Concentration-dependent effects of muscimol to enhance pulsatile GnRH release from GT1–7 neurons in vitro

Immortalized GT1–7 neurons were used to characterize the effect of muscimol, a GABA_A receptor agonist, to enhance pulsatile gonadotropin-releasing hormone (GnRH) release. GT1–7 neurons were grown on Cytodex-3 beads and placed in special superfusion microchambers. The cells were superfused at a rate of 6.2 ml·h⁻¹ with Media 199 (pH 7.35) using a commercially available perfusion system. After a pre-muscimol period of 120 min, the cells were exposed for 5 min to 0.35, 1, 5 or 10 μM muscimol or 5 μM muscimol+20 μM of the GABA_A receptor antagonist, bicuculline. Following removal of the muscimol (and bicuculline, in the case of the latter experiment), the superfusion was continued for another 115 min. Sample fractions were collected at 5 min intervals throughout the perfusion. Basal GnRH release from the GT1–7 neurons was pulsatile with an average interpulse interval of 45.4±0.5 min and an average pulse amplitude of 191.5±22.6 pg·min·ml⁻¹. Our results also demonstrated that the GABA_A receptor agonist, muscimol, enhances pulsatile GnRH release from GT1–7 neurons in culture. The response to muscimol was saturable and concentration-dependent with an EC₅₀ of 0.47 μM. The effects of 5 μM muscimol to increase GnRH pulsatility were blocked by co-exposure to the GABA_A receptor antagonist, bicuculline. The average GnRH interpulse intervals were 41.7±1.8 min, 32.5±2.9 min, 30.6±0.7 min and 25.5±0.4 min in the period following exposure to 0.35, 1, 5 and 10 μM of muscimol, respectively (post-muscimol period). GnRH pulse amplitude (mean-area for each pulse) was increased during exposure to muscimol but not during the pre- or post-muscimol periods. The GABA_A receptor antagonist, bicuculline, itself had no effect on pulsatile GnRH release. These results are consistent with previously published reports suggesting that activation of the GABA_A receptor stimulates hypothalamic GnRH release in embryonic and neonatal animals.     

Progesterone increases mRNA levels of pituitary adenylate cyclase-activating polypeptide (PACAP) and type I PACAP receptor (PAC(1)) in the rat hypothalamus

Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates pituitary hormone biosynthesis and secretion through its cognate receptors. PACAP also plays an important role in the regulation of ovarian steroid biosynthesis. If so, there might be a feedback regulation of hypothalamic PACAP synthesis by the pituitary and by ovarian steroids. In the present study, we used RNase protection assays to determine changes in mRNA levels of PACAP and type I PACAP receptor (PAC(1)) under the conditions of ovariectomy and replacement with ovarian steroids. Progesterone (P) alone or in combination with estradiol (E) induced significant increases in PACAP mRNA level in the medial basal hypothalamus (MBH) and PAC(1) mRNA levels in MBH and the preoptic area (POA). This finding suggests that feedback regulation takes place between the ovary and hypothalamic PACAP neurons. P is known to be a major regulatory feedback factor for hypothalamic luteinizing hormone-releasing hormone (LHRH) neurons, but P receptor is not present in these neurons. Therefore, we examined a possible involvement of PACAP in the feedback regulatory pathway of P to LHRH neurons. After an antisense PAC(1) oligodeoxynucleotide (ODN) was i.c.v.-injected into the third ventricle of E and P-treated rats, LHRH mRNA levels were determined. The ODN markedly decreased the P-induced increase in the LHRH mRNA level. Taken together, the present data suggest that PACAP may play a role as a mediator in the regulation of LHRH synthetic machinery by stimulatory feedback of P.     

Added Value of Arterial Spin-Labeling MR Imaging for the Differentiation of Cerebellar Hemangioblastoma from Metastasis

BACKGROUND AND PURPOSE:In adults with only cerebellar masses, hemangioblastoma and metastasis are the 2 most important differential diagnoses. Our aim was to investigate the added value of arterial spin-labeling MR imaging for differentiating hemangioblastoma from metastasis in patients with only cerebellar masses.MATERIALS AND METHODS:This retrospective study included a homogeneous cohort comprising patients with only cerebellar masses, including 16 hemangioblastomas and 14 metastases. All patients underwent enhanced MR imaging, including arterial spin-labeling. First, the presence or absence of a hyperperfused mass was determined. Next, in the hyperperfused mass, relative tumor blood flow (mean blood flow in the tumor divided by blood flow measured in normal-appearing cerebellar tissue) and the size ratio (size in the arterial spin-labeling images divided by size in the postcontrast T1WI) were measured. To validate the arterial spin-labeling findings, 2 observers independently evaluated the conventional MR images and the combined set of arterial spin-labeling images.RESULTS:All patients with hemangioblastomas and half of the patients with metastases presented with a hyperperfused mass (P < .001). The size ratio and relative tumor blood flow were significantly larger for hemangioblastomas than for metastases (P < .001 and P = .039, respectively). The size ratio revealed excellent diagnostic power (area under the curve = 0.991), and the relative tumor blood flow demonstrated moderate diagnostic power (area under the curve = 0.777). The diagnostic accuracy of both observers was significantly improved after the addition of arterial spin-labeling; the area under the curve improved from 0.574 to 0.969 (P < .001) for observer 2 and from 0.683 to 1 (P < .001) for observer 2.CONCLUSIONS:Arterial spin-labeling imaging can aid in distinguishing hemangioblastoma from metastasis in patients with only cerebellar masses.

