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Context Gonadotroph pituitary neuroendocrine tumors (PitNETs) can express follicle-stimulating hormone (FSH) and luteinizing hormone (LH) or be hormone negative, but they rarely secrete hormones. During tumor development, epithelial cells develop a mesenchymal phenotype. This process is characterized by decreased membranous E-cadherin and translocation of E-cadherin to the nucleus. Estrogen receptors (ERs) regulate both E-cadherin and FSH expression and secretion. Whether the hormone status of patients with gonadotroph PitNETs is regulated by epithelial-to-mesenchymal transition (EMT) and ERs is unknown. Objectives To study the effect of EMT on hormone expression in gonadotroph nonfunctioning (NF)-PitNETs. Design Molecular and clinical analyses of 105 gonadotroph PitNETs. Immunohistochemical studies and real-time quantitative polymerase chain reaction were performed for FSH, LH, E-cadherin, and ERα. Further analyses included blood samples, clinical data, and radiological images. Setting All patients were operated on in the same tertiary referral center. Results NF-PitNET with high FSH expression had decreased immunohistochemical staining for membranous E-cadherin (P < .0001) and increased staining for nuclear E-cadherin (P < .0001). Furthermore, high FSH expression was associated with increased ERα staining (P = .0002) and ERα mRNA (P = .0039). Circulating levels of plasma-FSH (P-FSH) correlated with FSH staining in gonadotroph NF-PitNET (P = .0025). Tumor size and invasiveness was not related to FSH staining, E-cadherin, or ERα. LH expression was not associated with E-cadherin or ERα. Conclusion In gonadotroph PitNETs, FSH staining is related to E-cadherin, ERα expression, and circulating levels of P-FSH. There was no association between FSH staining and invasiveness. The clinical significance of these findings will be investigated in ongoing prospective studies.

Objective The aim was to study the prevalence of secondary adrenal insufficiency before and after surgery for non-functioning pituitary adenomas, as well as determine risk factors for developing secondary adrenal insufficiency. A secondary aim was to determine adequate p-cortisol response to a 1-μg Short Synacthen Test after surgery. Design Longitudinal cohort study. Methods One hundred seventeen patients (52/65 females/males, age 59 years) undergoing primary surgery for clinically non-functioning pituitary adenomas were included. P-cortisol was measured in morning blood samples. Three months after surgery, a Short Synacthen Test was performed. Results All tumours were macroadenomas (mean size 26.9 mm, range 13–61 mm). The surgical indications were visual impairment (93), tumour growth (16), pituitary apoplexy (6) and headache (2). Before surgery, 17% of the patients had secondary adrenal insufficiency (SAI), decreasing to 15% 3 months postoperatively. Risk of SAI was increased in patients operated for pituitary apoplexy (p

Purpose Clinically non-functioning pituitary neuroendocrine tumours (NF-PitNETs) present a varying degree of aggressiveness, and reliable prognostic markers are lacking. We aimed to characterise the distribution of E- and N-cadherin in corticotroph, PIT1 and null-cell NF-PitNETs, and link it to the course of the tumours. Methods The distribution of E- and N-cadherin was investigated by immunohistochemistry in a retrospective cohort of 30 tumours of the less common NF-PitNETs (corticotroph (N = 18), PIT1 (N = 8) and null-cell PitNETs (N = 4)). Immunoreactive scores (IRS) were compared to previously presented cohorts of gonadotroph NF-PitNETs (N = 105) and corticotroph functioning PitNETs (N = 17). Results We found a low IRS for the extra-cellular domain of E-cadherin (median 0 (IQR 0–0, N = 135)), a medium to high IRS for the intra-cellular domain of E-cadherin (median 6 (IQR 4–9)) and a high IRS for N-cadherin (median 12 (IQR 10.5–12)) throughout the cohort of NF-PitNETs. The corticotroph NF-PitNETs presented a higher IRS for both the extra- and intra-cellular domain of E-cadherin (median 0 (IQR 0–1) and median 9 (IQR 6–12), respectively) than the gonadotroph NF-PitNETs (p p = 0.03). Conclusions Considering our results and the benign course of NF-PitNETs, we suggest that a high N-cadherin and downregulation of membranous E-cadherin are not associated with a more aggressive tumour behaviour in these subgroups of NF-PitNETs.

Background Tuberculum sellae meningiomas (TSMs) adherent to neurovascular structures are particularly challenging lesions requiring delicate and precise microneurosurgery. There is an ongoing debate about the optimal surgical approach. Method We describe technical nuances and challenges in TSM resection using the endoscopic endonasal approach (EEA) in two cases of fibrous tumors with adherence to neurovascular structures. The cases are illustrated with a video (case 1) and figures (cases 1 and 2). Conclusion A dedicated team approach and precise microsurgical technique facilitate safe resection of complex TSMs through the EEA.

Resection of clivus chordomas through extensive skull base approaches is associated with high mortality and morbidity even in experienced hands. We report our experience with endoscopic trans-sphenoidal surgery, or a “wait-and-scan” strategy in selected patients. Ten patients were diagnosed with clivus chordomas during an 8-year period. Six patients underwent primary treatment with endoscopic trans-sphenoidal surgery, followed by adjuvant proton-beam therapy in three of these patients. Four patients with minor symptoms were followed-up untreated. Mean follow-up was 91 months. Of the six patients operated on, total or gross total resection was achieved in four, partial resection in one and biopsy was taken in one. Preoperative cranial neuropathies resolved in three out of five patients, and no new cranial nerve palsies were encountered. Postoperative cerebrospinal fluid leak occurred in one patient. Four patients were initially followed-up without any treatment, and three of these have remained stable without tumour progression for a mean of 94 months. Due to a slow, though progressive growth of tumour, one patient was operated on after 80 months of initial observation. The natural course of clivus chordomas has yet to be defined. The endoscopic trans-sphenoidal approach is a valid, minimally invasive alternative for the treatment of clival chordomas, and in selected patients a “wait and scan” strategy can be considered. Our long-term results show low mortality and good functional outcome. An endonasal endoscopic trans-sphenoidal approach should be a principal part of the armamentarium of surgeons treating clivus chordomas.

