Serial electroconvulsive Seizure alters dendritic complexity and promotes cellular proliferation in the mouse dentate gyrus; a role for Egr3

BACKGROUND

Despite being one of the safest, most effective treatments for severe mood disorders, the therapeutic mechanisms of electroconvulsive therapy remain unknown. Electroconvulsive seizure (ECS) induces rapid, high-level expression of immediate early genes (IEGs) and brain-derived neurotrophic factor (BDNF), in addition to stimulation of neurogenesis and dendritic remodeling of dentate gyrus (DG) neurons. We have previously shown that this upregulation of BDNF fails to occur in the hippocampus of mice lacking the IEG Egr3. Since BDNF influences neurogenesis and dendritic remodeling, we hypothesized that Egr3-/- mice will exhibit deficits in neurogenesis and dendritic remodeling in response to ECS.

OBJECTIVE

To test this hypothesis, we examined dendritic remodeling and cellular proliferation in the DG of Egr3-/- and wild-type mice following repeated ECS.

METHODS

Mice received 10 daily ECSs. Dendritic morphology was examined in Golgi-Cox-stained tissue and cellular proliferation was analyzed through bromodeoxyuridine (BrdU) immunohistochemistry and confocal imaging.

RESULTS

Serial ECS in mice results in dendritic remodeling, increased spine density, and cellular proliferation in the DG. Loss of Egr3 alters the dendritic remodeling induced by serial ECS but does not change the number of dendritic spines or cellular proliferation consequences of ECS.

CONCLUSION

Egr3 influences the dendritic remodeling induced by ECS but is not required for ECS-induced proliferation of hippocampal DG cells.

Differential expression of transcriptional regulatory units in the prefrontal cortex of patients with bipolar disorder: potential role of early growth response gene 3

Bipolar disorder (BD) is a severe mental illness with a strong genetic component. Despite its high degree of heritability, current genetic studies have failed to reveal individual loci of large effect size. In lieu of focusing on individual genes, we investigated regulatory units (regulons) in BD to identify candidate transcription factors (TFs) that regulate large groups of differentially expressed genes. Network-based approaches should elucidate the molecular pathways governing the pathophysiology of BD and reveal targets for potential therapeutic intervention. The data from a large-scale microarray study was used to reconstruct the transcriptional associations in the human prefrontal cortex, and results from two independent microarray data sets to obtain BD gene signatures. The regulatory network was derived by mapping the significant interactions between known TFs and all potential targets. Five regulons were identified in both transcriptional network models: early growth response 3 (EGR3), TSC22 domain family, member 4 (TSC22D4), interleukin enhancer-binding factor 2 (ILF2), Y-box binding protein 1 (YBX1) and MAP-kinase-activating death domain (MADD). With a high stringency threshold, the consensus across tests was achieved only for the EGR3 regulon. We identified EGR3 in the prefrontal cortex as a potential key target, robustly repressed in both BD signatures. Considering that EGR3 translates environmental stimuli into long-term changes in the brain, disruption in biological pathways involving EGR3 may induce an impaired response to stress and influence on risk for psychiatric disorders, particularly BD.

Developmental differences in acute nigrostriatal and mesocorticolimbic system response to haloperidol

Dose-dependent effects of haloperidol (2.66 nmol/kg to 79.8 mmol/kg, IP) on levels of dopamine, homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) were assessed in the corpus striatum, nucleus accumbens, and medial prefrontal cortex (PFCTX) of 18-, 30-, and 110-day-old rats. Eighteen-day-old rats were 35% and 63% more sensitive than adults to the effects of haloperidol on striatal and accumbens turnover and had steeper dose-response curves. The dose-response function in the PFCTX was similar to striatum at 18 days, but became shallower and nonsigmoidal with age. Maximally effective doses of haloperidol produced, at all ages, a comparable percent rise in DOPAC levels in all regions. With maturation, the percent rise in HVA progressively outstripped DOPAC response in nucleus accumbens and striatum. Overall, prominent developmental differences emerged in these regions in their sensitivity and response to haloperidol, which are consistent with previously reported differences in behavioral sensitivity.

