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Biomedical subjects

E Hansson

Publications and source records attributed to E Hansson.

At least 109 records · Page 6Linked to original sources
PubMed1988

Neurons from substantia nigra increase the efficacy and potency of second messenger arising from striatal astroglia dopamine receptor.

Dopamine (D1) receptors were demonstrated to be present on astroglial cells from striatum in primary culture. In a cocultivation system, the astrocytes were influenced by neurons from one of their natural projection areas (substantia nigra) to increase the efficacy and potency of second messenger (cyclic AMP) from the dopamine receptor. This provides evidence for a heterogeneity among astroglia from the various brain regions with respect to the expression of receptors.

Animals↗
PubMed1988

Are astroglial cells involved in morphine tolerance?

Morphine gives rise to a cascade of events in the nervous system affecting, among others, neurotransmitter metabolism. Tolerance develops for various effects shortly after administration of the drug. Also, physical dependence develops and can be demonstrated by precipitation of withdrawal reactions. Biochemical events in nervous tissue have been extensively studied during morphine treatment. This overview will focus upon brain protein metabolism since macromolecular events might be of importance for development of long-term effects, such as tolerance and physical dependence. Both dose- and time-dependent changes in brain protein synthesis and the syntheses of specific proteins have been demonstrated after morphine treatment, although methodological considerations are important. Different experimental models (animal and tissue culture models) are presented. It might be interesting to note that astroglial protein synthesis and the secretion of proteins to the extracellular medium are both changed after morphine treatment, these having been evaluated in astroglial enriched primary cultures and in brain tissue slices. The possibility is suggested that proteins released from astroglial cells participate in the communication with other cells, including via synaptic regions, and that such communication might of significance in modifying the synaptic membranes during morphine intoxication.

Animals↗
PubMed1988

Interaction between catecholamines and vasoactive intestinal peptide in cultured astrocytes.

Receptors for vasoactive intestinal peptide (VIP) were demonstrated with cyclic AMP as the second messenger on astroglial cells cultured from the cerebral cortex, striatum, hippocampus and brain stem of the newborn rat. Vasoactive intestinal peptide produced increased accumulations of cyclic AMP in nM and microM concentrations, the former more pronounced in the cultures of brain stem, while the latter was more pronounced in the other cultures studied, indicating regional differences in the activation of cyclic AMP of VIP receptors. Vasoactive intestinal peptide inhibited isoproterenol-induced accumulation of cyclic AMP dose-dependently, with some regional differences, suggesting interactions between the second messenger systems of beta- and VIP receptors. On the other hand, there was no inhibition of the NA-induced accumulation of cyclic AMP in the presence of VIP, which is in agreement with an interaction between the second messenger systems for VIP and the alpha-adrenoceptor. The data support interactions between the second messenger systems for VIP and alpha- and beta-adrenoceptors on cultured astrocytes. The functional implications are at present unknown, but it might be that the peptide can modulate the response of the second messenger to catecholamines on astroglial cells through intramembrane mechanisms.

Animals↗
PubMed1988

Toluene induces changes in the morphology of astroglia and neurons in striatal primary cell cultures.

Toluene (4.7-150) mumol per ml) was added for 30 or 60 min to astroglial and neuronal primary cell cultures from rat striatum and changes in cell morphology were analyzed by light microscopy. After 60 min incubation in 40 mumol toluene/ml, the cell bodies of the astrocytes appeared contracted, and their processes and nuclei were clearly visible. At higher doses of toluene the astrocytes seemed to be flattened and major cell damage was visualized by the uptake of vital dyes. The neurons, however, became affected and judged by morphological criteria only at the higher toluene doses. In conclusion, toluene induced morphological changes in primary astrocyte cultures and also in primary neuronal cultures at higher toluene concentrations.

Animals↗
PubMed1988

Primary astroglial cultures in alcohol and drug research.

Primary cell cultures are a potent tool for studying effects of ethanol and drugs at the cellular and molecular level. Such investigations include effects on proliferating and non-dividing cells. Physiologic mechanisms of drug action can be studied as well as toxic effects. The culture conditions including the rate of cell growth, the cellular composition and the differentiation degree of the cells, must be defined before the results from culture studies can be interpreted and be attached any significance. Changes in cell morphology after addition of the drug can be followed over time and compared with results from electrophysiology and/or drug influences upon cell metabolism including specific biochemical/functional properties on small groups of cells. Interaction between drugs and substances or hormones added to the incubation media can be evaluated. From a physiological point of view it must always be remembered that primary cultures elucidate phenomena which are devoid of integrative function. In that context results from culture models must be confirmed in experimental systems, using the intact organism to prove validity. On the other hand, primary cultures of the nervous system are very suitable model systems for elucidating biochemical mechanisms, especially those at the membrane level. The culture system enables us to study biochemical mechanisms, like the receptor transduction, at a very precise level, avoiding e.g. drawbacks with the blood-brain barrier. Furthermore, specific cells derived either from glial or neuronal origin can be studied separately.

Astrocytes↗
PubMed1987

Quantitation and tissue localization of the cellular retinoic acid-binding protein.

