Association between left ventricular global longitudinal strain and natriuretic peptides in outpatients with chronic systolic heart failure.

BACKGROUND: Both impaired left ventricular (LV) global longitudinal strain (GLS) and increased plasma concentrations of natriuretic peptides(NP) are associated with a poor outcome in heart failure (HF). Increased levels of NP reflect increased wall stress of the LV. However, little is known about the relationship between LV GLS and NP. This aim of this study was to evaluate the relationship between the echocardiographic measure LV GLS and plasma levels of NP. METHODS: We prospectively included 149 patients with verified systolic HF at the baseline visit in an outpatient HF clinic. LV GLS was assessed by two dimension speckle tracking and plasma concentrations of N-terminal-pro-brain-natriuretic-peptide (NT-proBNP) and pro-atrial-natriuretic-peptide (proANP) were analysed. RESULTS: The patients had a median age of 70 years, 28.2 % were females, 26.5 % were in functional class III-IV, median left ventricular ejection fraction (LVEF) was 33 % and median LV GLS was -11 %. LV GLS was associated with increased plasma concentrations of NT-proBNP and proANP in multivariate logistic regression (NT-proBNP: Odds RatioGLS: 7.25, 95 %-CI: 2.48-21.1, P < 0.001 and proANP: Odds RatioGLS: 3.26, 95-%-CI: 1.28-8.30, P = 0.013) and linear regression (NT-proBNP: ßGLS: 1.19, 95 %-CI: 0.62-1.76, P < 0.001 and proANP: ßGLS: 0.42, 95-%-CI: 0.11-0.72, P = 0.007) models after adjustment for traditional confounders (age, gender, body-mass-index, atrial fibrillation, renal function) and left atrial volume index. CONCLUSION: Impaired LV GLS is associated with increased plasma concentrations of NP and our data suggest that left ventricular myocardial mechanics estimated by LV GLS reflects myocardial wall stress in chronic systolic HF.

A versatile system for the generation and the development of speech coding strategies in cochlear implants.

A signal processor-based (DSP32C) stimulation system for cochlear implants has been developed. This system allows up to 14 stimulation channels (place principle) and conserves the time structure of the acoustic signal (periodicity principle). Any combination of these features is possible; in compressed analogue mode, pulsatile mode, or combinations of both. The system also takes electrical crosstalk into account caused by the electrical properties of the inner ear and compensates for it. Lateral inhibition strategies improve spatial resolution. Finally, the system offers an interface for the generation of quick continuous interleaved sampling strategies (CIS); up to 11,000 pulses/s per channel.

Development of microglia in the prenatal rat hippocampus.

The distribution and appearance of microglia cell precursors in the prenatal hippocampus were examined in embryonic day 14 (E14) to E21 rats by nucleoside diphosphatase histochemistry. For comparison, the differentiation of astroglial cells was analyzed from E17 by vimentin and glial fibrillary acidic protein immunohistochemistry. Based on morphologic features, nucleoside diphosphatase-positive microglial cell precursors were classified as ameboid microglial cells and primitive ramified microglial cells. Ameboid microglia were present in the hippocampal primordium on E14. As the hippocampus developed, however, ameboid microglia gradually transformed into primitive ramified microglia, first recognized at E19. Microglial cell precursors, often related to nucleoside diphosphatase-labeled blood vessels, were particularly observed next to the pial surface on days E14 and E17 and in the highly vascularized area around the hippocampal fissure from E19. Within the brain parenchyma, the microglial cell precursors tended to be located within the differentiating cell and neuropil layers rather than in the germinative zones. The late developing dentate gyrus remained almost devoid of microglial cell precursors before birth. Vimentin-positive astroglial processes with radial orientation were observed throughout the hippocampal subregions from E17. In contrast, glial fibrillary acidic protein-positive, radial processes were barely discernible in the fimbria and the dentate gyrus before E19. The results are discussed in relation to the possible interactive role of microglial cells in central nervous tissue development and histogenesis. Regarding the origin of hippocampal microglial cell precursors, the present observations support the view that these cells may well originate from different mesodermal sources depending on time and localization.

No loss of hippocampal hilar somatostatinergic neurons after repeated electroconvulsive shock: a combined stereological and in situ hybridization study.

