This study was supported by a grant from the European Union&#39;s Horizon 2020 Work Programme (call H2020-FETOPEN-2018-2020) under grant agreement 964712 (PRIME; to M. Simonato).

Cerebrospinal Fluid and Blood Withdrawal from Rats with Concurrent EEG Recording

<ol>
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The authors have nothing to disclose.

The present work illustrates an easy-to-master technique of CSF and blood collection in rats, which may be useful not only for studies in models of epilepsy but also of other neurological conditions or diseases such as Alzheimer, Parkinson, or multiple sclerosis. In epilepsy research, both sampling procedures coupled with video-EEG are ideal when a correlation between the levels of different soluble molecules and seizure activity is pursued. For this specific reason, a continuous video-EEG recording was employed: i) in o...

Cerebrospinal fluid (CSF) and blood sampling are important to identify and validate biomarkers of epilepsy, in both preclinical and clinical research1,2. Nowadays, the diagnosis of epilepsy and most of the research on epilepsy biomarkers focus on EEG and neuroimaging3,4,5. These approaches, however, present several limitations. Apart from routine scalp measurements, in many cases, EEG requires invasive techniques like depth electrodes6. Brain imaging methods have poor temporal and spatial resolution and are relatively expensive and time-consuming7,8. For this reason, the identification of non-invasive, low-cost, and biofluid-based biomarkers would provide a very attractive alternative. In addition, these biofluid biomarkers could be combined with available diagnostic approaches to sharpen their predictiveness.
Patients diagnosed with epilepsy are routinely submitted to EEG9,10 and blood sampling11,12,13,14, and many also to CSF withdrawal to exclude life-threatening causes (i.e., acute infections, autoimmune encephalitis)15. These blood and CSF samples can be used in clinical research aiming to identify biomarkers for epilepsy. For example, Hogg and co-workers have found that an increase in three plasma tRNA fragments precedes seizure occurrence in human epilepsy14. Similarly, interleukin-1beta (IL-1&#946;) levels in human CSF and serum, expressed as ratio of IL-1&#946; levels in CSF over serum, can predict post-traumatic epilepsy development after traumatic brain injury16. These studies highlight the importance of biofluids sampling for epilepsy biomarkers research, but they face multiple limitations intrinsic to clinical trials, e.g., the cofounding factor of anti-epileptic drugs (AEDs) in blood, the frequent lack of etiology information, inadequate controls, modest numbers of patients, and others17,18.
Pre-clinical research offers other opportunities for investigating molecules in biofluids as potential biomarkers for epilepsy. In fact, it is possible to withdraw plasma and/or CSF from animals while performing EEG recordings. Moreover, sampling can be performed repeatedly across multiple days of the experiment, and a number of age, sex, and epileptic insult-matched controls can be used to improve the study&#39;s robustness. Here, a flexible technique to obtain CSF from cisterna magna with parallel withdrawal of plasma from the tail vein in EEG-monitored rats is described in detail. The presented technique has several advantages over alternative methods. By using a butterfly needle approach, it is possible to collect CSF several times without compromising the function of EEG electrodes or similar head implants. This represents a refinement of intrathecal catheter withdrawal procedures, which are associated with a relatively high risk of infection. In addition, the reported free fall dropping approach used for blood collection is superior to other approaches of tail vein blood withdrawal because of the highly reduced risk of hemolysis, due to the fact that blood does not pass through tubing and no vacuum pressure is applied. If performed under strict germ-free conditions, there is a particularly low risk of infection for animals. In addition, by starting the blood withdrawals at the very end of the animals&#39; tails, sampling can be repeated several times. Such techniques are easy to master and can be applied in many preclinical studies of central nervous system disorders.

