Studies on the role of brain cholinergic systems in the therapeutic mechanisms and adverse effects of ECT and lithium

Acute and Prophylactic Management of Postictal Agitation in Electroconvulsive Therapy

ABSTRACT

Postictal agitation (PIA) is a common adverse effect of electroconvulsive therapy (ECT), a treatment used for a variety of psychiatric disorders. Because of risk of harm to patients and health providers when patients develop PIA, its acute management and prophylaxis are of vital importance for ECT practitioners. This article describes PIA risk factors, as well as practical steps to manage this ECT complication. Nonpharmacologic patient safety interventions are critical components of PIA management. Benzodiazepines, antipsychotics, and additional anesthetic doses are discussed as acute treatment interventions. Prophylactic pharmacologic choices described include antipsychotics, postseizure anesthetics, and dexmedetomidine. Exploratory choices such as melatonin and intranasal formulations of sedatives are also discussed. This review suggests that common medication like olanzapine and propofol are cost-effective considerations to decrease PIA incidence and/or severity after ECT. In addition, dexmedetomidine presents a management alternative for treatment-resistant PIA. This literature review outlines treatment choices while suggesting future directions for considering effective treatments of postictal agitation in clinical settings.

The Role of Acetylcholinesterase Inhibitors in the Treatment of Prolonged Postelectroconvulsive Therapy Delirium

Electroconvulsive therapy (ECT) is an extremely effective treatment modality for severe depression but is often associated with transient or persistent cognitive impairment. ECT-induced cognitive impairment, however, can serve as a deterrent to completion of treatment. We present a case of a prolonged post-ECT delirium lasting approximately 3 weeks in which donepezil, an acetylcholinesterase inhibitor, was used and was successful in shortening the duration of post-ECT delirium.

Rivastigmine for ECT-induced cognitive adverse effects in late life depression (RECALL study): A multicenter, randomized, double blind, placebo-controlled, cross-over trial in patients with depression aged 55 years or older: Rationale, objectives and methods

BACKGROUND

Cognitive side-effects are an important reason for the limited use of electroconvulsive therapy (ECT). Cognitive side-effects are heterogeneous and occur frequently in older persons. To date, insight into these side-effects is hampered due to inconsistencies in study designs and small sample sizes. Among all cognitive side-effects, confusion and delirious states are especially troublesome for patients, relatives and clinicians. In particular inter-ictal delirium-like states are worrisome, since they may lead to premature treatment discontinuation. Besides a need for further insight into determinants of cognitive side-effects of ECT, there is a great need for treatment options.

METHODS AND DESIGN

The Rivastigmine for ECT-induced Cognitive Adverse effects in Late Life depression (RECALL) study combines a multicenter, prospective cohort study on older patients with depression, treated with ECT, with an embedded randomized, placebo-controlled cross-over trial to examine the effect of rivastigmine on inter-ictal delirium. Patients are recruited in four centers across the Netherlands and Belgium. We aim to include 150 patients into the cohort study, in order to be able to subsequently include 30 patients into the trial. Patients are included in the trial when inter-ictal delirium, assessed by the Confusion Assessment method (CAM), or a drop in Mini Mental State Examination (MMSE) score of ≥4 during ECT, develops. In the cohort study, comprehensive measurements of ECT-related cognitive side-effects-and their putative determinants-are done at baseline and during the ECT-course. The primary outcome of the clinical trial is the effectiveness of rivastigmine on inter-ictal delirium-severity, assessed with a change in the Delirium Rating Scale-Revised-98. Secondary outcomes of the clinical trial are several ECT-characteristics and side-effects of rivastigmine.

DISCUSSION

This study is the first clinical trial with a focus on ECT-induced, inter-ictal delirium. The cohort provides the basis for recruitment of patients for the cross-over trial and additionally provides an excellent opportunity to unravel cognitive side-effects of ECT and identify putative determinants. This paper describes the rationale and study protocol.

CLINICAL TRIAL REGISTRATION

EudraCT 2014-003385-24.

The Effect of Foot Reflexology on Amnesia in Patients Undergoing Electroconvulsive Therapy: A Randomized Clinical Trial

Introduction: Electroconvulsive therapy (ECT) is the oldest procedure among the early biological treatments introduced in psychiatry. However, the most debated and treatment-limiting adverse effect of ECT is amnesia. Therefore, due to the restriction of the use of drugs to manage amnesia in patients undergoing ECT, the present study investigated the effect of reflexology on amnesia.

Methods: In this randomized controlled trial, 68 patients who met the inclusion criteria were randomly allocated to intervention and control groups. The intervention group received foot reflexology with olive oil 20 minutes a day for 3 days, while the control group was given a gentle foot rub with olive oil 20 minutes a day for 3 days. The amnesia rate of all patients was measured by the Galveston Orientation and Amnesia Test (GOAT) 30 minutes after the end of ECT. The data were analyzed using SPSS software version 11.5 and t-test, chi-squared test, and repeated measures ANOVA.

Results: The results showed that reflexology significantly increased recalling scores in the intervention group compared to the control group. Foot reflexology seems to be effective in managing amnesia in patients after ECT.

Conclusion: Foot reflexology, as a relatively simple, inexpensive, and non-invasive technique with few side effects, can be used to manage amnesia in patients after ECT.

Prophylactic cognitive enhancers for improvement of cognitive function in patients undergoing electroconvulsive therapy: A systematic review and meta-analysis

OBJECTIVE

Cognitive enhancers, including cholinesterase inhibitors and memantine, are used to treat dementia, but their effect for reducing post-electroconvulsive therapy (post-ECT) cognitive side effects is unclear. We conducted a systematic review and meta-analysis to assess the effectiveness of cognitive enhancers in the prevention of cognitive side effects due to ECT.

METHODS

We identified relevant studies by searching electronic databases (e.g., PubMed, EMBASE, Web of Science, Cochrane Library). Only studies published up to October 2019 comparing cognitive enhancer vs placebo for cognitive function after ECT were included. The primary outcome extracted from the studies was cognitive function score.

RESULTS

Five studies with 202 patients were included in this study. The cognitive enhancer group (CEG) had a significantly higher cognitive function score. Moreover, sensitivity analysis showed that no individual study had a significant impact on the overall results.

