Keith E. Isenberg

Efficacy and Safety of Transcranial Magnetic Stimulation in the Acute Treatment of Major Depression: A Multisite Randomized Controlled Trial

BACKGROUND We tested whether transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (DLPFC) is effective and safe in the acute treatment of major depression. METHODS In a double-blind, multisite study, 301 medication-free patients with major depression who had not benefited from prior treatment were randomized to active (n = 155) or sham TMS (n = 146) conditions. Sessions were conducted five times per week with TMS at 10 pulses/sec, 120% of motor threshold, 3000 pulses/session, for 4-6 weeks. Primary outcome was the symptom score change as assessed at week 4 with the Montgomery-Asberg Depression Rating Scale (MADRS). Secondary outcomes included changes on the 17- and 24-item Hamilton Depression Rating Scale (HAMD) and response and remission rates with the MADRS and HAMD. RESULTS Active TMS was significantly superior to sham TMS on the MADRS at week 4 (with a post hoc correction for inequality in symptom severity between groups at baseline), as well as on the HAMD17 and HAMD24 scales at weeks 4 and 6. Response rates were significantly higher with active TMS on all three scales at weeks 4 and 6. Remission rates were approximately twofold higher with active TMS at week 6 and significant on the MADRS and HAMD24 scales (but not the HAMD17 scale). Active TMS was well tolerated with a low dropout rate for adverse events (4.5%) that were generally mild and limited to transient scalp discomfort or pain. CONCLUSIONS Transcranial magnetic stimulation was effective in treating major depression with minimal side effects reported. It offers clinicians a novel alternative for the treatment of this disorder.

Effect of concomitant pharmacotherapy on electroconvulsive therapy outcomes: short-term efficacy and adverse effects.

CONTEXT Medication resistance is the leading indication for use of electroconvulsive therapy (ECT) in major depression. The practice of stopping antidepressant medications prior to ECT derived from studies in the 1960s and 1970s in nonresistant samples. There is also continuing controversy regarding the relative efficacy and adverse effects of right unilateral and bilateral ECT. OBJECTIVE To test the hypotheses that, compared with placebo, concomitant treatment with nortriptline or venlafaxine during the ECT course enhances short-term efficacy without a meaningful effect on adverse effects and reduces the rate of post-ECT relapse, and to test the hypotheses that high-dose, right-sided, unilateral ECT is equivalent in efficacy to moderate-dosage bilateral ECT and retains advantages with respect to cognitive adverse effects. DESIGN Prospective, randomized, triple-masked, placebo-controlled study conducted from 2001 through 2005. SETTING Three university-based hospitals. PATIENTS Of approximately 750 consecutive patients referred for ECT, 319 with a major depressive episode consented, were randomized to pharmacological or ECT treatment conditions, and received at least 1 ECT treatment. MAIN OUTCOME MEASURES Scores on the Hamilton Rating Scale for Depression, remission rate following completion of ECT, and selective measures of cognitive adverse effects. RESULTS Treatment with nortriptyline enhanced the efficacy and reduced the cognitive adverse effects of ECT relative to placebo. Venlafaxine resulted in a weaker degree of improvement and tended to worsen cognitive adverse effects. High-dosage right unilateral ECT did not differ or was superior to bilateral ECT in efficacy and resulted in less severe amnesia. CONCLUSIONS The efficacy of ECT is substantially increased by the addition of an antidepressant medication, but such medications may differ in whether they reduce or increase cognitive adverse effects. High-dose, right-sided, unilateral ECT is at least equivalent to moderate-dosage bilateral ECT in efficacy, but retains advantages with respect to cognitive adverse effects.

Neuronal Expression of the Glutamate Transporter GLT-1 in Hippocampal Microcultures

