Chronic Electroconvulsive Seizure Research Articles

Influence of Chronic Electroconvulsive Seizures on Plasticity-Associated Gene Expression and Perineuronal Nets Within the Hippocampi of Young Adult and Middle-Aged Sprague-Dawley Rats.

Electroconvulsive seizure therapy is often used in both treatment-resistant and geriatric depression. However, preclinical studies identifying targets of chronic electroconvulsive seizure (ECS) are predominantly focused on animal models in young adulthood. Given that putative transcriptional, neurogenic, and neuroplastic mechanisms implicated in the behavioral effects of chronic ECS themselves exhibit age-dependent modulation, it remains unknown whether the molecular and cellular targets of chronic ECS vary with age. We subjected young adult (2-3 months) and middle-aged (12-13 months), male Sprague Dawley rats to sham or chronic ECS and assessed for despair-like behavior, hippocampal gene expression, hippocampal neurogenesis, and neuroplastic changes in the extracellular matrix, reelin, and perineuronal net numbers. Chronic ECS reduced despair-like behavior at both ages, accompanied by overlapping and unique changes in activity-dependent and trophic factor gene expression. Although chronic ECS had a similar impact on quiescent neural progenitor numbers at both ages, the eventual increase in hippocampal progenitor proliferation was substantially higher in young adulthood. We noted a decline in reelin⁺ cell numbers following chronic ECS only in young adulthood. In contrast, an age-invariant, robust dissolution of perineuronal net numbers that encapsulate parvalbumin⁺ neurons in the hippocampus were observed following chronic ECS. Our findings indicate that age is a key variable in determining the nature of chronic ECS-evoked molecular and cellular changes in the hippocampus. This raises the intriguing possibility that chronic ECS may recruit distinct, as well as overlapping, mechanisms to drive antidepressant-like behavioral changes in an age-dependent manner.

Electroconvulsive Seizures in Rats and Fractionation of Their Hippocampi to Examine Seizure-induced Changes in Postsynaptic Density Proteins

Electroconvulsive seizure (ECS) is an experimental animal model of electroconvulsive therapy, the most effective treatment for severe depression. ECS induces generalized tonic-clonic seizures with low mortality and neuronal death and is a widely-used model to screen anti-epileptic drugs. Here, we describe an ECS induction method in which a brief 55-mA current is delivered for 0.5 s to male rats 200 - 250 g in weight via ear-clip electrodes. Such bilateral stimulation produced stage 4 - 5 clonic seizures that lasted about 10 s. After the cessation of acute or chronic ECS, most rats recovered to be behaviorally indistinguishable from sham "no seizure" rats. Because ECS globally elevates brain activity, it has also been used to examine activity-dependent alterations of synaptic proteins and their effects on synaptic strength using multiple methods. In particular, subcellular fractionation of the postsynaptic density (PSD) in combination with Western blotting allows for the quantitative determination of the abundance of synaptic proteins at this specialized synaptic structure. In contrast to a previous fractionation method that requires large amount of rodent brains, we describe here a small-scale fractionation method to isolate the PSD from the hippocampi of a single rat, without sucrose gradient centrifugation. Using this method, we show that the isolated PSD fraction contains postsynaptic membrane proteins, including PSD95, GluN2B, and GluA2. Presynaptic marker synaptophysin and soluble cytoplasmic protein α-tubulin were excluded from the PSD fraction, demonstrating successful PSD isolation. Furthermore, chronic ECS decreased GluN2B expression in the PSD, indicating that our small-scale PSD fractionation method can be applied to detect the changes in hippocampal PSD proteins from a single rat after genetic, pharmacological, or mechanical treatments.

Electroconvulsive Seizures in Rats and Fractionation of Their Hippocampi to Examine Seizure-induced Changes in Postsynaptic Density Proteins.