Electrically induced seizures with anesthesia and muscle relaxation (ECT) is commonly used in the therapy of psychotic depression in humans. Unmodified electroshock (ECS) is used as a model for epilepsy in the rat. In several seizure models of epilepsy, in particular the dentate hilar somatostatin-containing (SSergic) neurons have been found to undergo degeneration. To assess the potential loss of SSergic hilar neurons after repeated ECS, 10 rats were given 110 ECS, one per day, 5 days a week. One day after the last ECS the rats were anesthesized, perfused, the brains cut on a vibratome and prepared for nonradioactive in situ hybridization for somatostatin along with five control rats. Like rats given 10-36 ECS in earlier studies, the ECS-treated rats displayed a markedly increased neuronal hybridization labeling when compared with control rats. The total number of dentate hilar SSergic neurons of each rat was estimated using the optical disector technique. The mean number of hilar SSergic neurons in the ECS-treated rats was 12,785, compared to 12,392 in the control rats. The total number of hilar SSergic neurons in ECS-treated versus control rats was not significantly different (Student's t test; t value = .35; p = .74). We conclude that repeated ECS treatment does not cause loss of hilar SSergic neurons.

Regulation of synaptic ribbons in rat pineal gland explants by norepinephrine and sympathetic neurons in a co-culture model.

The hypothesis that synaptic ribbons in the mammalian pinealocyte are influenced by adrenergic mechanisms was tested in the present study using a co-culture model of pineal glands and superior cervical ganglia from neonatal rats. Pineal gland explants survived and showed a high degree of differentiation when cultured for up to 30 days regardless of the presence or absence of superior cervical ganglia. Pineal glands also had neurotrophic properties promoting the survival and neurite extension from superior cervical ganglia. Synaptic ribbons were a common ultrastructural feature in all pineal cultures. There was a significant decline in synaptic ribbon numbers when co-cultured with superior cervical ganglia for both 7 and 30 days. A similar significant decrease in synaptic ribbon frequency was observed after treatment of pineal explants with norepinephrine (10(-5 )M) for both 7 and 30 days. These findings are consistent with the hypothesis that neural mechanisms play an important role in regulating synaptic ribbon numbers, at least during early development. The study also illustrates the utility of pineal gland-superior cervical ganglia co-cultures as a model for future investigations of neuron-target interactions in the pineal.

Connective integration of hippocampal grafts in excitotoxic hippocampal lesions in adult rats: an anterograde axonal tracing study.

Exchange of nerve connections between developing neural grafts and adult recipient brains is enhanced for grafts placed in excitotoxic lesions, which spare recipient brain afferent axons in otherwise neuron-depleted lesion areas. In previous studies of hippocampal grafts placed in such lesions, we have used anterograde axonal degeneration, histochemical Timm staining and acetylcholinesterase to demonstrate host-graft interconnectivity. In this study, we have now used three anterograde axonal tracers, Phaseoulus vulgaris-leukoaglutinin (PHA-L), biocytin and biotinylated dextran amine (BDA), which allow individual fibers to be traced. Adult male rats with 1-week-old axon-sparing ibotenic acid lesions of the dorsal CA3 region or fascia dentata were grafted into the respective lesions with suspensions of fetal (El8-19) CA3 cells or a block of neonatal fascia dentata tissue. One to twelve months later, recipients were injected with Phaseoulus vulgaris-leukoaglutinin or biocytin in the hippocampus contralateral to the graft to trace the possible ingrowth and distribution within the transplants of host commissural axons, or into the transplants with biotinylated dextran amine in order to trace outgrowing graft fibers. In rats with succesfull host Phaseoulus vulgaris-leukoaglutinin or biocytin injections, the CA3 and fascia dentata transplants were innervated by labelled host commissural fibers. In the dentate transplants, most commissural fibers projected as normally to the inner part of the molecular layer, with fewer aberrant fibers extending more superficially into the molecular layer. Following injections into the fascia dentata and CA3 grafts of biotinylated dextran amine, labelled graft fibers were traced into the ipsilateral host dentate hilus, CA3 and CA1. From some CA3 containing grafts, a few labelled fibers were also observed passing through the host fimbria-fornix to the lateral septum on the grafted side. A few fibers were projected as far as to the most septal levels of the contralateral CA1.

c-JUN, KROX-24, and c-FOS expression in hippocampal grafts placed in excitotoxic hippocampal lesions of the rat.