Hemangioblastoma and metastasis are the 2 most important differential diagnoses of cerebellar masses in adults. Hemangioblastomas are benign tumors of vascular origin and are the second most common infratentorial parenchymal tumor, accounting for 7% of posterior fossa tumors in adults.¹ Metastases are the most common type of brain tumor, and posterior fossa metastases represent approximately 8.7%–10.9% of all brain metastases.^2,3 Discriminating between hemangioblastoma and brain metastasis is important because their therapeutic approaches and prognoses are quite different. The standard treatment for hemangioblastoma is complete surgical resection. However, patients with a brain metastasis usually undergo surgery, stereotactic surgery, whole-brain radiation therapy, chemotherapy, or a combination of these. Furthermore, hemangioblastomas are associated with longer patient survival times,⁴ whereas brain metastases are associated with a poor prognosis.⁵ Because the frequency of metastasis increases with time, patient age is often helpful in distinguishing between these tumors but is not always reliable. In addition, although one-third of patients with cerebellar hemangioblastomas also have von Hippel-Lindau disease,⁶ a clinical history of von Hippel-Lindau disease may not be available at the time of initial presentation.Hemangioblastoma is characterized by markedly increased vascularity⁷; therefore, angiographically dense tumor staining may suggest hemangioblastoma rather than metastasis.⁸ However, cerebral angiography is invasive and involves risks of complications, such as stroke. MR perfusion imaging can provide useful information about vascularization in hemangioblastoma. Previous studies using dynamic susceptibility contrast and dynamic contrast-enhanced MR perfusion imaging have reported increased vascular perfusion in hemangioblastomas.^9,10Arterial spin-labeling (ASL), unlike DSC and dynamic contrast-enhanced perfusion imaging, is a noninvasive MR perfusion technique that uses electromagnetic endogenous arterial water as a freely diffusible tracer instead of an exogenous MR imaging contrast agent. The utility of ASL perfusion imaging in the evaluation of the vascularity of brain tumors has been explored in several recent studies.^11–14 One prior study differentiated hemangioblastomas from metastases on the basis of quantitative blood flow measurements using ASL.¹⁵ The authors reported that tumor blood flow was significantly higher in hemangioblastomas than in metastases. However, their study included a limited number of patients and examined metastatic tumors located primarily in the supratentorial region. Because metastasis usually presents with multiple enhancing supratentorial and infratentorial masses and 90%–95% of hemangioblastomas are in the posterior fossa, it is difficult to differentiate hemangioblastoma from metastasis in patients with only cerebellar masses in daily clinical practice.Therefore, the aim of this study was to determine whether the addition of ASL imaging is useful for differentiating hemangioblastoma from metastasis in a homogeneous cohort of patients with only cerebellar masses and to validate the findings by investigating observer performance.     

短暂脑缺血再灌流后ATP含量变化与细胞凋亡的关系

目的:探讨短暂脑缺血再灌流后能量的动态变化及其与细胞凋亡之间的关系。方法:采用线栓法建立大鼠大脑中动脉闭塞(MCAO)模型,缺血10min后于再灌流后0h、1h、3h、6h、12h、24h和72h应用毛细血管电泳法分别测定额顶叶皮质的ATP含量,同时采用荧光显微镜、流式细胞仪和脱氧核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测细胞凋亡情况,分析两者之间的关系。结果:缺血10min后额顶叶皮质ATP的含量急剧下降至对照组的20%。再灌流后ATP的含量逐渐恢复,于再灌流后1h、3h、6h和12h恢复至对照组的70.5%、65.7%、84.8%和86.9%。再灌流后24hATP含量再次下降,再灌流后24h和72hATP含量仅为对照组的50%,与对照组相比差异有统计学意义(P<0.01和0.05)。缺血10min再灌流24h额顶叶皮质开始出现细胞凋亡现象,并随着时间延长凋亡细胞数目逐渐增加。结论:短暂脑缺血再灌流后大鼠额顶叶皮质存在细胞能量系统功能恢复滞后的现象和继发性细胞能量系统功能衰竭的现象,其中继发性细胞能量系统功能衰竭现象与细胞凋亡之间可能存在互为因果的关系。     

Comparison of temporal lobectomies of children and adults with intractable temporal lobe epilepsy

Introduction

The aim of the study was to assess the difference in clinical characteristics and postsurgical outcomes between children and adults who have undergone temporal lobectomy (TL).