Electroconvulsive seizure (ECS) is an experimental animal model of electroconvulsive therapy, the most effective treatment for severe depression. ECS induces generalized tonic-clonic seizures with low mortality and neuronal death and is a widely-used model to screen anti-epileptic drugs. Here, we describe an ECS induction method in which a brief 55-mA current is delivered for 0.5 s to male rats 200 - 250 g in weight via ear-clip electrodes. Such bilateral stimulation produced stage 4 - 5 clonic seizures that lasted about 10 s. After the cessation of acute or chronic ECS, most rats recovered to be behaviorally indistinguishable from sham "no seizure" rats. Because ECS globally elevates brain activity, it has also been used to examine activity-dependent alterations of synaptic proteins and their effects on synaptic strength using multiple methods. In particular, subcellular fractionation of the postsynaptic density (PSD) in combination with Western blotting allows for the quantitative determination of the abundance of synaptic proteins at this specialized synaptic structure. In contrast to a previous fractionation method that requires large amount of rodent brains, we describe here a small-scale fractionation method to isolate the PSD from the hippocampi of a single rat, without sucrose gradient centrifugation. Using this method, we show that the isolated PSD fraction contains postsynaptic membrane proteins, including PSD95, GluN2B, and GluA2. Presynaptic marker synaptophysin and soluble cytoplasmic protein α-tubulin were excluded from the PSD fraction, demonstrating successful PSD isolation. Furthermore, chronic ECS decreased GluN2B expression in the PSD, indicating that our small-scale PSD fractionation method can be applied to detect the changes in hippocampal PSD proteins from a single rat after genetic, pharmacological, or mechanical treatments.

Acute and Chronic Electroconvulsive Seizures (ECS) Differentially Regulate the Expression of Epigenetic Machinery in the Adult Rat Hippocampus.

Background:Electroconvulsive seizure treatment is a fast-acting antidepressant therapy that evokes rapid transcriptional, neurogenic, and behavioral changes. Epigenetic mechanisms contribute to altered gene regulation, which underlies the neurogenic and behavioral effects of electroconvulsive seizure. We hypothesized that electroconvulsive seizure may modulate the expression of epigenetic machinery, thus establishing potential alterations in the epigenetic landscape.Methods:We examined the influence of acute and chronic electroconvulsive seizure on the gene expression of histone modifiers, namely histone acetyltransferases, histone deacetylases, histone methyltransferases, and histone (lysine) demethylases as well as DNA modifying enzymes, including DNA methyltransferases, DNA demethylases, and methyl-CpG-binding proteins in the hippocampi of adult male Wistar rats using quantitative real time-PCR analysis. Further, we examined the influence of acute and chronic electroconvulsive seizure on global and residue-specific histone acetylation and methylation levels within the hippocampus, a brain region implicated in the cellular and behavioral effects of electroconvulsive seizure.Results:Acute and chronic electroconvulsive seizure induced a primarily unique, and in certain cases bidirectional, regulation of histone and DNA modifiers, and methyl-CpG-binding proteins, with an overlapping pattern of gene regulation restricted to Sirt4, Mll3, Jmjd3, Gadd45b, Tet2, and Tet3. Global histone acetylation and methylation levels were predominantly unchanged, with the exception of a significant decline in H3K9 acetylation in the hippocampus following chronic electroconvulsive seizure.Conclusions:Electroconvulsive seizure treatment evokes the transcriptional regulation of several histone and DNA modifiers, and methyl-CpG-binding proteins within the hippocampus, with a predominantly distinct pattern of regulation induced by acute and chronic electroconvulsive seizure.

Secreted Frizzled-Related Protein 3 Regulates Activity-Dependent Adult Hippocampal Neurogenesis

Adult neurogenesis, the process of generating mature neurons from adult neural stem cells, proceeds concurrently with ongoing neuronal circuit activity and is modulated by various physiological and pathological stimuli. The niche mechanism underlying the activity-dependent regulation of the sequential steps of adult neurogenesis remains largely unknown. Here, we report that neuronal activity decreases the expression of secreted frizzled-related protein 3 (sFRP3), a naturally secreted Wnt inhibitor highly expressed by adult dentate gyrus granule neurons. Sfrp3 deletion activates quiescent radial neural stem cells and promotes newborn neuron maturation, dendritic growth, and dendritic spine formation in the adult mouse hippocampus. Furthermore, sfrp3 reduction is essential for activity-induced adult neural progenitor proliferation and the acceleration of new neuron development. Our study identifies sFRP3 as an inhibitory niche factor from local mature dentate granule neurons that regulates multiple phases of adult hippocampal neurogenesis and suggests an interesting activity-dependent mechanism governing adult neurogenesis via the acute release of tonic inhibition.