Hippocampal transplants were examined for the expression of three specific immediate early gene encoded proteins in order to establish if grafted immature tissue maintains the basic molecular program necessary for gene transcription after grafting to excitotoxic (ibotenic acid-induced) lesions in adult host rat brains. The transplants were derived from newborn donor rats and were analyzed immunocytochemically for the presence of c-JUN, KROX-24, and c-FOS transcription factors 5 months after grafting. The expression and distribution patterns of these genes in the host hippocampus were identical to those in hippocampal neurons of normal untreated animals. c-JUN-, KROX-24-, and c-FOS-labeled neurons were also present in the transplants, where KROX-24 and c-FOS exhibited a distribution similar to host hippocampus. In contrast, c-JUN was more extensively expressed in the transplants, suggesting a molecular response to the grafting conditions and the actual graft-host brain interactions.

Neurotrophic effects of the pineal gland: role of non-neuronal cells in co-cultures of the pineal gland and superior cervical ganglia.

The pineal gland (PG) is a source of several trophic factors. In this study, PG and superior cervical ganglia (SCG) from Sprague-Dawley neonates (1-day-old) were co-cultured to test the hypothesis that endogenous release of PG NGF (or an NGF-like cytokine) is sufficient to promote survival of SCG neurons. Neuronal density of SCG neurons was significantly enhanced when co-cultured with PG for 7 days compared to SCG cultured alone. SCG survival and neurite formation in PG co-cultures was less than in SCG treated with exogenous NGF (100 ng/ml). The neurotrophic effect of PG co-cultures was abolished when 1% anti-NGF was added to the medium. Co-cultures of SCG neurons with established 7-day PG cultures induced extensive SCG neurite formation within 24 hr compared to SCG co-cultured with 1-day PG cultures. This suggests that PG neurotrophic effects are due to PG non-neuronal cells (nnc) that proliferate to confluency by 7 days in culture. S-antigen-positive pinealocytes did not proliferate in culture. There was decreased SCG survival when neurons were seeded onto PG cultures that had been previously killed by drying, which suggests that the neurotrophic effects of nnc are not substrate-dependent. Immunocytochemical characterization of PG nnc revealed a heterogenous mixture of astrocytes, macrophage/microglia, and fibroblasts. These findings support the hypothesis that NGF is actively secreted by PG and that nnc are the principal source of this neurotophin.

Kindling induces transient changes in neuronal expression of somatostatin, neuropeptide Y, and calbindin in adult rat hippocampus and fascia dentata.

Fully hippocampus-kindled rats were examined 1 day and 1 month after the last stimulation for changes in somatostatin (SS)-, neuropeptide Y (NPY)-, and calbindin (CaBP)-immunoreactivity (ir) and SS- and NPY-mRNA in situ hybridization (ISH). One day after the last stimulation, there was marked, bilateral increase in SS- and NPY-ir in the outer part of the dentate molecular layer. The cell bodies of dentate hilar SS- and NPY-containing neurons, known to project to this area, also appeared to display increased immunoreactivity as well as an increased ISH signal for SS and NPY mRNA. Bilateral de novo expression of NPY-ir in dentate mossy fiber projection to dentate hilus and CA3 was also evident, but we noted no corresponding NPY-mRNA signal in the parent cell bodies, the dentate granule cells. After 1 month, the levels of NPY-ir and ISH signal appeared essentially normal. In contrast, the levels of SS apparently were decreased, although not yet normal. CaBP-ir was markedly and selectively reduced in dentate granule cell bodies, dendrites, and mossy fibers 1 day after the last stimulation, but after 1 month CaBP-ir appeared essentially normal. Because kindling, once established, is a permanent phenomenon, the observed transient changes in SS, NPY, and CaBP in specific hippocampal terminal fields and neuronal populations cannot be associated specifically with kindling. Rather, they relate to the repeated high-frequency stimulations and may serve as protective measures against deleterious effects of such stimulations.

The susceptibility of CA1 pyramidal cells to cerebral ischemia is maintained after neonatal, lesion-induced reorganization of the hippocampal circuitry.

