Cerebral Cortex Of Animals Research Articles

Purinergic signaling influences the neuroinflammatory outcomes of a testosterone-derived synthetic in female rats: Resistance training protective effects on brain health

Physical exercise is recognized as a non-pharmacological approach to treat and protect against several neuroinflammatory conditions and thus to prevent brain disorders. However, the interest in ergogenic resources by athletes and bodybuilding practitioners is widespread and on the rise. These substances shorten the process of performance gain and improve aesthetics, having led to the prominent use and abuse of hormones in the past years. Recent evidence has shown that the purinergic system, composed of adenine nucleotides, nucleosides, enzymes, and receptors, participates in a wide range of processes within the brain, such as neuroinflammation, neuromodulation, and cellular communication. Here, we investigated the effects of the anabolic androgenic steroid (AAS) testosterone (TES) at a dose of 70 mg/kg/week in female rats and the neuroprotective effect of resistance exercise related to the purinergic system and oxidative stress parameters. Our findings showed a decrease in ATP and ADO hydrolysis in treated and trained animals. Furthermore, there was an increase in the density of purinoceptors (P2X7 and A2A) and inflammatory markers (IBA-1, NRLP3, CASP-1, IL-1β, and IL-6) in the cerebral cortex of animals that received AAS. On the other hand, exercise reversed neuroinflammatory parameters such as IBA-1, NLRP3, CASP-1, and IL-1β and improved antioxidant response and anti-inflammatory IL-10 cytokine levels. Overall, this study shows that the use of TES without indication or prescription disrupts brain homeostasis, as demonstrated by the increase in neuroinflammation, and that the practice of exercise can protect brain health.

Dynamic Changes in the Activities and Contents of Particular Proteasome Forms in the Cerebral Cortex of C57BL/6 Mice during Aging

—Proteasomes are key components of the ubiquitin–proteasome system. Various forms of proteasomes are known. During aging, disturbances in the functioning of proteasomes have been revealed, as well as increased expression of their particular forms. Considering these data, we studied the expression of genes encoding the constitutive and immune subunits of proteasomes in cerebral cortex samples from C57BL/6 mice at the ages of 60, 190, 380, and 720 days. In addition, the contents of constitutive and immune proteasome subunits, chymotrypsin-like and caspase-like activities of proteasome pools, as well as the activity of the β5i immune subunit were studied in tissue homogenates. The chymotrypsin-like activity and the activity of the β5i subunit of different forms of proteasomes separated by electrophoresis in native gel were characterized. Compared with samples from young animals, in the cerebral cortex of animals at an age of 720 days the following changes in the expression patterns of proteasome genes were revealed: a decreased expression of the PSMB5 gene encoding constitutive proteasome subunit β5; increased expression of genes encoding immune proteasome subunits β5i and β1i. In tissue homogenates of aged mice, an increase in the content of immune subunits β1i and β2i was shown. In samples from old animals, chymotrypsin-like activity was decreased and a tendency to a decrease in caspase-like activity of proteasomes as well as the β5i subunit activity was revealed. Analysis of the activity of native complexes in tissues obtained from old animals revealed decreased chymotrypsin-like activity of 26S and 20S proteasomes containing the β5i subunit. Based on the obtained data, it can be assumed that changes in the pool of nonconstitutive proteasomes reflect aging-associated adaptive processes in the mouse brain.

Changes in the Activity and Content of Individual Forms of Proteasomes in Samples of the Cerebral Cortex during Pathology Development in 5xFAD Mice

The ubiquitin-proteasome system (UPS) provides hydrolysis of most intracellular proteins in proteasomes. There are various forms of proteasomes differing, among other things, in the set of proteolytic subunits and the presence of activators. Alzheimer’s disease (AD) is characterized by disturbances in the functional state of the UPS. At the same time, an increase in the expression of certain forms of proteasomes, in particular, proteasomes containing immune subunits (non-constitutive proteasomes), was shown. Here, we studied dynamic changes in the expression of catalytic proteasome subunit genes and protein content in the cerebral cortex of animals using a mouse model of AD (5xFAD transgenic mice). In samples from 5xFAD mice, at the age of 380 days, compared with samples from mice of 60 days of age, 4 and 6 times more gene transcripts of the immune subunits PSMB9 and PSMB8 were detected, as well as a significant increase in the number of immune β-subunits (2.8 times – β1i, 2.2 times – β2i) was observed. The results obtained indicate activation of the synthesis of immune subunits and assembly of non-constitutive proteasomes at the terminal stage of pathology development. At the same time, the results of electrophoresis in native conditions indicate the activation of both 20S and 26S proteasomes containing immune subunits in samples from 5xFAD mice, 380 days of age. The obtained data, in combination with available literature, indicate that the activation of non-constitutive proteasomes is a universal phenomenon characteristic of various animal models of AD, that may reflect both the development of neuroinflammation and adaptive processes in tissues.

