Brain research. Brain research protocols最新文献

A problem frequently facing researchers examining abundance of expression of a given antigen is measurement. When the antigen is confined to the nucleus, absolute numbers of nuclei or a percentage of nuclei expressing the antigen in a given region can be estimated. When the antigen is localized to cytoplasm, cytoplasmic organelles or processes or membranes, the assessment becomes more difficult. In these settings, an observer/experimenter may assign a density score but intra- and inter-observer agreement using a three-tiered system, and finer resolution than this, is unlikely to be reproducible. Digital image analysis provides an opportunity to minimize observer bias in quantification of immunohistochemical staining. Previously, reported digital methods have mostly employed chromogen-staining methods and often report mean image brightness. We report a method for quantitatively assessing and expressing abundance of expression of an antigen in neural tissue stained with immunofluorescent methods by determining the brightness-area-product (BAP). The described protocol utilizes simple to use commercially available software and calculates BAP rather than mean brightness as a measure more representative of antigen abundance and visual interpretation. Accordingly, we propose this protocol as a useful adjunct to observer interpretation of fluorescent immunohistochemistry and its application to assessment of antigen abundance for varying patterns of antigen localization.

Drug-induced changes in somatosensory-evoked potentials (SEPs) are considered to reflect an altered nociceptive state. Therefore, the SEP is proposed to be a parameter of analgesic efficacy. However, at present, SEPs have not been studied in relation to animal pain. The present study aims to develop a rat model in which this relationship can be studied based on Pavlovian fear conditioning. Therefore, rats, implanted with epidural electro-encephalogram recording electrodes, were randomly assigned to either a paired or random-control group and subjected to an aversive-to-appetitive transfer paradigm. During the aversive phase, the SEP-stimulation paradigm (5 mA square wave pulses, n = 72, of 2 ms duration each, with a stimulus frequency of 0.5 Hz; total duration 144 s) was used as the unconditioned stimulus (US), while a tone (40 s, 1500 Hz, 85 dB sound pressure level) was used as the conditioned stimulus (CS). During the appetitive phase, the CS was presented paired to the presentation of a sugar pellet. When compared to the random-control group, the paired group showed significantly more freezing behavior and significantly less reward-directed behavior in response to the CS in the appetitive phase. In addition, SEPs were not significantly affected by fear conditioning. Based on these results, we conclude that the SEP-stimulation paradigm can be successfully employed as a US in fear conditioning. In future studies, fear conditioning can be carried out under different levels of an analgesic regimen to allow the changes in SEP parameters to be compared to changes in fear-induced behavior making this model potentially useful to validate SEP parameters as indicators of analgesia.

A growing body of evidence suggests that the drug concentration in the effect compartment of the body is the major factor regulating self-administration behavior. A novel computer-based protocol was developed to facilitate studies on mechanisms of drug addiction by determining correlations between drug levels and behavior during multiple drug injections and infusions. The core of the system is a user's program written in Medstate Notation language® (Med-Associates, Inc.), which runs the self-administration session (with MED-PC® software and hardware, Med-Associates, Inc.) and calculates the levels of infused and/or injected drugs in real time during the session. From the comparison of classical exponential and simple linear models of first-order kinetics, it is concluded that exponential solutions for the appropriate differential equations may be replaced with linear equations if the cycle of computation is much shorter than the shortest half-life for the drug. The choice between particular computation equations depends on assumptions about the pharmacokinetics of the particular drug: (i) one-, two- or three-compartment model, (ii) zero-, first- or second-order process of elimination, (iii) the constants of distribution and elimination half-lives of the drug are known or can be reasonably assumed, (iv) dependence of the constants on the drug level, and (v) temporal stability of all parameters during the session. This method of drug level computation can be employed not only for self-administration but also for other behavioral paradigms to advance pharmacokinetic/pharmacodynamic modeling.

γ-Hydroxybutyric acid (GHB)-sensitive (GHB-S) and GHB-resistant (GHB-R) rats have been selectively bred for their opposite sensitivity to the sedative/hypnotic effect of GHB. This opposite sensitivity has been found to generalize to the GABA_B receptor agonist, baclofen. A control line [named GHB-control (GHB-C)] has been derived from the foundation stock of GHB-S and GHB-R rats. GHB-C rats have been bred without any evaluation of their sensitivity to GHB. The experiments described here were designed to evaluate the sensitivity of GHB-C rats, from the 13th generation, to the sedative/hypnotic effect of GHB (1 g/kg, i.p.) and baclofen (20 mg/kg, i.p.). All measures (onset, sleep time and r = sleep time/onset) of sensitivity to GHB- and baclofen-induced sedation/hypnosis in GHB-C rats were significantly different from and intermediate to those recorded in GHB-S and GHB-R rats. Furthermore, these values were similar to those recorded in the foundation stock. These results suggest that GHB-C rats may constitute a valid control line for GHB-S and GHB-R rats, representing the “general population” from which GHB-S and GHB-R rats were derived. Furthermore, the relative equidistance of sensitivity to GHB- and baclofen-induced sedation/hypnosis of GHB-C rats from those of GHB-S and GHB-R rats suggests that genetic factors contributes to the development of both sensitivity in GHB-S rats and resistance in GHB-R rats.