The distribution of the cellular retinoic acid-binding protein (CRABP) in some rat tissues has been determined, and the protein has been localized by immunocytochemical techniques in sections from rat testis. In the testis CRABP was found in the seminiferous tubuli with Sertoli cells and the spermatogonia most intensely stained. All other cells of the germinal epithelium appeared largely devoid of CRABP. By use of an enzyme-linked immunosorbent assay CRABP was quantitatively estimated in several tissues and the highest levels were found in testis and eye. Comparisons of the tissue levels of CRABP and of the cellular retinol-binding protein (CRBP) did not reveal any apparent correlation.

Amino Acid Sequence↗
PubMed1987

Amino acid content in astroglial primary cultures from different brain regions during cultivation.

Free amino acids in astroglial primary cultures obtained from newborn rat cerebral cortex, striatum and hippocampus were analyzed and compared during cultivation. Glutamate and taurine exhibited the highest concentrations. Aspartate and glutamate showed the highest values after 1 and 3 weeks of cultivation with lower values after 2 weeks in culture, while taurine, beta-alanine/hypotaurine and phosphoethanolamine showed the highest value after 2 weeks in culture. The non-neuroactive amino acids and gamma-aminobutyric acid were present at a low level and the former showed the lowest concentration at 2 weeks of cultivation. Astrocytes from the different regions did generally not differ with respect to amino acid content. We conclude that the morphological and biochemical maturation of glia in culture is accompanied with marked quantitative changes in amino acid pattern.

Amino Acids↗
PubMed1987

5-Hydroxytryptamine stimulates the formation of inositol phosphate in astrocytes from different regions of the brain.

5-Hydroxytryptamine (5-HT) stimulated the turnover of phosphoinositide in primary cultures of astroglia from the cerebral cortex, striatum, hippocampus and brain stem. Ketanserin and ritanserin, selective antagonists for the central 5-HT2 receptor, inhibited the 5-HT-stimulated formation of inositol monophosphate. In contrast, there was no statistically significant accumulation of cyclic AMP after incubation with different concentrations of 5-HT in any of the cultures studied. The results indicate that astrocytes from various regions of the brain possess 5-HT2 receptors coupled to the formation of inositol phosphates.

Animals↗
PubMed1986

Stimulation of brain-stem protein synthesis by morphine.

Rats were intoxicated with morphine as intraperitoneal (i.p.) single doses, or for 4 days (final dose 130 mg/kg b.w.) or for 13 days (final dose 340 mg/kg b.w.) using an ingestion method where intoxicated and control rats received the same amount of calories and fluid. The intoxicated groups showed different degrees of physical dependence, demonstrated by variously expressed abstinence symptoms after withdrawal of the drug or after administration of the opiate receptor antagonist naloxone. Soluble protein synthesis was measured in vivo in brain stem by double labelling with 3H and 14C valine and followed over time in the various rat groups after i.p. morphine injection in different doses. Protein synthesis in astroglial-enriched primary cultures from brain stem and secretion of labelled protein to the serum free incubation medium was also evaluated after morphine treatment. There were dose- and time-dependent effects of morphine on brain stem protein synthesis with an initial decrease and a later increase, 1-3 hr after a single dose of morphine administration. Following a morphine single dose of 25 mg/kg b.w. the stimulation was more rapid in onset and more pronounced in rats with a higher degree of physical dependence. Specific protein fractions including one with a subunit M.W. of approx. 80,000 were identified by electrophoretic separation of labelled proteins. Some similar protein fractions increased in synthesis and were released to the serum-free incubation medium when separating astroglial primary culture proteins after morphine treatment. It might be that the biphasic changes in protein synthesis after morphine administration underlie adaptive phenomena such as tolerance/physical dependence development and that some of the identified proteins including proteins synthesized in astroglial cells and secreted to the incubation media participate in these processes.

Animals↗
PubMed1986

Co-cultivation of astroglial enriched cultures from striatum and neuronal containing cultures from substantia nigra.

A co-cultivation system was developed with neuron-containing (neuron-specific enolase (NSE) positive) primary cultures from the substantia nigra of 15 to 17-day old embryonic rats which were grown 1 mm apart from astroglial-enriched (glial fibrillary acidic protein (GFAp) positive) primary cultures from the striatum of neonatal rats. The astroglial cells went through a morphological differentiation with extension of processes after co-cultivation with the immunohistochemically-identified neuronal cells. The astroglial-enriched striatum cultures showed a higher active uptake of 3H-L-glutamate after co-cultivation for one week, compared to control cultures from striatum. Vmax (nmol X mg protein-1 X min-1 X was 58.4 +/- 8.3 after co-cultivation and 37.2 +/- 6.3 for control cultures. The glutamine synthetase (GS) activity was slightly increased after co-cultivation. The validity and specificity of the results were ensured. The data suggest that astroglial cells in a primary culture are influenced by co-cultivation with fetal neuron containing cultures resulting in morphological differentiation, and increases in 3H-L-glutamate uptake and GS activity.

Animals↗
PubMed1986

Co-cultivation of astroglial and neuronal primary cultures from rat brain.