Swollen middle cerebral artery infarction is a life-threatening disease and decompressive craniectomy is improving survival significantly. Despite decompressive surgery, however, many patients are not discharged from the hospital alive. We therefore wanted to search for predictors of early in-hospital death after craniectomy in swollen middle cerebral artery infarction. All patients operated with decompressive craniectomy due to swollen middle cerebral artery infarction at the Department of Neurosurgery, Oslo University Hospital Rikshospitalet, Oslo, Norway, between May 1998 and October 2010, were included. Binary logistic regression analyses were performed and candidate variables were age, sex, time from stroke onset to decompressive craniectomy, NIHSS on admission, infarction territory, pineal gland displacement, reduction of pineal gland displacement after surgery, and craniectomy size. Fourteen out of 45 patients (31%) died during the primary hospitalization (range, 3–44 days). In the multivariate logistic regression model, middle cerebral artery infarction with additional anterior and/or posterior cerebral artery territory involvement was found as the only significant predictor of early in-hospital death (OR, 12.7; 95% CI, 0.01–0.77; p = 0.029). The present study identified additional territory infarction as a significant predictor of early in-hospital death. The relatively small sample size precludes firm conclusions.

Resection within the supplementary motor area (SMA) may be accompanied by dramatic motor deficits and speech arrest when the dominant hemisphere is involved, termed the SMA syndrome. Typically, the muscle tone of the paralyzed extremities is preserved, and in most cases, a complete or near complete recovery is seen within a few months. The SMA syndrome has not been recognized for extra-axial tumor surgery in approximation of the SMA. We observed the SMA syndrome in a patient operated for a parasagittal meningioma in the posterior frontal region, and this observation intrigued us to prospectively collect similar cases. In the period from January 2010 to December 2015, we observed five patients who developed a partial SMA syndrome after surgery for frontal parasagittal meningiomas. The muscle tone was preserved in the affected extremities. All patients experienced improvement in motor function within a few days, and on follow-up, three out of five patients had recovered completely. Three of the patients had meningioma WHO grade II. Surgically induced SMA syndrome can easily be confused with pyramidal weakness. This series of cases demonstrate that the syndrome may also develop after removal of extra-axial tumors and is probably underdiagnosed and underreported. The good functional prognosis is helpful in the preoperative counseling and follow-up of these patients.

Background Renewed interest has developed in decompressive craniectomy, and improved survival is shown when this treatment is used after malignant middle cerebral artery infarction. The aim of this study was to investigate the frequency and possible risk factors for developing surgical site infection (SSI) after delayed cranioplasty using autologous, cryopreserved bone. Methods This retrospective study included 74 consecutive patients treated with decompressive craniectomy during the time period May 1998 to October 2010 for various non-traumatic conditions causing increased intracranial pressure due to brain swelling. Complications were registered and patient data was analyzed in a search for predictive factors. Results Fifty out of the 74 patients (67.6 %) survived and underwent delayed cranioplasty. Of these, 47 were eligible for analysis. Six patients (12.8 %) developed SSI following the replacement of autologous cryopreserved bone, whereas bone resorption occurred in two patients (4.3 %). No factors predicted a statistically significant rate of SSI, however, prolonged procedural time and cardiovascular comorbidity tended to increase the risk of SSI. Conclusions SSI and bone flap resorption are the most frequent complications associated with the reimplantation of autologous cryopreserved bone after decompressive craniectomy. Prolonged procedural time and cardiovascular comorbidity tend to increase the risk of SSI.

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be reconstructed to protect the brain and normalize the cerebral hemodynamics. The conventional method is to cover the defect with bone cement. Custom-made implants designed for the individual patient are now available. We report our experience with one such product in patients with large cranial defects (>7.6 cm in diameter). A CT scan with 2 mm slices and a three-dimensional reconstruction were obtained from the patient. This information was dispatched to the company and used as a template to form the implant. The cranial implant was received within four weeks. From 2005 to 2010, custom-made cranial implants were used in 13 patients with large cranial defects. In 10 of the 13 patients, secondary deep infection was the cause of the cranial defect. All the implants fitted well or very well to the defect. No infections were seen after implantation; however, one patient was reoperated on for an epidural hematoma. A custom-made cranial implant is considerably more expensive than an implant made of bone cement, but ensures that the defect is optimally covered. The use of custom-made implants is straightforward and timesaving, and they provide an excellent medical and cosmetic result.

Background A rare, but important cause of torticollis in children is atlantoaxial rotatory fixation. If the patient remains undiagnosed for more than three months, surgery is generally the only therapeutic alternative. In this article we present our experiences of surgical treatment of late-diagnosed atlantoaxial rotatory fixation in children. Material and method This article is based on a review of the case notes of patients who underwent surgery for atlantoaxial rotatory fixation in the Department for Neurosurgery at Oslo University Hospital, Rikshospitalet, during the period 2004-10. Results The material sample consists of six children aged from seven to 14 years. Five had suffered minor trauma to the upper neck region, while one had had an upper respiratory tract infection. The diagnosis was made 5-36 months after the onset of symptoms. In three of the patients, an attempt was made at closed reduction without success. A CT scan one year postoperatively showed a normal position of the atlantoaxial joint in two patients and partial reduction in three. In the sixth patient there was bone fusion at the time of the operation, and open reduction was unsuccessful. All six patients had reduced rotational movement of the neck at the one-year check-up. Interpretation All our patients were diagnosed more than five months after the onset of symptoms. Full or partial reduction was achieved in five of the six.

Background Real-time reverse transcription quantitative PCR (RT-qPCR) has become the method of choice for quantification of gene expression changes. The most important limitations of RT-qPCR are inappropriate data normalization and inconsistent data analyses. Pituitary adenomas are common tumours, and the appropriate interpretation of increasingly published data within this field is prevented by the lack of a proper selection and validation of stably expressed reference genes. Aim To find and validate the optimal reference gene or gene combination for reliable RT-qPCR gene expression in both non-functioning (NFPA) and hormone secreting (GH and ACTH) pituitary adenomas. Material and methods Thirty commonly used reference genes (PCR array reference gene panel, BioRad, Hercules, CA) were quantified by RT-qPCR in 24 pituitary adenomas (12 NFPA, 8 GH and 4 ACTH). The data was analysed using three programs: geNorm (Qbase+), Normfinder and BestKeeper having different algorithms to identify the most stable reference gene or combination of reference genes. Three reference genes ALAS1, PSMC4 and GAPDH, were selected for further validation in a larger cohort of 223 adenomas (141 NFPA, 63 GH and 19 ACTH). Results In all adenomas, ALAS1 and PSMC4 were the most stable reference genes as estimated by geNorm and Normfinder, whereas Bestkeeper ranked RPLP0 and ACTB as the two most stable out of 10 carefully selected genes. The best gene combination was PSMC4 and ALAS1 (geNorm) or PSMC4 and GAPDH (Normfinder). The validation experiment (geNorm) showed that the most stable gene combinations were ALAS1 and GAPDH in NFPA, and PSMC4 and GAPDH in hormone secreting adenomas. Conclusions Several of the reference genes expressed good stability yielding several candidate genes. PSMC4 and ALAS1 were overall the most stably expressed genes in pituitary adenoma merely differing in ranking order. PSMC4 and ALAS1 have so far not been reported as reference genes in pituitary adenomas. The various reference gene algorithms showed a mixed selection of top ranked genes, thus suggesting a need for an individualised and rational choice of reference genes.