CONCLUSIONS

This meta-analysis revealed that cognitive enhancers might improve cognitive function and reduce ECT-induced cognitive side effects. Nevertheless, more high-quality randomized controlled trials (RCTs) with long-term follow-up are still needed to make the final conclusion.

The incidence of prolonged post-electroconvulsive therapy delirium: A retrospective study

OBJECTIVE

The objective of the study was to assess the incidence and determinants of electroconvulsive therapy (ECT)-induced delirium.

MATERIALS AND METHODS

Using a retrospective study design, data of 488 patients undergoing modified ECT were evaluated for the development of new-onset prolonged delirium. Demographic and clinical parameters of patients who developed delirium and those who did not develop delirium were compared.

RESULTS

5.7% of the patients developed prolonged post-ECT delirium. The use of quetiapine in higher doses and the lack of use of antidepressants while receiving ECT were associated with the development of prolonged post-ECT delirium. None of the other clinical and ECT-related parameters emerged as a significant factor associated with the development of prolonged post-ECT delirium.

CONCLUSIONS

A small proportion of patients undergoing ECT develop post-ECT prolonged delirium.

Therapeutic and prophylactic role of cognitive enhancers in electroconvulsive therapy-induced cognitive deficits

OBJECTIVES

The objective is to evaluate the pattern of cognitive deficits after electroconvulsive therapy (ECT); to ascertain the role of various psychosocial, illness and treatment-related parameters on cognitive functions after ECT; and to evaluate the effect of donepezil on various cognitive deficits.

MATERIALS AND METHODS

A triple-blind randomized controlled trial was undertaken. Ninety patients undergoing ECT were included into study after due consent and institutional ethical approval. They were randomized into two groups: one using donepezil with ECT and the other using placebo with ECT. Various cognitive parameters were studied before ECT, after a course of ECT and after 4 weeks of last ECT. Findings were assessed in the light of available socialdemographic and clinical parameters and existing literature.

RESULTS

ECT was found to be an effective therapeutic modality. Immediate memory worsened over the course of ECT till after 4 weeks of ECT. Augmentation of donepezil was found useful. It sped up the improvement of general memory and working memory during ECT.

CONCLUSION

Donepezil has therapeutic and prophylactic benefit on cognition of patients undergoing ECT over the course of treatment till 4 weeks after the ECT.

Lithium Preparations in Psychiatry, Addiction Medicine and Neurology. Part II. Biochemical Mechanisms of Its Action

Lithium is the first and the lightest in the series of alkali metals, to which, in addition to lithium, two very biologically important elements – sodium and potassium, as well as trace elements rubidium and cesium, belong. Despite its formal affiliation to the group of alkali metals, lithium, like many other chemical elements of the «atypical» second period of the periodic table (for example, boron), is more similar in its chemical properties not to its counterparts in the group, but to its «diagonal brother» – magnesium. As we will show in this article, the diagonal chemical similarity between lithium and magnesium is of great importance for understanding the mechanisms of its intracellular biochemical action. At the same time, the intragroup chemical similarity of lithium with sodium and potassium is more important for understanding the mechanisms of its absorption, its distribution in the body and its excretion. Despite the 70 years that have passed since John Cade’s discovery of the antimanic effect of lithium, the mechanisms of its therapeutic action are still not completely understood. In the end, it turns out that the mechanism of the therapeutic action of lithium is extremely complex, multicomponent, unique and not imitable. Certain aspects of the mechanism of its action may be compatible with the mechanisms of action of other mood stabilizers, or with the mechanisms of action of so-called «lithium-mimetics», such as ebselen. However, no other drug to date failed to fully reproduce the biochemical effect of lithium on the body.

Cognitive Impairment and Electroconvulsive Therapy in Geriatric Depression, What Could be the Role of Rivastigmine? A Case Series

Electroconvulsive therapy (ECT), albeit highly effective in treating depression, is frequently associated with cognitive impairment, either temporary or more persistent. Especially in older patients, who generally respond even better, serious cognitive impairment during the course of ECT may lead to premature termination of ECT. Treatment of this cognitive impairment is of utmost importance. In this case series report, we present the effect of rivastigmine, an acetylcholinesterase inhibitor, on cognitive impairment in three older, severely depressed patients during or after a course of ECT. An improvement of cognitive functioning, in particular a decline of confusional symptoms, was observed in two patients with structural brain alterations associated with aging. In the other patient, who suffered primarily from amnesia, no effect of rivastigmine was observed. These preliminary results emphasize the need for detailed profiling of cognitive impairment when developing a research design to study the potential benefits of rivastigmine in the prevention or treatment of cognitive impairment in severely depressed patients treated with ECT.

Modeling bipolar disorder in mice by increasing acetylcholine or dopamine: chronic lithium treats most, but not all features

RATIONALE

Bipolar disorder (BD) is a disabling and life-threatening disease characterized by states of depression and mania. New and efficacious treatments have not been forthcoming partly due to a lack of well-validated models representing both facets of BD.

OBJECTIVES

We hypothesized that cholinergic- and dopaminergic-pharmacological manipulations would model depression and mania respectively, each attenuated by lithium treatment.

METHODS

C57BL/6 J mice received the acetylcholinesterase inhibitor physostigmine or saline before testing for "behavioral despair" (immobility) in the tail suspension test (TST) and forced swim test (FST). Physostigmine effects on exploration and sensorimotor gating were assessed using the cross-species behavioral pattern monitor (BPM) and prepulse inhibition (PPI) paradigms. Other C57BL/6 J mice received chronic lithium drinking water (300, 600, or 1200 mg/l) before assessing their effects alone in the BPM or with physostigmine on FST performance. Another group was tested with acute GBR12909 (dopamine transporter inhibitor) and chronic lithium (1000 mg/l) in the BPM.

RESULTS

Physostigmine (0.03 mg/kg) increased immobility in the TST and FST without affecting activity, exploration, or PPI. Lithium (600 mg/l) resulted in low therapeutic serum concentrations and normalized the physostigmine-increased immobility in the FST. GBR12909 induced mania-like behavior in the BPM of which hyper-exploration was attenuated, though not reversed, after chronic lithium (1000 mg/ml).