A technique is described for a two-cell co-cultivation system which permits in vitro evaluation of neuron-glia interactions. Primary astroglial enriched cultures from newborn rat cerebral hemispheres, striatum or cerebral cortex, grown for 3 days, were co-cultivated with primary neuron-containing cultures from 15- to 17-day rat embryo cerebral hemispheres, substantia nigra or brainstem, respectively, grown for 10 days on polylysine-coated surfaces. The neuronal cells were identified morphologically and immunohistochemically by antibodies to neuron-specific enolase. The two cultures were grown together for 7 days, separated by a U-formed 1 mm glass-rod. The results show that neurons exert a morphogenetic effect on astroglial cells in the form of extension of cell processes. The co-culture system allows investigation of potent local humoral interactions between astroglial cells and neurons.

Animals↗
PubMed1986

Protein metabolism and electrophoretic profiles in astroglial primary cultures from different regions of newborn rat brain.

Primary astroglial cultures (14 days of age) from cerebral cortex, striatum, and hippocampus of newborn rat brain contained similar amounts of soluble proteins. Uptake and incorporation of [3H]valine into soluble protein measured after 30 and 60 min of incubation, respectively, was on a similar level in the various cultures. [3H]valine labeling of protein bands from the cell soluble fractions and incubation media of hemisphere cultures, and which were separated by isoelectric focusing (IEF) or sodium-dodecyl-sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), indicated that proteins are released to the extracellular medium after being synthesized within cultivated cells. Acidic and high molecular weight proteins were more heavily labelled in the incubation media than in the cell soluble fractions. Two-dimensional electrophoresis (IEF X SDS-PAGE) of soluble proteins from the different cultures showed similar patterns, which were quite different from the serum-free extracellular protein patterns. Both fractions were different from the pattern obtained from fetal calf-serum. In striatum and hippocampus culture media a "spot" was seen with Ip 6.0-6.8 and m.w. 105,000, and in the media from cerebellar cultures another "spot" was observed with Ip 5.2-5.6 and m.w. 55,000. The results show that the different cultures are similar in their protein synthetic capacity and protein composition. The specific differences observed in proteins obtained from the serum-free incubation media might indicate specific properties among astroglial cells from various brain regions.

Animals↗
PubMed1986

Neurotransmitter uptake in various brain regions of chronically morphinized rats.

Rats were long-term morphine-intoxicated by a fluid-diet model ensuring an equal nutrient intake in morphinized and control rats. Uptake of neurotransmitters and D-ala2-met5-enkephalinamide (Enk) was studied in the particulate fractions (obtained at 10,000 g) from well defined brain regions of long-term intoxicated and morphine withdrawn rats. In control animals the accumulation of [3H]glutamate and [3H]gamma-aminobutyric acid (GABA) reached the highest tissue/medium (T/M) ratio values, 30-120, in the regions studied while monoamine T/M values were 2-10. No active uptake of [3H]Enk could be demonstrated. Striatum showed the most evident modifications in neurotransmitter uptake. In this region the equilibrium T/M ratio for [3H]glutamate and [3H]GABA was significantly lower in intoxicated rats versus controls. Moreover, the T/M ratio for [3H]5-hydroxytryptamine (5-HT) was lower, while that for [3H]dopamine (DA) was higher in abstinent rats in comparison with the controls. [3H]glutamate and [3H]GABA uptakes were also significantly lower, respectively, in frontal cortex, hippocampus and brain stem in intoxicated rats, while [3H]5-HT uptake was significantly lower in hypothalamus after morphine withdrawal. The possible involvement of the endogenous opioid system in the etiology of the alterations is discussed.

Administration, Oral↗
PubMed1986

Primary cultures from defined brain areas. III. Effects of seeding time on [3H]L-glutamate transport and glutamine synthetase activity.

Primary astroglial-enriched cultures from various brain regions were studied with respect to age at seeding and time in culture and its effect on the [3H]L-glutamate transport capacity and glutamine synthetase (G.S.) activity. Three phylogenetically different rat brain areas were used: cerebral cortex, striatum and brainstem. There was a high-affinity and high-capacity [3H]glutamate uptake during development in all cultures studied with Km in the microM range and Vmax in the nmol range. Vmax was most prominent in cultures seeded from newborn rat cerebral cortex and striatum when grown for 2 weeks and in brainstem cultures seeded from 17-day-old rat embryos when grown for 4 weeks. There were no significant differences in Vmax comparing the cultures from the various brain regions, that is when seeded from 17-day-old embryos and grown for 2 or 3 weeks in culture. The G.S. activity was determined under similar culture conditions as above. The highest enzyme activities were found in cultures from cerebral cortex and striatum seeded from newborn and 7-day-old rats and grown for 2 or 3 weeks. G.S. activity increased during postnatal maturation in cerebral cortex, striatum and brainstem, the highest activity values being found in cerebral cortex and striatum. Vmax for glutamate uptake and G.S. activity showed many similarities in the respective cultures during cultivation. Both parameters were affected by age at seeding and time in culture. The differences between the cultures from the various brain regions, with lower values in cultures from brainstem, indicated a heterogeneity among astroglial cells in the brain regions studied.

Aging↗