Stem cells have been isolated from several CNS regions, including the spinal cord. However, the terminal end of the spinal cord, filum terminale, has been referred to as a fibrovascular tag without neurogenic potential and of no clinical significance. Recently, we were fortunate to acquire some samples of this tissue. We show for the first time that progenitor cells exhibiting the hallmarks of stem cells can be isolated from adult human filum terminale (FTNPs). More specifically, FTNPs self-renew and proliferate to form neurospheres, and exhibit tripotent differentiation into neurons, astrocytes, and oligodendrocytes. Equally important, FTNPs develop the electrophysiological profile of neurons and glia. Whole-cell patch-clamp recordings show beta-III-tubulin(+) neurons exhibiting overshooting action potentials, displaying both the fast inactivating TTX-sensitive sodium current as well as 4-AP and TEA sensitive potassium currents. To assess potency in vivo, FTNPs were transplanted into the posterior periventricular region of control or ischemic rat brains. Despite a vigorous immune response against the xenograft, FTNPs survived and were found not only in the graft area but had also migrated to the lesioned CA1 region. Notwithstanding the immune response, FTNPs differentiated into astrocytes, but no neuronal differentiation was observed in the transplant milieu tested. However, neuronal differentiation in vivo cannot be ruled out and assessment of the conditions necessary to promote neurogenesis in vivo requires more research. Significantly, no tumor formation or aberrant cell morphology was seen in or adjacent to the graft area. Thus, filum terminale provides a novel source of adult human neural progenitor cells that develop into functional neurons with possible clinical applications.

Background and objectives The mitochondrial membrane potential (DeltaPsi(m)) drives the three fundamental functions of mitochondria, namely adenosine triphosphate (ATP) generation, Ca(2+) uptake/storage, and generation/detoxification of ROS. Isoflurane depolarizes neural mitochondria. The sensitivity for general anesthetics increases with age, but the mechanism for this age-related sensitivity is still unknown. We compared the effect of isoflurane on [Ca(2+)](i) and DeltaPsi(m) in isolated pre-synaptic terminals (synaptosomes) from neonatal, adolescent, and adult rats and the influence of interventions in the respiratory chain was assessed. Methods Synaptosomes were loaded with the fluorescent probes fura-2 ([Ca(2+)](i)) and JC-1 (DeltaPsi(m)) and exposed to isoflurane 1 and 2 minimum alveolar concentration (MAC). The effect on the electron transport chain was investigated by blocking complexes I and V. Results In neonatal rats isoflurane had no significant effect on DeltaPsi(m). In adolescent and adult synaptosomes, however, isoflurane 1 and 2 MAC decreased DeltaPsi(m). Isoflurane 2 MAC increased [Ca(2+)](i) in neonatal and adolescent rats, but not in adult synaptosomes. In Ca(2+)-depleted medium, isoflurane still decreased DeltaPsi(m), while [Ca(2+)](i) remained unaltered. By blocking complex V of the respiratory chain, the isoflurane-induced mitochondrial depolarization was enhanced in all age groups. Blocking complex I depolarized the mitochondria to the same extent as isoflurane 2 MAC, but without any additive effect. Conclusions The depolarizing effect of isoflurane on neural mitochondria is more pronounced in the adolescent and adult than in neonatal synaptosomes. The increased mitochondrial sensitivity with age seems to be related to the reversed function of the ATP synthase of the electron transport chain.

Background Cushing’s disease is an ACTH-producing pituitary adenoma, and the primary treatment is microscopic or endoscopic transsphenoidal selective adenectomy. The aims of the present study were to evaluate whether the early postoperative S-cortisol level can serve as a prognostic marker for short- and long-term remission, and retrospectively review our own short and long term results after surgery for Cushing’s disease. Methods This single centre, retrospective study consists of 19 consecutive patients with Cushing’s disease who underwent transsphenoidal surgery. S-cortisol was measured every 6 h after the operation without any glucocorticoid replacement. We have follow-up on all patients, with a mean follow-up of 68 months. Results At the three-month follow-up, 16 patients (84 %) were in remission; at 12 months, 18 (95 %) were in remission and at the final follow-up (mean 68 months), 13 (68 %) were in remission. Five-years recurrence rate was 26 %. The mean postoperative S-cortisol nadir was significantly lower in the group of patients in remission than in the non-remission group at 3 months, but there was no difference between those in long-term remission compared to those in long-term non-remission. The optimal cut-off value for classifying 3-month remission was 74 nmol/l. Conclusion We achieved a 95 % 1-year remission rate with transsphenoidal surgery for Cushing’s disease in this series of consecutive patients. However, the 5-year recurrence rate was 26 %, showing the need for regular clinical and biochemical controls in this patient group. The mean postoperative serum-cortisol nadir was significantly lower in patients in remission at 3 months compared to patients not in remission at 3 months, but a low postoperative S-cortisol did not predict long-term remission.

OBJECTIVE: The discovery of stem cells in the adult human brain and developing stem cell technology open a possible future scenario of autotransplantation, where stem cells are harvested from the patient and propagated in vitro before they are used as transplants. The objectives of this study were: 1) to investigate the feasibility of harvesting tissue containing neural stem cells by endoscopy; 2) to study the possibility of propagating and multiplying stem cells from this tissue efficiently in vitro; and 3) to examine whether the stem cells differentiate into functional neurons. METHODS: In 13 patients with hydrocephalus undergoing routine neurosurgical procedures, we used an endoscope and a 3-mm biopsy forceps (Medtronic) to harvest the small piece of the ventricular wall that is detached by the introduction of the endoscope. Cells were cultured as neurospheres, and after induced differentiation, they were investigated with immunocytochemistry and whole-cell patch-clamp recordings. All cells characterized were propagated under strict clonal conditions. RESULTS: We found it uncomplicated to harvest the part of the lateral ventricular wall that compares with the inner lumen of the endoscope. Single cells, isolated and cultivated in vitro, multiplied to form neurospheres in a serum-free environment. A single stem cell had the potential to give rise to approximately 9 x 10 5 new cells after two passages. The total number of cells produced from a single biopsy was already, after the second passage, far beyond the number required in, for instance, Parkinson's disease. Within 1 week of induced differentiation, cells expressing markers for neurons (β-III-tubulin or NeuN), oligodendrocytes (RIP or 04), and astrocytes (glial fibrillary acidic protein) appeared. After 3 weeks, cells with a neuronal phenotype showed a firing pattern distinctive of mature neurons, including repetitive, short-lasting, and overshooting action potentials that were blocked by inhibiting voltage-dependent Na + -channels with tetrodotoxin. CONCLUSION: These results indicate that it may be feasible to produce neural tissue for autotransplantation from endoscopically harvested stem cells, but further work is needed in refining culture protocols to control phenotype fate.