P.2.b.010 Effects of chronic mild stress and electroconvulsive seizure on memory functions in rats

P.2.b.010 Effects of chronic mild stress and electroconvulsive seizure on memory functions in rats

Analysis of Target Genes Regulated by Chronic Electroconvulsive Therapy Reveals Role for Fzd6 in Depression

Chronic electroconvulsive seizure (chr-ECS), one of the most efficacious treatments for depressed patients, increases the levels of transcription factor cyclic adenosine monophosphate response element binding protein (CREB) in rodent models and mediates the effects of chronic antidepressant treatment. The objective of this study was to determine the changes in CREB occupancy at gene promoters and subsequent gene expression changes induced by chr-ECS. We use chromatin immunoprecipitation followed by microarray analysis to identify CREB binding promoters that are influenced by chr-ECS (n = 6/group). Selected genes are confirmed by secondary validation techniques, and the functional significance of one target was tested in behavioral models (n = 8/group) by viral mediated inhibition of gene expression. The results demonstrate that chr-ECS enhances CREB binding and activity at a select population of genes in the hippocampus, effects that could contribute to the efficacy of chr-ECS. Viral vector-mediated inhibition of one of the CREB-target genes regulated by chr-ECS, Fzd6, produced anxiety and depressive-like effects in behavioral models of depression. The results identify multiple gene targets differentially regulated by CREB binding in the hippocampus after chr-ECS and demonstrate the role of Fzd6, a Wnt receptor in behavioral models of depression.

Characterization of electroconvulsive seizure-induced TIMP-1 and MMP-9 in hippocampal vasculature

Degradation of the vascular basement membrane stimulates angiogenesis and is tightly controlled by balancing the actions of metalloproteases and their inhibitors. Previous work demonstrated that electroconvulsive seizure (ECS) elevates angiogenic factors and endothelial proliferation in the hippocampus. The robust induction of tissue inhibitor of matrix metalloprotease 1 (TIMP-1) in the stratum lacunosum moleculare (SLM) corresponds to sites of increased vascular density. This led us to examine the spatial and cellular expression of TIMP-1 and its substrate, matrix metalloprotease 9 (MMP-9). Chronic ECS increased TIMP-1 by 12-fold and MMP-9 by 3-fold in discrete SLM cells. We then characterized the expression of TIMP-1 mRNA in relation to vasculature in the SLM and glial-limiting membrane (GLM). Employing laser microdissection we identified the cell types associated with SLM vasculature and also phenotyped the cells expressing TIMP-1 and MMP-9. We concluded that TIMP-1 is produced by perivascular cells positive for alpha smooth actin and that MMP-9 is expressed by GFAP-positive astrocytes. These studies suggest that ECS-induced remodelling occurs at the vascular basement membrane and facilitates neovascularization.

Macrophage migration inhibitory factor mediates the antidepressant actions of voluntary exercise

Voluntary exercise is known to have effects on various brain functions, including an antidepressant action. However, underlying mechanism of exercise effects on psychological disease is still ambiguous. We identified the candidate target genes for alleviating depression by the analysis of existing microarray data sets of mouse hippocampus mRNA from voluntary exercise and ECS (Electroconvulsive seizure) stimulated experiments. To validate the precise changes of those candidate genes, we conducted 28 day voluntary exercise and 10 day chronic ECS treatment with rats. Reverse transcription‐PCR and real‐time PCR analysis showed 5 genes; BDNF, COX‐2, SLC1A1, NPY and MIF were commonly induced by both ECS and voluntary exercise experiments. Furthermore, immunohistochemistry analysis firmly remarked that the amount of MIF, a proinflammatory cytokine, was also increased by voluntary exercise. We showed that recombinant MIF administration produced antidepressant‐like behavior in animal FST (Forced swim test). Moreover, MIF treatment for 1 hour increased the expression of TPH2, a rate‐limiting enzyme in synthesis of serotonin, and 12 hour treatment increased the amount of BDNF in Neuro‐2a neuroblastoma cell line. These results suggest the new role of MIF in relieving the symptom of depression by exercise, probably via enhancing neurotransmitter and neurotrophic factor in the brain.