CONCLUSIONS

Increased cholinergic levels induced depression-like behavior and hyperdopaminergia induced mania-like behavior in mice, while chronic lithium treated some, but not all, facets of these effects. These data support a cholinergic-monoaminergic mechanism for modeling BD aspects and provide a way to assess novel therapeutics.

Pharmacogenetics in electroconvulsive therapy and adjunctive medications

Electroconvulsive therapy (ECT) has shown apparent efficacy in treatment of patients with depression and other mental illnesses who do not respond to psychotropic medications or need urgent control of their symptoms. Pharmacogenetics contributes to an individual's sensitivity and response to a variety of drugs. Clinical insights into pharmacogenetics of ECT and adjunctive medications not only improves its safety and efficacy in the indicated patients, but can also lead to the identification of novel treatments in psychiatric disorders through understanding of potential molecular and biological mechanisms involved. In this review, we explore the indications of pharmacogenetics role in safety and efficacy of ECT and present the evidence for its role in patients with psychiatric disorders undergoing ECT.

In vivo oxymetric analysis of mild hypercapnia upon cerebral oxygen, temperature and blood flow: markers of mood as proposed by concomitant bupropion challenge and electrochemical analysis?

Scientific interest has increased the influence of temperature in neurodegenerative and psychiatric disorders, and according to the monoamine hypothesis, depression is a neurochemical disorder arising from hypofunctioning of brain monoamine systems. Here, in vivo flow-oxymetry is applied to verify relationships between cerebral oxygen tension (pO2), blood flow (CBF), that are markers of brain metabolism, and temperature (T), while in vivo voltammetry is concomitantly applied in the medial prefrontal cortex of anaesthetized rats to monitor monoamine levels such as dopamine (DA) and serotonin. An induced mild hypercapnia via increasing exogenous carbon dioxide (CO2) concentration resulted in increased pO2, CBF and T in discrete brain areas. Concomitant in situ voltammetric analysis of extracellular levels of serotonin and DA has revealed significant changes in the latter, only. Parallel treatment with antidepressant bupropion has confirmed its described central thermogenic properties and its positive influence on dopaminergic activity. CBF was also enhanced by such antidepressant. Altogether these data support direct relationships between markers of brain metabolism such as pO2, CBF, T and brain monoamine[s], indicating the coupled in vivo methodology: oxymetry-voltammetry as a rapid in vivo tool for analyses of such indicators in psychiatric disorders.

Possible glutamatergic and lipid signalling mechanisms in ECT-induced retrograde amnesia: experimental evidence for involvement of COX-2, and review of literature

We sought to explore nonselective vs. selective COX mechanisms in ECS-induced retrograde amnesia using indomethacin and celecoxib as in vivo probes. Adult Wistar rats (n=72) which showed adequate learning on a passive avoidance task received 5 once-daily 30 mC true or sham ECS. During the learning and ECS periods, indomethacin (4 mg/kg/day), celecoxib (15 mg/kg/day), or vehicle were orally administered. One day after the fifth ECS, recall of pre-ECS learning was tested. There were no baseline or pre-ECS differences in learning between groups. ECS seizure duration did not differ across groups. ECS-treated rats showed impaired recall in the vehicle but not indomethacin and celecoxib groups. Celecoxib but not indomethacin significantly protected against ECS-induced retrograde amnesia. We interpret these results as follows: ECS may impair cognition by pathologically upregulating glutmatergic signalling, thereby causing cation and water influx, oxidative stress, and saturation of hippocampal LTP. These may result from glutamatergic disinhibition through COX-2-mediated removal of endogenous cannabinoids, and by ECS-activated, NMDA-mediated upregulation of platelet activating factor and COX-2 signalling pathways. Thus, indomethacin and celecoxib, by inhibiting COX-2, may protect against ECS-induced amnesia. Furthermore, COX-2 mediated increase in hippocampal kynurenic acid may impair glutamate-dependent learning and memory processes at ionotropic glutamatergic receptor sites; the inhibition of kynurenic acid synthesis by celecoxib and its induction by indomethacin may explain the greater benefits with celecoxib. These findings suggest new avenues for the study of the neurobiology of ECT-induced amnesia and the attenuation thereof.

Celecoxib as an in vivo probe of cyclooxygenase-2 mechanisms underlying retrograde amnesia in an animal model of ECT

BACKGROUND

Cyclooxygenase-2 (COX-2) mechanisms are involved in glutamate-mediated learning and memory as well as in glutamatergic excitotoxicity. Electroconvulsive therapy (ECT)-induced amnesia may arise from glutamatergic excitotoxicity; if so, COX-2 inhibition may attenuate retrograde amnesia with ECT.

METHODS

Wistar rats which received celecoxib (15 mg/kg per day) or vehicle for 18 days were trained for 3 days on a passive avoidance task. On each of the next 3 days, rats which showed perfect learning (n=51) received true or sham suprathreshold electroconvulsive shocks (ECS; 60 mC) in a factorial design; daily dosing with drug or vehicle was continued. One day after the last ECS, recall of pre-ECS learning was tested.

RESULTS

ECS-treated rats showed impaired recall in the vehicle but not celecoxib group. Celecoxib significantly protected against ECS-induced retrograde amnesia; this benefit was independent of the drug-induced attenuation of ECS seizure duration.

CONCLUSIONS

Celecoxib may protect against ECS-induced retrograde amnesia by attenuating ECS-induced, COX-2-mediated glutamatergic excitotoxicity.

The impact of galantamine on cognition and mood during electroconvulsive therapy: a pilot study

OBJECTIVES

The purpose of this study was to: (1) assess the effectiveness of galantamine in the prevention of cognitive impairments during ECT treatment and (2) to explore the safety and tolerability of galantamine during ECT treatment.

METHODS

Nine consecutive ECT patients were given galantamine 4 mg bid throughout the course of their ECT treatments followed by a second cohort of eight consecutive ECT patients who did not receive galantamine. Objective measures of cognitive functioning and depression severity were performed pre-ECT and post-ECT. Subjective ratings of depression, confusion, and side effects were obtained weekly.