It was long held as an axiom that new neurons are not produced in the adult human brain. More recent studies have identified multipotent cells whose progeny express glial or neuronal markers. This discovery may lead to new therapeutic strategies for CNS disorders, either by stimulating neurogenesis in vivo or by transplanting multipotent progenitor cells (MPCs) that have been propagated and differentiated in vitro. The clinical application of such approaches will be limited by the ability of these cells to develop into functional neurons. To facilitate an understanding of mechanisms regulating neurogenesis in the adult human brain, we characterized the developmental processes MPCs go through when progressing to a neuron. Human tissue was harvested during temporal lobe resections because of epilepsy, and cells were cultured as neurospheres. Our findings demonstrate that at an early stage, these cells often stain with neuronal markers without possessing any functional neuronal properties. Over a period of 4 weeks in culture, cells go through characteristic steps of morphological and electrophysiological development towards functional neurons; they develop a polarized appearance with multiple dendrites, whereas the membrane potential becomes more negative and the input resistance decreases [from -48 +/- 10 mV/557 +/- 85 MOmega (n = 15) between days 7 and 11 to -59 +/- 9 mV/380 +/- 79 MOmega (n = 9) between days 25 and 38, respectively]. Active membrane properties were first observed on day 7 and consisted of a voltage-gated K+-current. Later in the second week the cells developed voltage-gated Ca2+-channels and fired small Ca2+-driven action potentials. Immature Na+-driven action potentials developed from the beginning of the third week, and by the end of the fourth week the cells fired repetitive action potentials with a completely mature waveform generated by the combined action of the voltage-gated ionic channels INa, IA and IK. After 4 weeks, the newly formed neurons also communicated by the use of GABAergic and glutamatergic synapses. The adult human brain thus harbours MPCs, which have the ability to develop into neurons and in doing this follow characteristic steps of neurogenesis as seen in the developing brain.

OBJECTIVE: It was long held as an axiom that new neurons are not produced in the adult human brain. More recent studies, however, have identified multipotent cells whose progeny express glial or neuronal markers. This discovery may lead to new therapeutic strategies against central nervous system disorders by transplanting stem cells that have been propagated in vitro. Still, it is not known whether stem cells from the adult human brain retain the potential to mature into neurons that integrate and communicate in a network. METHODS: We cultured cells from the ventricular wall of the adult human brain as monoclonal neurospheres. After two passages, the neurospheres were dissociated and the cells were allowed to differentiate. After 4 weeks of maturation, the cells were studied by immunocytochemistry, confocal microscopy, and whole-cell patch-clamp. RESULTS: We show that monoclonal stem cells harvested from the ventricular wall of the adult human brain develop into mature neurons with functional glutamate receptors and glutamatergic nerve terminals. By patching pairs of cells simultaneously, we also present direct evidence for synaptic communication between neurons developed from the same monoclonal cell. CONCLUSION: Neural stem cells harvested from the adult human brain retain the potential to mature into fully differentiated neurons that integrate and communicate by synapses. This opens a possible future scenario of autotransplantation, in which stem cells are harvested from small biopsies of the ventricular wall and propagated in vitro before transplantation.

Cellular transplantation therapy is thought to play a central role in the concept of restorative neurosurgery, which aims to restore function to the damaged nervous system. Stem cells represent a potentially renewable source of transplantable cells. However, control of the behavior of these cells, both in the process of clonogenic expansion and post-transplantation, represents formidable challenges. Stem cell behavior is thought to be directed by extracellular signals in their in vivo niches, many of which are protein or peptide based. As only one example, activation of Notch plays an important role in normal development and is the strongest known signal for stem cells to choose glial over neuronal fates. Therefore, artificial extracellular matrix proteins represent a potentially powerful tool to custom design artificial niches to strategically control stem cell behavior. We have developed a family of aECM proteins that incorporate the active domains of the DSL ligands to the Notch receptor into an elastin-based backbone. The development of our DSL-elastin artificial proteins demonstrates the design strategy and methodology for the production of bioactive artificial extracellular matrix proteins aimed at modulating stem cell behavior, and this method can be used to design other bioactive aECM proteins. In addition, we have developed a method for the isolation and characterization of adult human neural stem cells from periventricular tissue harvested from living patients. This paper reviews cellular transplantation therapy from the clinical perspective and summarizes ongoing work aimed at exploring the intriguing possibility of autologous transplantation, whereby neural stem cells can be harvested from adult patients, expanded or modified in vitro in artificial niches, and retransplanted into the original patient.

Recent research communications indicate that the adult human brain contains undifferentiated, multipotent precursors or neural stem cells. It is not known, however, whether these cells can develop into fully functional neurons. We cultured cells from the adult human ventricular wall as neurospheres and passed them at the individual cell level to secondary neurospheres. Following dissociation and plating, the cells developed the antigen profile of the three main cell types in the brain (GFAP, astrocytes; O2, oligodendrocytes; and beta-III-tubulin/NeuN, neurons). More importantly, the cells developed the electrophysiological profiles of neurons and glia. Over a period of 3 weeks, neuron-like cells went through the same phases as neurons do during development in vivo, including up-regulation of inward Na+ -currents, drop in input resistance, shortening of the action potential, and hyperpolarization of the cell membrane. The cells developed overshooting action potentials with a mature configuration. Recordings in voltage-clamp mode displayed both the fast inactivating TTX-sensitive sodium current (INa) underlying the rising phase of the action potential and the two potassium currents terminating the action potential in mature neurons (IA and IK, sensitive to 4-AP and TEA, respectively). We have thus demonstrated that the human ventricular wall contains multipotent cells that can differentiate into functionally mature neurons.