Differential expression and regulation of the cAMP‐selective phosphodiesterase type 4A splice variants in rat brain by chronic antidepressant administration

Chronic antidepressant treatment up-regulates the cAMP cascade in limbic brain regions, suggesting that activation of this pathway contributes to the therapeutic efficacy of antidepressants. A role for cAMP signaling is supported by the finding that rolipram, a selective inhibitor of cAMP-specific phosphodiesterases type 4 (PDE4), has antidepressant efficacy in behavioral models of depression and in clinical trials. To elucidate further the role of PDE4 isozymes, we characterized the expression and regulation of PDE4A splice variants (i.e. PDE4A1, PDE4A5, PDE4A8 and PDE4A10) in rat brain by chronic antidepressant treatment. Initial in situ hybridization studies (ISH) revealed high levels of PDE4A1 mRNA in medial septum, diagonal band, olfactory system, hippocampus and cerebellum. PDE4A5 mRNA expression was restricted to the olfactory nuclei, deep cortical layers, dentate and CA1 pyramidal layers. PDE4A10 mRNA was localized in the dentate gyrus and CA1 pyramidal layers. PDE4A8 mRNA was absent in rat brain. We determined the influence of chronic fluoxetine or electroconvulsive seizure (ECS) treatments on PDE4A splice variants expression in various brain regions. ISH analysis indicated that chronic fluoxetine or ECS treatments significantly increased PDE4A1, but not PDE4A5 or PDE4A10, mRNA levels in frontal and parietal cortices. ECS increased PDE4A5 levels in the anterior cingulate and frontoparietal cortices, CA1 and dentate gyrus, whereas chronic fluoxetine or ECS treatment increased PDE4A10 levels in the hippocampus. The differential up-regulation of PDE4A splice variants suggests compensatory region-specific responses to the antidepressant-induced increase in cAMP signaling and suggests that these splice variants may be relevant as targets for antidepressant intervention.

Electroconvulsive Seizures Increase the Expression of MAP Kinase Phosphatases in Limbic Regions of Rat Brain

The mitogen-activated protein (MAP) kinase cascades regulate a variety of cellular activities, including cell growth, proliferation, and apoptosis, and are reported to play a role in the actions of antidepressant treatment. There are a number of different classes of protein phosphatases that could influence the MAP kinase cascade. One of these, the MAP kinase phosphatase (MKP) family, is known to play a key role in dephosphorylation of activated MAP kinase. In the present study, we analyzed the expression of the MKP1, MKP2, and MKP3 isoforms in rat brain after electroconvulsive seizure (ECS), considered the most effective treatment for depression. In situ hybridization analysis demonstrates that ECS differentially regulates the expression of the MKP isoforms. Expression of MKP1 mRNA is robustly increased by acute ECS in the major cell layers of the hippocampus, including the dentate gyrus granule cell layer and the CA1 and CA3 pyramidal cell layers. In contrast, MKP2 is induced mainly in the dentate gyrus and MKP3 is preferentially increased in the CA1 and CA3 cell layers. In the prefrontal cortex, all three MKP isoforms are upregulated by acute ECS administration. Chronic ECS resulted in a similar pattern of induction for each of the MKP subtypes, demonstrating that there is little or no desensitization of the response to repeated ECS. The induction of MKP expression serves as negative feedback control for the MAP kinase cascades. Upregulation of MKP expression could dampen the actions of ECS, indicating that blockade of the MKPs could enhance the actions of antidepressant treatment.

Regulation of growth factor receptor bound 2 by electroconvulsive seizure

Electroconvulsive seizure (ECS) is a well-established non-chemical antidepressant that is effective in the treatment of severe depression and also in subjects resistant to chemical antidepressant treatment. Although the molecular mechanism governing the antidepressant efficacy of ECS is unknown, recent work suggests that an amplification of growth/neurotrophic signaling might play a role in mediating the therapeutic effects. In this context, we examined the regulation of growth factor receptor bound 2 (Grb2), an important adaptor molecule in several growth factor signaling cascades. In situ hybridization analysis revealed a more than 2-fold induction of Grb2 mRNA in the hippocampal dentate gyrus as well as superficial and deep layers of the cortex with both acute and chronic ECS. Grb2 also exhibited a time-dependent induction 4 and 8 h after acute ECS, returning to basal levels at 24 h. These results provide further evidence of increased growth factor signaling in response to ECS.