RESULTS

The two groups were similar in age, gender and admission Global Assessment Functioning (GAF) scores. There were no significant between group differences found with regards to mean seizure duration, energy administered to induce seizures, blood pressure, or heart rate during and post-ECT treatment. None of the patients discontinued galantamine due to side effects and there were no severe adverse drug reactions. Patients receiving galantamine performed significantly better on delayed memory and abstract reasoning following ECT. The galantamine group showed a greater but non-significant mood improvement (repeated measure ANOVA).

CONCLUSIONS

Our data support the hypothesis that galantamine may reduce cognitive impairment during ECT, especially with regards to new learning. In addition, galantamine may also enhance the antidepressant action of ECT. Galantamine was both safe and well tolerated during ECT.

Pharmacological attenuation of electroconvulsive therapy--induced cognitive deficits: theoretical background and clinical findings

Electroconvulsive therapy (ECT) is an effective treatment for depression and other psychiatric disorders. However, the practice of ECT is limited by memory and nonmemory cognitive adverse effects. Technical strategies such as a preference for unilateralover bilateral ECT and low-dose over high-dose stimulation reduce these cognitive adverse effects but may also be associated with lesser treatment efficacy or slower treatment response. This article therefore reviews the use of psychopharmacological agents in the attenuation of ECT-induced cognitive deficits with 2 objectives: the identification of implicated mechanisms and the identification of putative efficacy in both animal and human studies. Drugs examined include N-methyl-d-aspartate receptor antagonists, cyclooxygenase inhibitors, calcium channel blockers, cholinesterase inhibitors, glucocorticoid receptor antagonists, thyroid hormones, opioid antagonists, NO donors, nootropic agents, and other medications. Although the clinical data at present are sparse and inconsistent, many recently opened lines of research improve our understanding of the mechanisms involved as well as suggest possible avenues for the testing of new treatments with the potential to attenuate the cognitive adverse effects of ECT.

Neurobiological correlates of the cognitive side effects of electroconvulsive therapy

Although electroconvulsive therapy (ECT) is a highly effective form of treatment, its use is limited by the emergence of cognitive side effects, notably anterograde and retrograde amnesia. Despite a large literature on the neurobiology of therapeutic mechanisms of ECT, very little is known about the neurobiological underpinnings of its cognitive effects. On theoretical grounds, structures within the medial temporal lobes, especially the hippocampus, are predicted to be critical regions mediating anterograde and, possibly, retrograde amnesia. However, functional neuroimaging studies in normal volunteers have demonstrated that frontal cortical regions are also involved in human memory processes. This review will highlight some of the biochemical, electrophysiological, and neuroimaging correlates of the amnestic side effects of ECT. In terms of electrophysiological and functional imaging studies, there are data that implicate both medial temporal and frontal regions as being associated with cognitive dysfunction. Interestingly, such data also appear to indicate a dissociation of the neural systems critical to the efficacy and adverse cognitive effects of ECT.

Brain temperature may influence mood: a hypothesis

Lowering core body and brain temperature has been shown to be beneficial for multiple sclerosis, cardiovascular accidents, traumatic brain injuries and myocardial infarction. Svante Arrhenius' rate law governs human thermoregulation and all biochemical reactions including complex chemical processes involved in mood disorders. We reviewed the studies on core body and brain temperature's influence on mood, mood disorders and their treatment. Our review suggests the majority of therapeutic strategies against mania are hypothermic while thermogenic strategies are used to combat depressive disorders. We hypothesize that therapeutic manipulation of brain temperature may represent a key mechanism in the treatment of mood disorders possibly because of brain temperature's profound influence on human biology governed by Svante Arrhenius' rate law. We postulate that brain temperature may rise with mania and fall with depression.

Glucocorticoid mechanisms may contribute to ECT-induced retrograde amnesia

RATIONALE

Cortisol levels rise sharply immediately after electroconvulsive therapy (ECT); the resultant stimulation of steroid receptors in the hippocampus may be beneficial or harmful to cognition, depending on the magnitude of the stimulation. Steroid mechanisms may therefore modulate ECT-induced amnesia.

OBJECTIVES

Using mifepristone (a glucocorticoid receptor antagonist) as a chemical probe, we sought to examine steroid mechanisms in an animal model of ECT-induced retrograde amnesia.

MATERIALS AND METHODS

Adult, male Wistar rats (n = 68) trained in a step-through passive-avoidance task were randomized to receive mifepristone (20 or 40 mg kg(-1) day(-1)) or vehicle (control). These treatments were administered 1 day before the electroconvulsive shock (ECS) course and, again, 1 h before each of five once-daily true (30 mC) or sham ECS. Recall of pre-ECS learning was tested 1 day after the last ECS.

RESULTS

Relative to sham ECS, true ECS resulted in significant retrograde amnesia in the vehicle group but not in either of the mifepristone groups. In sham ECS-treated animals, mifepristone did not significantly influence recall. In ECS-treated rats, the higher but not the lower dose of mifepristone was associated with significant protection against the retrograde amnesia evident in the vehicle group.

CONCLUSION

Mifepristone administered before the ECT seizure may attenuate ECT-induced retrograde amnesia. This suggests that glucocorticoid mechanisms may contribute to ECT-induced retrograde amnesia.

Therapeutic and prophylactic utility of the memory-enhancing drug donepezil hydrochloride on cognition of patients undergoing electroconvulsive therapy: a randomized controlled trial

OBJECTIVES

Substantial progress has been made in identifying how the treatment parameters used in electroconvulsive therapy (ECT) impact its cognitive side effects. However, there is limited information regarding the role of memory enhancers in post-ECT cognitive disturbances. We evaluated the therapeutic and prophylactic efficacy of the memory-enhancing drug donepezil hydrochloride on cognition of patients undergoing ECT.

METHODS

A triple blind (the study subjects, clinician assessing the cognition, and the data analyst were unaware of subject allocation for trial assessment) randomized controlled trial was carried out in a General Hospital Psychiatry Unit. Subjects were randomized into 2 groups. One group received ECT with placebo, whereas the other group received ECT and donepezil (a memory-enhancing drug). Study participants were assessed in post-ECT period to analyze cognitive deficits and to compare the differences in 2 groups, as regards recovery of various aspects of cognition.