<table><tbody><tr><td>Blood collection set BD Vacutainer Safety-Lok</td><td>BD Italy SpA, Milan, Italy</td><td>367246</td><td>Material</td></tr><tr><td>Blood Collection tubes (Microtainer K2E)</td><td>BD Italy SpA, Milan, Italy</td><td>365975</td><td>Material</td></tr><tr><td>Butterfly Winged Infusion Set 23G x 3/4&#039;&#039; 0.6 x 19 mm</td><td>Nipro, Osaka, Japan&amp;nbsp;</td><td>PSY-23-ET-ICU</td><td>Material</td></tr><tr><td>Centrifuge refrigerated ALC PK 130R</td><td>DJB Labcare Ltd, Buckinghamshire, England</td><td>112000033</td><td>Material</td></tr><tr><td>Cotton suture 3-0</td><td>Ethicon, Johnson &amp;amp; Johnson surgical technologies, Raritan, New Jersey, USA</td><td>7343H</td><td>Material</td></tr><tr><td>Diazepam 5 mg/2ml, Solupam</td><td>Dechra Veterinary Products, Torino, Italy</td><td>105183014 (AIC)</td><td>Solution</td></tr><tr><td>Digital video 8-channel media recorder system of telemetry EEG set up</td><td>Data Sciences International (DSI), St Paul, MN, USA</td><td>PNM-VIDEO-008</td><td>Equipment</td></tr><tr><td>Digital video surveillance system of tethered EEG set up</td><td>EZVIZ Network, Hangzhou, Cina</td><td>EZVIZ (V5.3.2)</td><td>Equipment</td></tr><tr><td>Disinfectant based on stabilized peroxides and quaternary ammonium activity</td><td>Laboratoire Garcin-Bactinyl, France</td><td>LB 920111</td><td>Solution</td></tr><tr><td>Dummy guide cannula 8 mm</td><td>Agn Tho&#039;s, Lindig&amp;ouml;, Sweden</td><td>CXD-8</td><td>Material</td></tr><tr><td>Electrode 3-channel two-twisted</td><td>Invivo1, Plastic One, Roanoke, Virginia, USA</td><td>MS333/3-B/SPC</td><td>Material</td></tr><tr><td>Electrode holder for stereotxic surgery</td><td>Agn Tho&#039;s, Lindig&amp;ouml;, Sweden</td><td>1776-P1</td><td>Equipment</td></tr><tr><td>Eppendorf BioSpectrometer basic</td><td>Eppendorf AG, Hamburg, Germany</td><td>6137</td><td>Equipment</td></tr><tr><td>&lt;br/&gt; Eppendorf PCR Tubes 0.2 mL</td><td>Eppendorf Srl, Milan, Italy</td><td>30124332</td><td>Material</td></tr><tr><td>Eppendorf &amp;mu;Cuvette G1.0</td><td>Eppendorf AG, Hamburg, Germany</td><td>6138</td><td>Equipment</td></tr><tr><td>Feeding needle flexible 17G for rat</td><td>Agn Tho&#039;s, Lindig&amp;ouml; Sweden</td><td>7206</td><td>Material</td></tr><tr><td>Grass Technology apparatus</td><td>Grass Technologies, Natus Neurology Incorporated, Pleasanton, California, USA</td><td>M665G08</td><td>Equipment (AS40 amplifier, head box, interconnecting cables, telefactor model RPSA S40)</td></tr><tr><td>Isoflurane 100%, IsoFlo</td><td>Zoetis, Rome, Italy</td><td>103287025 (AIC)</td><td>Solution</td></tr><tr><td>Ketamine (Imalgene)</td><td>Merial, Toulouse, France</td><td>221300288 (AIC)</td><td>Solution</td></tr><tr><td>Lithium chloride&amp;nbsp;</td><td>Sigma-Aldrich, Milan, Italy</td><td>L9650</td><td>Material</td></tr><tr><td>Microinjection cannula 31G 9 mm</td><td>Agn Tho&#039;s, Lindig&amp;ouml; Sweden</td><td>CXMI-9</td><td>Material</td></tr><tr><td>MP150 modular data acquisition and&amp;nbsp;analysis system&amp;nbsp;</td><td>Biopac, Goleta, California, USA</td><td>MP150WSW</td><td>Equipment</td></tr><tr><td>Ophthalmic vet ointment, Hylo night</td><td>Ursapharm, Milan, Italy</td><td>941791927 (AIC)</td><td>Material</td></tr><tr><td>Pilocarpine hydrochloride</td><td>Sigma-Aldrich, Milan, Italy</td><td>P6503</td><td>Material</td></tr><tr><td>PTFE Tube with joint</td><td>Agn Tho&#039;s, Lindig&amp;ouml;, Sweden</td><td>JT-10</td><td>Material</td></tr><tr><td>Saline</td><td>0.9% NaCl, pH adjusted to 7.0</td><td></td><td>Solution</td></tr><tr><td>Scopolamine hydrobromide trihydrate</td><td>Sigma-Aldrich, Milan, Italy</td><td>S2250</td><td>Material</td></tr><tr><td>Scopolamine methyl nitrate</td><td>Sigma-Aldrich, Milan, Italy</td><td>S1876</td><td>Material</td></tr><tr><td>Silver&amp;nbsp;sulfadiazine 1% cream&amp;nbsp;</td><td>Sofar, Trezzano Rosa, Milan, Italy</td><td>025561010 (AIC)</td><td>Material</td></tr><tr><td>Simplex rapid dental methacrylic cement&amp;nbsp;&amp;nbsp;</td><td>Kemdent, Associated Dental Products Ltd, Swindon, United Kingdom</td><td>ACR811</td><td>Material</td></tr><tr><td>Stereotaxic apparatus</td><td>David Kopf Instruments, Los Angeles, CA, USA</td><td>Model 963</td><td>Equipment</td></tr><tr><td>Sucrose solution</td><td>10% sucrose in distilled water</td><td>Home-made</td><td>Solution</td></tr><tr><td>Syringe 1 mL&amp;nbsp;</td><td>Biosigma, Cona, Venezia, Italy</td><td>20,71,26,03,00,350</td><td>Material</td></tr><tr><td>Telemeters</td><td>Data Sciences International (DSI), St Paul, MN, USA</td><td>CTA-F40</td><td>Material</td></tr><tr><td>Telemetry EEG traces analyzer</td><td>Data Sciences International (DSI), St Paul, MN, USA</td><td>NeuroScore v3-0</td><td>Equipment</td></tr><tr><td>Telemetry system</td><td>Data Sciences International (DSI), St Paul, MN, USA</td><td>Hardware plus software Ponemah core 6.51</td><td>Equipment</td></tr><tr><td>Xylazine hydrochloride</td><td>Sigma-Aldrich, Milan, Italy</td><td>X1251</td><td>Material</td></tr></tbody></table>