Acute lesions of hippocampal pathways have been shown previously to ameliorate CA1 pyramidal cell loss after subsequent transient cerebral ischemia. In this study, we examined the effect of chronic neonatal lesion with reorganization of hippocampal circuitry on adult postischemic neuron loss in the hippocampus. Newborn rats were subjected to unilateral knife-cut lesions at various positions along the trisynaptic entorhino-dentato-hippocampal pathway. Seven months later, the rats were subjected to transient cerebral ischemia using the four-vessel occlusion technique. At the time of killing 4 days later, a Nissl stain was used to demonstrate neuronal degeneration, while connective reorganization resulting from the neonatal lesions was monitored by Timm staining. In one group of rats, neonatal lesions had caused severe depletion of entorhinal projections to the septodorsal fascia dentata and hippocampus (CA1 and CA3), without any direct damage to the dorsal hippocampus itself. Another group had extensive damage of the dorsal CA3, with removal of the Schaffer collaterals from these levels to CA1, and variable damage to the entorhinal afferents. In both groups, the extent and pattern of ischemia-induced degeneration of CA1 pyramidal cells were the same on the lesioned and nonlesioned sides of the brain, demonstrating that neonatal lesions and the subsequent connective reorganization did not have a sparing effect. Seen in relationship to previous observations in adult rats of the neuroprotective actions of acute, preischemic lesions of the trisynaptic hippocampal pathway, it is concluded that CA1 pyramidal cell loss requires the presence of intact excitatory afferents rather than an intact hippocampal circuitry.

Transient decrease in calbindin immunoreactivity of the rat fascia dentata granule cells after repeated electroconvulsive shocks.

Changes in hippocampal calbindin immunoreactivity were investigated after repeated electroconvulsive shocks. Adult rats were subjected to 10, 20, or 36 electroconvulsive shocks (50 mA, 0.5 seconds), given as on shock per day, 5 days a week. The rats were sacrificed and processed for calbindin immunohistochemistry 1, 2, and 30 days after the last electroconvulsive shock. In the rats receiving 10 or 20 electroconvulsive shocks, a selective reduction of the calbindin immunoreactivity of the dentate granule cell bodies, dendrites, and mossy fibers was noted 1 and 2 days after the last electroconvulsive shock. After 36 electroconvulsive shocks there was an almost complete loss of calbindin immunoreactivity from the granule cell bodies and dendrites, and the calbindin immunoreactivity of the mossy fibers was markedly reduced. Thirty days after the last of 36 electroconvulsive shocks, the calbindin immunoreactivity was back to normal. Besides demonstrating pronounced changes associated with repeated electroconvulsive shocks, the results confirm the transient nature of these changes.

Repeated electroconvulsive shocks cause transient changes in rat hippocampal somatostatin and neuropeptide Y immunoreactivity and mRNA in situ hybridization signals.

Increased levels of somatostatin (SS) and neuropeptide Y (NPY) have been demonstrated in the hippocampal formation after kindling. The increase might be specifically associated with kindling, or be an effect of repeated seizures per se. In order to separate these two components we studied the effects of repeated electroconvulsive shocks (ECS) on hippocampal SS-like and NPY-like immunoreactivity and SS mRNA and NPY mRNA in situ hybridization. ECS elicit seizures without having a demonstrable kindling effect. Rats were subjected to 10, 20, or 36 ECS (50 mA, 0.5 s), given as one shock per day, 5 days per week. One, 2 and 30 days after the last ECS, the rats were killed, together with sham-treated control rats, and processed for immunocytochemistry and non-radioactive in situ hybridization. There was a bilateral increase in SS-like and NPY-like immunoreactivity 1 and 2 days after the last ECS in the outer part of the dentate molecular layer. This is the terminal field of the hilar SS-containing and NPY-containing neurons, which displayed both increased immunoreactivity and hybridization signal of the cell bodies. There was also a bilateral de novo expression of NPY-like immunoreactivity in the mossy fiber system, but this was not accompanied by the appearance of a detectable NPY hybridization signal over the parent dentate granule cell bodies. The increase in SS-like immunoreactivity and hybridization signal was most pronounced in the rats that had received the largest number of ECS. This was not observed for the NPY-like immunoreactivity and hybridization signal, where the increase appeared similar after 10, 20 and 36 ECS.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient forebrain ischemia-induced neuronal degeneration in fascia dentata transplants.