RESULTS

The post-ECT recovery of various components of cognition was more rapid in patients using donepezil as compared to those not given donepezil (P < 0.05).

CONCLUSIONS

This significant improvement in recovery time among patients receiving donepezil bears therapeutic implication in immediate post-ECT cognitive deficits.

Chronic lithium chloride administration to unanesthetized rats attenuates brain dopamine D2-like receptor-initiated signaling via arachidonic acid

We studied the effect of lithium chloride on dopaminergic neurotransmission via D2-like receptors coupled to phospholipase A2 (PLA2). In unanesthetized rats injected i.v. with radiolabeled arachidonic acid (AA, 20:4 n-6), regional PLA2 activation was imaged by measuring regional incorporation coefficients k* of AA (brain radioactivity divided by integrated plasma radioactivity) using quantitative autoradiography, following administration of the D2-like receptor agonist, quinpirole. In rats fed a control diet, quinpirole at 1 mg/kg i.v. increased k* for AA significantly in 17 regions with high densities of D2-like receptors, of 61 regions examined. Increases in k* were found in the prefrontal cortex, frontal cortex, accumbens nucleus, caudate-putamen, substantia nigra, and ventral tegmental area. Quinpirole, 0.25 mg/kg i.v. enhanced k* significantly only in the caudate-putamen. In rats fed LiCl for 6 weeks to produce a therapeutically relevant brain lithium concentration, neither 0.25 mg/kg nor 1 mg/kg quinpirole increased k* significantly in any region. Orofacial movements following quinpirole were modified but not abolished by LiCl feeding. The results suggest that downregulation by lithium of D2-like receptor signaling involving PLA2 and AA may contribute to lithium's therapeutic efficacy in bipolar disorder.

Chronic lithium administration to rats selectively modifies 5-HT2A/2C receptor-mediated brain signaling via arachidonic acid

The effects of chronic lithium administration on regional brain incorporation coefficients k* of arachidonic acid (AA), a marker of phospholipase A2 (PLA2) activation, were determined in unanesthetized rats administered i.p. saline or 1 mg/kg i.p. (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), a 5-HT2A/2C receptor agonist. After injecting [1-(14)C]AA intravenously, k* (brain radioactivity/integrated plasma radioactivity) was measured in each of 94 brain regions by quantitative autoradiography. Studies were performed in rats fed a LiCl or a control diet for 6 weeks. In the control diet rats, DOI significantly increased k* in widespread brain areas containing 5-HT2A/2C receptors. In the LiCl-fed rats, the significant positive k* response to DOI did not differ from that in control diet rats in most brain regions, except in auditory and visual areas, where the response was absent. LiCl did not change the head turning response to DOI seen in control rats. In summary, LiCl feeding blocked PLA2-mediated signal involving AA in response to DOI in visual and auditory regions, but not generally elsewhere. These selective effects may be related to lithium's therapeutic efficacy in patients with bipolar disorder, particularly its ability to ameliorate hallucinations in that disease.

Lithium alters measures of auditory gating in two strains of mice

BACKGROUND

There are similarities between schizophrenia and bipolar disorder, especially during the psychotic phase. Auditory gating deficits are common in both schizophrenia (does not remit postpsychotic event) and bipolar disorder (only during the manic phase). Lithium has been used to treat psychosis acutely in both bipolar disorder and schizophrenia. An animal model was used to assess the effects of lithium treatment on normal and deficient auditory gating.

METHODS

Mice of the DBA/2 (deficient gating) and C3H (normal gating) strains were treated for 6 weeks with either standard rodent chow or rodent chow supplemented with 2.55g/kg lithium carbonate. After 6 weeks of treatment, auditory evoked potentials were recorded under anesthesia. Differences between the groups and treatments were determined using analysis of variance.

RESULTS

The normally impaired DBA/2 mice showed improved auditory gating following lithium treatment, while the C3H mice, the benchmark "normal" mouse strain, were impaired after lithium treatment.

CONCLUSIONS

C3H mice treated with lithium had significantly impaired auditory gating as a result of treatment. This may be due to norepinephrine facilitation, through a blockade of presynaptic alpha(2) autoreceptors. DBA/2 mice had improved gating as a result of treatment with lithium, likely due to improved functioning of the gamma-aminobutyric acid system.

Chronic lithium administration potentiates brain arachidonic acid signaling at rest and during cholinergic activation in awake rats

Studies were performed to determine if the reported 'proconvulsant' action of lithium in rats given cholinergic drugs is related to receptor-initiated phospholipase A2 signaling via arachidonic acid. Regional brain incorporation coefficients k* of intravenously injected [1-14C]arachidonic acid, which represent this signaling, were measured by quantitative autoradiography in unanesthetized rats at baseline and following administration of subconvulsant doses of the cholinergic muscarinic agonist, arecoline. In rats fed LiCl for 6 weeks to produce a therapeutically relevant brain lithium concentration, the mean baseline values of k* in brain auditory and visual areas were significantly greater than in rats fed control diet. Arecoline at doses of 2 and 5 mg/kg intraperitoneally increased k* in widespread brain areas in rats fed the control diet as well as the LiCl diet. However, the arecoline-induced increments often were significantly greater in the LiCl-fed than in the control diet-fed rats. Lithium's elevation of baseline k* in auditory and visual regions may correspond to its ability in humans to increase auditory and visual evoked responses. Additionally, its augmentation of the k* responses to arecoline may underlie its reported 'proconvulsant' action with cholinergic drugs, as arachidonic acid and its eicosanoid metabolites can increase neuronal excitability and seizure propagation.

Choline rise in the rat hippocampus induced by electroconvulsive shock treatment

BACKGROUND

Human hippocampal choline decreases in major depression episodes. This decrease was recently measured by 1H magnetic resonance spectroscopy (MRS), and it has been found that its level normalizes during antidepressive electroconvulsive therapy. We hypothesized a hippocampal choline increase in the rat brain under electroconvulsive shock (ECS) treatment.

METHODS

Rat hippocampi (n = 28) were investigated via magnetic resonance spectroscopy and signal intensities of choline (Cho), total creatine (tCr), and N-acetyl aspartate (NAA) were measured and expressed as ratios before and after six ECS treatments.