sampling cerebrospinal fluid and blood from lateral tail vein in rats during eeg recordings

Because the composition of body fluids reflects many physiological and pathological dynamics, biological liquid samples are commonly obtained in many experimental contexts to measure molecules of interest, such as hormones, growth factors, proteins, or small non-coding RNAs. A specific example is the sampling of biological liquids in the research of biomarkers for epilepsy. In these studies, it is desirable to compare the levels of molecules in cerebrospinal fluid (CSF) and in plasma, by withdrawing CSF and plasma in parallel and considering the time distance of the sampling from and to seizures. The combined CSF and plasma sampling, coupled with video-EEG monitoring in epileptic animals, is a promising approach for the validation of putative diagnostic and prognostic biomarkers. Here, a procedure of combined CSF withdrawal from cisterna magna and blood sampling from the lateral tail vein in epileptic rats that are continuously video-EEG monitored is described. This procedure offers significant advantages over other commonly used techniques. It permits rapid sampling with minimal pain or invasiveness, and reduced time of anesthesia. Additionally, it can be used to obtain CSF and plasma samples in both tethered and telemetry EEG recorded rats, and it may be used repeatedly across multiple days of experiment. By minimizing the stress due to sampling by shortening isoflurane anesthesia, measures are expected to reflect more accurately the true levels of investigated molecules in biofluids. Depending on the availability of an appropriate analytical assay, this technique may be used to measure the levels of multiple, different molecules while performing EEG recording at the same time.