Fascia dentata tissue blocks from newborn rats were grafted into one-week-old, ibotenic acid-induced lesions of the fascia dentata, or the normal fascia dentata of adult rats. After at least 2 months survival the recipient rats were subjected to 10 min of forebrain ischemia (4-vessel occlusion), and examined 2 or 4 days later for neuronal degeneration in the host hippocampi and the transplants, by silver staining and immunohistochemistry. Transplants survived well in both normal and lesioned host brains, with easily recognizable subfields and layers and presence of normal types of principal and non-principal neurons. As expected, argyrophilic, degenerating neurons were present in the pyramidal cell layer of CAl and CA3c of the non-grafted contralateral host hippocampus and in the contralateral dentate hilus (CA4). In the hilus the degeneration corresponded to the loss of somatostatin-immunoreactive neurons, while parvalbumin-immunoreactive neurons were spared. In the dentate transplants degenerating neurons were observed in the granule cell layer, the hilus and the adjacent CA3 pyramidal cell layer. There was no obvious loss of either somatostatin- or parvalbumin-immunoreactive neurons. The degeneration varied considerably between transplants, from a few to large groups of silver stained neurons, but this difference did not display any obvious relation to grafting into normal or lesioned hosts, the exact location of the grafts or the general organization and distribution of intrinsic or extrinsic host afferents in the grafts. The results demonstrate that both ischemia-susceptible and -resistant types of neurons grafted to normal and lesioned adult rat brains are susceptible to transient forebrain ischemia after transplantation. In spite of an extensive reorganization of transplant nerve connections, the physiologicalbiochemical mechanisms necessary for the induction of ischemic cell death were accordingly present in the transplants.

A developmental study of lactate dehydrogenase isozyme and aspartate aminotransferase activity in organotypic rat hippocampal slice cultures and primary cultures of mouse neocortical and cerebellar neurons.

The development of enzyme activity and isozyme distribution of lactate dehydrogenase (LDH) was studied in murine organotypic hippocampal slice cultures and dissociated cultures of neocortical neurons and cerebellar granule cells and compared with that of the respective brain regions in vivo. In the hippocampal slice cultures and the hippocampus in vivo, the activity of aspartate aminotransferase (AAT) was also measured. During development in culture the specific activity of LDH increased in all types of cultures reaching values similar to that found in the corresponding brain areas in vivo. However, significant differences in the isozyme distribution were observed between the preparations in vitro and in vivo. During development in vivo, the LDH isozyme pattern changed from a preferential M-subunit composition to a preferential H-subunit composition regardless of the brain area. This shift was not observed in the respective cultures where the M4-isozyme prevailed at all culture periods examined accounting for 30-45% of the total LDH activity. The cultured cerebellar granule cells did not express the H4-isozyme at all, while in the hippocampal slice cultures and the cultured neo-cortical neurons this isozyme accounted for about 5% of the total LDH activity. The activity of AAT in the hippocampal organotypic slice cultures increased considerably during the culture period in parallel with the increase in AAT activity during postnatal development of hippocampus in vivo. The activity of AAT in the slice cultures was, however, consistently lower than the corresponding activity in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Time course of hippocampal glucose utilization and persistence of parvalbumin immunoreactive neurons after ibotenic acid-induced lesions of the rat dentate area.

The effects of ibotenic acid induced lesions of the dentate gyrus on hippocampal glucose utilization and parvalbumin-positive neurons were evaluated in male Wistar rats. Ibotenic acid was injected in the right dorsal dentate gyrus. Quantification of glucose utilization was performed 3 days, 3 weeks, or 3 months after the lesion using the 14C-2-deoxyglucose method. Nissl-stained sections and sections stained for acetylcholinesterase were used as references for anatomical delineation of the hippocampal cytoarchitecture. Additional sections were stained for parvalbumin. The results revealed widespread reductions of glucose utilization in all layers and sectors of the hippocampus in the ipsilateral lesioned hemisphere and also in the nonlesioned contralateral hemisphere. The reductions occurred as early as 3 days after the lesion and persisted up to 3 months. In neither hippocampal structure did glucose utilization return to control levels. Immunohistochemical visualization of parvalbumin-containing neurons revealed that these putatively inhibitory neurons persisted in the otherwise granule-cell-depleted area. The data show that interruption of the excitatory trisynaptic pathway from the entorhinal cortex to the CA1 at the level of the dentate gyrus affects hippocampal glucose utilization irreversibly and uniformly. Since some inhibitory neurons seem to survive the ibotenic acid lesion, we suggest that the reductions of hippocampal glucose utilization reflect an imbalance in favor of inhibitory neurons in the ipsilateral hippocampus after the lesion, which manifests also in the contralateral hemisphere via the commissural pathways.

Zinc-positive afferents to the rat septum originate from distinct subpopulations of zinc-containing neurons in the hippocampal areas and layers. A combined fluoro-gold tracing and histochemical study.