Changes in the Activities and Contents of Individual Forms of Proteasomes in Samples of the Cerebral Cortex during Pathology Development in 5xFAD Mice

The ubiquitin-proteasome system (UPS) provides hydrolysis of most intracellular proteins in proteasomes. There are various forms of proteasomes that differ, among other things, in the set of proteolytic subunits and the presence of activators. Alzheimer's disease (AD) is characterized by disturbances in the functional state of the UPS. At the same time, an increase in the expression of certain forms of proteasomes, in particular, proteasomes containing immune subunits (nonconstitutive proteasomes), has been shown. Here, we studied dynamic changes in the expression of catalytic proteasome subunit genes and corresponding proteins in the cerebral cortex of animals using a mouse model of AD (5xFAD transgenic mice). Increases by 4 and 6 folds in transcripts of the PSMB9 and PSMB8 genes encoding immune proteasome subunits were detected, as well as a significant increase in the content of immune β-subunits (by 2.8 folds, β1i; 2.2 folds, β2i) in samples from 5xFAD mice at the age of 380 days, compared with samples from mice at 60 days of age. Moreover, the activation of both 20S and 26S proteasomes containing immune subunits were revealed in samples from 380 days old 5xFAD mice by electrophoresis in native conditions. This indicates activated synthesis of the immune subunits and assembly of nonconstitutive proteasomes at the terminal stage of pathology development. The obtained data, in combination with the available literature, indicate that the activation of nonconstitutive proteasomes is a universal phenomenon characteristic of various animal models of AD, which may reflect both the development of neuroinflammation and adaptive processes in tissues induced by the accumulation of toxic protein aggegates.

Dynamic Changes in the Activities and Contents of Particular Proteasome Forms in the Cerebral Cortex of C57BL/6 Mice during Aging

Proteasomes are key components of the ubiquitin-proteasome system. Various forms of proteasomes are known. During aging, disturbances in the functioning of proteasomes have been revealed, as well as increased expression of their particular forms. Considering these data, we studied the expression of genes encoding the constitutive and immune subunits of proteasomes in cerebral cortex samples from C57BL/6 mice at the ages of 60, 190, 380, and 720 days. In addition, the contents of constitutive and immune proteasome subunits, chymotrypsin-like and caspase-like activities of proteasome pools, as well as the activity of the β5i immune subunit were studied in tissue homogenates. The chymotrypsin-like activity and the activity of the β5i subunit of different forms of proteasomes separated by electrophoresis in native gel were characterized. Compared with samples from young animals, in the cerebral cortex of animals at an age of 720 days the following changes in the expression patterns of proteasome genes were revealed: a decreased expression of the PSMB5 gene encoding constitutive proteasome subunit β5; increased expression of genes encoding immune proteasome subunits β5i and β1i. In tissue homogenates of aged mice, an increase in the content of immune subunits β1i and β2i was shown. In samples from old animals, chymotrypsin-like activity was decreased and a tendency to a decrease in caspase-like activity of proteasomes as well as the β5i subunit activity was revealed. Analysis of the activity of native complexes in tissues obtained from old animals revealed decreased chymotrypsin-like activity of 26S and 20S proteasomes containing the β5i subunit. Based on the obtained data, it can be assumed that changes in the pool of nonconstitutive proteasomes reflect aging-associated adaptive processes in the mouse brain.

