Basic and Clinical Neuroscience
Volume:3 Issue: 2, Winter 2012

This study examined the effects of administration of subcutaneous β-estradiol on PTSD-like symptoms (the enhanced conditioned fear response, CFR) that induced by a single-prolonged stress (SPS) and shock in rats. Adult male Wistar rats were exposed to SPS procedure: restraint for 2 h, forced swim for 20 min, and ether anesthesia. Then the rats were placed in fear conditioning system and received 1 mA electric foot shock for 4 s. Following, stressed rats injected with β-estradiol (600 μg/kg) or sesame oil. For CFR testing, 24 h later animals were re-exposed to the shock chamber for 3-min without further shock application. Percent of freezing was scored. Following testing, the animals were anesthetized and their brains were removed for histological examination (cell count) of the hippocampus that stained with cresyl violet. Our results indicated that rats who received electric shock after the SPS exhibited the CFR. β-estradiol significantly reduced the CFR in the SPS rats as compared with control rats. No significant differences were found in cell count in different regions of the hippocampus between experimental groups. Our findings indicated that β-estradiol administration after SPS prevents the enhanced CFR in an animal model of PTSD, suggesting a possible role for β-estradiol in the prevention of PTSD

Stroke is the third important reason of death in adults and an important cause of adult disability. Previous studies suggest that TGF-alpha can induce neurogenesis after stroke. Here in, we studied neurogenesis effects of the TGF-alpha on subventricular zone following ischemia-reperfusion. Male wistar rats (250-300 g) were divided into ischemia and treatment groups. After induction of ischemia-reperfusions, PBS (phosphate buffer salin) and TGF-alpha 50 ng were injected stereotaxicaly in lateral ventricle in ischemia and treatment respectively. After 12 days, the nestin expression in subventricular zone was assessed by immunohistochemical staining method. Our results showed that nestin expression increased significantly in treatment group in comparison with ischemia group (p<0.05). Expression of nestin in SVZ indicates that TGF- α can stimulate the neural stem cells proliferation after ischemia –reperfusion injury.

Previous studies have suggested that the cerebellum is a primary site of motor learning. The cerebellar cortex has a particular glial architecture with large astroglial cells. In addition, more recent works have revealed that astrocytes play a more active role in neuronal activity. The aim of this study was to evaluate the number of astrocytes in the molecular layer of rat's cerebellum after spatial learning. 21 male albino wistar rats were used in this study. Reference and working memory methods of Morris Water Maze (MWM) were used. Following behavioral testing, animals were decapitated under diethyl ether anesthesia. Brains were removed and fixed for 2 weeks for histological assessment. Finally, 7 μm thick coronal slices were cut and stained with PTAH staining for showing the astrocytes. Our results showed a significant difference in the number of astrocytes between the control, reference and working memory groups. On the other hand, the number of astrocytes in the working memory group was more than the other groups. There was no difference in density of astrocytes between the lateral and medial parts of the cerebellum in any group. It seems that the distribution of astrocytes in the lateral and medial parts of cerebellum is similar. We concluded that spatial learning such as reference or working memory methods, can increase the number of astrocytes in the cerebellum and this increase is similar in the cerebellar cortex.

A two-variable integrate and fire model is presented to study the role of transient outward potassium currents in producing temporal aspects of dorsal cochlear nucleus (DCN) pyramidal cells with different profiles namely the chopper, the pauser and the buildup. This conductance based model is a reduced version of KM-LIF model (Meng & Rinzel, 2010) which captures qualitative firing features of a detailed physiological model (Kanold & Manis, 2000). For our development we benefit from transient potassium currents properties i.e. fast activation and slow inactivation to generate long latency before start of firing. We compare our minimal model outputs in response to a hyperpolarizing stimulus fallowed by a depolarizing one with the data of KM-LIF model. The results conform well to the KM-LIF model with lower complexity.