The present study was designed to assess the potential of marrow stromal cells (MSCs) to deliver therapeutic genes to the brain and result in biologically significant functional recovery. The tyrosine hydroxylase (TH) gene was transfected to MSCs with an adeno-associated virus (AAV) vector. MSCs expressing TH gene were transplanted into the striatum of Parkinson's disease (PD) rat. The asymmetric rotation of these models after apomorphine administration was detected every week after transplantation. Six weeks after grafting, animals were sacrificed. Some brains were sectioned to do TH immunohistochemistry. The others were used to detect the dopamine levels by high-performance liquid chromatograph and electrochemical detection (HPLC-ECD). The results showed that MSCs multiply rapidly and formed fibroblast colony-forming units in primary culture. The gene expression efficiency was about 75%. The rounds of asymmetric rotation after apomorphine administration decreased after TH-engineered MSCs were grafted. Histological examination showed that TH gene was expressed around the transplantation points. The dopamine level in the lesioned striatum of rats injected with TH-MSCs was significantly greater than that in rats treated with LacZ-MSCs (P < 0.05). All the data demonstrated that MSCs could readily be genetically engineered. Therefore, MSCs could be useful gene delivery vehicles of gene therapy for Parkinson's disease.

The pluripotency and high proliferative capacity of embryonic stem (ES) cells make them an attractive source of different cell types for biomedical research and cell replacement therapies. It has been demonstrated that ES cells can be induced into neural precursor cells (NPCs) under conditions. NPCs can be expanded in large numbers for significant periods of time to provide a reliable source of cells for transplantation in neurodegenerative disorders and injury of the central nervous system. This study describes a modified method for generation of NPCs from cultured mouse ES cells.

Background and purpose: In a rat model of middle cerebral artery occlusion (MCAO) with intraluminal technique, lesion volume and its reproducibility vary among laboratories. Although laser-Doppler flowmetry (LDF) is useful to optimize the reliability, conventional methods require a craniotomy and special apparatus. The purpose of this study was to evaluate a novel approach for LDF monitoring of rCBF through lateral aspect of the skull without a craniotomy.

Methods: SD rats were subjected to 45 min of MCAO using an intraluminal thread. MCAO was achieved by an examiner who had been trained 4 weeks for making the model with no LDF monitoring (Group-1, n = 12), while in the other group, the same examiner induced MCAO using a novel approach of LDF monitoring (Group-2, n = 12). rCBF was detected through an LDF probe attached to the lateral aspect of the skull. The survival rate and the infarct volume were estimated for comparison between the two groups 2 days after MCAO.

Results: The mortality rate was 25% in Group-1 and 0% in Group-2. The lesion volume of the cortex in Group-2 was 167.21 +/− 48.54 mm³ (mean +/− SD), which was larger than that in Group-1 (112.77 +/− 36.03 mm³, P = 0.026). The coefficient variation of the lesion volume was smaller in Group-2 (29%) than in Group-1 (35%), indicating better reproducibility of the lesion volume in Group-2 than in Group-1.

Conclusions: The approach of LDF monitoring through the lateral aspect of skull was useful for making large consistent infarct with reducing intraanimal variability and unexpected animal death for rat MCAO model.

Telemetric EEG recording plays a crucial role in the neurological characterization of various transgenic mouse models giving valuable information about epilepsies and sleep disorders in humans. In the past different experimental approaches have been described using tethered systems and jacket systems containing recorders. A main disadvantage of these is their sometimes unphysiological, restraining character. Telemetric EEG recording overcomes most of these disadvantages and allows precise and highly sensitive measurement under various physiological and pathophysiological conditions and different stages of consciousness, as during seizure activity and different sleep stages.

Here we present the first contiguous, detailed description of a successful and quick technique for intraperitoneal implantation or subcutaneous pouch implantation of a radiofrequency transmitter in mice and subsequent lead placement in both epidural and deep intracerebral position. Preoperative preparation of the mice, suitable anesthesia, as well as postoperative treatment including pain management are described in detail to provide optimal postoperative recovery. Finally, we display examples of electrocorticograms and deep intracerebral recordings, present strategies to maximize signal-to-noise ratio, paying special attention to major pitfalls and possible artefacts occurring in telemetric EEG recording in mice.