Thoracic spine thrust manipulation for individuals with cervicogenic headache: a crossover randomized clinical trial.

OBJECTIVE: To determine if thoracic spine manipulation (TSM) improves pain and disability in individuals with cervicogenic headache (CeH). METHODS: A randomized controlled crossover trial was conducted on 48 participants (mean age: 34.4 years) with CeH symptoms. Participants were randomized to 6 sessions of TSM or no treatment (Hold) and after 4-weeks, groups crossed over. Outcomes were collected at 4, 8 and 12 weeks and included: headache disability inventory (HDI), neck disability index (NDI), and the global rating of change (GRC). Outcomes were analyzed using a linear mixed-effects model with Bonferroni correction. Odds of achieving the minimal clinically important difference (MCID) on the GRC of +4 or greater were also calculated. Scores at 4 weeks represent the only timepoint where 1 group is fully treated and other group has not received any treatment. RESULTS: Comparing hold to active treatment, HDI were not significantly different between groups (mean difference = 7.39, 95 CI: -4.39 to 19.18; P = 0.214) at any timepoint; the NDI was significant (mean difference = 6.90, 95 CI: 0.05 to 13.75; P = 0.048) at 4 weeks. Odds of achieving the +4 MCID on the GRC (OR = 38.0, 95 CI: 6.6 to 220.0; p < 0.001) favored TSM at 4 weeks. CONCLUSION: TSM had no effect on headache-related disability but resulted in significant improvements in neck-related disability and participant reported perceived improvement. Future studies are needed to examine the long-term impact of TSM in this population.

Inhibition of neuroinflammatory nitric oxide signaling suppresses glycation and prevents neuronal dysfunction in mouse prion disease.

Several neurodegenerative diseases associated with protein misfolding (Alzheimer's and Parkinson's disease) exhibit oxidative and nitrergic stress following initiation of neuroinflammatory pathways. Associated nitric oxide (NO)-mediated posttranslational modifications impact upon protein functions that can exacerbate pathology. Nonenzymatic and irreversible glycation signaling has been implicated as an underlying pathway that promotes protein misfolding, but the direct interactions between both pathways are poorly understood. Here we investigated the therapeutic potential of pharmacologically suppressing neuroinflammatory NO signaling during early disease progression of prion-infected mice. Mice were injected daily with an NO synthase (NOS) inhibitor at early disease stages, hippocampal gene and protein expression levels of oxidative and nitrergic stress markers were analyzed, and electrophysiological characterization of pyramidal CA1 neurons was performed. Increased neuroinflammatory signaling was observed in mice between 6 and 10 wk postinoculation (w.p.i.) with scrapie prion protein. Their hippocampi were characterized by enhanced nitrergic stress associated with a decline in neuronal function by 9 w.p.i. Daily in vivo administration of the NOS inhibitor L-NAME between 6 and 9 w.p.i. at 20 mg/kg prevented the functional degeneration of hippocampal neurons in prion-diseased mice. We further found that this intervention in diseased mice reduced 3-nitrotyrosination of triose-phosphate isomerase, an enzyme involved in the formation of disease-associated glycation. Furthermore, L-NAME application led to a reduced expression of the receptor for advanced glycation end-products and the diminished accumulation of hippocampal prion misfolding. Our data suggest that suppressing neuroinflammatory NO signaling slows functional neurodegeneration and reduces nitrergic and glycation-associated cellular stress.

Neuropathy target esterase (NTE/PNPLA6) and organophosphorus compound-induced delayed neurotoxicity (OPIDN).

Systemic inhibition of neuropathy target esterase (NTE) with certain organophosphorus (OP) compounds produces OP compound-induced delayed neurotoxicity (OPIDN), a distal degeneration of axons in the central nervous system (CNS) and peripheral nervous system (PNS), thereby providing a powerful model for studying a spectrum of neurodegenerative diseases. Axonopathies are important medical entities in their own right, but in addition, illnesses once considered primary neuronopathies are now thought to begin with axonal degeneration. These disorders include Alzheimer's disease, Parkinson's disease, and motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Moreover, conditional knockout of NTE in the mouse CNS produces vacuolation and other degenerative changes in large neurons in the hippocampus, thalamus, and cerebellum, along with degeneration and swelling of axons in ascending and descending spinal cord tracts. In humans, NTE mutations cause a variety of neurodegenerative conditions resulting in a range of deficits including spastic paraplegia and blindness. Mutations in the Drosophila NTE orthologue SwissCheese (SWS) produce neurodegeneration characterized by vacuolization that can be partially rescued by expression of wild-type human NTE, suggesting a potential therapeutic approach for certain human neurological disorders. This chapter defines NTE and OPIDN, presents an overview of OP compounds, provides a rationale for NTE research, and traces the history of discovery of NTE and its relationship to OPIDN. It then briefly describes subsequent studies of NTE, including practical applications of the assay; aspects of its domain structure, subcellular localization, and tissue expression; abnormalities associated with NTE mutations, knockdown, and conventional or conditional knockout; and hypothetical models to help guide future research on elucidating the role of NTE in OPIDN.

