Minimally-invasive approach to posterior fossa decompression: Initial experience in Adult Chiari Type 1 Malformation patients.

We report our initial experience using Minimally-Invasive Surgery (MIS) technique for Posterior Fossa Decompression (PFD) in Adult Chiari 1 Malformation (C1M) patients. Five subjects who were treated with MIS PFD at our center and followed up over a 5-year period. Another nine subjects who were treated with Open PFD and follow up over the same period were used for comparison. This study suggests that there are little differences in efficacy and safety between MIS and Open PFD. Larger series and prospective randomized trials comparing the two methods would provide higher-quality evidence and clarify the role of either technique in the treatment of C1M.

Predicting primary outcomes of brain tumor patients with advanced neuroimaging MRI measures.

BACKGROUND: Advanced neuroimaging measures along with clinical variables acquired during standard imaging protocols provide a rich source of information for brain tumor patient treatment and management. Machine learning analysis has had much recent success in neuroimaging applications for normal and patient populations and has potential, specifically for brain tumor patient outcome prediction. The purpose of this work was to construct, using the current patient population distribution, a high accuracy predictor for brain tumor patient outcomes of mortality and morbidity (i.e., transient and persistent language and motor deficits). The clinical value offered is a statistical tool to help guide treatment and planning as well as an investigation of the influential factors of the disease process. METHODS: Resting state fMRI, diffusion tensor imaging, and task fMRI data in combination with clinical and demographic variables were used to represent the tumor patient population (n = 62; mean age = 51.2 yrs.) in a machine learning analysis in order to predict outcomes. RESULTS: A support vector machine classifier with a t-test filter and recursive feature elimination predicted patient mortality (18-month interval) with 80.7% accuracy, language deficits (transient) with 74.2%, motor deficits with 71.0%, language outcomes (persistent) with 80.7% and motor outcomes with 83.9%. The most influential features of the predictors were resting fMRI connectivity, and fractional anisotropy and mean diffusivity measures in the internal capsule, brain stem and superior and inferior longitudinal fasciculi. CONCLUSIONS: This study showed that advanced neuroimaging data with machine learning methods can potentially predict patient outcomes and reveal influential factors driving the predictions.

P2 purinergic receptor activation of neuronal nitric oxide synthase and guanylyl cyclase in the dorsal facial area of the medulla increases blood flow in the common carotid arteries of cats.

In the dorsal facial area (DFA) of the medulla, an activation of either P2 purinergic receptor or nitric oxide synthase (NOS) results in the release of glutamate, leading to an increase in blood flow of the common carotid artery (CCA). It is not known whether activation of the P2 receptor by ATP may mediate activation of NOS/guanylyl cyclase to cause glutamate release and/or whether L-Arg (nitric oxide (NO) precursor) may also cause ATP release from any other neuron, to cause an increase in CCA flow. We demonstrated that microinjections of P2 receptor agonists (ATP, α,ß-methylene ATP) or NO precursor (L-arginine) into the DFA increased CCA blood flow. The P2-induced CCA blood flow increase was dose-dependently reduced by pretreatment with NG-nitro-arginine methyl ester (L-NAME, a non-specific NOS inhibitor), 7-nitroindazole (7-NI, a relatively selective neuronal NOS inhibitor) or methylene blue (MB, a guanylyl cyclase inhibitor) but not by that with D-NAME (an isomer of L-NAME) or N5-(1-iminoethyl)-L-ornithine (L-NIO, a potent endothelial NOS inhibitor). Involvement of glutamate release in these responses were substantiated by microdialysis studies, in which perfusions of ATP into the DFA increased the glutamate concentration in dialysates, but co-perfusion of ATP with L-NAME or 7-NI did not. Nevertheless, the arginine-induced CCA blood flow increase was abolished by combined pretreatment of L-NAME and MB, but not affected by pretreatment with a selective P2 receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS). In conclusion, ATP activation of the P2 receptor in the DFA induced activation of neuronal NOS/guanylyl cyclase, which causes glutamate release leading to an increase in CCA blood flow. However, arginine activation of neuronal NOS/guanylyl cyclase, which also caused glutamate release and CCA blood flow increase, did not induce activation of P2 receptors. These findings provide important information for drug design and/or developing therapeutic strategies for the diseases associated with CCA blood flow that supplies intra- and extra-cranial tissues.