Structural and functional transformations of the brain in experimental mild traumatic brain injury

In mild traumatic brain injury, it is of interest to study neurode-generative conditions resulting from inflammatory changes in the nervous tissue. Purpose of the study: in the acute period in case of mild experimental traumatic brain injury, to reveal structural transformations of the nervous tissue of the brain. A modified model of a falling weight was used to reproduce of these trauma in adult rats. An immunohistochemical study of the brain with using rat-specific monoclonal antibodies to endothelin-1, glial fibrillar acidic protein, vimentin, and blood-brain barrier endothelial protein (SMI 71) was performed. It has been established that on the first day after injury in the cerebral cortex of animals, the spasm of blood vessels with capillary ischemia predominates. On day 8, there is an increase in the number of hyper- and hypochromic neurons, and after 14 days, restoration of the tone of the microcircu-latory bed is detected with signs of a violation of the permeability of the blood-brain barrier. A significant redistribution in the tissues of the cerebral hemispheres of glial elements containing acid glial protein and vimentin, as well as neurons producing endothelin-1, was noted. In the delayed post-traumatic period, compensatory reactions of the nervous tissue were revealed, which are characterized by the presence of morphological changes in neurons (an increase in the diameter and number of nucleoli in size) associated with intracellular regeneration, as well as the synthesis of various protein factors in them. Thus, the pathogenesis of mild experimental craniocerebral injury in the ischemic (1 day) and intermediate (8 days) periods is characterized by the presence of mild violations of the structural integrity of the nervous tissue of the brain. In the late post-traumatic period (14 days), neurons and astrocytes exhibit compensatory reactions.

Detecting mTBI by Learning Spatio-temporal Characteristics of Widefield Calcium Imaging Data Using Deep Learning.

Early diagnosis of mild traumatic brain injury (mTBI) is of great interest to the neuroscience and medical communities. Widefield optical imaging of neuronal populations over the cerebral cortex in animals provides a unique opportunity to study injury-induced alternations in brain function. Using this technique, along with deep learning, the goal of this paper is to develop a framework for the detection of mTBI. Cortical activities in transgenic calcium reporter mice expressing GCaMP6s are obtained using widefield imaging from 8 mice before and after inducing an injury. Two deep learning models for differentiating mTBI from normal conditions are proposed. One model is based on the convolutional neural network-long short term memory (CNN-LSTM), and the second model is based on a 3D-convolutional neural network (3D-CNN). These two models offer the ability to capture features both in the spatial and temporal domains. Results for the average classification accuracy for the CNN-LSTM and the 3D-CNN are 97.24% and 91.34%, respectively. These results are notably higher than the case of using the classical machine learning methods, demonstrating the importance of utilizing both the spatial and temporal information for early detection of mTBI.

EFFECTS OF WILDFIRE EMISSION ON THE MORPHOFUNCTIONAL STATE OF THE CENTRAL NERVOUS SYSTEM IN WHITE RATS

Introduction. The study of the mechanisms of action of combustion products released during natural fires on the body and the development of appropriate preventive measures is an actual hygienic problem at the present stage. Material and methods. Experimental modeling of landscape fire was carried out for 7 days, 4 hours per day. Forest fuel, which is a living ground cover and plant residues, was used as a combustible substrate. The concentration of carbon monoxide, formaldehyde, furfural, and acetaldehyde was determined in the exposure chamber, the general qualitative composition of air and the target qualitative analysis for volatile aldehydes and ketones were carried out. After exposure rat behavior was observed through an open field test and Morris water maze, histological studies of brain tissue were done. Results. During the experiment changes in the structure of the behavior of white rats exposed to smoke were established to be characterized by a decrease in motor and exploratory activity, and an increase in the level of anxiety in females was also observed. When testing in the water maze of Morris revealed violations of spatial memory and the ability to navigational learning. Histological examination of the cerebral cortex in animals of the experimental groups revealed multiple foci of neuronophagy, expansion of perivascular spaces, and the development of glial cell replacement hyperplasia was noted. Conclusion. The results indicate the presence of a neurotoxic effect of combustion products, characterized by a decrease in the motor activity of animals, increased anxiety and impaired memory processes, as well as morphological changes in the brain tissue of white rats. However, in order to reveal the role of the impact of a complex of substances released during forest fires, their contribution to morphological and functional disorders, furthermore in-depth studies are required.

