cell adhesion molecules and glial fibrillary acid protein (GFAP) was examined in isografts of embryonic mouse cerebellum. Donor embryonic cerebella with the meninges removed were implanted into the lateral cerebral ventricles of adult host animals and examined after 2-6 weeks. Indirect immunofluorescence staining was performed on fresh frozen sections, using antibodies against the cell adhesion molecules L1, N-CAM, J1, myelin associated glycoprotein (MAG), and their shared L2/HNK-1 carbohydrate epitope, as well as GFAP. Nissl staining revealed that a normal trilaminar cytoarchitecture developed in some areas of implanted cerebella. Antibodies against cell adhesion molecules showed patterns of immunoreactivity generally similar to those present during normal cerebellar development. Expression of the L2 epitope in normal cerebellum is transiently observed in the molecular layer and is primarily seen in the substantia medullaris of mature cerebellum. This pattern was altered in the grafts, with a persistent expression of the L2 epitope in the molecular layer and less pronounced L2 immunoreactivity in the substantia medullaris cerebelli. These results may reflect a retardation of granule neuron differentiation due to abnormal or missing efferents and afferents in transplanted cerebellum. Also, the characteristic GFAP-positive radially oriented elongated fibers of Bergmann glia were not detected, even though passage of granule cells from their germinating zone to the internal granular layer was observed. The data presented here suggest that the developmental appearance and pattern of expression of cell adhesion molecules during morphogenesis of the cerebellum occurs largely independently of the normal complement of afferent and efferent connections.

Animals↗
PubMed1989

Transplantation of B16/C3 melanoma cells into the brains of rats and mice.

The B16/C3 mouse melanoma cell line produces L-DOPA, catecholamines and melanin in tissue culture. Growth and development of these cells after transplantation into the rat and mouse brain were studied by immunocytochemical and histological techniques. The implanted cells were localized by prelabelling the cell nuclei with bisbenzimide, a fluorescent marker which binds to DNA. Following transplantation into rats, B16/C3 melanoma cells were found to survive for at least 4-6 weeks. These cells initially expressed tyrosinase and tyrosine hydroxylase immunoreactivity and in some cases contained catecholamines. After 3 weeks, the cytoplasm of the transplanted cells began to accumulate melanin; catecholamines and tyrosinase immunoreactivity were no longer detected. Ultimately the cells became round in shape and densely pigmented. Growth of the tumor in the rats was restricted and the implant was encapsulated within a glial sheath. There was evidence of an immune reaction to the tumor in that cells with Ia antigen immunoreactivity were present surrounding the graft. The rat hosts were not adversely affected by the presence of the tumor, nor did the tumor cell grafts alter rotational behavior consequent to unilateral substantia nigra lesions. In mouse hosts, however, the melanoma grew rapidly, was not encapsulated by glia and led to death of all animals. These data suggest that the tumor was not rapidly destroyed in rats, even though its growth was controlled through immunological mechanisms. Both trophic and immunological mechanisms may therefore be involved in the regulation of survival and differentiation of intracerebral grafts of tumor cells.

Animals↗
PubMed1989

Cortical lesions interfere with behavioral recovery from unilateral substantia nigra lesions induced by brain grafts.

Effects of aspiration lesions of the cerebral cortex on the behavioral effects of intraventricular substantia nigra grafts were investigated. Apomorphine-induced rotational behavior consequent to unilateral lesions of the substantia nigra was used as a behavioral measure. Substantia nigra grafts reduced rotational behavior in animals with sham cortical lesions. Cortical lesions also decreased rotational behavior and, in these animals, no additional decrease in rotational behavior was induced by substantia nigra grafts. It is concluded that cortical lesions alter striatal circuitry so as to preclude a behavioral effect of substantia nigra grafts.

Afferent Pathways↗
PubMed1989

Immunoreactive phosphorylated epitopes on neurofilaments in neuronal perikarya may be obscured by tissue preprocessing.

Monoclonal antibodies (SMI 31 and SMI 34) against phosphorylated epitopes on neurofilaments react almost exclusively with neuronal axons in paraffin sections of perfused animals. Using fresh frozen (unfixed) rodent brain sections the immunoreactivity with these antibodies was also present in numerous neuronal cell bodies. Both antibodies also recognized intracellular antigens in the soma of living cells of a human neuroblastoma clone. These data suggest that phosphorylation of neurofilaments in neuronal perikarya is common in vivo. The phosphorylated neurofilament epitopes in neuronal perikarya may become hidden during tissue preprocessing and fixation.