L-type calcium channels in sympathetic α3ß2-nAChR-mediated cerebral nitrergic neurogenic vasodilation.

AIM: Nicotine stimulation of α3ß2-nicotinic acetylcholine receptors (α3ß2-nAChRs) located on sympathetic nerves innervating basilar arteries causes calcium-dependent noradrenaline release, leading to activation of parasympathetic nitrergic nerves and dilation of basilar arteries. This study aimed to investigate the major subtype of calcium channels located on cerebral peri-vascular sympathetic nerves, which is involved in nicotine-induced α3ß2-nAChR-mediated nitrergic vasodilation in basilar arteries. METHODS: Nicotine- and transmural nerve stimulation (TNS)-induced dilation of isolated porcine basilar arteries was examined using in vitro tissue bath. Nicotine-induced calcium influx, nicotine-induced noradrenaline release and nicotine-induced inward currents were evaluated in rat superior cervical ganglion (SCG) neurones, peri-vascular sympathetic nerves of porcine basilar arteries and α3ß2-nAChRs-expressing oocytes respectively. mRNA and protein expression of Cav 1.2 and Cav 1.3 channels were detected by RT-PCR, Western blotting and immunohistochemistry. RESULTS: Nicotine-induced vasodilation was not affected by ω-agatoxin TK (selective P/Q-type calcium channel blocker) or ω-conotoxin GVIA (N-type calcium channel blocker). The vasodilation, however, was inhibited by nicardipine (L-type calcium channel blocker) in concentrations which did not affect TNS-induced vasodilation, suggesting the specific blockade. Nicardipine concentration-dependently inhibited nicotine-induced calcium influx in rat SCG neurones and reduced nicotine-induced noradrenaline release from peri-vascular sympathetic nerves of porcine basilar arteries. Nicardipine (10 µm), which significantly blocked nicotine-induced vasorelaxation by 70%, did not appreciably affect nicotine-induced inward currents in α3ß2-nAChRs-expressing oocytes. Furthermore, the mRNAs and proteins of Cav 1.2 and Cav 1.3 channels were expressed in porcine SCG and peri-vascular nerve terminals. CONCLUSION: The sympathetic neuronal calcium influx through L-type calcium channels is modulated by α3ß2-nAChRs. This calcium influx causes noradrenaline release, initiating sympathetic-parasympathetic (axo-axonal) interaction-induced nitrergic dilation of porcine basilar arteries.

Impact of brain tumor location on morbidity and mortality: a retrospective functional MR imaging study.

BACKGROUND AND PURPOSE: fMRI is increasingly used in neurosurgery to preoperatively identify areas of eloquent cortex. Our study evaluated the efficacy of clinical fMRI by analyzing the relationship between the distance from the tumor border to the area of functional activation (LAD) and patient pre- and postoperative morbidity and mortality. MATERIALS AND METHODS: The study included patients with diagnosis of primary or metastatic brain tumor who underwent preoperative fMRI-based motor mapping (n=74) and/or language mapping (n=77). The impact of LAD and other variables collected from patient records was analyzed with respect to functional deficits in terms of morbidity (paresis and aphasia) and mortality. RESULTS: Significant relationships were found between motor and language LAD and the existence of either pre- or postoperative motor (P < .001) and language deficits (P=.009). Increasing age was associated with motor and language deficits (P=.02 and P=.04 respectively). Right-handedness was related to language deficits (P=.05). Survival analysis revealed that pre- and postoperative deficits, grade, tumor location, and LAD predicted mortality. Motor deficits increased linearly as the distance from the tumor to the primary sensorimotor cortex decreased. Language deficits increased exponentially as the distance from the tumor to the language areas decreased below 1 cm. Postoperative mortality analysis showed an interaction effect between motor or language LAD and mortality predictors (grade and tumor location, respectively). CONCLUSIONS: These findings indicate that tumors may affect language and motor function differently depending on tumor LAD. Overall, the data support the use of fMRI as a tool to evaluate patient prognosis and are directly applicable to neurosurgical planning.

Axo-axonal interaction in autonomic regulation of the cerebral circulation.