Hyperglycemia decreases expression of 14-3-3 proteins in an animal model of stroke

Diabetes is a severe metabolic disorder and a major risk factor for stroke. Stroke severity is worse in patients with diabetes compared to the non-diabetic population. The 14-3-3 proteins are a family of conserved acidic proteins that are ubiquitously expressed in cells and tissues. These proteins are involved in many cellular processes including metabolic pathways, signal transduction, protein trafficking, protein synthesis, and cell cycle control. This study investigated 14-3-3 proteins expression in the cerebral cortex of animals with diabetes, cerebral ischemic injury and a combination of both diabetes and cerebral ischemic injury. Diabetes was induced by intraperitoneal injection of streptozotocin (40mg/kg) in adult male rats. After 4 weeks of treatment, middle cerebral artery occlusion (MCAO) was performed for the induction of focal cerebral ischemia and cerebral cortex tissue was collected 24h after MCAO. We confirmed that diabetes increases infarct volume following MCAO compared to non-diabetic animals. In diabetic animals with MCAO injury, reduction of 14-3-3 β/α, 14-3-3 ζ/δ, 14-3-3 γ, and 14-3-3 ε isoforms was detected. The expression of these proteins was significantly decreased in diabetic animals with MCAO injury compared to diabetic-only and MCAO-only animals. Moreover, Western blot analysis ascertained the decreased expression of 14-3-3 family proteins in diabetic animals with MCAO injury, including β/α, ζ/δ, γ, ε, τ, and η isoforms. These results show the changes of 14-3-3 proteins expression in streptozotocin-induced diabetic animals with MCAO injury. Thus, these findings suggest that decreases in 14-3-3 proteins might be involved in the regulation of 14-3-3 proteins under the presence of diabetes following MCAO.

Effects of beta-hydroxybutyrate on brain vascular permeability in rats with traumatic brain injury

This study investigates the effect of beta-hydroxybutyrate (BHB) on blood–brain barrier (BBB) integrity during traumatic brain injury (TBI) in rats. Evans blue (EB) and horseradish peroxidase (HRP) were used as determinants of BBB permeability. Glutathione (GSH) and malondialdehyde (MDA) levels were estimated in the right (injury side) cerebral cortex of animals. The gene expression levels for occludin, glucose transporter (Glut)-1, aquaporin4 (AQP4) and nuclear factor-kappaB (NF-κB) were performed, and Glut-1 and NF-κB activities were analyzed. BHB treatment decreased GSH and MDA levels in intact animals and in those exposed to TBI (P<0.05). Glut-1 protein levels decreased in sham, BHB and TBI plus BHB groups (P<0.05). NF-κB protein levels increased in animals treated with BHB and/or exposed to TBI (P<0.05). The expression levels of occludin and AQP4 did not significantly change among experimental groups. Glut-1 expression levels increased in BHB treated and untreated animals exposed to TBI (P<0.05). While NF-κB expression levels increased in animals in TBI (P<0.01), a decrease was noticed in these animals upon BHB treatment (P<0.01). In animals exposed to TBI, EB extravasation was observed in the ipsilateral cortex regardless of BHB treatment. Ultrastructurally, BHB attenuated but did not prevent the presence of HRP in brain capillary endothelial cells of animals with TBI; moreover, the drug also led to the observation of the tracer when used in intact rats (P<0.01). Altogether, these results showed that BHB not only failed to provide overall protective effects on BBB in TBI but also led to BBB disruption in healthy animals.

Electroencephalographic recordings of physiological activity of the sheep cerebral cortex.

This paper presents the physiological activity of the cerebral cortex in sheep in electroencephalo- graphic findings. The study was performed to evaluate and improve understanding of brain monitor- ing methods in freely moving animals without the use of any anaesthetic methods during the acquisi- tion stage. The aim of the study was to determine the physiological activity of the cerebral cortex in animals in a sheep model (using clinically healthy Polish Merino rams, aged 1 yr.) to determine its clinical EEG protocol. The EEG was registered using an in-lab EEG device as well as ambulatory systems (Holter EEG). The bioelectrical activity of the sheep cerebral cortex was recorded using gold disc and needle electrodes placed on experimentally determined locations on the scalp. The main finding of this study was the rhythmic EEG activity of the sheep brain in wakeful and conscious states (eyes open). The rhythm was bilaterally synchronous and determined a basic pattern in the registra- tion of physiological activity of the cerebral cortex. The acquired rhythm may correspond to the theta rhythm in humans, which is a normal activity controlled by the hippocampus. This background activity comprised intermittent episodic slow waves and synchronous beta waves.