Protein kinase C (PKC) is an important enzyme involved in the regulation of neurotransmission and might also be important in the mediation of ischemic neuronal death. PKC has been implicated as a target of volatile anesthetics as well as in anesthetic protection against ischemia. The present study tested the effect of isoflurane and sevoflurane, both used in neuroanesthetic practice, on presynaptic free cytosolic Ca2+ ([Ca2+](i)) and PKC activity. To measure [Ca2+](i) and PKC activation simultaneously, rat synaptosomes, mostly containing presynaptic terminals, were loaded with the fluorescent probes fura-2 and fim-1, respectively. The synaptosomes were exposed to either isoflurane or sevoflurane in concentrations corresponding to 1 and 2 MAC values in rats, both in Ca2+-containing and Ca2+-free medium. After 8 minutes of anesthetic exposure, 1 mM 4-aminopyridine was added to induce membrane depolarization. Isoflurane 1 and 2 MAC increased the basal PKC activity after 8 minutes in Ca2+-containing medium by 15.1% (3.6%) and 30.5% (5.5%) compared with control, respectively [mean (SEM); n = 9, both values P < 0.05]. Sevoflurane 2 MAC transiently decreased but thereafter increased the PKC activity (P < 0.05). In Ca2+ -free medium sevoflurane attenuated the PKC activity (P < 0.05). The anesthetics did not alter the depolarization-evoked enzyme activation. Furthermore, 2 MAC of both isoflurane and sevoflurane increased the basal- and attenuated the depolarization-evoked increase in [Ca2+](i) (P < 0.05). The present study supports the hypotheses that volatile anesthetics affect presynaptic PKC activity and that the anesthetic effect on enzyme activation seems to be related to an increase in [Ca2+](i).

Background: Volatile anaesthetics exert their effect in the brain mainly by reducing synaptic excitability. Isoflurane abates excitation by reducing the release and increasing the uptake of transmitter glutamate into the presynaptic terminal. The exact molecular mechanisms exerting these effects, however, are not clear. Voltage-gated calcium channels have been proposed as the pharmacological target. The present study examines the effect of sevoflurane on synaptic glutamate release and free cytosolic calcium and the effect on high- and low-affinity uptake of L-glutamate using isolated presynaptic terminals prepared from rat cerebral cortex. Methods: Released glutamate was measured fluorometrically in a spectrophotometer as the fluorescence of NADPH and calcium as the fluorescence of fura-2. 4-aminopyridine was used to induce membrane depolarization. Glutamate uptake was measured in a series of different concentrations of L-glutamate corresponding to the high- and the low- affinity uptake systems adding a fixed concentration og radiolabelled glutamate. The labelling was measured by counting disintegrations per min in a β-scintillation counter. Results: Sevoflurane reduced the calcium-dependent glutamate release in a dose-dependent manner as sevoflurane 1.5, 2.5 and 4.0% reduced the release by 58, 69 and 94%, respectively (P

Decompressive craniectomy in malignant middle cerebral artery infarction (MMCAI) reduces mortality. Whether speech-dominant side infarction results in less favorable outcome is unclear. This study compared functional outcome, quality of life, and mental health among patients with speech-dominant and non-dominant side infarction. All patients undergoing decompressive craniectomy for MMCAI were included. Demographics, side of infarction, and speech-dominant hemisphere were recorded. Outcome at follow-up was assessed by global functioning (modified Rankin Scale score), neurological impairment (National Institutes of Health Stroke Scale score), dependency (Barthel Index), anxiety and depression (Hospital Anxiety and Depression scale), and quality of life (Short Form-36). Twenty-nine out of 45 patients (mean age ± SD, 48.1 ± 11.6 years; 58 % male) were alive at follow-up, and 26 were eligible for analysis [follow-up, median (interquartile range): 66 months (32–93)]. The speech-dominant hemisphere was affected in 13 patients. Outcome for patients with speech-dominant and non-dominant side MMCAI was similar regarding neurological impairment (National Institutes of Health Stroke Scale score, mean ± SD: 10.3 ± 7.0 vs. 8.9 ± 2.7, respectively; p = 0.51), global functioning [modified Rankin Scale score, median (IQR): 3.0 [2–4] vs. 4.0 [3–4]; p = 0.34], dependence (Barthel Index, mean ± SD: 16.2 ± 5.0 vs. 13.1 ± 4.8; p = 0.12), and anxiety and depression (Hospital Anxiety and Depression scale, mean ± SD: anxiety, 5.0 ± 4.5 vs. 7.3 ± 5.8; p = 0.30; depression, 5.0 ± 5.2 vs. 5.9 ± 3.9; p = 0.62). The mean quality of life scores (Short Form-36) were not significantly different between the groups. There was no statistical or clinical difference in functional outcome and quality of life in patients with speech-dominant compared to non-dominant side infarction. The side affected should not influence suitability for decompressive craniectomy.

Idiopathic spinal cord herniation (ISCH), where a segment of the spinal cord has herniated through a ventral defect in the dura, is a rarely encountered cause of thoracic myelopathy. The purpose of our study was to increase the clinical awareness of this condition by presenting our experience with seven consecutive cases treated in our department since 2005. All the patients developed pronounced spastic paraparesis or Brown-Séquard syndrome for several years (mean, 4.7 years) prior to diagnosis. MRI was consistent with a transdural spinal cord herniation in the mid-thoracic region in all the cases. The patients underwent surgical reduction of the herniated spinal cord and closure of the dural defect using an artificial dural patch. At follow-up, three patients experienced considerable clinical improvement, one had slight improvement, one had transient improvement, and two were unchanged. Two of the four patients with sphincter dysfunction regained sphincter control. MRI showed realignment of the spinal cord in all the patients. ISCH is probably a more common cause of thoracic myelopathy than previously recognized. The patients usually develop progressive myelopathy for several years before the correct diagnosis is made. Early diagnosis is important in order to treat the patients before the myelopathy has become advanced.

The purpose of the present study was to investigate the possible role of chloride influx and GABA release during cerebral energy deprivation (ED). The functional activity measured by evoked activity (population spike) in hippocampal slices was recorded during nine minutes of ED and 60 minutes recovery. Treatment groups were exposed to ED following administration of the GABAA antagonist penicillin G (pc G) or substitution of extracellular chloride. The release of glutamate and GABA was measured by HPLC. The efflux of 36Cl from preloaded slices was measured during ED with and without blocking the GABAA receptor. The population spike disappeared during ED, and there was a marked release of GABA and glutamate. During recovery the population spike recovered partially. Both application of pc G and substitution of extracellular chloride during ED improved population spike recovery. Uptake of radiolabeled chloride was significantly reduced by pc G. Glutamate release, but not GABA, was significantly reduced by chloride substitution. These results indicate a possible role of chloride mediated injury during ED, and suggest that chloride entry may partly occur through ligand-operated channels. Furthermore there may be an early chloride dependent release of glutamate during cerebral ischemia, whereas later release seems to be chloride independent.