Noradrenaline (NE) and acetylcholine (ACh) released from the sympathetic and parasympathetic neurones in cerebral blood vessels were suggested initially to be the respective vasoconstricting and dilating transmitters. Both substances, however, are extremely weak post-synaptic transmitters. Compelling evidence indicates that nitric oxide (NO) which is co-released with ACh from same parasympathetic nerves is the major transmitter for cerebral vasodilation, and its release is inhibited by ACh. NE released from the sympathetic nerve, acting on presynaptic ß2-adrenoceptors located on the neighbouring parasympathetic nitrergic nerves, however, facilitates NO release with enhanced vasodilation. This axo-axonal interaction mediating NE transmission is supported by close apposition between sympathetic and parasympathetic nerve terminals, and has been shown in vivo at the base of the brain and the cortical cerebral circulation. This result reveals the physiological need for increased regional cerebral blood flow in 'fight-or-flight response' during acute stress. Furthermore, α7- and α3ß2-nicotinic ACh receptors (nAChRs) on sympathetic nerve terminals mediate release of NE, leading to cerebral nitrergic vasodilation. α7-nAChR-mediated but not α3ß2-nAChR-mediated cerebral nitrergic vasodilation is blocked by ß-amyloid peptides (Aßs). This may provide an explanation for cerebral hypoperfusion seen in patients with Alzheimer's disease. α7- and α3ß2-nAChR-mediated nitrergic vasodilation is blocked by cholinesterase inhibitors (ChEIs) which are widely used for treating Alzheimer's disease, leading to possible cerebral hypoperfusion. This may contribute to the limitation of clinical use of ChEIs. ChEI blockade of nAChR-mediated dilation like that by Aßs is prevented by statins pretreatment, suggesting that efficacy of ChEIs may be improved by concurrent use of statins.

Glutamate release upon purinergic action in the dorsal facial area of the medulla increases blood flow in the common carotid artery in cats.

Interactions of glutamatergic and purinergic actions in the medulla regulate important cardiovascular functions. The glutamatergic action in dorsal facial area (DFA) of the medulla increases blood flow of common carotid artery (CCA) in cats. We hypothesized that interactions of glutamatergic and purinergic actions in the DFA may regulate the CCA blood flow. Purinergic and glutamatergic agonists and antagonists were microinjected into the DFA through a four-barrel tubing in anesthetized cats. Drug effects were evaluated by changes in the CCA blood flow. Microinjection with 20 nmol ATP or alpha,beta-methyleneATP (alpha,beta-MeATP, a P2 purinergic receptor agonist) induced an increase of the CCA blood flow. This increase was dose-dependently reduced by prior administration with 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX, a specific P1 purinergic receptor antagonist), or pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, a selective P2 purinergic receptor antagonist) as well as with MK-801 (a non-competitive NMDA receptor antagonist) or glutamate diethyl ester (GDEE, a competitive AMPA/kainate receptor antagonist). It was almost completely blocked by administrations with combined maximal doses of P1 and P2 receptor antagonists as well as NMDA and AMPA receptor antagonists. Nevertheless, P1 receptor agonist induced only mild and poorly reproducible increase in the CCA blood flow. In conclusion, prominent P2 and minor P1 purinergic receptors appear to be present in the DFA; the purinergic activation can mediate a release of glutamate that stimulates NMDA and AMPA to induce the increase of the CCA blood flows. These findings may provide important information for developing therapeutic strategy for diseases involving the CCA blood flow, such as hypertensive disease and cerebral ischemia.

Regulation of the common carotid arterial blood flow by nicotinic receptors in the medulla of cats.

BACKGROUND AND PURPOSE: Actions of glutamate and serotonin on their respective receptors in the dorsal facial area (DFA) of the medulla are known to regulate common carotid arterial (CCA) blood flow in cats. Less is known about acetylcholine action on its nicotinic receptor (nAChR) subtypes in the DFA for regulation of CCA blood flow and this aspect was investigated. EXPERIMENTAL APPROACH: Nicotinic and muscarinic agonists and antagonists were microinjected into the DFA through a three-barrel tubing in anesthetized cats. RESULTS: CCA blood flow was dose-dependently increased by nicotine (a non-selective nAChR agonist) and choline (a selective alpha7-nAChR agonist). These effects of nicotine were attenuated by alpha-bungarotoxin (an alpha7-nAChR antagonist), methyllycaconitine (an alpha7-nAChR antagonist), mecamylamine (a relatively selective alpha3beta4-nAChR antagonist) and dihydro-beta-erythroidine (a relatively selective alpha4beta2-nAChR antagonist). The choline-induced flow increase was attenuated by alpha-bungarotoxin and mecamylamine, but not by dihydro-beta-erythroidine. Muscarinic agonists (muscarine and methacholine) and antagonist (atropine) affected neither the basal nor the nicotine-induced increase in the CCA blood flow. CONCLUSIONS AND IMPLICATIONS: Functional alpha7, alpha4beta2, and alpha3beta4 subunits of the nAChR appear to be present on the DFA neurons. Activations of these receptors increase the CCA blood flow. The present findings do not preclude the presence of other nAChRs subunits. Muscarinic receptors, if any, on the DFA are not involved in regulation of the CCA blood flow. Various subtypes of nAChRs in the DFA may mediate regulation of the CCA and cerebral blood flows.