Animals↗
PubMed1989

Immunological reactions induced by intracerebral transplantation: evidence that host microglia but not astroglia are the antigen-presenting cells.

The immunological reactions to embryonic cerebellar xenografts (n = 16) and allografts (n = 8) in host rat brain were studied after 2, 4, and 6 weeks of survival and compared to a control group consisting of 10 rats with isografts. Indirect immunofluorescence was performed on fresh frozen brain sections using antibodies against antigen presenting cells (Ia/Ox-6+ cells) and T helper (W3/25+) cells. Massive infiltrations of both cell types were found within xenografts. Ia antigen was present in the walls of small vessels near the transplant as well as in the ventricles on supra- and subependymal cells. In host tissue surrounding the grafts, Ox-6+ immunoreactivity was also observed in a population of cells ranging from an irregular rod-like shape with short branching processes to more rounded cell bodies with retracted processes. The appearance of these cells was characteristic of microglia. These cells were GFAP-negative. These cellular reactions were associated with rejection of the grafts. In contrast, the allografts survived, but nevertheless cells expressing Ox-6+ and to a lesser extent W3/25+ immunoreactivity were found along the injection needle tract and in damaged host tissue surrounding the grafts. No Ox-6+ perivascular infiltrations were seen. Some staining was also found within the allografts, mainly associated with damaged tissue. Ox-6+ ramified cells were also observed. Both Ox-6+ and W3/25+ immunoreactivity decreased with the time of survival. Host and donor GFAP-positive astrocytes did not express Ox-6+ molecules, and therefore probably were not involved in presenting antigen to effector cells. The control isografts also survived very well, but nevertheless Ox-6+ and less widespread W3/25+ cells were present in surrounding injured host tissue. Ox-6+ perivascular infiltration was not found in the host brain of animals with isografts. Ox-6+ and W3/25+ immunoreactivities were present primarily in graft areas that appeared damaged, often closely associated with injured host tissue. These results indicate that the process of implantation of grafts and associated brain injury induces enhanced Ia/Ox-6+ immunoreactivity, primarily on microglia in brain parenchyma surrounding grafts, and suggest that host microglia may substantially contribute to the initiation of immune reactions against intracerebral grafts. Despite this predisposition to an immunological response, only in the case of xenografts did these reactions, with the addition of Ox-6+ perivascular cuffing and cell infiltrations within the grafts, lead ultimately to graft rejection.

Animals↗
PubMed1989

Attenuation of the behavioral response to quisqualic acid and glutamic acid diethyl ester by chronic haloperidol administration.

Long-term neuroleptic administration produces a behavioral supersensitivity to dopamine agonists. Tyrosine hydroxylase immunoreactive synapses in the striatum are closely associated with putative glutamate-mediated synapses, on dendrites and dendritic spines of the same neuronal population. The purpose of the present study was to determine whether chronic neuroleptic administration would alter the behavioral response to glutamatergic drugs. Mice were chronically administered haloperidol for 28 days. After four days of withdrawal, behavioral activity was measured following intraventricular administration of quisqualic acid or intraperitoneal injection of glutamic acid diethyl ester. Both agents decreased behavioral activity. This response to glutamatergic drugs at low dosages was attenuated by chronic haloperidol administration. It is concluded that chronic haloperidol administration alters the behavioral responsivity of animals to glutamatergic drugs.

Animals↗
PubMed1989

Impaired motor coordination in mice induced by 2-amino-7-phosphonoheptanoic acid (APH), glutamic acid diethyl ester (GDEE), and other compounds.

Impairment of motor coordination by the excitatory amino acid antagonists 2-amino-7-phosphonoheptanoic acid (APH) and glutamic acid diethyl ester (GDEE) was measured and compared to GABA agonists and anticonvulsants and other compounds by the Coughenour inverted screen test. The GABA agonists muscimol and imidazole acetic acid, and the GABA analogue gamma-hydroxybutyric acid were found to produce a marked impairment of motor coordination. The dosages of phenytoin and valproate which impaired motor coordination, on the other hand, were considerably above the dosages which have been reported to inhibit seizures. APH caused motor incoordination at a dosage of 125 mg/kg, and a prolonged motor impairment was present after administration of APH, 250 mg/kg. GDEE did not significantly impair motor coordination in any dosage tested up to 1920 mg/kg. These results further encourage development of more potent GDEE-like compounds as potential anticonvulsants.