The molecular mechanism of volatile anaesthetic action on presynaptic glutamate release is not clear. An inhibitory effect on voltage-gated calcium channels has been proposed. The present study examines the effect of isoflurane on cytosolic free calcium and synaptic glutamate release from isolated nerve terminals. Synaptosomes from rat cerebral cortex were used. Glutamate was measured with a continuous fluorometric measurement in a spectrophotometer as the fluorescence of NADPH and calcium as the fluorescence of fura-2. Isoflurane reduced the calcium-dependent glutamate release evoked by membrane depolarization with 4-aminopyridine in an inversely dose-dependent manner. The glutamate release was reduced by 56, 43 and 36% in response to isoflurane 0.5, 1.5 and 3.0%, respectively (for all: P < 0.05). Membrane depolarization evoked a rise in cytosolic free calcium of approximately 34%. Addition of isoflurane (0.5, 1.5 and 3.0%) produced no significant change in cytosolic free calcium. These results indicate that the isoflurane-induced reduction in presynaptic glutamate release is caused by other mechanisms than blocking voltage-gated calcium channels. As the release is inversely dose-dependent, two or more mechanisms could be involved.

he French physician Alexis Carrel opened the field of revascularization when he published the first end-to-end T anastomosis in 1902. Ten years later, he received the Nobel Prize in Physiology or Medicine “in recognition of his work on vascular suture and the transplantation of blood vessels and organs” (2). Since then vascular procedures for augmentation or replacement of blood flow to certain organs have been gradually refined to the benefit of selected groups of patients, for example, bypass for cardiac ischemia. The development of cerebral revascularization (for review, see [4]) has, however, followed a more troubled path and criteria for if, how and when to offer such treatment to the patients have not been agreed upon.

This single-institution, consecutive series of transsphenoidal procedures included all patients in a defined population of 2.6 million inhabitants who underwent surgery during a specific time period.We sought to determine the surgical complication rate and overall survival rate after transsphenoidal surgery for pituitary adenoma.All transsphenoidal procedures for histologically verified pituitary adenomas performed between September 2002 and February 2011 at our institution were included in this study. The data were obtained from a prospectively collected database and from reviewing medical records. No patients were lost to follow-up, and the median follow-up time was 28 months.A total of 506 transsphenoidal procedures were performed on 446 patients. There were 268 microscopic and 238 endoscopic procedures involving 352 non-functioning and 154 hormone-secreting adenomas. A total of 73% of the procedures were primary surgeries, and 27% were repeat surgeries for tumor recurrence. The overall complication rate was 9.1%. The three most frequent complications were cerebrospinal fluid (CSF) leakage (4.7%), meningitis (2%), and visual deterioration (2%). Multivariate analyses showed that the overall risk for complications increased with older age, surgery for recurrent tumors, and surgery performed by a low-volume surgeon. There was no significant difference in the overall complication rate between the microsurgical and endoscopic techniques. The rate of surgical mortality was 0.6%, and the overall survival rates at 1 and 5 years were 95% and 90%, respectively. The only negative predictor of survival was older age.Transsphenoidal surgery for pituitary adenomas has a low complication rate and a low rate of mortality. We did not find a significant difference in the complication rate between endoscopic and microscopic techniques.

A rare, but important cause of torticollis in children is atlantoaxial rotatory fixation. If the patient remains undiagnosed for more than three months, surgery is generally the only therapeutic alternative. In this article we present our experiences of surgical treatment of late-diagnosed atlantoaxial rotatory fixation in children.This article is based on a review of the case notes of patients who underwent surgery for atlantoaxial rotatory fixation in the Department for Neurosurgery at Oslo University Hospital, Rikshospitalet, during the period 2004-10.The material sample consists of six children aged from seven to 14 years. Five had suffered minor trauma to the upper neck region, while one had had an upper respiratory tract infection. The diagnosis was made 5-36 months after the onset of symptoms. In three of the patients, an attempt was made at closed reduction without success. A CT scan one year postoperatively showed a normal position of the atlantoaxial joint in two patients and partial reduction in three. In the sixth patient there was bone fusion at the time of the operation, and open reduction was unsuccessful. All six patients had reduced rotational movement of the neck at the one-year check-up.All our patients were diagnosed more than five months after the onset of symptoms. Full or partial reduction was achieved in five of the six.

The aim of the present study was to investigate the release of amino-acids in human cerebral cortex during membrane depolarization and simulated ischaemia (energy deprivation). Superfluous tissue from temporal Iobe resections for epilepsy was cut into 500 microns thick slices and incubated in vitro. Membrane depolarization with 50 mM K+ caused a release of glutamate, aspartate, GABA and glycine, but not glutamine or leucine. The release of glutamate and GABA was Ca(++)-dependent. Slices were exposed to simulated ischaemia (energy deprivation; ED) by combined glucose/oxygen deprivation. This caused a Ca(++)-independent release of glutamate, aspartate, GABA, glycine, and taurine which started after 8 min, peaked at the end or shortly after the 27 min period of ED, and returned to control levels within 11 min following termination of ED. Preloaded D-[3H]aspartate was released both during K(+)-stimulation and ED. Release of D-[3H]aspartate during ED was delayed compared to glutamate supporting an initial phase of synaptic glutamate release. Uptake of L-[3H]glutamate was increased during the period of glutamate release, suggesting passive diffusion across the cell membrane or enhanced transport efficacy in cellular elements with functioning uptake mechanisms.

Excessive release of glutamate is believed to play a major role in the susceptibility of neurons to ischaemia. Whether the glutamate release is the primary event or occurs in response to electrophysiologic alterations has not been clarified. In the present study, the amino acid release was therefore correlated to changes in electrophysiological parameters and energy status during conditions of low oxygen tension and varying glucose concentrations in rat hippocampal slices. Plain hypoxia failed to produce glutamate release. All neurons underwent, however, a slow depolarization causing most of the neurons to lose their membrane potential within 10 minutes. By restoring the membrane potential to resting level by current injection, the neurons could still be activated synaptically and respond to transmitter application. Following reoxygenation most of the cells regained their resting membrane potential, but showed reduced excitability. When the slices were exposed to hypoxia combined with glucose deprivation (simulated ischaemia), there was a pronounced increase in the glutamate release. This glutamate release was always preceded by a fast anoxic depolarization. Whereas hypoxia reduced the ATP content only to approximately 50%, ATP was depleted in slices exposed to simulated ischaemia. The results demonstrate that although the neurons lose their membrane potential completely during hypoxia, there is no glutamate release. A fast anoxic depolarization provoked by simulated ischaemia, however, is always followed by glutamate release, probably due to a more severe ATP depletion.