Advances in the treatment of pediatric brain tumors.

Brain tumors are a heterogeneous group of neoplasms with different origins, pathobiologies, treatments and prognoses. The collective contributions from the fields of neuro-oncology, neurosurgery, radiation oncology, neurology, neuropathology, neuroradiology and molecular biology have all led to significant advances in the treatment of certain brain tumors. Ideas from these fields, under the cooperative umbrella of clinical cancer trial consortia, have been tested in large-scale studies. As a result, patient survivals have increased markedly for these tumor types. Unfortunately, there are certain brain tumors in childhood, such as the diffuse intrinsic pontine glioma and atypical teratoid rhabdoid tumor, for which survival advantages have not been found. This review will discuss the current and possible future therapies of the most common pediatric brain tumors and highlight some of the novel imaging modalities that are used pre- and intraoperatively.

Simultaneous monitoring of extracellular glucose, pyruvate, and lactate in rat testies during ischemia: a microdialysis study.

A dual-probe microdialysis technique was developed for the simultaneous monitoring of glucose and related metabolite levels during testicular ischemia in rats. The determinations of lactate and pyruvate were achieved by liquid chromatography within 5 min. Glucose was determined by a microdialysis analyzer. A unilateral ligation was produced by occlusion of the right artery for 2 or 4 h in anesthetized rats. Microdialysis probes were inserted in both sides of the testis to simultaneously monitor glucose, lactate and pyruvate during basal, ischemia and reperfusion periods. Dynamic and comparative changes in these analytes in ipsilateral and contralateral testes were demonstrated. The present technique can be used as a tool for exploring energy related metabolites and their relationships in testicular ischemia.

Nitric oxide produces different actions in different areas of the periaqueductal grey in cats.

In 20 urethane-anaesthetised cats, microinjection of N-methyl-D-aspartate (NMDA) into the intermediate-lateral (IL-) or the dorsolateral (DL-) periaqueductal grey areas (PAG) of the midbrain elicited similar patterns of cardiovascular responses: increases in mean systemic arterial pressure (MSAP), heart rate (HR) and mean blood flows (F) of the common carotid and femoral arteries, accompanied with a 'hissing-howling' response. Similar increases in MSAP and Fs were induced by microinjections of S-nitroso-N-acetylpenicillamine (SNAP), a potent nitric oxide (NO) donor, on the IL-PAG (A2.5-A0.5). In contrast, microinjections of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, in the same area elicited a decrease in MSAP and Fs. On the other hand, microinjections of either SNAP or L-NAME reversed the original IL-PAG responses when injected into the DL-PAG. Pretreatments with SNAP significantly inhibited NMDA-induced responses in the DL-PAG but potentiated such responses in the IL-PAG. In contrast, pretreatments with L-NAME potentiated the NMDA-induced responses in the DL-PAG but inhibited such responses in the IL-PAG. These data suggest that NO may be a neurotransmitter or neuromodulator that exerts differential function in different defense areas, namely the IL- and the DL-PAG.

The involvement of glutamate in recall of the conditioned NK cell response.

The molecular mechanisms responsible for the conditioned enhancement of natural killer (NK) cell activity were investigated. The primary goal of the study was to examine the roles of glutamate and gamma-aminobutyric acid (GABA) in recall of the conditioned NK cell response. Both neurochemical blocking assay and high performance liquid chromatography (HPLC) technique were used in the study. Results from the neurochemical blocking assay demonstrated that glutamate but not GABA was required in recall of the conditioned NK cell response. NMDA but not the kainate/AMPA receptors, are believed to be involved. The levels of glutamate that were released and/or taken up also appeared to be critical in that interruption of glutamate release and/or uptake blocked the conditioned NK cell response. Results from the HPLC analysis, however, did not show any significant difference in the glutamate content between the conditioned and control brains.