RESULTS

After ECS treatment, hippocampal choline increases significantly: Cho/tCr ratio: +13% and Cho/NAA ratio: +19% increase.

CONCLUSIONS

We found a rise of relative choline concentration induced by ECS treatment in rat hippocampus measured in vivo with magnetic resonance spectroscopy. This increase corresponds to the increase of choline in human hippocampus after electroconvulsive shock treatment. Because choline measured via 1H-spectroscopy is believed to represent primarily phosphocholine and glycerophosphocholine, and therefore phospholipase A2 activity and membrane turnover, our results are in good agreement with reported ECS-induced hippocampal mossy fiber sprouting, increased synaptic plasticity, and neurogenesis.

Electroconvulsive therapy in a patient receiving rivastigmine

We report the case of an 81-year-old woman, suffering from a major depressive episode and incipient Alzheimer disease, whom we treated with ECT without interrupting therapy with the acetylcholinesterase inhibitor (ACHE-I) rivastigmine. After eight right unilateral ECT sessions, the patient remitted completely without any significant deterioration of memory and cognitive abilities or cholinergic side effects. This report demonstrates that ECT was safely used in one elderly and mildly demented person with continuous ACHE-I therapy. The hypothesis that this drug may indeed protect against unfavorable side effects of ECT should be further tested in clinical trials.

Subtypes of memory dysfunction associated with ECT: characteristics and neurobiological bases

Electroconvulsive therapy (ECT) is an effective treatment for a variety of psychiatric syndromes. However, one of its adverse secondary effects is neurocognitive dysfunction. The aim of this paper is to review different subtypes of memory dysfunction associated with ECT from a neuropsychological perspective. Declarative memory is clearly impaired after ECT. Immediate memory, however, is broadly preserved. Few studies have addressed procedural and incidental memory. Selective memory is impaired, probably due to the disruption of specific brain regions. Some of the possible neurobiological bases of ECT memory dysfunction are discussed in this paper. Synaptic plasticity, the cerebral neurotransmission system, and cerebral metabolism are examined in relation to the dysfunction and subsequent recovery of each memory subtype.

Pharmacological adaptations and muscarinic receptor plasticity in hypothalamus of senescent rats treated chronically with cholinergic drugs

Receptor plasticity is an important compensatory process by which the central nervous system adapts to pathological insult or long-term exposure to drugs. Senescent animals may show an age-related impairment of muscarinic receptor up- or down-regulation after chronic exposure to cholinergic drugs. The purpose of this study was to assess biochemical and pharmacological endpoints of muscarinic receptor plasticity in young, adult and senescent animals. Male, Fischer 344 rats (ages 3, 9, and 27 months) were administered methylatropine or oxotremorine intracerebroventricularly (IVT) for 3 weeks and tested for their functional response to a muscarinic agonist. The density of hypothalamic, muscarinic receptors was also estimated from analysis of 3H-QNB binding isotherms. In young rats, parallel changes in muscarinic receptors and response were noted, but chronic administration of cholinergic drugs to senescent animals had no effect. Thus, 3H-QNB binding in hypothalamus of young and adult rats was increased (31% and 17%) after chronic IVT methylatropine and decreased (20% and 15%) after IVT oxotremorine. Also, young rats treated with IVT methylatropine were supersensitive to the hypothermic effects of a muscarinic agonist (oxotremorine), while young and adult animals administered chronic IVT oxotremorine exhibited marked tolerance. In contrast, identically treated senescent rats showed no changes in 3H-QNB binding or oxotremorine-induced hypothermia. These results demonstrate the impaired ability of senescent rats to up- or down-regulate brain muscarinic receptors and to exhibit functional adaptations seen in young animals treated chronically with cholinergic drugs.

NS-3, a TRH analog, reverses repeated ECS-induced deficits in water maze performance in the rat

Rats given five consecutive daily electroconvulsive shock (ECS) treatments and trained to run in the Morris water maze, starting three days posttreatment, showed deficits in learning and memory functions. Treatment before each training session with the thyrotropin-releasing hormone (TRH) analog NS-3 [(CG-3703), (3R),(6R)-6-methyl-5-oxo-3-thiomorphorinyl-l-histidyl-l-prolinamid e tetrahydrate] reversed these behavioral deficits. The possible use of TRH and its analogs as therapeutic treatment for the cognitive dysfunctions resulting from electroconvulsive shock treatment for depression and the possible involvement of central cholinergic systems in the cognitive dysfunctions are discussed.

The Flinders sensitive line rats: a genetic animal model of depression

The Flinders Sensitive Line (FSL) rat, selectively bred for increased responses to the anticholinesterase DFP, was originally proposed as an animal model of depression because, like depressed humans, it is supersensitive to the behavioral and hormonal effects of cholinergic (muscarinic) agonists. The present review critically examines earlier and recent data collected on FSL rats to assess whether the model has good face, construct and/or predictive validity. With respect to face validity, FSL rats resemble depressed humans, at least superficially, in that they demonstrate: (a) reduced locomotor activity, (b) reduced body weight, (c) increased REM sleep, and (d) cognitive (learning) difficulties. So far, studies designed to assess the presence of anhedonia, a cardinal symptom of melancholic depression, have been inconclusive, but there are trends for the FSL rats to be more anhedonic than their control counterparts, the Flinders Resistant Line (FRL) rats, when exposed to chronic mild stress. Thus, FSL rats fulfill the criterion of face validity. Because FSL rats also are more sensitive to cholinergic agonists and have phase advanced circadian rhythms, they meet the criteria for the cholinergic and circadian rhythm models of depression and, therefore, have good construct validity. A key behavioral symptom exhibited by the FSL rat is demonstration of an exaggerated immobility when exposed to stressors such as foot shock and forced swimming. This behavioral abnormality has been normalized by a number of well-recognized antidepressant drugs such as imipramine and desipramine, as well as newer generation antidepressants with promising clinical effects such as sertraline and rolipram. However, several treatments that have not been routinely used to treat depression (lithium, exposure to bright light, the anticholinesterase DFP) have been ineffective in reversing the exaggerated immobility. Thus, the evidence in the present review indicates that the FSL rat model of depression fulfills the criteria of face, construct, and predictive validities.