Differential regulation of Brain Derived Neurotrophic Factor transcripts by antidepressant treatments in the adult rat brain

Antidepressants are known to increase brain derived neurotrophic factor (BDNF) mRNA in the adult rat brain. The BDNF gene has four differentially regulated promoters that generate four transcript forms, each containing a unique non-coding 5′ exon (exon I–IV) and a common 3′ coding exon. Using in situ hybridization with exon-specific riboprobes, we have examined whether diverse classes of antidepressants recruit a single or multiple BDNF promoters to regulate BDNF mRNAs. The antidepressants tested were electroconvulsive seizure (ECS) and the pharmacological antidepressants tranylcypromine, desipramine and fluoxetine. The effects of both acute and chronic ECS were the most prominent on exon I and II containing BDNF mRNAs in hippocampal and cortical subfields. Chronic ECS enhanced the acute induction of exon I, II and IV mRNAs but did not influence the acute upregulation of exon III mRNAs. Acute pharmacological antidepressants resulted in region-specific decreases in distinct exon-specific BDNF transcripts. In contrast, chronic administration with tranylcypromine and desipramine enhanced exon II and exon III mRNAs, respectively, in discrete hippocampal and cortical subfields. Chronic fluoxetine treatment did not have a significant effect on the exon-specific BDNF transcripts. The results indicate that distinct antidepressants differentially regulate BDNF mRNAs through a region-specific recruitment of the four BDNF promoters and suggest that diverse signaling mechanisms may be recruited to regulate BDNF transcripts.

Regulation of GFRalpha-1 and GFRalpha-2 mRNAs in rat brain by electroconvulsive seizure.

The influence of both acute and chronic electroconvulsive seizure (ECS) or antidepressant drug treatments on expression of mRNAs encoding glial cell line-derived neurotrophic factor (GDNF) and its receptors, GFRalpha-1, GFRalpha-2, and c-Ret proto-oncogene (RET) in the rat hippocampus was examined by in situ hybridization. Two hours after acute ECS, levels of GFRalpha-1 mRNA in the dentate gyrus were significantly increased. This increase peaked to nearly 3-fold at 6 h after acute ECS and returned to basal levels 24 h after treatment. Chronic (once daily for 10 days) ECS significantly increased the expression of GFRalpha-1 mRNA nearly 5-fold after the last treatment. Levels of GFRalpha-2 mRNA in the dentate gyrus were also significantly increased by acute and chronic ECS, although this effect was less than that observed for GFRalpha-1. Maximum induction of GFRalpha-2 was 30% and 70% compared to sham in response to acute or chronic ECS, respectively. Levels of GDNF and RET mRNAs were not significantly changed following either acute or chronic ECS treatment at the time points examined. Chronic (14 days) administration of different classes of antidepressant drugs, including tranylcypromine, desipramine, or fluoxetine, did not significantly affect the GDNF, GFRalpha-1, GFRalpha-2, or RET mRNA levels in CA1, CA3, and dentate gyrus areas of hippocampus. The results demonstrate that acute ECS increases the expression of GFRalpha-1 and GFRalpha-2 and that these effects are enhanced by chronic ECS. The results also imply that regulation of the binding components of GDNF receptor complex may mediate the adaptive responses of the GDNF system to acute and chronic stimulation.

Regulation of GFR?-1 and GFR?-2 mRNAs in rat brain by electroconvulsive seizure

The influence of both acute and chronic electroconvulsive seizure (ECS) or antidepressant drug treatments on expression of mRNAs encoding glial cell line-derived neurotrophic factor (GDNF) and its receptors, GFRalpha-1, GFRalpha-2, and c-Ret proto-oncogene (RET) in the rat hippocampus was examined by in situ hybridization. Two hours after acute ECS, levels of GFRalpha-1 mRNA in the dentate gyrus were significantly increased. This increase peaked to nearly 3-fold at 6 h after acute ECS and returned to basal levels 24 h after treatment. Chronic (once daily for 10 days) ECS significantly increased the expression of GFRalpha-1 mRNA nearly 5-fold after the last treatment. Levels of GFRalpha-2 mRNA in the dentate gyrus were also significantly increased by acute and chronic ECS, although this effect was less than that observed for GFRalpha-1. Maximum induction of GFRalpha-2 was 30% and 70% compared to sham in response to acute or chronic ECS, respectively. Levels of GDNF and RET mRNAs were not significantly changed following either acute or chronic ECS treatment at the time points examined. Chronic (14 days) administration of different classes of antidepressant drugs, including tranylcypromine, desipramine, or fluoxetine, did not significantly affect the GDNF, GFRalpha-1, GFRalpha-2, or RET mRNA levels in CA1, CA3, and dentate gyrus areas of hippocampus. The results demonstrate that acute ECS increases the expression of GFRalpha-1 and GFRalpha-2 and that these effects are enhanced by chronic ECS. The results also imply that regulation of the binding components of GDNF receptor complex may mediate the adaptive responses of the GDNF system to acute and chronic stimulation.