Association of immune responses and ischemic brain infarction in rat.

Inflammation plays an important role in the pathogenesis of neurodegenerative diseases including ischemia. Occlusion of common carotid artery and middle cerebral artery has been used to produce focal ischemic lesions in the rat. Here, we examined the associations between immune reactions and postischemic brain infarction. Ischemia/reperfusion time-dependently caused brain infarction. The kinetics of inflammatory reactions in rat brain including inflammatory cell infiltration, edema formation, cytokines/chemokines and adhesion molecules production and matrix metalloproteinase activation were relevant to the progression of ischemic infarction. Differential induction profile after ischemia suggests that this activation might contribute to secondary brain damage in ischemic tissues. On the other hand, another possibility of this response is to trigger processes that mediate the neural regeneration after ischemic injury.

Cerebral ischemia/reperfusion injury in rat brain: effects of naloxone.

The pathogenesis of cerebral ischemia/reperfusion (I/R) involves cytokine/chemokine production, inflammatory cell influx, astrogliosis, cytoskeletal protein degradation and breakdown of the blood-brain barrier. (-)-Naloxone is able to reduce infarct volume and has been used as a therapeutic agent for cerebral I/R injuries. However, its effects on the mentioned pathophysiologic changes have scarcely been addressed. Cerebral I/R was produced by occluding and opening bilateral common carotid artery and unilateral middle cerebral artery in Sprague-Dawley rats. After cerebral I/R, the degradation of neuronal microtubule-associated protein-2 (MAP-2) was strongly associated with astrogliosis, inflammatory cell infiltration, cytokine/chemokine overproduction, and matrix metalloproteinase-9 activation. (-)-Naloxone pretreatment suppresses post-ischemic activation and preserves more MAP-2 protein. Therefore, (-)-naloxone administration might be an effective therapeutic intervention for reducing ischemic injuries.

Dehydroepiandrosterone inhibits lipopolysaccharide-induced nitric oxide production in BV-2 microglia.

Levels of dehydroepiandrosterone (DHEA) and its sulfated derivative (DHEAS) decline during aging and reach even lower levels in Alzheimer's disease (AD). DHEA is known to exhibit a variety of functional activities in the CNS, including an increase of memory and learning, neurotrophic and neuroprotective effects, and the reduction of risk of age-related neurodegenerative disorders. However, the influence of DHEA on the immune functions of glial cells is poorly understood. In this study, we investigated the effect of DHEA on activated glia. The production of inducible nitric oxide synthase (iNOS) was studied in lipopolysaccharide (LPS)-stimulated BV-2 microglia, as a model of glial activation. The results showed that DHEA but not DHEAS significantly inhibited the production of nitrite in the LPS-stimulated BV-2 cell cultures. Pretreatment of BV-2 cells with DHEA reduced the LPS-induced iNOS mRNA and protein levels in a dose-dependent manner. The LPS-induced iNOS activity in BV-2 cells was decreased by the exposure of 100 microM DHEA. Moreover, DHEA suppressed iNOS gene expression in LPS-stimulated BV-2 cells did not require de novo synthesis of new proteins or destabilize of iNOS mRNA. Since DHEA is biosynthesized by astrocytes and neurons, our findings suggest that it might have an important regulatory function on microglia.

On-line, continuous and automatic monitoring of extracellular malondialdehyde concentration in anesthetized rat brain cortex.

An assay for in vivo, continuous and automatic monitoring of extracellular malondialdehyde concentrations in anesthetized rat brain cortex was developed. This method involved the use of microdialysis perfusion, on-line derivatization and on-line high-performance liquid chromatographic analysis. Microdialysate from an implanted microdialysis probe was on-line reacted with thiobarbituric acid at 80 degrees C for 10 min prior to on-line collection and automatic injection into a HPLC system equipped with a fluorescence detector. This method gave a linear response between the concentrations of the malondialdehyde in the microdialysates and the TEP solution where the microdialysis probe was placed. This method was used to observe the increased extracellular malondialdehyde production following elevated extracellular glutamate levels, which were achieved by perfusion of L-trans-pyrrolidine-2,4-dicarboxylate, a competitive inhibitor of glutamate uptake transporter.

Expression of neural cell adhesion molecule in spinal cords following a complete transection.