ß1-adrenoceptor-stimulated lactate production in cultured astrocytes is predominantly glycogen-independent.

Noradrenaline (NA) promotes breakdown of the glucose-polymer, glycogen, and hence enhances glycolytic production of lactate in astrocytes. Here, in cultured rat cerebrocortical astrocytes, we examined the contributions of different adrenoceptor subtypes to NA-modulated glucose metabolism, and the relationship of NA-induced glycogenolysis to lactate production. Stimulation of astrocytic glucose metabolism by NA was mediated predominantly via ß1-adrenoceptors and cAMP. Constitutive ß 1-adrenoceptor activity - in the absence of exogenous NA - contributed to the basal rate of glycogen turnover. Although mRNAs encoding both ß 1- and ß 2-adrenoceptors were detected in these astrocytes, ß 2-adrenoceptors contributed little to NA-induced modulation of glucose metabolism. Activation of α2- and α 1-adrenoceptors in these cells decreased cAMP and increased cytosolic Ca2+, respectively, but did not modulate NA-induced glycogenolysis: α 2-adrenoceptors because glycogenolysis was induced maximally by NA concentrations that only began to inhibit cAMP production; and α 1-adrenoceptors possibly because of desensitisation and depletion of Ca2+ stores. Under basal conditions, astrocytes converted glucose to extracellular lactate in near stoichiometric manner. When glucose-starved astrocytes were given fresh glucose-containing medium, lactate accumulation displayed a brief lag period before attaining a steady-state rate. During this lag period NA, acting at ß 1-adrenoceptors, increased the rate of lactate accumulation both in the absence and presence of an inhibitor of glycogen turnover. At the steady-state, the rate of glucose incorporation into accumulated glycogen was ~ 5% of that into lactate, but NA enhanced lactate output by 20-50%: this further indicates that NA, via ß 1-adrenoceptors and cAMP, can enhance astrocytic lactate production independently of its effect on glycogen turnover.

Derived variants at six genes explain nearly half of size reduction in dog breeds.

Selective breeding of dogs by humans has generated extraordinary diversity in body size. A number of multibreed analyses have been undertaken to identify the genetic basis of this diversity. We analyzed four loci discovered in a previous genome-wide association study that used 60,968 SNPs to identify size-associated genomic intervals, which were too large to assign causative roles to genes. First, we performed fine-mapping to define critical intervals that included the candidate genes GHR, HMGA2, SMAD2, and STC2, identifying five highly associated markers at the four loci. We hypothesize that three of the variants are likely to be causative. We then genotyped each marker, together with previously reported size-associated variants in the IGF1 and IGF1R genes, on a panel of 500 domestic dogs from 93 breeds, and identified the ancestral allele by genotyping the same markers on 30 wild canids. We observed that the derived alleles at all markers correlated with reduced body size, and smaller dogs are more likely to carry derived alleles at multiple markers. However, breeds are not generally fixed at all markers; multiple combinations of genotypes are found within most breeds. Finally, we show that 46%-52.5% of the variance in body size of dog breeds can be explained by seven markers in proximity to exceptional candidate genes. Among breeds with standard weights <41 kg (90 lb), the genotypes accounted for 64.3% of variance in weight. This work advances our understanding of mammalian growth by describing genetic contributions to canine size determination in non-giant dog breeds.

Neuronal phospholipid deacylation is essential for axonal and synaptic integrity.