The effect of isoflurane on inhibitory postsynaptic potentials (IPSPs) was studied in rat hippocampal slices by intracellular recordings from pyramidal neurons (n = 34). The amplitude of the IPSP was transiently increased and subsequently reduced in a dose-dependent manner. The duration of the IPSP was increased. The reduction in the IPSP persisted after correction was made for the anesthetic-induced hyperpolarization. The reversal potential for the IPSP was slightly displaced in the depolarizing direction. The depolarizing gamma-aminobutyric acid (GABA) response was unaltered, while the hyperpolarizing GABA response was reduced, suggesting a postsynaptic action. The reduction in the IPSP produced by isoflurane is at least partly due to an altered reversal potential for the IPSP (EIPSP).

Background During trans-sphenoidal microsurgical resection of pituitary adenomas, the extent of resection may be difficult to assess, especially when extensive suprasellar and parasellar growth has occurred. In this prospective study, we investigated whether intra-operative magnetic resonance imaging (iMRI) can facilitate tumour resection. Methods Twenty patients with macroadenomas, (16 non-functioning, three growth-hormone secreting and one pharmaco-resistant prolactinoma) were selected for surgery in the iMRI. The mean tumour diameter was 27 mm (range 11–41). The mean parasellar grade, according to the Knosp classification, was 2.3. Pre-operative coronal and sagittal T1-weighted and T2-weighted images were obtained. The trans-sphenoidal tumour resection was performed at the edge of the tunnel of a Signa SP 0.5-Tesla MRI. The surgeon aimed at a radical tumour resection that was followed by a peri-operative MRI scan. When a residual tumour was visualised and deemed resectable, an extended resection was performed, followed by another MRI scan. This procedure was repeated until the imaging results were satisfactory. In all patients, we were able to obtain images to assess the extent of resection and to classify the resection as either total or subtotal. Results After primary resection, eight out of 20 cases were classified as total resections. A second resection was performed in 11 of 12 cases classified as subtotal resections, and in four of these, total resection was achieved. A third resection was performed in three of the remaining seven cases with subtotal resections, but we did not achieve total resection in any of these cases. Therefore, the use of iMRI increased the number of patients with total resection from 8/20 (40%) to 12/20 (60%). The only observed complication was a transient spinal fluid leakage. Conclusion Intra-operative MRI during trans-sphenoidal microsurgery is useful in selected patients for a safe and more complete resection. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

The effect of isoflurane on penicillin- and picrotoxin-induced epileptiform activity was tested using hippocampal slice preparations. Isoflurane reduced both the frequency of spontaneous epileptiform bursts and the number of population spikes within each burst in a dose-dependent manner. The last population spikes in the burst were most sensitive to the anesthetic, whereas the first 4–6 spikes were quite resistant and persisted until spontaneous activity was abolished at 3% isoflurane. Isoflurane increased the stimulus current required to evoke epileptiform bursts and shifted the relationship between stimulus current and population spike amplitude to the right. At 3% isoflurane, a dose that usually causes iso-electric EEG and abolishes all spontaneous epileptiform activity, responses could still be evoked, and then invariably had an epileptiform pattern. The maximum response was reduced compared to control and 1.5% isoflurane. With isoflurane there was a reduced tendency for activity to be transmitted from one region within the hippocampus to the other. This effect was also dose-dependent. However, transmitted activity always retained a typical epileptiform character, although the number of population spikes within a train to some extent decreased with increasing concentrations of isoflurane.

Presynaptic terminals (synaptosomes) prepared from guinea pig and rat cerebral cortex release endogenous glutamate in a Ca(2+)-dependent manner in response to membrane depolarisation. In the present study, synaptosomes were prepared from human cerebral cortex removed in association with temporal lobe resections in epileptic patients. The cytosolic free Ca(2+) concentration increased from 474+/-66 before to 649+/-89 nM after 2 min depolarisation. The basal level of free cytosolic Ca(2+) is higher and the increase in response to depolarisation is more pronounced in human synaptosomes than observed in animal experiments. The Ca(2+)-dependent glutamate release, estimated as the difference between total - and the Ca(2+)-independent glutamate release, increased from 0 to 5.4+/-1.9 nmol/mg protein. The released amount of glutamate is larger than reported in animal models. These results demonstrate that membrane depolarisation of synaptosomes from human brain evokes a rapid rise in cytosolic free Ca(2+) and a more prolonged rise in synaptic, Ca(2+)-dependent glutamate release.

OBJECTIVE: To directly compare stem cells from the normal adult human brain (adult human neural stem cells [AHNSC]), Grade II astrocytomas (AC II), and glioblastoma multiforme (GBM), with respect to proliferative and tumor-forming capacity and differentiation potential. METHODS: Cells were isolated from tissue obtained during epilepsy surgery (AHNSCs) or tumor surgery (glioma stem cells [GSC]). They were cultured and investigated in vitro or after transplantation in immunodeficient mice. RESULTS: Under identical experimental conditions, the following were found: 1) GBM stem cells formed tumors after orthotopic transplantation; AHNSCs showed no sign of tumor formation; 2) GSCs showed a significantly higher growth rate and self-renewal capacity; 3) both the growth rate and telomerase expression were high in GSCs and correlated with malignancy grade (GBM higher than AC II); AHNSCs had low telomerase expression; 4) GSCs invaded normal neurospheres, not vice versa; 5) both AHNSCs and stem cells from AC II and GBM responded to differentiation cues with a dramatic decrease in the proliferation index (Ki-67); 6) GSCs differentiated faster than AHNSCs; 7) upon differentiation, AHNSCs produced normal glia and neurons; GSCs produced morphologically aberrant cells often expressing both glial and neuronal antigens; and 8) differentiation of AHNSCs resulted in 2 typical functional phenotypes: neurons (high electrical membrane resistance, ability to generate action potentials) and glial cells (low membrane resistance, no action potentials). In contrast, GSCs resulted in only 1 functional phenotype: cells with high electrical resistance and active membrane properties capable of generating action potentials. CONCLUSION: AHNSCs and stem cells from AC II and GBM differ with respect to proliferation, tumor-forming capacity, and rate and pattern of differentiation.

Hypoxic-ischemic brain injury subsequent to asphyxia represents a major cause of morbidity and death in the newborn. The newborn brain has been considered more resistant to hypoxia than the adult brain because of lower energy demand. The mechanisms underlying hypoxic brain injury, in particular the age-related vulnerability, are still only partially understood. The mitochondrial function is pivotal for the function and survival of neurons. Acutely isolated CA1 neurons from neonatal (3-6 days) and adult rats (5-6 weeks) were loaded with Rh 123, and the effect of hypoxia on the inner mitochondrial membrane potential (Delta psi(m)) was compared. During prolonged hypoxia (15 min), Delta psi(m) was lost in a majority of the neonatal neurons (83%) and in all the adult neurons. During hypoxia (5 min) followed by reoxygenation the mitochondria in 23% of the neonatal neurons were completely depolarized, whereas 85% of the adult neurons demonstrated a complete loss of Delta psi(m). In conclusion hippocampal CA1 mitochondria in the newborn rat are more resistant to hypoxic depolarization than in the adult rat.