The outcome of different CSF and blood withdrawal procedures performed in 9 control and 18 chronic epileptic rats, all implanted with electrodes at 1-month post-SE, is reported in terms of success rate. After implantation, all rats were video-EEG monitored for 1 month, during which the CSF plus blood was withdrawn 5x every 3 days during the two last weeks of the experiment (i.e., at days 52, 55, 58, 61, and 64 post-SE; dpSE). Data from multiple withdrawals in different animals were used to compare the success rate of CSF...

Watch this Scientific Journal Video about Obtaining High-Quality CSF and Blood Samples for Epilepsy Biomarker Discovery at JoVE.com

Author Spotlight: Obtaining High-Quality CSF and Blood Samples for Epilepsy Biomarker Discovery 

The protocol shows repeated cerebrospinal fluid and blood collections from epileptic rats performed in parallel with continuous video-electroencephalogram (EEG) monitoring. These are instrumental for exploring possible links between changes in various body fluid molecules and seizure activity.

Sampling Cerebrospinal Fluid and Blood from Lateral Tail Vein in Rats During EEG Recordings

Because the composition of body fluids reflects many physiological and pathological dynamics, biological liquid samples are commonly obtained in many ...

sampling-cerebrospinal-fluid-blood-from-lateral-tail-vein-rats-during

Research

JoVE Journal

Neuroscience

2.7K Views.  Universita degli Studi di Ferrara. In ons onderzoek willen we diagnostische en prognostische biomarkers voor epilepsie vinden. Om ze te valideren in biologische vloeistoffen, vergelijken we de niveaus van specifieke stoffen in het hersenvocht en plasma met het optreden van spontane aanvallen bij ratten. Tegenwoordig zijn sommige kleine niet-coderende ribonucleïnezuren zoals miRNA's of tRNA-fragmenten geïdentificeerd als een circulerende biomarker voor epilepsie, maar hun nut als een effectief en betrouwbaar diagnostisch of p...

Video: Auteur in de schijnwerpers: het verkrijgen van hoogwaardige CSF- en bloedmonsters voor de ontdekking van epilepsiebiomarkers 

A Technique for Serial Collection of Cerebrospinal Fluid from the Cisterna Magna in Mouse 

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is pathologically characterized by extracellular deposition of &#946;-amyloid peptide (A&#946;) and intraneuronal accumulation of hyperphosphorylated tau protein. Because cerebrospinal fluid (CSF) is in direct contact with the extracellular space of the brain, it provides a reflection of the biochemical changes in the brain in response to pathological processes. CSF from AD patients shows a decrease in the 42 amino-acid form of A&#946; (A&#946;42), and increases in total tau and hyperphosphorylated tau, though the mechanisms responsible for these changes are still not fully understood. Transgenic (Tg) mouse models of AD provide an excellent opportunity to investigate how and why A&#946; or tau levels in CSF change as the disease progresses. Here, we demonstrate a refined cisterna magna puncture technique for CSF sampling from the mouse. This extremely gentle sampling technique allows serial CSF samples to be obtained from the same mouse at 2-3 month intervals which greatly minimizes the confounding effect of between-mouse variability in A&#946; or tau levels, making it possible to detect subtle alterations over time. In combination with A&#946; and tau ELISA, this technique will be useful for studies designed to investigate the relationship between the levels of CSF A&#946;42 and tau, and their metabolism in the brain in AD mouse models. Studies in Tg mice could provide important validation as to the potential of CSF A&#946; or tau levels to be used as biological markers for monitoring disease progression, and to monitor the effect of therapeutic interventions. As the mice can be sacrificed and the brains can be examined for biochemical or histological changes, the mechanisms underlying the CSF changes can be better assessed. These data are likely to be informative for interpretation of human AD CSF changes.

A Technique for Serial Collection of Cerebrospinal Fluid from the Cisterna Magna in Mouse

Transgenic (Tg) mouse models of AD provide an excellent opportunity to investigate how and why A&#946; or tau levels in CSF change as the disease progresses in human patients. Here, we demonstrate a refined cisterna magna puncture technique for serial CSF sampling from the mouse.

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is pathologically characterized by extracellular deposition of &#946;-amyloid ...