Recessively-inherited deficiency in the catalytic activity of calcium-independent phospholipase A2-beta (iPLA2ß) and neuropathy target esterase (NTE) causes infantile neuroaxonal dystrophy and hereditary spastic paraplegia, respectively. Thus, these two related phospholipases have non-redundant functions that are essential for structural integrity of synapses and axons. Both enzymes are expressed in essentially all neurons and also have independent roles in glia. iPLA2ß liberates sn-2 fatty acid and lysophospholipids from diacyl-phospholipids. Ca(2+)-calmodulin tonically-inhibits iPLA2ß, but this can be alleviated by oleoyl-CoA. Together with fatty acyl-CoA-mediated conversion of lysophospholipid to diacyl-phospholipid this may regulate sn-2 fatty acyl composition of phospholipids. In the nervous system, iPLA2ß is especially important for the turnover of polyunsaturated fatty acid-associated phospholipid at synapses. More information is required on the interplay between iPLA2ß and iPLA2-gamma in deacylation of neuronal mitochondrial phospholipids. NTE reduces levels of phosphatidylcholine (PtdCho) by degrading it to glycerophosphocholine and two free fatty acids. The substrate for NTE may be nascent PtdCho complexed with a phospholipid-binding protein. Protein kinase A-mediated phosphorylation enhances PtdCho synthesis and may allow PtdCho accumulation by coordinate inhibition of NTE activity. NTE operates primarily at the endoplasmic reticulum in neuronal soma but is also present in axons. NTE-mediated PtdCho homeostasis facilitates membrane trafficking and this appears most critical for the integrity of axon terminals in the spinal cord and hippocampus. For maintenance of peripheral nerve axons, iPLA2ß activity may be able to compensate for NTE-deficiency but not vice-versa. Whether agonists acting at neuronal receptors modulate the activity of either enzyme remains to be determined. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.

Myxomatous mitral valve disease in dogs: does size matter?

Myxomatous mitral valve disease (MMVD) is the most commonly diagnosed cardiovascular disease in the dog accounting for more than 70% of all cardiovascular disease in dogs. As are most canine diseases with genetic underpinnings, risk of MMVD is greatly increased in a subset of breeds. What is uncommon is that the vast majority of the breeds at elevated risk for MMVD are small or toy breeds with average adult weights under 9 kg. These breeds appear to have little in common other than their diminutive size. In the following review we propose a number of mechanisms by which relatively unrelated small breeds may have developed a predisposition for chronic valvular disorders. Although factors such as age are key in the expression of MMVD, taking a comprehensive look at the commonalities, as well as the differences, between the susceptible breeds may assist in finding the causal variants responsible for MMVD and translating them to improved treatments for both dogs and humans.

A treatment-based classification approach to examination and intervention of lumbar disorders.

CONTEXT: Low back injuries are a common occurrence in athletes and often result in missed competition and practice time. The examination of athletes with low back pain commonly involves diagnostic imaging, which rarely guides the clinician in selecting the appropriate interventions. DATA ACQUISITION: All years of PubMed, CINAHL, PEDro, and SPORTDiscus were searched in December 2010. Keywords included treatment based classification and lumbar with the following terms: rehabilitation, treatment, athlete, low back pain, sports, and outcomes. RESULTS: A treatment-based classification approach is preferred for the management of the athlete with low back pain. The treatment-based classification approach involves 3 steps. First is to screen the patient for potentially serious conditions that are not appropriate for conservative management. Second is staging the athlete (based on current disability ratings and ability to perform functional activities). Finally, treatment interventions are selected on the basis of the athlete's signs and symptoms. CONCLUSION: The treatment-based classification scheme provides the clinician with a reliable algorithm for matching an athlete's symptom presentation to the optimal intervention, potentially reducing participation loss. Managing individuals with low back pain using a treatment-based classification approach significantly reduces disability and pain compared with current clinical practice guideline standards.

Examination of a clinical prediction rule to identify patients with neck pain likely to benefit from thoracic spine thrust manipulation and a general cervical range of motion exercise: multi-center randomized clinical trial.