Localization of sources in patients with focal seizure has recently attracted many attentions. In the severe cases of focal seizure, there is a possibility of doing neurosurgery operation to remove the defected tissue. The prosperity of this heavy operation completely depends on the accuracy of source localization. To increase this accuracy, this paper presents a new weighted beamforming method to precisely localize the focal seizure sources from the electroencephalogram (EEG) signals. First, synchronization value is determined just between each two adjacent channels, and the channel with maximum average in synchronization index is selected as the nearest channel to the dominant focal sources. Next, weight of each channel is determined based on its Euclidean's distance to the selected channel. The determined weights act as a prior knowledge, incorporating in multiple signal classification (MUSIC) and some other beamforming methods to localize the exact place of seizure source. Next, the effect of estimated source is removed from the signals repeatedly to find the second focal source. This process continues till all focal sources being determined. To verify and validate the proposed scheme, 65 channels EEG signals were simulated and a linear weighting was applied to the three groups based on some sources. The proposed scheme and some known beamforming methods such as conventional beamformer, MUSIC, Weighted MUSIC, Capon’s, Eigenvector and also SLORETA were applied to the simulated epileptic signals to find the location of sources. Experimental results reveal the superiority of the proposed method to the rival schemes in terms of localization accuracy, both in clean and noisy environments

The inflammatory response requires a coordinated integration of various signaling pathway including cyclooxygenase (COX). COX catalyzes the formation of prostaglandins from arachidonic acid. Among prostaglandins, 15-Deoxy-D12, 14-prostaglandin J2 (15d-PGJ2), an endogenous ligand of Peroxisome proliferator-activated receptor-gamma (PPAR-γ), has been demonstrated to have anti-inflammatory actions. In this study, we investigated whether 15d-PGJ2 as a PPAR-γ ligand could exert neuroprotective effects in rat pheochromocytoma (PC12) cells in PPAR-γ dependent manner. In our experiment, using PC12 cells, the levels of NF-κB, Nrf2, γ-glutamylcysteine synthetase (γ-GCS), hemeoxygenase (HO-1) and apoptosis factors were determined using Western blot in different groups. Also cell viability was determined by the conventional MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) reduction assay and two staining involved Hoechst staining and Acridine Ordange/Ethidiume Bromide staining respectively. Our results show that NS-398, a selective COX-2 inhibitor and 15d-PGJ2, a natural potent ligand of PPAR-γ, were neuroprotective through modulation of at least three different, but related pathways and molecules, including NF-κB and Nrf2 signaling pathway. Our data showed that 15d-PGJ2 and NS-398 induced Nrf2 signaling pathway and its downstream factors such as HO-1 and γ-GCS, while 15d-PGJ2 and NS-398 decreased NF-κB level. Interestingly, the observed protective effects were mediated through PPAR-γ-dependent mechanisms, as they reversed by GW9662, an irreversible antagonist of PPAR-γ receptor. Thus we conclude that 15d-PGJ2 as well as NS-398 exert anti cell death effect in a PPAR-γ dependent mechanisms.

Skull base chordomas are rare neoplasms arising from the notochord. Although histologically benign, these tumors are locally aggressive and present significant management challenges. There are some studies on chordoma cases but there was no study about Iranian cases. In this study we evaluated the location, age and gender of the patients with Chordoma in two referral centers in Tehran. A database of patients with chordoma tumors referred to two centers (Shariati and Imam Hospitals, Tehran) from 2001 to 2011 was retrospectively reviewed. In our subjects tumors affect men nearly twice as frequently as women, and they are most commonly diagnosed in middle-aged (mean age was 50.6). Tumors typically occur in the axial skeleton and have a tendency for the spheno-occipital region of the skull base and sacral region. In adults 33.3% of chordomas involve the sacrococcygeal region, 53% occured at the base of the skull near the spheno-occipital area, and near 14% were found in the vertebral column. The cranial nerves mostly affected were abducens, oculomotor and trochlear, with some overlaps. All patients were treated with surgery and some cases referred for gamma-knife radiosurgery (GKS). Findings of this study showed more involvement of males compare to females; that is different from other studies, however, few studies reported more male to female ratio. Despite the progress in current surgical techniques and some encouraging results with the use of targeted therapy, disease control and long-term prognosis of patients are still poor.