Background The mitochondrial membrane potential (DeltaPsim) controls the generation of adenosine triphosphate (ATP) and reactive oxygen species, and sequesteration of intracellular Ca2+[Ca2+]i. Clinical concentrations of sevoflurane affect the DeltaPsim in neural mitochondria, but the mechanisms remain elusive. The aim of the present study was to compare the effect of isoflurane and sevoflurane on DeltaPsim in rat pre-synaptic terminals (synaptosomes), and to investigate whether these agents affect DeltaPsim by inhibiting the respiratory chain. Methods Synaptosomes were loaded with the fluorescent probes JC-1 (DeltaPsim) and Fura-2 ([Ca2+]i) and exposed to isoflurane or sevoflurane. The effect of the anaesthetics on the electron transport chain was investigated by blocking complex I and complex V. Results Isoflurane 1 and 2 minimum alveolar concentration (MAC) decreased the normalized JC-1 ratio from 0.92 +/- 0.03 in control to 0.86 +/- 0.02 and 0.81 +/- 0.01, respectively, reflecting a depolarization of the mitochondrial membrane (n = 9). Isoflurane 2 MAC increased [Ca2+]i. In Ca2+-depleted medium, isoflurane still decreased DeltaPsim while [Ca2+]i remained unaltered. The effect of isoflurane was more pronounced than for sevoflurane. Blocking complex V of the respiratory chain enhanced the isoflurane- and sevoflurane-induced mitochondrial depolarization, whereas blocking complex I and V decreased DeltaPsim to the same extent in control, isoflurane and sevoflurane experiments. Conclusions Isoflurane and sevoflurane may act as metabolic inhibitors by depolarizing pre-synaptic mitochondria through inhibition of the electron transport chain, although isoflurane seems to inhibit mitochondrial function more significantly than sevoflurane. Both agents inhibit the respiratory chain sufficiently to cause ATP synthase reversal.

During cerebral ischemia neuronal injury is induced by a combination of hypoxia, hypoglycemia and glutamate excitotoxicity. To evaluate the relative importance of these factors on the mitochondrial function, acutely isolated rat hippocampal CA1 neurons were loaded with Rhodamine 123 to monitor the mitochondrial membrane potential (Deltapsim). During 15 min of hypoxia, a rapid and complete mitochondrial depolarization was observed in all neurons also when complex V of the respiratory chain was blocked by oligomycin. Glucose deprivation caused 77% of the neurons to loose the Deltapsim completely, whereas most oligomycin-treated neurons retained their Deltapsim. During oxygen and glucose deprivation, a similar mitochondrial response was seen as in hypoxia. Although 15 min of high glutamate concentration (1 mM) provoked a rapid and irreversible increase in [Ca2+]i, only 25% of the neurons lost the Deltapsim. All oligomycin-treated neurons, however, lost the Deltapsim during glutamate exposure. In conclusion, the mitochondrial function of acutely isolated CA1 neurons is more sensitive to hypoxia than to glucose deprivation and glutamate excitotoxicity.

Glutamate excitotoxicity and necrotic cell death are characteristic features of ischemic neuronal injury. In the penumbral area, glutamate exposure is less pronounced and neuronal death is delayed. Recent studies suggest that delayed neuronal death is propagated by intracellular signalling pathways. Protein kinase C (PKC) activation may initiate apoptosis, but its role in ischemia is still not clear. In this study the PKC activity was investigated during non-excitotoxic ischemia in acutely dissociated rat CA1 neurons. During oxygen and glucose deprivation (OGD) the PKC activity measured with the fluorescent dye Fim-1 increased rapidly reaching a maximum of 31+/-8% (P0.05) after 5 min. When extracellular Ca2+ was depleted, the fluorescence intensity increased by 20+/-8% (P0.05), but with a slower onset. In neurons treated with thapsigargin in a Ca2+ depleted solution, however, OGD did not trigger PKC activation. The results suggest that the PKC activation is mainly triggered by Ca2+ release from endogenous stores.

BACKGROUND: Volatile anaesthetics protect the heart from ischaemic injury by activating mitochondrial signalling pathways. The aim of this study was to test whether sevoflurane, which is increasingly used in neuroanaesthesia, affects mitochondrial function in the central nervous system by altering the mitochondrial membrane potential (DeltaPsi(m)). METHODS: In order to correlate free cytosolic Ca(2+) ([Ca(2+)](i)) and DeltaPsi(m), rat neural presynaptic terminals (synaptosomes) were loaded with the fluorescent probes fura-2 and JC-1. During sevoflurane exposure, 4-aminopyridine (4-AP) 500 micro M to induce pre-synaptic membrane depolarization or carbonylcyanide-p-(trifluoromethoxy)-phenylhydrazone (FCCP) 1 micro M to induce maximum mitochondrial depolarization was added. In order to block mitochondrial ATP-regulated K(+)-channels (mitoK(ATP)), the antagonist 5-hydroxydecanoate (5-HD) 500 micro M was added. RESULTS: In Ca(2+)-containing medium, both sevoflurane 1 and 2 MAC gradually decreased the normalized JC-1 ratio from 0.96 +/- 0.01 in control to 0.92 +/- 0.01 and 0.89 +/- 0.01, representing a depolarization of DeltaPsi(m) (n = 9, P < 0.05). Sevoflurane 2 MAC increased [Ca(2+)](i). In Ca(2+)-depleted medium, sevoflurane 1 and 2 MAC depolarized DeltaPsi(m), while [Ca(2+)](i) remained unaltered. Sevoflurane 2 MAC attenuated the 4-AP-induced depolarization of DeltaPsi(m). When mitoK(ATP) was blocked, the sevoflurane-induced depolarization of DeltaPsi(m) was attenuated, but not blocked. The depolarizing effect of sevoflurane on DeltaPsi(m) compared with FCCP was calculated to 13.2 +/- 1.3% in Ca(2+)-containing and 15.1 +/- 1.2% in Ca(2+)-depleted medium (n = 7). CONCLUSIONS: Sevoflurane depolarizes DeltaPsi(m) in rat synaptosomes, and the effect is not dependent on Ca(2+)-influx to the cytosol. Opening of mitoK(ATP) is partly responsible for the depolarizing effect of sevoflurane.