Expression and characterization of the rat D3 dopamine receptor: pharmacologic properties and development of antibodies

A baculovirus expression system provided an enriched source of biologically and immunologically active D3 dopamine receptors. Receptors expressed in Spodoptera frugiperda insect (Sf9) cells at a density of 5 to 15 pmol/mg of protein displayed high affinity for the antagonists, eticlopride, fluphenazine and spiroperidol, and the agonist, N-propylnorapomorphine. The binding of agonists was not sensitive to GTP. Antisera raised against synthetic peptides in the third intracellular loop of the D3 dopamine receptor immunoprecipitated binding sites for (S)-3-[125I]-iodo-2-hydroxy-5,6-dimethoxy-N-[(1-ethyl-2-pyrrolidinyl)- methyl]-benzamide from solubilized extracts of infected Sf9 cells and detergent extracts of rat caudate. These antisera specifically recognized a single band on immunoblots of Sf9 cells infected with recombinant D3 baculovirus. Both the immunoprecipitation and immunoblot reactions were blocked by preincubation of the antisera with the immunization peptide. These results suggest that the D3 receptor protein is expressed in rat brain.

Dopamine D1 autoreceptor function: possible expression in developing rat prefrontal cortex and striatum

Synthesis-modulating dopamine (DA) autoreceptor function was studied in vivo using gamma-butyrolactone (GBL) to block propagation along DA axons. DA synthesis was measured by the accumulation of L-3,4-dihydroxyphenylalanine (L-DOPA) after inhibition of aromatic L-amino acid decarboxylase. GBL treatment markedly increased DOPA accumulation in both the striatum and prefrontal cortex of developing rats. The selective DA partial D1 agonist SKF-38393 inhibited this GBL-induced rise in DA synthesis in both the striatum and prefrontal cortex of 15- and 22-day-old rats, but not in adults. The effects of SKF-38393 in developing rats were mimicked by the non-catechol D1 partial agonist CY-208-243, and were blocked by the D1 antagonist SCH-23390, suggesting receptor mediation. The mixed D2/D3 agonist quinpirole attenuated DA synthesis in striatum of both two-week-old and adult rats, but failed to inhibit the GBL-induced increase in DA synthesis in the developing prefrontal cortex. These findings suggest that synthesis-modulating D1-like receptor function may emerge transiently in the developing mammalian forebrain. In the adult striatum these functions appear to be subsumed by D2-like receptors, whereas all synthesis-modulating DA receptor function in prefrontal cortex appears to be essentially lost with maturation.

The closure of abdominal wounds in cancer patients

A total of 102 abdominal surgical wounds in cancer patients were closed with absorbable suture material. The object of the study was to evaluate whether patients with cancer having possible wound healing impairments could be closed with absorbable sutures, thereby omitting the difficulties involved with retention sutures or nonabsorbable material. Polyglycolic acid sutures were used in the fascia in all of these patients, and they were studied regarding the incidence of wound infection, wound dehiscence, and incisional hernias. There were no instances of wound dehiscence in the entire series. A wound infection rate of 14.8% was encountered. The incidence of incisional hernia following either infection or primary healing was noted to be markedly decreased. The rate of wound dehiscence and wound hernia was sufficiently low to lead us to recommend this type of abdominal wound closure in all cancer patients.

Near-fatal hemorrhage following gastrografin studies

The use of upper gastrointestinal studies followed by gastric drainage and observation is recommended for the evaluation and treatment of stomal dysfunction due to edema or gastric atony. Gastrografin though, may be precipitated out and can cause gastrointestinal bleeding if left in the gastric remenant. This agent should be used with proper precautions in the evaluation of postoperative gastric retention.

A new variant of intra-abdominal hernia

A new variant of intra-abdominal hernia is presented. Available evidence suggests that this type of intra-abdominal hernia may be more prevalent than previously reported. Patients suffering from crampy, intermittent abdominal pain whose routine radiographic gastrointestinal studies are unrevealing often are labeled as having psychogenic disorders. Three cases are present giving similar histories and routine findings in which mesenteric arteriography coupled with careful small bowel series has revealed a surgically curable lesion. Such patients should have judicious mesenteric angiography coupled with routine radiographic gastrointestinal studies in search of small intramesenteric herniae which are readily correctible.

The anterior approach to percutaneous liver biopsy

Anterior subcostal percutaneous liver biopsy using the Tru-cut disposable needle is safe and simple; there were no major complications in our experience. It avoids completely the known thoracic complications of the posterior or lateral approach to percutaneous liver biopsy and has the added benefit of making any of the remaining complications easier to manage.