BACKGROUND: A clinical prediction rule (CPR) purported to identify patients with neck pain who are likely to respond to thoracic spine thrust manipulation has recently been developed, but has yet to be validated. OBJECTIVE: The purpose of this study was to examine the validity of this CPR. DESIGN: This was a multi-center randomized clinical trial. METHODS: One hundred forty patients with a primary report of neck pain were randomly assigned to receive either 5 sessions of stretching and strengthening exercise (exercise-only group) or 2 sessions of thoracic spine manipulation and cervical range of motion exercise followed by 3 sessions of stretching and strengthening exercise (manipulation + exercise group). Data on disability and pain were collected at baseline, 1 week, 4 weeks, and 6 months. The primary aim (treatment group x time x status on the prediction rule) was examined using a linear mixed model with repeated measures. Time, treatment group, and status on the rule, as well as all possible 2-way and 3-way interactions, were modeled as fixed effects, with disability (and pain) as the dependent variable. Effect sizes were calculated for both pain and disability at each follow-up period. RESULTS: There was no 3-way interaction for either disability or pain. A 2-way (group x time) interaction existed for both disability and pain. Pair-wise comparisons of disability demonstrated that significant differences existed at each follow-up period between the manipulation + exercise group and the exercise-only group. The patients who received manipulation exhibited lower pain scores at the 1-week follow-up period. The effect sizes were moderate for disability at each follow-up period and were moderate for pain at the 1-week follow-up. LIMITATIONS: Different exercise approaches may have resulted in a different outcome. CONCLUSIONS: The results of the current study did not support the validity of the previously developed CPR. However, the results demonstrated that patients with mechanical neck pain who received thoracic spine manipulation and exercise exhibited significantly greater improvements in disability at both the short- and long-term follow-up periods and in pain at the 1-week follow-up compared with patients who received exercise only.

Organophosphates induce distal axonal damage, but not brain oedema, by inactivating neuropathy target esterase.

Single doses of organophosphorus compounds (OP) which covalently inhibit neuropathy target esterase (NTE) can induce lower-limb paralysis and distal damage in long nerve axons. Clinical signs of neuropathy are evident 3weeks post-OP dose in humans, cats and chickens. By contrast, clinical neuropathy in mice following acute dosing with OPs or any other toxic compound has never been reported. Moreover, dosing mice with ethyloctylphosphonofluoridate (EOPF) - an extremely potent NTE inhibitor - causes a different (subacute) neurotoxicity with brain oedema. These observations have raised the possibility that mice are intrinsically resistant to neuropathies induced by acute toxic insult, but may incur brain oedema, rather than distal axonal damage, when NTE is inactivated. Here we provide the first report that hind-limb dysfunction and extensive axonal damage can occur in mice 3weeks after acute dosing with a toxic compound, bromophenylacetylurea. Three weeks after acutely dosing mice with neuropathic OPs no clinical signs were observed, but distal lesions were present in the longest spinal sensory axons. Similar lesions were evident in undosed nestin-cre:NTEfl/fl mice in which NTE had been genetically-deleted from neural tissue. The extent of OP-induced axonal damage in mice was related to the duration of NTE inactivation and, as reported in chickens, was promoted by post-dosing with phenylmethanesulfonylfluoride. However, phenyldipentylphosphinate, another promoting compound in chickens, itself induced in mice lesions different from the neuropathic OP type. Finally, EOPF induced subacute neurotoxicity with brain oedema in both wild-type and nestin-cre:NTEfl/fl mice indicating that the molecular target for this effect is not neural NTE.

The efficacy of an integrated neuromuscular inhibition technique on upper trapezius trigger points in subjects with non-specific neck pain: a randomized controlled trial.

Currently, large levels of practice variability exist regarding the clinical deactivation of trigger points. Manual physical therapy has been identified as a potential means of resolving active trigger points; however, to date the ideal treatment approach has yet to be elucidated. The purpose of this clinical trial was to compare the effects of two manual treatment regimens on individuals with upper trapezius trigger points. Sixty patients, 19-38 years of age with non-specific neck pain and upper trapezius trigger points, were randomized into one of two, 4 week physical therapy programs. One group received muscle energy techniques while the second group received an integrated neuromuscular inhibition technique (INIT) consisting of muscle energy techniques, ischemic compression, and strain-counterstrain (SCS). Outcomes including a visual analog pain scale (VAS), the neck disability index (NDI), and lateral cervical flexion range of motion (ROM) were collected at baseline, 2 and 4 weeks after the initiation of therapy. Results revealed large pre-post-effect sizes within the INIT group (Cohen's d  =  0.97, 0.94 and 0.97). Additionally, significantly greater improvements in pain and neck disability and lateral cervical flexion ROM were detected in favor of the INIT group (0.29-0.57, 0.57-1.12 and 0.29-0.57) at a 95% CI respectively. The findings of this study indicate the potential benefit of an integrated approach in deactivating upper trapezius trigger points. Further research should be performed to investigate the long-term benefits of the current treatment approach.

Neuropathy target esterase is required for adult vertebrate axon maintenance.