Materials and methods

We retrospectively reviewed the medical records of 52 patients who had undergone TL between 2006 and 2008. Nineteen patients were classified as children (≤18 years old), and 33 patients were classified as adults (>18 years old) according to the age when TL had been performed.

Results

Twelve of 19 (63.2%) children and 24 of 33 (72.7%) adults became seizure free. Rapid secondary generalization such as generalized tonic or tonic–clonic seizures showed a tendency to be more prominent in children (four of 19, 21.1%) than in adults (three of 33, 9.1%). Patients in childhood had significantly more multifocal discharges on interictal electroencephalography (EEG) (42.1%) compared to adults (15.2%, p?=?0.014). The mean extent of surgical excision was 5.0 cm in children and 4.1 cm in adults (p?=?0.001). The incidence of hippocampal sclerosis, the most common pathologic finding in the two groups, was 57.9% (11 of 19) in children and 78.8% (26 of 33) in adults. Malformations of cortical development were significantly more frequent in children (nine of 19, 47.4%) than in adults (seven of 33, 21.2%). Dual pathology was found in 31.6% of children and in 12.1% of adults. The intelligence quotient and memory quotient values in children with temporal lobe resection remained nearly steady during follow-up period without significant decline.

Conclusion

Patients undergoing TL during childhood compared to during adulthood had distinctively different interictal EEG, resectional extents, and pathologic findings.     

Neuroprotective effects of Alpinia katsumadai against neuronal damage in the gerbil hippocampus induced by transient cerebral ischemia

Alpinia katsumadai, one of the family Zingiberaceae, contains chalcone, flavonoids, diarylheptanoids, monoterpenes, sesquiterpenoids, stilbenes, and labdanes. It has been reported that the extract of Alpinia katsumadai seed (EAKS) has antiinflammatory effects, and enhances antioxidant activities. We observed the neuroprotective effects of EAKS against ischemic damage in gerbils received oral administrations of EAKS (50 mg/kg) once a day for 7 days before transient cerebral ischemia. In the EAKS-treated ischemia group, neuronal nuclei (NeuN, a marker for neurons)-immunoreactive pyramidal neurons were abundant (68.3% of the sham group) in the hippocampal CA1 region (CA1) 4 days after ischemia/reperfusion (I/R) compared to those in the vehicle-treated ischemia group (13.18%). We also observed that EAKS treatment significantly decreased the activation of astrocytes and microglia in the CA1 compared with the vehicle-treated ischemia group 4 days postischemia. In addition, protein levels of GFAP and Iba-1 in the EAKS-treated ischemia group were much lower than those in the vehicle-treated ischemia group 4 days after I/P. Our findings indicate that the repeated supplements of EAKS could protect neurons from an ischemic damage, showing that glial activation is markedly decreased in the ischemic area.     

The Processing Time for Recanalization and Size of Ischemic Lesions on DWI is Related With Complete Reperfusion After Mechanical Thrombectomy

Recent studies demonstrated that modified thrombolysis in cerebral infarction (TICI) 3 reperfusion have better functional outcomes than modified TICI 2b after mechanical thrombectomy in acute ischemic stroke with large vessel occlusion. The purpose of this study was to determine significant factors to forecast the presence of complete reperfusion after mechanical thrombectomy based on multimodal magnetic resonance imaging (MRI). We investigated 96 consecutive patients with acute large intracranial artery occlusion of anterior circulation who based on multimodal MRI. Also, we compared clinical and radiologic parameters between patients with modified TICI 3 and those with modified TICI 0-2b. Among 96 eligible subjects received mechanical thrombectomy, 39 patients (40.6%) showed complete reperfusion and 57 partial or nonreperfusion (mTICI 2b-26, mTICI 2a-9, mTICI 1-8, and mTICI 0-14) after mechanical thrombectomy. Patients with mTICI 3 had significantly smaller initial Diffusion weighted images (DWI) lesion volume (P < .01) and much shorter time interval from onset to reperfusion (P < .01) than those patients with mTICI (0-2b). In multivariate analysis, smaller initial DWI volume (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.23-2.57; P < .01) and faster reperfusion time (OR, 1.07; 95% CI 1.01-1.14; P = .015) had an independence significance for complete reperfusion after mechanical thrombectomy. In this study, the ischemic lesion volume on DWI and faster processing time are critical factor to predict the state of complete reperfusion after mechanical thrombectomy.