Early History of Electroencephalography and Establishment of the American Clinical Neurophysiology Society

The field of electroencephalography (EEG) had its origin with the discovery of recordable electrical potentials from activated nerves and muscles of animals and in the last quarter of the 19th century from the cerebral cortex of animals. By the 1920s, Hans Berger, a neuropsychiatrist from Germany, recorded potentials from the scalp of patients with skull defects and, a few years later, with more sensitive equipment from intact subjects. Concurrently, the introduction of electronic vacuum tube amplification and the cathode ray oscilloscope was made by American physiologists or "axonologists," interested in peripheral nerve recordings. Berger's findings were independently confirmed in early 1934 by Lord Adrian in England and by Hallowell Davis at Harvard, in the United States. In the United States, the earliest contributions to human EEG were made by Hallowell Davis, Herbert H. Jasper, Frederic A. Gibbs, William Lennox, and Alfred L. Loomis. Remarkable progress in the development of EEG as a useful clinical tool followed the 1935 report by the Harvard group on the electrographic and clinical correlations in patients with absence (petit mal) seizures and altered states of consciousness. Technical aspects of the EEG and additional clinical EEG correlations were elucidated by the above investigators and a number of others. Further study led to gatherings of the EEG pioneers at Loomis' laboratory in New York (1935-1939), Regional EEG society formation, and the American Clinical Neurophysiology Society in 1946.

Structural Changes in Dendritic Loci and Protective Effect of Neurotrophic Factors from the Cerebral Cortex of Animals with Favorable Outcome of Experimental Hemorrhagic Stroke

Structural changes in the sensorimotor cortex of the cerebral hemispheres were studied in rats with experimental hemorrhagic stroke in the internal capsule. Changes in the shape and decrease in the density distribution of spines on apical dendrites of layer V pyramidal neurons of the sensorimotor cortex were revealed. Some fractions isolated from the complex of neurotrophic factors of the cerebral cortex of animals with a favorable outcome of hemorrhagic stroke were shown to affect the distal and proximal dendritic loci. As differentiated from the "nonactive" fraction, the "active" fraction improved the behavior of rats surviving hemorrhagic stroke. The density distribution of spines (particularly in the distal region of apical dendrites of pyramidal neurons in layer V of the cerebral cortex) was stabilized after treatment with the "active" fraction. The "nonactive" fraction had a selective effect on the proximal loci.

Impact on electroencephalography of Adolf Beck, a prominent Polish scientist and founder of the Lviv School of Physiology

Adolf Beck (1863–1942) can be regarded as the co-founder of electroencephalography. His studies on the cerebral cortex of animals have facilitated the introduction of the electroencephalogram (EEG) as a main tool for studying the brain. The localization of senses on the cortex with evoked potentials and the description of the desynchronization of the electrical brain activity upon stimulation, are hallmarks of the research of Beck. He performed his groundbreaking studies under supervision of the famous Napoleon Cybulski at the Jagiellonian University in Cracow (Poland) between 1888 and 1895. In that last year Beck was appointed professor at the University of Lemberg (Lviv), where he founded the Department of Physiology and recruited scientists to the Lviv School of Physiology. Beck was the leading authority of the University of Lemberg in the most turbulent period of the town's history. Together with Cybulski he wrote the influential textbook ‘Human physiology’ in 1915.

How attention and reinforcers jointly optimize the associations between sensory representations, working memory and motor programs