To address the question of the relative contributions of glial and neuronal glutamate transport in the vertebrate CNS, we studied the distribution of forebrain glutamate transporters in rat hippocampal microcultures, a preparation in which physiological functions of glutamate transporters have been well characterized. Two of the three transporters, GLAST (EAAT1) and EAAC1 (EAAT3), are localized to microculture glia and neurons, respectively, as expected. However, we find strong immunoreactivity for the third glutamate transporter GLT-1 (EAAT2), a putatively glial transporter, in microculture neurons and in a small subset of microculture glia. Indistinguishable immunohistochemical staining patterns for GLT-1 were obtained with antibodies directed against both the N terminal and C terminal of the GLT-1 protein. Double-labeling experiments suggest that neuronal GLT-1 protein is primarily localized to the dendrites of excitatory neurons. Neuronal electrogenic transport currents in response tod-aspartate applications were occluded by the selective GLT-1 inhibitor dihydrokainate. In contrast, glia exhibited a larger transporter current density than did neurons, and the glial transport current was less sensitive to dihydrokainate. Neuronal transport currents were potentiated less than were glial currents when the chaotropic anion thiocyanate was substituted for gluconate in the whole-cell recording pipette, consistent with the previously reported lower anion permeability of EAAC1 and GLT-1 compared with that of GLAST. After microculture glia were rendered nonviable, excitatory autaptic currents (EACs) were prolonged in the presence of dihydrokainate, suggesting that neuronal GLT-1 is capable of participating in the clearance of synaptically released glutamate. Our results suggest that the initially proposed characterization of GLT-1 as a purely glial transporter is too simplistic and that under certain conditions functional GLT-1 protein can be expressed in brain neurons. The study suggests that changes in GLT-1 levels that occur with pathology or experimental manipulations cannot be assumed to be glial.

Developmental alteration in GABAA receptor structure and physiological properties in cultured cerebellar granule neurons

Although we now have extensive knowledge about the GABAA receptor subunits determining benzodiazepine modulation of channel function, little is known about subunits influencing other modulatory sites on the GABAA receptor-chloride channel complex. We have identified a developmental change in subunit composition of the GABAA receptor in cultured cerebellar granule neurons that eliminates benzodiazepine-mediated enhancement of GABA responses and alters modulation by a substituted gamma-butyrolactone. Based on data from sequential PCR experiments, we mimicked the functional properties of early and mature receptors with heterologous expression of specific subunit combinations. This report describes one of the most extensive cell- and site-specific developmental changes for an ion channel seen to date.

Possible involvement of opiate receptors in the pharmacological profiles of antidepressant compounds

Tricyclic antidepressants and selected hydroxylated metabolites were found to inhibit [3H]naltrexone binding in whole rat brain. The drug concentrations required to inhibit binding appeared to be within pharmacological relevant brain concentrations. Carbamazepine and several monoamine oxidase inhibitors (with the exception of clorgyline) were inactive in this regard. The relative potency of the tricyclic antidepressants with regard to inhibitions of opiate binding in brain did not correlate with their clinical efficiency as antidepressants, suggesting that these compounds probably do not exert their antidepressant effects through opioid peptidergic systems in brain. In addition, we found that imipramine (30 mg/kg) had antinociceptive properties, as assessed by the hot plate procedure, which were partially, but not significantly, reversed by naloxone (2 mg/kg). The possibility that opioid receptors may be involved in the analgesic properties of the tricyclic antidepressants has been discussed.

Co-Morbidity and Utilization of Medical Services by Pain Patients Receiving Opioid Medications: Data from an Insurance Claims Database

ABSTRACT We used a large medical insurance claims database to identify three groups: chronic opioid use (>180 therapeutic days, N = 3726); acute opioid use (<10 therapeutic days, N = 37,108); and a non‐opioid group (N = 337,366) who filed at least one insurance claim but none for opioids. Our results showed that although chronic opioid users represented only 0.65% of the total population, they filed 4.56% of all insurance claims, used 45% of all opioid analgesics and had much more physical and psychiatric co‐morbidity than the acute opioid or non‐opioid samples. Women were substantially over‐represented (>63%) in the chronic pain group and used a much greater share of all medical services than males, especially as they grew older. Although our data suggest that chronic pain is optimally managed in a multidisciplinary patient‐ and gender‐specific treatment plan, this was rarely the case with internists being the primary, and often only, physician seen. Moreover, our data suggest that opioids were often used for conditions in which they are generally not indicated (e.g. arthritis and headaches) or contraindicated by co‐existing physical ailments (COPD). Finally, we conclude that adherence to the WHO analgesic ladder and other pain treatment guidelines was relatively infrequent: first, opioid extended release preparations which are ideally suited for chronic pain were used only in one in four patients; and, second, the selection of a weak (propoxyphene, codeine, and tramadol) or strong opioid (e.g. morphine and oxycodone) seemed to be driven by numerous factors not necessarily related to the intensity or duration of pain.