The purpose of the present study was to examine whether zinc-positive and zinc-negative hippocampal neurons in rats differed with respect to their projections to the septum. By combining retrograde axonal transport of the fluorescent tracer Fluoro-Gold with histochemical demonstration of zinc selenide complexes in zinc-containing neurons after intraperitoneal injection of sodium selenite, we were able to visualize the distribution of retrogradely Fluoro-Gold labeled neurons and zinc-containing neurons in the same sections. After unilateral injection of Fluoro-Gold into the rat septum a few retrogradely labeled cells were observed in layer IV of the ipsilateral medial entorhinal area, and numerous labeled cells were observed mainly in the superficial layers of the ipsilateral subicular areas and throughout the CA1 and CA3 pyramidal cell layers, as well as in the contralateral CA3 pyramidal cell layer. Zinc-containing neurons were observed in layers IV-VI of the medial entorhinal area, layers II and III of the parasubiculum, layers II, III and V of presubiculum, and in the superficial CA1 and deep CA3 pyramidal cell layers. Cells double-labeled with Fluoro-Gold and zinc selenide complexes were primarily located in distal (relative to the area dentata) parts of the superficial CA1 pyramidal cell layer and distal parts of the deep CA3 pyramidal cell layer and in layers II and III of presubiculum. Only a very few double-labeled cells were seen in the contralateral CA3. The result demonstrates that the hippocampo-septal projection of rats is a mixture of zinc-positive and zinc-negative fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of microglial immunomolecules by anterogradely degenerating mossy fibres in the rat hippocampal formation.

Degeneration of myelinated axonal connections is generally held to provide a strong stimulus for microglial expression of major histocompatibility complex (MHC) class II antigen. The present study demonstrates that strong microglial reactions also are induced by axonal and terminal degeneration of the unmyelinated hippocampal mossy fibres. After destruction of dentate granule cells by focal injections of colchicine (or transection of the mossy fibres) in adult rats, immunocytochemical analysis of the mossy fibre terminal fields in the dentate hilus and regio inferior of hippocampus proper (CA3) revealed profound changes in microglial cells with increased expression of the complement receptor type 3 and induction of MHC class I antigen, leukocyte common antigen, lymphocyte function-associated antigen-1 and MHC class II antigen. The microglial reaction, first detectable 4 days after the lesion, became maximal during the third postlesional week, and had almost vanished 6 weeks after the lesion. From recent studies we know that anterograde degeneration of myelinated Schaffer-collaterals from CA3 to regio superior of hippocampus proper and myelinated entorhinal perforant path fibres to fascia dentata is accompanied by microglial expression of MHC class I antigen, but not class II. Together with the present findings, this demonstrates that myelin debris is neither necessary nor sufficient to induce expression of microglial MHC class II antigen within the hippocampus.

Biocytin pellets: an alternative technique for massive anterograde labeling of neuronal pathways in vivo and in vitro.

The present study demonstrates that biocytin suspended in pellets of either coagulated chicken plasma (plasmaclot) or gelatine, produces intense anterograde axonal and terminal labeling and dense retrograde Golgi like labeling of neurons when injected into the brain parenchyma of young adult rats. The technique worked perfectly on hippocampal pathways like the mossy fiber system, the hilodentate associational and commissural fiber systems, CA3 Schaffer collaterals, the entorhinal perforant path to fascia dentata and hippocampus, as well as frontal motor cortical efferent and afferent fiber tracts. This pellet tracer delivery technique also proved very useful when applied on hippocampal slice cultures, where small pellets of plasmaclot embedded biocytin resulted in very discrete uptake sites with dense labeling of small groups of neurons and their projections.

Area specific functional activity in organotypic hippocampal slice cultures. A 2-deoxyglucose study.

Slices of hippocampus from 5 day old rats were cultured by the roller-tube technique. After 4 weeks [14C]-2-deoxyglucose (2-DG) was added to the medium for 45 min, whereafter the cultures were frozen and cut on a cryostat. The sections were thawed onto coverslips and processed for autoradiography. Image analysis of the resulting autoradiographs showed a higher uptake of 2-DG in CA3 than in CA1 and fascia dentata, whereas CA1 and fascia dentata did not differ significantly with respect to 2-DG uptake. The study demonstrates, that organotypic hippocampal slice cultures display an area specific glucose utilization, and thus functional activity, which is similar to that observed in adult conscious rats. We therefore anticipate that the method can be used to examine the integrated activity of the whole neuronal network in these cultures under various manipulations, like hypoxia or additions of various drugs.