Biology

Brain Source Imaging in Preclinical Rat Models of Focal Epilepsy using High-Resolution EEG Recordings

Electroencephalogram (EEG) has been traditionally used to determine which brain regions are the most likely candidates for resection in patients with focal epilepsy. This methodology relies on the assumption that seizures originate from the same regions of the brain from which interictal epileptiform discharges (IEDs) emerge. Preclinical models are very useful to find correlates between IED locations and the actual regions underlying seizure initiation in focal epilepsy. Rats have been commonly used in preclinical studies of epilepsy1; hence, there exist a large variety of models for focal epilepsy in this particular species. However, it is challenging to record multichannel EEG and to perform brain source imaging in such a small animal. To overcome this issue, we combine a patented-technology to obtain 32-channel EEG recordings from rodents2 and an MRI probabilistic atlas for brain anatomical structures in Wistar rats to perform brain source imaging. In this video, we introduce the procedures to acquire multichannel EEG from Wistar rats with focal cortical dysplasia, and describe the steps both to define the volume conductor model from the MRI atlas and to uniquely determine the IEDs. Finally, we validate the whole methodology by obtaining brain source images of IEDs and compare them with those obtained at different time frames during the seizure onset.

This video introduces the preparation, recording, and source analysis procedures of high-resolution EEG on sedated rats with a particular preclinical model of focal epilepsy under noninvasive conditions.

Electroencephalogram (EEG) has been traditionally used to determine which brain regions are the most likely candidates for resection in patients with ...

Medicine

Simultaneous Recordings of Cortical Local Field Potentials, Electrocardiogram, Electromyogram, and Breathing Rhythm from a Freely Moving Rat

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls body functions and internal organ rhythms when animals are exposed to emotional challenges and changes in their living environments. In general experiments, signals from different organs, such as the brain and the heart, are recorded by independent recording systems that require multiple recording devices and different procedures for processing the data files. This study describes a new method that can simultaneously monitor electrical biosignals, including tens of local field potentials in multiple brain regions, electrocardiograms that represent the cardiac rhythm, electromyograms that represent awake/sleep-related muscle contraction, and breathing signals, in a freely moving rat. The recording configuration of this method is based on a conventional micro-drive array for cortical local field potential recordings in which tens of electrodes are accommodated, and the signals obtained from these electrodes are integrated into a single electrical board mounted on the animal's head. Here, this recording system was improved so that signals from the peripheral organs are also transferred to an electrical interface board. In a single surgery, electrodes are first separately implanted into the appropriate body parts and the target brain areas. The open ends of all of these electrodes are then soldered to individual channels of the electrical board above the animal's head so that all of the signals can be integrated into the single electrical board. Connecting this board to a recording device allows for the collection of all of the signals into a single device, which reduces experimental costs and simplifies data processing, because all data can be handled in the same data file. This technique will aid the understanding of the neurophysiological correlates of the associations between central and peripheral organs.

This study introduces a method for the simultaneous recording of local field potentials in the brain, electrocardiograms, electromyograms, and breathing signals of a freely moving rat. This technique, which reduces experimental costs and simplifies data analysis, will contribute to the understanding of the interactions between the brain and peripheral organs.

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls ...

Repeated Blood Collection from Tail Vein of Non-Anesthetized Rats with a Vacuum Blood Collection System

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the tail vein is thin so that it is sometimes hard to puncture. In addition, the tail vein has low blood flow and requires a long sampling time to get sufficient blood. The present report describes a simple blood sampling method, the vacuum blood collection method, which is usually used to obtain blood samples from patients, here used for non-anesthetized rats. The 22 G butterfly needle tip was inserted into one of the lateral tail veins approximately 2-3 cm from the tip of the tail at an angle of approximately 20&#176;, and blood was collected in the vacuum collection tube by inserting the rubber end of the butterfly needle into the vacuum blood collection tube. The present experimental results show that the success rate was 95% in the experimental group and 90% in the beginner group. The success rate and puncture times were similar between two groups. The sampling duration was significantly shorter in the experimental group compared to beginner group. In conclusion, this vacuum blood collection method for sequential blood sampling from the tail vein of non- anesthetized rats is feasible and easy-to-learn, which might serve as a reliable alternative to other conventionally used blood sampling techniques for rats.