Transcriptional and translational regulation of phosphodiesterase type IV isozymes in rat brain by electroconvulsive seizure and antidepressant drug treatment.

We examined the influence of electroconvulsive seizure (ECS) and imipramine (IMI) treatment on the transcription and translation of cyclic nucleotide phosphodiesterase type IV (PDE IV) isozymes in the rat brain. Our in situ hybridization studies revealed an increase of PDE IV-B mRNA level in various brain regions after acute ECS. However, the increase of PDE IV activity was produced not by acute but by chronic ECS treatment in the frontal cortex. Increased PDE IV-B mRNA expression in frontal but not in hippocampal subfields was induced also after chronic ECS treatment. Although an increase in PDE IV-A mRNA expression of the dentate gyrus in the hippocampus was observed, no change of PDE IV activity was produced in the hippocampus by acute or chronic ECS treatment. These results suggest that the repeated increases of PDE IV-B mRNA expression are attributable to the increase of PDE IV translation. Increased PDE IV-B transcription and PDE IV translation in the frontal cortex were also produced after chronic IMI treatment. This is the first report demonstrating an expressional regulation of Drosophila melanogaster dunce (dnc) gene homologue PDE IV isozymes in the brain. Although no pathophysiological conditions with reduced PDE IV activity in the nervous system are known except for a learning deficit in the mutant fly dnc-, our results suggest possible treatments to cope with reduced PDE IV activity.

Regulation of BDNF and trkB mRNA in rat brain by chronic electroconvulsive seizure and antidepressant drug treatments

The influence of chronic electroconvulsive seizure (ECS) or antidepressant drug treatments on expression of brain-derived neurotrophic factor (BDNF) and its receptor, trkB, was examined by in situ hybridization and Northern blot. In frontal cortex, acute ECS increased BDNF mRNA approximately twofold, an effect significantly augmented by a prior course of chronic ECS treatment (10 d). In the hippocampus, the influence of chronic ECS varied between the major subfields. In the dentate gyrus granule cell layer, chronic ECS decreased the acute induction of BDNF and trkB mRNA by approximately 50%, but prolonged their expression: levels remained elevated two- to threefold 18 hr later after the last chronic ECS treatment, but returned to control 18 hr after acute ECS. In CA3 and CA1 pyramidal cell layers, chronic ECS significantly elevated the acute induction of BDNF, and tended to prolong the expression of BDNF and trkB mRNA. A similar effect was observed in layer 2 of the piriform cortex, where chronic ECS significantly increased the acute induction and prolonged the expression of BDNF and trkB mRNA. Chronic (21 d), but not acute (1 d), administration of several different antidepressant drugs, including tranylcypromine, sertraline, desipramine, or mianserin, significantly increased BDNF mRNA and all but mianserin increased trkB mRNA in hippocampus. In contrast, chronic administration of nonantidepressant psychotropic drugs, including morphine, cocaine, or haloperidol, did not increase levels of BDNF mRNA. Furthermore, chronic administration of ECS or antidepressant drugs completely blocked the down-regulation of BDNF mRNA in the hippocampus in response to restraint stress. The enhanced induction and prolonged expression of BDNF in response to chronic ECS and antidepressant drug treatments could promote neuronal survival, and protect neurons from the damaging effects of stress.

Chronic electroconvulsive seizure (ECS) treatment results in expression of a long-lasting AP-1 complex in brain with altered composition and characteristics