Pharmacological and physiological properties of a putative ganglionic nicotinic receptor, α3β4, expressed in transfected eucaryotic cells

Abstract Neuronal nicotinic acetylcholine receptor subunits α 3 (PCA48E) and β 4 S (ZPC13) were expressed in human embryonic kidney (HEK)-293 cells by calcium phosphate transfection. In the presence of atropine, acetylcholine (ACh) induced fast activating currents which exhibited desensitization and inward rectification. The EC 50 for ACh was 202 ± 32 μM with a Hill coefficient of 1.9 ± 0.4. The rank order of nicotinic agonist potency was 1,1-dimethyl-4-phenylpiperozinium (DMPP) > cytisine = nicotine ≊ ACh. The maximal response elicited by DMPP was substantially less than that elicited by other agonists, suggesting that DMPP is a partial agonist. ACh (500 μM) responses were very effectively blocked by equimolar concentrations (100 μM) of the ganglionic antagonists d-tubocurarine, mecamylamine and hexamethonium. Equal concentrations of the potent muscle receptor antagonist decamethonium and the competitive antagonist dihydro-β-erythroidine were much less effective. α bungarotoxin (1 μM) had little effect on ACh-induced responses. This physiological and pharmacological profile is consistent with a ganglionic nicotinic response.

Partial cDNA cloning and NGF regulation of a rat 5-HT3 receptor subunit.

Nerve growth factor (NGF) stimulates 5-HT3 receptor expression although the mechanism(s) responsible for this effect are unknown. We report the nucleotide and deduced amino acid sequences of a nearly complete rat 5-HT3 receptor subunit and use the sequence to develop a reverse transcription-polymerase chain reaction (RT-PCR) assay that measures 5-HT3 mRNA. Exposure of PC12 cells to NGF results in increasing steady-state levels of 5-HT3 mRNA. The four-fold increase in mRNA correlates with and is sufficient to account for increases in receptor measured by agonist induction of whole cell currents.

No Evidence for Linkage between Chromosome 5 Markers and Schizophrenia

Linkage between chromosome 5 markers and schizophrenia has been proposed for a small number of Icelandic and English families. Three subsequent reports have failed to replicate this report. To increase the number of tested kindreds, we collected seven North American families with schizophrenia and genotyped them at 4 loci that span the region 5p13-5q11-14, including the two markers used in the single positive linkage report. The data were analyzed with models of affection status similar to those utilized in the positive report. We observed no evidence of linkage between these markers and psychiatric disorders, regardless of the definition of affection status. Additionally, we can exclude most of the region for linkage with schizophrenia in these families. This and other negative reports of linkage between schizophrenia and chromosome 5 markers suggest that genetic defects in this region are rarely, if ever, etiologically related to schizophrenia.

Site-directed mutagenesis identifies amino acid residues associated with the dehydrogenase and isomerase activities of human type I (placental) 3β-hydroxysteroid dehydrogenase/Isomerase

3beta-hydroxysteroid dehydrogenase/steroid delta5-->4-isomerase (3beta-HSD/isomerase) was expressed by baculovirus in Spodoptera fungiperda (Sf9) insect cells from cDNA sequences encoding human wild-type I (placental) and the human type I mutants - H261R, Y253F and Y253,254F. Western blots of SDS-polyacrylamide gels showed that the baculovirus-infected Sf9 cells expressed the immunoreactive wild-type, H261R, Y253F or Y253,254F protein that co-migrated with purified placental 3beta-HSD/isomerase (monomeric Mr=42,000 Da). The wild-type, H261R and Y253F enzymes were each purified as a single, homogeneous protein from a suspension of the Sf9 cells (5.01). In kinetic studies with purified enzyme, the H261R mutant enzyme had no 3beta-HSD activity, whereas the Km and Vmax values of the isomerase substrate were similar to the values obtained with the wild-type and native enzymes. The Vmax (88 nmol/min/mg) for the conversion of 5-androstene-3,17-dione to androstenedione by the Y253F isomerase activity was 7.0-fold less than the mean Vmax (620 nmol/min/mg) measured for the isomerase activity of the wild-type and native placental enzymes. In microsomal preparations, isomerase activity was completely abolished in the Y253,254F mutant enzyme, but Y253,254F had 45% of the 3beta-HSD activity of the wild-type enzyme. In contrast, the purified Y253F, wild-type and native enzymes had similar Vmax values for substrate oxidation by the 3beta-HSD activity. The 3beta-HSD activities of the Y253F, Y253,254F and wild-type enzymes reduced NAD+ with similar kinetic values. Although NADH activated the isomerase activities of the H261R and wild-type enzymes with similar kinetics, the activation of the isomerase activity of H261R by NAD+ was dramatically decreased. Based on these kinetic measurements, His261 appears to be a critical amino acid residue for the 3beta-HSD activity, and Tyr253 or Tyr254 participates in the isomerase activity of human type I (placental) enzyme.