Here, we describe a simple tail vein blood sampling method in non-anesthetized rats using a vacuum extraction tube system. This method reduces the risk of direct exposure to blood and simplifies taking multiple samples from a single venipuncture.

Blood can be collected from rats in a number of sampling locations. For instance, the tail vein is a superior location for blood sampling. However, the ...

Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats

Microdialysis is a well-established neuroscience technique that correlates the changes of neurologically active substances diffusing into the brain interstitial space with the behavior and/or with the specific outcome of a pathology (e.g., seizures for epilepsy). When studying epilepsy, the microdialysis technique is often combined with short-term or even long-term video-electroencephalography (EEG) monitoring to assess spontaneous seizure frequency, severity, progression and clustering. The combined microdialysis-EEG is based on the use of several methods and instruments. Here, we performed in vivo microdialysis and continuous video-EEG recording to monitor glutamate and aspartate outflow over time, in different phases of the natural history of epilepsy in a rat model. This combined approach allows the pairing of changes in the neurotransmitter release with specific stages of the disease development and progression. The amino acid concentration in the dialysate was determined by liquid chromatography. Here, we describe the methods and outline the principal precautionary measures one should take during in vivo microdialysis-EEG, with particular attention to the stereotaxic surgery, basal and high potassium stimulation during microdialysis, depth electrode EEG recording and high-performance liquid chromatography analysis of aspartate and glutamate in the dialysate. This approach may be adapted to test a variety of drug or disease induced changes of the physiological concentrations of aspartate and glutamate in the brain. Depending on the availability of an appropriate analytical assay, it may be further used to test different soluble molecules when employing EEG recording at the same time.

Here, we describe a method for in vivo microdialysis to analyze aspartate and glutamate release in the ventral hippocampus of epileptic and non-epileptic rats, in combination with EEG recordings. Extracellular concentrations of aspartate and glutamate may be correlated with the different phases of the disease.

Microdialysis is a well-established neuroscience technique that correlates the changes of neurologically active substances diffusing into the brain ...

A Benchtop Approach to the Location Specific Blood Brain Barrier Opening using Focused Ultrasound in a Rat Model

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic delivery including precise localization to a target brain region and reduction of off target side effects. However, stereotaxic surgery is highly invasive which limits its translational efficacy, requires long recovery times, and provides challenges when targeting multiple brain regions. Focused ultrasound (FUS) can be used in combination with circulating microbubbles to transiently open the blood brain barrier (BBB) in millimeter sized regions. This allows intracranial localization of systemically delivered agents that cannot normally cross the BBB. This technique provides a noninvasive alternative to stereotaxic surgery. However, to date this technique has yet to be widely adopted in neuroscience laboratories due to the limited access to equipment and standardized methods. The overall goal of this protocol is to provide a benchtop approach to FUS BBB opening (BBBO) that is affordable and reproducible and can therefore be easily adopted by any laboratory.

Focused ultrasound with microbubble agents can open the blood brain barrier focally and transiently. This technique has been used to deliver a wide range of agents across the blood brain barrier. This article provides a detailed protocol for the localized delivery to the rodent brain with or without MRI guidance.

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic ...

Intraventricular Drug Delivery and Sampling for Pharmacokinetics and Pharmacodynamics Study

Although the blood-brain barrier (BBB) protects the brain from foreign entities, it also prevents some therapeutics from crossing into the central nervous system (CNS) to ameliorate diseases or infections. Drugs are administered directly into the CNS in animals and humans to circumvent the BBB. The present protocol describes a unique way of treating brain infections through intraventricular delivery of antibiotics, i.e., polymyxins, the last-line antibiotics to treat multi-drug resistant Gram-negative bacteria. A straightforward stereotaxic surgery protocol was developed to implant a guide cannula reaching into the lateral ventricle in rats. After a recovery period of 24 h, rats can be injected consciously and repeatedly through a cannula that is fitted to the guide. Injections can be delivered manually as a bolus or infusion using a microinjection pump to obtain a slow and controlled flow rate. The intraventricular injection was successfully confirmed with Evans Blue dye. Cerebrospinal fluid (CSF) can be drained, and the brain and other organs can be collected. This approach is highly amenable for studies involving drug delivery to the CNS and subsequent assessment of pharmacokinetic and pharmacodynamic activity.