The enzyme neuropathy target esterase (NTE) is present in neurons and deacylates the major membrane phospholipid, phosphatidylcholine (PtdCho). Mutation of the NTE gene or poisoning by neuropathic organophosphates--chemical inhibitors of NTE--causes distal degeneration of long spinal axons in humans. However, analogous neuropathological changes have not been reported in nestin-cre:NTEfl/fl mice with NTE-deficient neural tissue. Furthermore, altered PtdCho homeostasis has not been detected in NTE-deficient vertebrates. Here, we describe distal degeneration of the longest spinal axons in approximately 3-week-old nestin-cre:NTEfl/fl mice and in adult C57BL/6J mice after acute dosing with a neuropathic organophosphate: in both groups early degenerative lesions were followed by swellings comprising accumulated axoplasmic material. In mice dosed acutely with organophosphate, maximal numbers of lesions, in the longest spinal sensory axon tract, were attained within days and were preceded by a transient rise in neural PtdCho. In nestin-cre:NTEfl/fl mice, sustained elevation of PtdCho over many months was accompanied by progressive degeneration and massive swelling of axons in sensory and motor spinal tracts and by increasing hindlimb dysfunction. Axonal lesion distribution closely resembled that in hereditary spastic paraplegia (HSP). The importance of defective membrane trafficking in HSP and the association of NTE with the endoplasmic reticulum--the starting point for the constitutive secretory pathway and transport of neuronal materials into axons--prompted investigation for a role of NTE in secretion. Cultured NTE-deficient neurons displayed modestly impaired secretion, consistent with neuronal viability and damage in vivo initially restricted to distal parts of the longest axons.

Desmethylclomipramine induces the accumulation of autophagy markers by blocking autophagic flux.

Alterations in the autophagic pathway are associated with the onset and progression of various diseases. However, despite the therapeutic potential for pharmacological modulators of autophagic flux, few such compounds have been characterised. Here we show that clomipramine, an FDA-approved drug long used for the treatment of psychiatric disorders, and its active metabolite desmethylclomipramine (DCMI) interfere with autophagic flux. Treating cells with DCMI caused a significant and specific increase in autophagosomal markers and a concomitant blockage of the degradation of autophagic cargo. This observation might be relevant in therapy in which malignant cells exploit autophagy to survive stress conditions, rendering them more susceptible to the action of cytotoxic agents. In accordance, DCMI-mediated obstruction of autophagic flux increased the cytotoxic effect of chemotherapeutic agents. Collectively, our studies describe a new function of DCMI that can be exploited for the treatment of pathological conditions in which manipulation of autophagic flux is thought to be beneficial.

The hips influence on low back pain: a distal link to a proximal problem.

Low back pain (LBP) is a multifactorial dysfunction, with one of the potential contributing factors being the hip joint. Currently, research investigating the examination and conservative treatment of LBP has focused primarily on the lumbar spine. The objective of this clinical commentary is to discuss the potential link between hip impairments and LBP using current best evidence and the concept of regional interdependence as tools to guide decision making and offer ideas for future research.

Psychometric properties of the shortened disabilities of the Arm, Shoulder, and Hand Questionnaire (QuickDASH) and Numeric Pain Rating Scale in patients with shoulder pain.

PURPOSE: To examine the psychometric properties of the Shortened Disabilities of the Arm, Shoulder, and Hand Questionnaire (QuickDASH) and the Numeric Pain Rating Scale (NPRS) in patients with shoulder pain. METHODS: Single-group repeated measures design in which 101 patients presenting to physical therapy completed the QuickDASH and the NPRS at the baseline examination and at a follow-up visit. At the follow-up all patients also completed the Global Rating of Change (GRC), which was used to dichotomize patients as improved or stable. Baseline and follow-up scores were used to determine the test-retest reliability, construct validity and minimal levels of detectable and clinically important change for both the QuickDASH and NPRS. RESULTS: Test-retest reliability was 0.90 for the QuickDASH and 0.74 for the NPRS. The minimal clinically important difference (MCID) was 8.0 points for the QuickDASH and 1.1 for the NPRS. CONCLUSION: The NPRS and QuickDASH exhibit good test-retest reliability and responsiveness in patients with shoulder pain.

Axonal degeneration and neuropathy target esterase.

This brief review summarizes recent observations which suggest a possible mechanism for organophosphate-induced delayed neuropathy (OPIDN). Neuropathy target esterase (NTE) has been shown to deacylate endoplasmic reticulum (ER) membrane phosphatidylcholine (PtdCho). Raised levels of PtdCho are present in the brains of Swiss cheese/NTE mutant Drosophila together with abnormal membrane structures, axonal and dendritic degeneration and neural cell loss. Similar vacuolated pathology is found in the brains of mice with brain-specific deletion of the NTE gene and, in old age, these mice show clinical and histopathological features of neuropathy resembling those in wild-type mice chronically dosed with tri-ortho-cresylphosphate. It is suggested that OPIDN results from the loss of NTE's phospholipase activity which in turn causes ER malfunction and perturbation of axonal transport and glial-axonal interactions.