Increased CSF HVA response to arecoline challenge in Alzheimer's disease

The effects of the muscarinic agonist, arecoline, on the concentration of homovanillic acid (HVA) in the cerebrospinal fluid of patients with Alzheimer's disease (AD) and controls were examined. Patients and controls received intravenous infusions of arecoline and a lumbar puncture was performed four hours after the infusion began. Arecoline induced a significant increase in the concentration of HVA in cerebrospinal fluid of Alzheimer's disease patients (p < .01) but not in controls. The differential HVA response to a muscarinic agonist in Alzheimer's disease is suggestive of an alteration in muscarinic receptor response. This finding may have potential implications for the pathophysiology and treatment of Alzheimer's disease.

Clinical and biochemical aspects of depressive disorders: II. Transmitter/receptor theories

The present document is the second of three parts in a review that focuses on recent data from clinical and animal research concerning the biochemical bases of depressive disorders, diagnosis, and treatment. Various receptor/transmitter theories of depressive disorders are discussed in this section. Specifically, data supporting noradrenergic, serotonergic, cholinergic, dopaminergic, GABAergic, and peptidergic theories, as well as interactions between noradrenergic and serotonergic, or cholinergic and catecholaminergic systems are presented. Problems with the data and future directions for research are also discussed. A previous publication, Part I of this review, dealt with the classification of depressive disorders and research techniques for studying the biochemical mechanisms of these disorders. A future publication, Part III of this review, discusses treatments for depression and some of the controversies in this field.

Lithium and electroconvulsive therapy: adversaries, competitors, allies?

As treatments for manic-depressive illness, lithium and electroconvulsive therapy (ECT) share the properties of efficacy, diagnostic specificity, and action on both mania and depression. Therapeutic and prophylactic similarities and dissimilarities are analyzed, as well as the use of lithium continuation treatment following ECT. Possible adverse interaction is discussed, and a strategy is proposed for studying biologic modes of action.

Electroconvulsive therapy. Current concepts

Recent developments in the practice and theory of ECT are reviewed. Indications, efficacy, and risk/benefit considerations are discussed with emphasis on the clinical utility and cost-effectiveness of increased and earlier usage of ECT in hospitalized patients. Treatment procedures are presented in some detail with listings of medical considerations, management of complications, and other applications to general hospital practice. Research on the mechanism of action, potential future developments, and some training issues are briefly discussed.

The effect of imipramine and lithium on "learned helplessness" and acetylcholinesterase in rat brain

The effect of short- and long-term treatment with imipramine and lithium on shock stress-induced escape failures in a shuttlebox (the "learned helplessness" model of depression) was investigated in rats. Acetylcholinesterase (AChE) activity was measured in the frontal cortex, hippocampus and striatum after the shuttlebox test. Imipramine was found to normalize escape behavior, whereas lithium further aggravated escape behavior. No correlation was found between escape behavior and AChE activity in the three brain areas investigated. However, a significant decrease in AChE activity in striatum was found in rats exposed either to shock stress and no drug treatment or to drug treatment and no shock stress. In rats exposed to the combination of shock stress and drug (imipramine or lithium), a slight or no decrease of AChE activity occurred. Exposure to shock stress alone produced no changes in AChE activity in the hippocampus and frontal cortex. In conclusion, lithium did not have an antidepressant effect on "learned helplessness" and AChE activity was not correlated to escape behavior. However, both imipramine and lithium normalized the decreased level of AChE activity in striatum in rats exposed to shock stress.

Lithium enhances neuronal muscarinic excitation by presynaptic facilitation

The mechanisms underlying the psychotropic actions of lithium are not established, but modulation of endogenous brain neurotransmitter systems is likely to be important. Several interactions of lithium with muscarinic responses have been reported, including a marked potentiation of seizures produced by muscarinic agonists. Because the mechanism by which lithium augments muscarinic seizures may be related to the mechanism by which it produces its psychotropic effects, we have studied the interaction of lithium and muscarinic agonists in vitro. Using rat hippocampal slices, we found that a muscarinic agonist, pilocarpine, increased postsynaptic neuronal excitability, but simultaneously decreased synaptic transmission because of presynaptic inhibition. Lithium did not alter pilocarpine's postsynaptic excitatory actions, but reversed its presynaptic inhibitory action, leading to markedly increased action potential firing. These presynaptic effects are not caused by alterations in presynaptic action potential shape or reliability of conduction, and do not involve pertussis toxin-sensitive G proteins. Activation of protein kinase C with phorbol-12,13-dibutyrate, or inhibition with H-7 and sphingosine, did not affect muscarinic presynaptic inhibition, but abolished lithium's ability to enhance synaptic transmission, suggesting that this effect of lithium involves protein kinase C. We propose that presynaptic facilitation accounts for lithium's potentiation of muscarinic seizures. Since these effects occur with concentrations of lithium used clinically, similar presynaptic effects in endogenous brain neurotransmitter systems may be important for lithium's psychotropic actions.

Peripheral versus central manifestations in the toxic interaction of lithium and pilocarpine

Administration of a cholinomimetic agent 24 hr after a single injection of lithium chloride results in a profoundly toxic interaction. The lethality of the interaction was completely blocked by prior administration of scopolamine, but was not reduced by the peripherally acting cholinergic antagonist methscopolamine. Examination of the relative time courses of central neurotoxic and peripheral cholinergic manifestations showed that the peripheral manifestations were transient and were not enhanced by lithium pretreatment. The profoundly toxic consequences of lithium-cholinomimetic interaction may thus occur in the absence of enhanced cholinergic function in the periphery.

Chronic electroconvulsive shock and neurotransmitter receptors--an update

Electroconvulsive shock (ECS) produces many neurochemical alterations which may be related to its efficacy in the treatment of different psychiatric disorders. This review focuses particularly on experimental findings of CNS receptor changes in animals following chronic ECS and relates them to neurotransmitter and behavioral changes. Also, the pharmacological effect of other antidepressant treatment are compared. Possible mechanisms of action are discussed.

Amitriptyline-induced supersensitivity of a central muscarinic mechanism: lithium blocks amitriptyline-induced supersensitivity

Chronic treatment with amitriptyline produces dose-dependent super-sensitivity of a central muscarinic cholinergic mechanism involved in the regulation of core body temperature. The authors demonstrated that chronic treatment with lithium prevents the induction of this response. The potential clinical and theoretical significance of this finding is set forth.