2-Amino-5-phosphonovalerate↗
PubMed1989

An hypothesis regarding the antipsychotic effect of neuroleptic drugs.

The antipsychotic effect of neuroleptic drugs appears gradually over the course of several weeks of chronic drug administration. Neuroleptic drugs are thought to act by blocking dopamine receptors; however, the dopamine-blocking effect of neuroleptics appears rapidly. One effect of dopamine antagonists which develops slowly is dopaminergic supersensitivity. It is suggested that this dopaminergic supersensitivity is related to the development of tolerance to some of the acute sedative properties of neuroleptics, but not to the antipsychotic effect. A population of glutamate receptors which are postsynaptic to the cortico-striatal afferents is located on the same neurons as striatal dopamine receptors. These glutamate synapses are located on the heads of dendritic spines of striato-nigral projection neurons, while the dopaminergic synapses are predominantly located on the necks of these same dendritic spines. Similar relationships could exist for mesolimbic and mesocortical dopamine systems. In peripheral systems, postjunctional denervation supersensitivity is known to be nonspecific; in other words, denervation of a single innervation of an excitable cell can alter the response to a range of stimuli. The antipsychotic effect of neuroleptics is therefore suggested to be due to nonspecific postjunctional subsensitivity at glutamate synapses, which develops concomitant with supersensitivity at dopaminergic synapses.

Antipsychotic Agents↗
PubMed1989

Behavioral effects of diltiazem injected into the paraventricular nucleus of the hypothalamus.

The calcium channel inhibitor diltiazem is widely used as a medication for cardiovascular diseases. Some side effects have been reported after its administration, including changes in activity (apathy or hyperactivity) and feeding behavior (anorexia). Previous experiments have found that local administration of various peptides into the paraventricular nucleus of the hypothalamus can have profound effects on these two behaviors. In the present study, effects of local infusions of diltiazem into the paraventricular nucleus on locomotor activity and food intake have been tested. A marked hyperactivity, greater than the hyperactivity caused by intraperitoneal injection of amphetamine was produced. Feeding behavior was not affected one hour after the infusions but intraventricular diltiazem infusions decreased feeding behavior. It is concluded that the paraventricular nucleus of the hypothalamus has an important role in the regulation of locomotor activity and that diltiazem can act at this level to produce behavioral changes.

Amphetamine↗
PubMed1989

[Results of cross-species transplantation of substantia nigra to the lateral ventricle of the brain of rats with experimentally-induced Parkinson disease].

The method of compensation of dopamine (DA) deficit in the striatum by living, DA producing cells implanted into the brain, creates new hopes for patients with Parkinson's disease. In view of many ethical and legal problems, connected in some countries with obtaining human fetal tissue for transplantation, cross-species transplants would be an attractive alternative. The subject of our investigation was the problem of survival and functioning of embryonal substantia nigra (SN) neurons, taken from four species, implanted into the lateral ventricle of rats with denervated striatum. The recipients were 100 inbred rats of the Fisher 344 strain in which hemiparkinsonism was induced by unilateral chemical (6-OHDA) lesion of SN. As donor served foetuses of rabbits, hamsters, mouse CF1 and Sprague-Dawley rats. Immunosuppressive drugs were not applied. The effectiveness of the transplants was estimated by testing the rotational behaviour before and after transplantation over a period of 8 weeks at weekly intervals. Survival of the transplant was evaluated by histological and immunocytochemical methods. Behavioural tests demonstrated a statistically significant improvement persisting in groups of xenografts for three to five weeks. Histological investigations revealed that the time of graft survival corresponds roughly to the period of improvement in the rotational behaviour. The results indicate that without application of immunosuppressive drugs intracerebral transplant between different species survive no more than several weeks. Thus, it is necessary to search for homogenic material for therapeutic transplantations in parkinsonian patients.

Animals↗