Short-term effects of thrust versus nonthrust mobilization/manipulation directed at the thoracic spine in patients with neck pain: a randomized clinical trial.

BACKGROUND AND PURPOSE: Evidence supports the use of manual physical therapy interventions directed at the thoracic spine in patients with neck pain. The purpose of this study was to compare the effectiveness of thoracic spine thrust mobilization/manipulation with that of nonthrust mobilization/manipulation in patients with a primary complaint of mechanical neck pain. The authors also sought to compare the frequencies, durations, and types of side effects between the groups. SUBJECTS: The subjects in this study were 60 patients who were 18 to 60 years of age and had a primary complaint of neck pain. METHODS: For all subjects, a standardized history and a physical examination were obtained. Self-report outcome measures included the Neck Disability Index (NDI), a pain diagram, the Numeric Pain Rating Scale (NPRS), and the Fear-Avoidance Beliefs Questionnaire. After the baseline evaluation, the subjects were randomly assigned to receive either thoracic spine thrust or nonthrust mobilization/manipulation. The subjects were reexamined 2 to 4 days after the initial examination, and they again completed the NDI and the NPRS, as well as the Global Rating of Change (GROC) Scale. The primary aim was examined with a 2-way repeated-measures analysis of variance (ANOVA), with intervention group (thrust versus nonthrust mobilization/manipulation) as the between-subjects variable and time (baseline and 48 hours) as the within-subject variable. Separate ANOVAs were performed for each dependent variable: disability (NDI) and pain (NPRS). For each ANOVA, the hypothesis of interest was the 2-way group x time interaction. RESULTS: Sixty patients with a mean age of 43.3 years (SD=12.7) (55% female) satisfied the eligibility criteria and agreed to participate in the study. Subjects who received thrust mobilization/manipulation experienced greater reductions in disability, with a between-group difference of 10% (95% confidence interval [CI]=5.3-14.7), and in pain, with a between-group difference of 2.0 (95% CI=1.4-2.7). Subjects in the thrust mobilization/manipulation group exhibited significantly higher scores on the GROC Scale at the time of follow-up. No differences in the frequencies, durations, and types of side effects existed between the groups. DISCUSSION AND CONCLUSION: The results suggest that thoracic spine thrust mobilization/manipulation results in significantly greater short-term reductions in pain and disability than does thoracic nonthrust mobilization/manipulation in people with neck pain.

Phospholipase B activity and organophosphorus compound toxicity in cultured neural cells.

Organophosphorus compounds (OP) such as phenyl saligenin phosphate (PSP) and mipafox (MPX) which cause delayed neuropathy, inhibit neuropathy target esterase (NTE), while OPs such as paraoxon (PXN) react more readily with acetylcholinesterase. In yeast and mammalian cell lines, NTE has been shown to have phospholipase B (PLB) activity which deacylates intracellular phosphatidylcholine to glycerophosphocholine (GroPCho) and can be detected by metabolic labeling with [(14)C]choline. Here we investigated PLB activity in primary cultures of mouse neural cells. In cortical and cerebellar granule neurons and astrocytes, [(14)C]GroPCho labeling was inhibited by PSP and MPX: phenyl dipentylphosphinate (PDPP), a non-neuropathic NTE inhibitor, was more potent, while PXN, was substantially less so. In all three cell types, conversion of [(14)C]phosphatidylcholine to [(14)C]GroPCho over 24 h was relatively small (2.3-14%). Consequently, even with >80% inhibition of [(14)C]GroPCho production, increased [(14)C]phosphatidylcholine was not detected. At concentrations of 1-10 microM, only PSP was cytotoxic to cortical and cerebellar granule neurons after 24-h exposure. Moreover, dramatic changes in glial cell morphology were induced by PSP, but not PDPP or MPX, with rapid (2-3 h) rounding up of astrocytes and of Schwann cells in cultures of dissociated mouse dorsal root ganglia. We conclude that PLB activity is present in a variety of cultured mouse neural cell types but that acute loss of this activity is not cytotoxic. Conversely, the rapid toxic effects of PSP in vitro suggest that a serine hydrolase distinct from NTE is required continuously by neurons and glia.