Genetic and pharmacological models of cholinergic supersensitivity and affective disorders

Increased muscarinic sensitivity has been associated with altered hormonal states (hypothyroidism and hyperadrenocorticism), chronic administration of muscarinic antagonists or antidepressants with muscarinic actions, selective breeding for anticholinesterase sensitivity, and certain inbred strains of rats and mice. Thus, both genetic and environmental factors may influence muscarinic receptor sensitivity. The reasonably detailed studies on the selectively-bred rats have revealed that the Flinders Sensitive Line (FSL) rats weigh less, are less active, are more sensitive to muscarinic agonists and to stressors, and have higher concentrations of hippocampal and striatal muscarinic receptors than 'normal', or the selectively-bred, Flinders Resistant Line (FRL) rats. Thus, there are a number of parallels between FSL rats and depressed humans. The FSL rats may be the first animal model of depression to mimic the actual trait of depression, and not just the state.

Acetylcholine content in rat brain is elevated by status epilepticus induced by lithium and pilocarpine

The effects of status epilepticus on the concentration, synthesis, release, and subcellular localization of acetylcholine, the concentration of choline, and the activity of acetylcholinesterase in rat brain regions were studied. Generalized convulsive status epilepticus was induced by the administration of pilocarpine to lithium-treated rats. The concentration of acetylcholine in the cortex, hippocampus, and striatum decreased prior to the onset of spike activity or status epilepticus. Once status epilepticus began, the concentration of acetylcholine increased over time in the cortex and hippocampus, reaching peak levels that were 461% and 304% of control levels, respectively, after 2 h of seizures. Such high in vivo levels of acetylcholine had not been reported previously following any treatment. During status epilepticus, the concentration of acetylcholine in the striatum returned to control levels after the initial depression, but did not accumulate to high levels as it did in the other two regions. The in vivo cortical efflux of acetylcholine was also increased during the seizures. Choline levels were increased by status epilepticus in all three brain regions. Inhibition of seizures by pretreatment with atropine blocked the increases of acetylcholine and choline. Synaptosomes prepared from the cortex and from the hippocampus of rats with status epilepticus had elevated concentrations of acetylcholine: in the hippocampus the acetylcholine was principally in the cytoplasmic fraction, whereas in the cortex the acetylcholine was elevated in both the cytoplasmic and the vesicular fractions. The extra acetylcholine was in a releasable compartment, since increased K+ in the media or ouabain increased the release of acetylcholine from cortical slices to a greater extent in tissue from seized rats than from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Conditioned avoidance acquisition and extinction following repeated electroconvulsive shock: strain effect and response to vasopressin

Male albino rats (Sabra strain) were exposed to electroconvulsive shock (ECS) once daily for periods ranging from 1 to 13 days, and proactive effects on conditioned avoidance response (CAR) acquisition and extinction were studied. CAR acquisition was intact following both single and repeated ECS, but extinction was accelerated by multiple ECS administration. These findings resembled the effect of repeated ECS on anterograde memory function in humans and confirmed previous observations based on a passive avoidance paradigm. However, extinction was not accelerated in a different rat strain (LC2). Parallel open field activity measures suggested that these findings were not related to ECS-induced alterations in locomotor activity. Administration of arginine vasopressin prior to each ECS, or following acquisition sessions, as well as 1-desamino-8-D-arginine vasopressin administration following acquisition sessions, did not ameliorate ECS-induced deficits in the Sabra rats. Differences between the present paradigm of ECS administration and those in which positive effects of vasopressin and other neuropeptides have been reported are discussed. The potential research applications of a rodent model of ECS-induced memory impairment that parallels deficits encountered in the clinical context are considered.

Cholinergic mechanisms in affective disorders. Future directions for investigation

Advances in clinical and basic research methodology combined with clearly articulated concepts create new opportunities for researching the roles of cholinergic mechanisms in the pathophysiology of affective disorders. Areas for study include: roles of cholinergic mechanisms in mediating effects of stress and cholinergic mechanisms linking the pathophysiologies of affective and panic disorders, use of pharmacologic agents to produce cholinergic system supersensitivity in modeling biologic aspects of affective illness, use of multigenerational intrapedigree studies of cholinergic markers associated with affective disease, research into the neurobiology of lithium and ECT as they pertain to muscarinic cholinergic mechanisms, study of the interrelationship of sodium, calcium and lithium ion metabolism and their relationship to cholinergic-monoaminergic interaction, the development of brain imaging strategies and techniques, e.g., positron emission tomography (PET), to measure changes in cholinergic receptor density and affinity as a function of clinical state, identification and validation of a peripheral model of the central muscarinic receptor, study of the pharmacology of abusable substances and its relationship to mechanisms regulating mood, affect, psychomotor function and other variables related to the affective disorders, and development of in vitro and in vivo models useful in studying the physiology and biochemistry of the interaction of cholinergic and monoaminergic neurons. These models may allow us to bridge the traditional cholinergic and monoamine hypotheses of affective disorders.

Stress-induced immobility in rats with cholinergic supersensitivity

Immobility during forced swimming or after mild footshock (1 mA for 2 sec) was observed in five groups of rats. The Flinders Sensitive Line (FSL) of rats, known to be more sensitive to cholinergic agonists, exhibited the greatest degree of immobility in the forced swim test. Rats chronically treated with, and subsequently withdrawn from, either scopolamine (2 mg/kg, once daily) or amitriptyline (10 mg/kg, once daily) were also significantly more immobile than either a control group treated chronically with isotonic saline or the Flinders Resistant Line (FRL) of rats in the forced swim test. Similar trends were observed for locomotor depression in the open field following exposure to footshock. Receptor binding studies indicated significantly greater concentrations of muscarinic acetylcholine receptors in the hippocampus of the scopolamine, and amitriptyline, withdrawn rats. These findings indicate that rats with increased cholinergic sensitivity are more sensitive to the immobility-inducing effects of mild stressors. Thus, they may prove to be useful models for studying the relationship between affective disorders and the cholinergic system.