Almost all animal behaviors can be seen as sequences of actions towards achieving certain goals. How the association cortices learn to link sensory stimuli to a correct sequence of motor responses is not well understood, especially when only a correct sequence of responses is rewarding. We present a biologically plausible neuronal network model that can be trained to perform a large variety of tasks when only stimuli and reward contingencies are varied. The model’s aim is to learn action values in a feedforward neuronal network and we present mechanisms to overcome the structural and temporal credit assignment problems. The temporal credit assignment problem is solved by a form of Q-learning [1]. The structural credit assignment problem is solved by a form of ‘attentional’ feedback from motor cortex to association cortex that delineates the units that should change connectivity to improve behavior [2]. Moreover, the model has a new mechanism to store traces of relevant sensory stimuli in working memory. During learning, the sensory stimuli, in combination with traces of previous stimuli in working memory become associated with a unique set of action values. Learning in the model is biologically realistic as model units have Hebbian plasticity that is gated by two factors [2]. Firstly, reinforcers or increases in reward expectancy cause the global release of neuromodulatory signals that inform all synapses of the network if the outcome of a trial was better or worse than expected [3]. Selective attention is the second factor that gates plasticity. Attentional feedback highlights the chain of neurons between sensory and motor cortex responsible for the selected action. Only neurons that are causally linked to the action receive attentional feedback, and change the strength of their connections. Selective attention thereby solves the structural credit assignment problem. The resulting learning rule is a form of AGREL [2], which was previously shown to be on average equivalent to error-backpropagation in classification tasks with immediate reward. The present generalization of the learning scheme is based on temporal difference learning and it can train multilayer feedforward networks to perform delayed reward tasks with multiple epochs that require multiple behavioral responses. Importantly, the generalization MQ-AGREL learns to store in working memory information that is relevant at a later stage during a task. This memory is maintained by persistent activity of units at the intermediate network layers. We show that MQ-AGREL can be trained in many tasks that are in use in neurophysiology, including (1) (delayed) saccade-antisaccade tasks; (2) categorization tasks; and (3) probabilistic classification tasks. Neurons at intermediate levels of the network acquire visual responses and memory responses as the result of training that resemble the tuning of neurons in association areas of the cerebral cortex of animals that are trained in these same tasks. We conclude that MQ-AGREL is a powerful and biologically realistic learning rule that accounts for learning in delayed reward tasks that involve non-linear mappings from sensory stimuli and working memory onto motor responses.

Cerebral cortex demyelination and oligodendrocyte precursor response to experimental autoimmune encephalomyelitis

Experimentally induced autoimmune encephalomyelitis (EAE) in mice provides an animal model that shares many features with human demyelinating diseases such as multiple sclerosis (MS). To what extent the cerebral cortex is affected by the process of demyelination and how the corollary response of the oligodendrocyte lineage is explicated are still not completely known aspects of EAE. By performing a detailed in situ analysis of expression of myelin and oligodendrocyte markers we have identified areas of subpial demyelination in the cerebral cortex of animals with conventionally induced EAE conditions. On EAE-affected cerebral cortices, the distribution and relative abundance of cells of the oligodendrocyte lineage were assessed and compared with control mouse brains. The analysis demonstrated that A2B5+ glial restricted progenitors (GRPs) and NG2+/PDGFR-α+ oligodendrocyte precursor cells (OPCs) were increased in number during “early” disease, 20days post MOG immunization, whereas in the “late” disease, 39days post-immunization, they were strongly diminished, and there was an accompanying reduction in NG2+/O4+ pre-oligodendrocytes and GST-π mature oligodendrocytes. These results, together with the observed steady-state amount of NG2−/O4+ pre-myelinating oligodendrocytes, suggested that oligodendroglial precursors attempted to compensate for the progressive loss of myelin, although these cells appeared to fail to complete the last step of their differentiation program. Our findings confirm that this chronic model of EAE reproduces the features of neocortex pathology in progressive MS and suggest that, despite the proliferative response of the oligodendroglial precursors, the failure to accomplish final differentiation may be a key contributing factor to the impaired remyelination that characterizes these demyelinating conditions.

Effects of an inhibitor of α-secretase, which metabolizes the amyloid peptide precursor, on memory formation in rats

Intracortical administration of 10(-4) M batimastat, a specific inhibitor of alpha-secretase (a metalloproteinase which cleaves the amyloid peptide precursor), decreased the number of correct runs in a single-level eight-arm maze to 92.78 +/- 1.03% compared with baseline (p < 0.01) within 60 min. However, injection of batimastat into the cerebral cortex of animals during the early postnatal period (days 5 and 7 of life) led to impaired orientation in the simple single-level maze when these adults reached adulthood (90.92 +/- 2.21% correct runs, p < 0.001) as compared with controls. The data obtained here provide evidence for the important role of alpha-secretase in memory processes. The possible role of alpha-secretase in memory processes and the pathogenesis of Alzheimer's disease is discussed.