Gene transcription is likely to play a role in the biochemical adaptations thought to underlie the long-term behavioral changes observed following various chronic treatments. The AP-1 (activator protein-1) complex is a well-studied transcription factor capable of regulating gene transcription. We therefore examined the regulation of the AP-1 complex in rat cerebral cortex and hippocampus following electroconvulsive seizures (ECS), known to induce biochemical alterations in the brain after chronic treatment. We show that 10 d of chronic ECS treatment results in an AP-1 binding complex that persists for at least 7 d in the cortex and hippocampus. In contrast, AP-1 binding returns to control levels within 18 hr of a single acute ECS. Supershift experiments and Western blots show that the chronic AP-1 complex contains two novel Fos-related antigens (Fras) of 35 and 37 kDa that do not appear following a single acute ECS. The chronically induced 35 and 37 kDa Fras and the chronic AP-1 complex show similar time courses for induction by repeated ECS. Moreover, the 37 kDa Fra band persists for at least 7 d following chronic ECS treatment, as observed for the chronic AP-1 complex. Competition experiments indicate that the relative affinities of the acute and chronic AP-1 complexes for several AP-1-like sites are similar, although there was approximately a twofold difference in the affinity for one particular AP-1-like site. The altered composition of the chronic AP-1 complex, and differences in half-life, DNA binding affinity, and possibly transcriptional activating properties are likely to cause changes in the overall pattern of gene expression, which may underlie some of the long-term biochemical adaptations observed following chronic ECS and other chronic perturbations.

Chronic electroconvulsive seizures increase the expression of serotonin2 receptor mRNA in rat frontal cortex.

The present study examines the influence of electroconvulsive seizure (ECS), as well as antidepressant drugs, on levels of serotonin2 (5-HT2) receptor mRNA in rat frontal cortex. Using a sensitive RNase protective assay, preliminary studies demonstrated the predicted regional distribution for the 5-HT2 receptor mRNA: levels of 5-HT2 mRNA were highest in frontal cortex (2.58 amol/micrograms of total RNA), intermediate in neostriatum, thalamus, and midbrain, and lowest in hippocampus, cerebellum, and choroid plexus. Chronic (10 or 14 days), but not acute (1 or 3 days), ECS treatment significantly increased levels of 5-HT2 receptor mRNA. ECS treatment resulted in a similar time-dependent up-regulation of 5-HT2 receptor ligand binding; chronic, but not acute, ECS treatment significantly increased levels of [3H]ketanserin ligand binding, confirming previous reports. Northern blot analysis demonstrated that 5-HT2 receptor mRNA occurs as two bands (approximately 5 and 6 kb in size), both of which were increased by chronic ECS treatment. The influence of antidepressant drug treatments on 5-HT2 receptor mRNA was also examined. Chronic fluoxetine treatment increased levels of 5-HT2 receptor mRNA, although levels of [3H]ketanserin ligand binding were not altered. In contrast, chronic administration of imipramine, mianserin, and tranylcypromine, treatments that decreased ligand binding, did not decrease levels of 5-HT2 receptor mRNA. In fact, mianserin treatment caused a small, but significant, increase in levels of receptor mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of beta 1-adrenergic receptor mRNA and ligand binding by antidepressant treatments and norepinephrine depletion in rat frontal cortex.

The number of beta 1-adrenergic receptor (beta 1AR) binding sites is decreased by chronic antidepressant treatments, including electroconvulsive seizure (ECS) and imipramine, whereas administration of agents that deplete norepinephrine (NE) increases the number of beta 1AR binding sites in cerebral cortex. The present study was carried out to examine the influence of these treatments on levels of beta 1AR mRNA in frontal cortex to study the molecular mechanisms that underlie the regulation of beta 1ARs in brain. Levels of beta 1AR mRNA were measured by RNase protection analysis using a riboprobe derived from rat beta 1AR cDNA, and the levels of beta AR binding were measured using the nonselective ligand [3H]CGP-12177. Studies to verify the specificity of the RNase protection assay revealed that the distribution of beta 1AR mRNA was in agreement with the reported distribution of beta 1AR ligand binding: Levels of beta 1AR mRNA were highest in cerebral cortex or frontal cortex, intermediate in neostriatum, hippocampus, lung, and heart, and lowest in cerebellum, kidney, and liver. Chronic ECS treatment (once daily for 10 days) significantly decreased levels of beta AR ligand binding and resulted in a corresponding, time-dependent down-regulation of beta 1AR mRNA levels in frontal cortex. However, imipramine administration regulated levels of beta 1AR mRNA in a biphasic manner, with treatments for 7-14 days increasing and treatments for 18-21 days decreasing levels of beta 1AR mRNA in frontal cortex. In contrast, levels of [3H]CGP-12177 ligand binding were decreased at all time points examined (3-21 days).(ABSTRACT TRUNCATED AT 250 WORDS)