Neural cell adhesion molecule (NCAM) regulates tissue organization during development and in the adult. NCAM upregulation occurs after an injury to brains and sciatic nerves. However, little is known about NCAM expression after spinal cord injury (SCI). By using a complete spinal cord transection with a 5 mm tissue removal, an increase in the NCAM level is detected in spinal cord stumps proximal and distal to the transection site at 1 d and 3 d post injury, while its expression at 8 d is declined to a lower level than that observed in sham-operated spinal cords. The strong NCAM expression is present in motor neurons at 3 d post transection whereas the intensive NCAM immunostaining is localized in dorsal sensory and corticospinal fiber tracts at 8 d following injury. Collectively, NCAM level is elevated and strongly expressed in dorsal fiber tracts after SCI, implying that the endogenous process for spinal cord regeneration may take place after SCI.

Dorsomedial medulla is more susceptible than rostral ventrolateral medulla to hypoxic insult in cats.

We investigated the responses of systemic arterial pressure and vertebral sympathetic nerve activity to glutamate microinjections (0. 1 M, 70 nl) in the dorsomedial (DM) and the rostral ventrolateral medulla (RVLM) before hypoxia and after reoxygenation (posthypoxia) after various degrees of hypoxia in anesthetized cats. Hypoxia was produced by ventilating 5% O(2) and 95% N(2) for different durations (hypoxia I-III). In intact cats, the glutamate-induced systemic arterial pressure and vertebral nerve activity responses of the DM were depressed after all degrees of hypoxia. Posthypoxic depression in the RVLM, however, was not observed until hypoxia II and III. Precollicular decerebration prevented depression in the RVLM, but, for the DM, it was effective only for hypoxia I. Baro- and chemoreceptor denervation abolished all posthypoxic depression in both the DM and the RVLM. Pressor responses to tyramine (100-400 microg/kg iv) remained unchanged after all degrees of hypoxia. These results suggest that the DM is more susceptible to hypoxia than the RVLM. The peripheral baro- and chemoreceptors and the suprapontine structures apparently play an important role in posthypoxic depression. Moreover, the depression is not due to the postganglionic norepinephrine depletion.

Resveratrol inhibits interleukin-6 production in cortical mixed glial cells under hypoxia/hypoglycemia followed by reoxygenation.

Reactive oxygen intermediates (ROIs) are important mediators of a variety of pathological processes, including inflammation and ischemia/reperfusion injury. Cytokines and chemokines are detected at mRNA level in human and animal ischemic brains. This suggests that hypoxia/reoxygenation may induce cytokine production through generation of ROIs. In this study, we investigated the cytokine induction and inhibition by antioxidants in rat cortical mixed glial cells exposed to in vitro ischemia-like insults (hypoxia plus glucose deprivation). The results showed that interleukin-6 (IL-6) mRNA and protein, but not tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), were induced during hypoxia/hypoglycemia followed by reoxygenation in the mixed glial cells. The accumulation of IL-6 mRNA was induced as early as 15 min after hypoxia/hypoglycemia and its level was further increased after subsequent reoxygenation. Among the antioxidants studied, only resveratrol suppressed IL-6 gene expression and protein secretion in mixed glial cultures under hypoxia/hypoglycemia followed by reoxygenation. These findings suggest that resveratrol might be useful in treating ischemic-induced inflammatory processes in stroke.

Induction of cytokine genes and IL-1alpha by chemical hypoxia in PC12 cells.

The role of cytokine in neuronal injury was examined in rat pheochromocytoma (PC12) cells under chemical hypoxia (i.e. KCN) and glucose deprivation. The mRNA levels of interleukin-1alpha (IL-1alpha), IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured by reverse transcription-polymerase chain reaction (RT-PCR) in PC12 cells exposed to 0.5 mM KCN for various time intervals. Cytokine mRNA levels expressed to peak levels 30 minutes after KCN treatment and declined gradually until 240 min. The IL-1alpha activity reached the highest levels 2 hr after the same KCN treatment. Under parallel conditions, KCN increased cytosolic free calcium concentration ([Ca2+]i) in the absence of glucose. However, IL-1alpha mRNA induction by KCN was not altered under calcium-free conditions in PC12 cells, indicating its induction was Ca2+-independent. However, the phosphatidylcholine (PC)-specific phospholipase C (PLC) inhibitor D609 decreased the KCN-induced IL-1alpha mRNA and protein in PC12 cells suggests that PC-PLC might play a role in cytokine induction during hypoxia.