Activation of caspase-12, an endoplasmic reticulum resident caspase, after permanent focal ischemia in rat.

The endoplasmic reticulum (ER) is emerging as a contributory component of cell death after ischemia. Since caspase-12 has been localized to the ER and is a novel signal for apoptosis, we examined the message levels and protein expression of caspase-12 after cerebral ischemia in vivo. Animals underwent permanent middle cerebral artery occlusion (MCAO) and were sacrificed 24 h after ischemia. Protein analysis revealed a significant increase in caspase-12 and a corresponding up-regulation of caspase-12 mRNA in the ischemia group compared with that in the sham group. Immunohistochemical analysis revealed diffuse positive immunostaining of caspase-12 throughout the striatum and cerebral cortex in animals that underwent ischemia, with more intense caspase-12 immunostaining in the striatum than in the cortex after ischemia. These results demonstrate that cerebral ischemia initiates an ER-based stress response that results in the transcriptional up-regulation and corresponding increased expression of caspase-12 protein, and may provide a new area for therapeutic intervention to ameliorate outcomes following stroke.

Long-term treatment with some methylxanthines decreases the susceptibility to bicuculline- and pentylenetetrazol-induced seizures in mice. Relationship to c-fos expression and receptor binding.

The effects of long-term oral administration of low doses of caffeine (0.3 g/l) and its metabolites theophylline, theobromine and paraxanthine (each at 0.5 g/l in drinking water) on bicuculline- and pentylenetetrazol (PTZ)-induced seizures and c-fos expression were studied in mice. In addition, adenosine and benzodiazepine receptor density was examined. The plasma levels of the methylxanthines were much higher during the active period at night than during the day. The maximal level of caffeine was 14 microM. Brain theophylline levels (8-13 nmol/g) tended to be higher and more constant than brain caffeine levels in caffeine-consuming mice. Clonic seizures induced by bicuculline (4 mg/kg i.p.) were significantly reduced in severity by 14 day caffeine treatment and mortality was also reduced. Long-term treatment with caffeine metabolites was less effective. The seizures induced by PTZ (60 mg/kg i.p.) were also significantly reduced by long-term caffeine treatment. After bicuculline or PTZ treatment, c-fos mRNA expression was weaker in the cerebral cortex in animals receiving caffeine, irrespective of whether the animals had seizures or not. No significant changes in the binding of adenosine receptor ligands or benzodiazepines were seen after long-term caffeine treatment. These results show that long-term treatment with caffeine in a dose that is commonly seen in humans decreases the seizures induced by bicuculline, and to a lesser extent, those induced by PTZ. This may be related to a decreased neuronal excitability. The effect is due to the combined effects of theophylline, to which caffeine is metabolized in brain, and caffeine itself, but could not be ascribed to changes in A1 and A2A adenosine or benzodiazepine receptors.

Amygdala kindling potentiates seizure-stimulated immediate-early gene expression in rat cerebral cortex.

Kindling induces long-term adaptations in neuronal function that lead to a decreased threshold for induction of seizures. In the present study, the influence of amygdala kindling on levels of mRNA for the immediate-early genes (IEGs) c-fos, c-jun, and NGF1-A were examined both before and after an acute electroconvulsive seizure (ECS). Although amygdala kindling did not significantly influence resting levels of c-fos mRNA in cerebral cortex, ECS-stimulated levels of c-fos mRNA (examined 45 min after ECS) were approximately twofold greater in the cerebral cortex of kindled rats relative to sham-treated controls. The influence of kindling on IEG expression was dependent on the time course of kindling, as ECS-stimulated levels of c-fos mRNA were not significantly increased in stage 2 kindled animals. ECS-stimulated levels of c-jun and NGF1-A mRNA were also significantly increased in cerebral cortex of kindled rats relative to sham-treated controls. The influence of kindling on IEG expression was long-lasting because an acute ECS stimulus significantly elevated levels of c-fos and c-jun mRNA in the cerebral cortex of animals that were kindled 5 months previously. In contrast to these effects in cerebral cortex, kindling did not influence ECS-stimulated levels of c-fos mRNA in hippocampus. Finally, immunohistochemical studies revealed lamina-specific changes in the cerebral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)