Delivery of therapeutics directly into the central nervous system is one way of circumventing the blood-brain barrier. The present protocol demonstrates intracerebroventricular injection for subsequent collection of cerebrospinal fluid and bodily organs. This facilitates the investigation of drug pharmacokinetics and pharmacodynamics in animal models for developing new treatments.

Although the blood-brain barrier (BBB) protects the brain from foreign entities, it also prevents some therapeutics from crossing into the central nervous ...

Sampling Blood from the Lateral Tail Vein of the Rat

Blood samples are commonly obtained in many experimental contexts to measure targets of interest, including hormones, immune factors, growth factors, proteins, and glucose, yet the composition of the blood is dynamically regulated and easily perturbed. One factor that can change the blood composition is the stress response triggered by the sampling procedure, which can contribute to variability in the measures of interest. Here we describe a procedure for blood sampling from the lateral tail vein in the rat. This procedure offers significant advantages over other more commonly used techniques. It permits rapid sampling with minimal pain or invasiveness, without anesthesia or analgesia. Additionally, it can be used to obtain large volume samples (upwards of 1 ml in some rats), and it may be used repeatedly across experimental days. By minimizing the stress response and pain resulting from blood sampling, measures can more accurately reflect the true basal state of the animal, with minimal influence from the sampling procedure itself.

Blood samples are useful for assessing biomarkers of physiological states or disease in vivo. Here we describe the methodology to sample blood from the lateral tail vein in the rat. This method provides rapid samples with minimal pain and invasiveness.

Blood samples are commonly obtained in many experimental contexts to measure targets of interest, including hormones, immune factors, growth factors, ...

Real-Time Dynamic Collection of Hippocampal Extracellular Fluid from Conscious Rats Using a Microdialysis System

A variety of central nervous system (CNS) diseases are associated with changes in the composition of hippocampal extracellular fluid (HECF). However, difficulty in obtaining HECF in real time from conscious rats has long restricted the evaluation of CNS disease progression and the effectiveness of ethnomedicine therapy. Encouragingly, a brain microdialysis technique can be used for continuous sampling with the advantages of dynamic observation, quantitative analysis, and a small sampling size. This allows the monitoring of changes in the extracellular fluid content for compounds from traditional herbs and their metabolites in the brain of living animals. The aim of this study was thus to accurately implant a cerebrospinal fluid microdialysis probe into the hippocampal region of Sprague Dawley (SD) rats with a three-dimensional brain stereotaxic apparatus, cutting off molecular weights greater than 20 kDa. The high-quality HECF was then obtained from conscious rats using a microdialysis sampling control system with an adjustable sampling rate from 2.87 nL/min - 2.98 mL/min. In conclusion, our protocol provides an efficient, rapid, and dynamic method to obtain HECF in awake rats with the help of microdialysis technology, which provides us with unlimited possibilities to further explore the pathogenesis of CNS-related diseases and evaluate drug efficacy.

The protocol here provides a detailed real-time dynamic sampling of extracellular fluid from the hippocampus of awake rats using a microdialysis system.

A variety of central nervous system (CNS) diseases are associated with changes in the composition of hippocampal extracellular fluid (HECF). However, ...

Electroencephalographic Recording of Epileptic Seizures in Epilepsy-Induced Rats

Source: Soukupov&#225;, M., et al. <a href="https://app.jove.com/v/58455">Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats.</a> J. Vis. Exp. (2018)
This video demonstrates electroencephalographic (EEG) recording of epileptic seizures in epilepsy-induced rats. A rat with electrodes implanted in the ventral hippocampus is connected to the EEG recording system and placed in a plexiglass chamber. The rat is allowed to move freely while the brain activity is recorded to monitor the occurrence of seizures.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
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Sampling Cerebrospinal Fluid and Blood from Lateral Tail Vein in Rats During EEG Recordings

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