This study was supported by grant Scientific Research Foundation for the High-level Talents, Fujian University of Traditional Chinese Medicine (X2019002-talents).

Procedures involving animal subjects have been approved by the Medical Norms and Ethics Committee of Wenzhou Medical University and are in accordance with the China legislation on the use and care of laboratory animals.
1. Preparation of the thread plug, SD rats, and experimental equipment
<ol>
	<li>Use a nylon thread with a diameter of 0.28 mm as the main body of the thread plug. 
	NOTE: The softness and hardness of the nylon thread should be moderate.</li>
	<li>Cover one end of the nylon thread with silicone material. The length of the silicone part of the thread plug is approximately 1.2 cm, and the diameter is approximately 1.2 mm. The head end is tapered, and the silicone part is cylindrical. Reserve another 5-7 cm. The nylon thread is easy to clamp and can be cut according to specific needs after the operation.</li>
	<li>Use 75% ethanol to soak the thread plug for 3 min before the operation and rinse any residual ethanol with normal saline before plugging.</li>
	<li>Select 12 male SD rats weighing between 280 and 320 g, and randomly divide them into a sham group and experimental group (n = 6 per group). After a week of environmental adaptation, fast the rats for 12 h and water-deprive them for 4 h before the operation.</li>
	<li>Prepare the following experimental equipment needed for the experiment: a small animal anesthesia machine, a brain stereotaxic instrument, a dissecting microscope, a high-speed skull drill, scissors, tweezers, vascular forceps, a needle holder, a needle thread, a 2 mL syringe, a laser-speckle blood-flow imaging system, and a small-animal MRI scanner.</li>
</ol>
2. Construction of SD-Rat SSS-Embolization Model via Thread Embolization
<ol>
	<li>Place the SD rat into an anesthesia-induction box and use a small-animal anesthetic machine to deliver 4% isoflurane to induce anesthesia. Thereafter, use forceps to confirm that the SD rat&#39;s hind limbs and toes do not respond to moderate pinching.</li>
	<li>Quickly fix the SD ratwith shaved top hair in the prone position on a brain stereotaxic device. Maintain anesthesia with 1.5-2.0% isoflurane (at a speed of 0.5 L/min), and stabilize the respiratory rate at 40-60 breaths/min. Stabilize the rat&#39;s body temperature via a heating pad at 37&#177;0.2 &#176;C.
	<ol>
		<li>Apply sterile ophthalmic eye lubricant after the rat is placed on the stereotaxic frame to protect the corneas from drying during anesthesia.</li>
	</ol>
	</li>
	<li>Sterilize the surface on the top of the rat&#39;s head with 5% povidone iodine alternating three times with 75% ethanol. Make a skin incision (2.0-cm long) in the middle of the head, and then carefully peel off the top fascia and periosteum to fully expose the skull.
	<ol>
		<li>Confirm the positions of the anterior fontanelle, posterior fontanelle, coronal suture, sagittal suture, and herringbone suture.</li>
	</ol>
	</li>
	<li>Use the area between the coronal suture and the herringbone suture as the blood-flow observational area. To prevent the skull from affecting observation during laser-speckle blood-flow imaging, thin the skull in the observation area until the blood vessels are clearly visible. The size of the thinned skull should be approximately 1.0 cm &#215; 1.0 cm. This step and the following are all performed under a dissecting microscope.
	<ol>
		<li>During skull grinding, use normal-temperature saline to rinse the drill repeatedly to avoid high-temperature burns to the cerebral cortex.</li>
	</ol>
	</li>
	<li>Use a high-speed drill to grind the skull within a 6.0 mm x 4.0 mm bone window centered at bregma to expose the SSS of the bregma area.
	<ol>
		<li>Use normal saline to cool the skull during grinding. When the skull becomes thin, use tweezers to carefully remove the remaining bone pieces to avoid tearing the SSS.</li>
	</ol>
	</li>
	<li>Choose a suitable thread plug, use the SSS bregma point as the plug point, carefully puncture it with a 2 mL syringe needle, and quickly insert the thread plug head into the plug point.
	<ol>
		<li>At this time, the angle between the end of the thread-plug head and the SSS should be approximately 30-45&#176;; then adjust the angle between the end of the thread plug and the SSS to 0-10 degrees, and slowly insert the SSS into the center until the head reaches the posterior edge of the sinus confluence. Thereafter, cut off the excess part of the tail. 
		&#8203;NOTE: Rapid bleeding may occur when the SSS is punctured. If the end of the thread plug cannot be quickly inserted into the plug point at one time, use a small gauze or cotton ball to gently press the plug point while slowly sliding down to expose the plug point carefully, and then quickly insert the end of the wire bolt into the SSS. After the thread plug is inserted, if there is bleeding at the plug point, hemostatic materials such as a gelatin sponge can be used to stop the bleeding.</li>
	</ol>
	</li>
</ol>
3. Detection of Blood Flow on the Brain Surface of SD Rats
<ol>
	<li>Use a laser light source to uniformly illuminate the blood-flow observational area. The reflected light is collected by a camera and is transmitted to a computer for analysis. Use the following parameter settings for the laser-speckle blood-flow imaging system: wavelength: &#955; = 785 nm; and image exposure time: T = 10 ms.</li>
	<li>Center the SD-rat blood-flow observational area into the field of view of the laser-speckle blood-flow imaging system and conduct continuous monitoring of blood flow on the brain surface for 2 min. Collect and process the blood flow data before and after embolization for each SD rat, and obtain the laser-speckle blood-flow map of the observed area.</li>
	<li>Repeatedly rinse the operated area with normal saline to wash away bone debris and residue. Suture the skin (0# thread) and disinfect with iodophor.</li>
	<li>Maintain body temperature until the rat awakens after surgery and then house in a single cage with food and water provided ad libitum. The sham group cannot be plugged.</li>
	<li>After data collection is completed, perform post-processing.
	<ol>
		<li>Complete selection of the region of interest (ROI) via the tools provided by the laser-speckle blood-flow imaging system software. The values obtained are the average blood-flow value in the ROI, and the local cerebral-blood-flow values before and after embolization. Use the blood-flow value before embolization as the baseline value.</li>
		<li>Select four ROIs and measure the relative change in cerebral blood flow in each ROI, expressed as the percent change from the baseline value.</li>
	</ol>
	</li>
</ol>
4. Detection of thread position on small animals MRI
<ol>
	<li>Use the following T2-weighted imaging (T2WI) parameters for MRI imaging system: time of echo (TE) = 33 ms, time of repeat (TR) = 3000 ms, number of excitation (NEX) = 4, Slices = 28, slice thickness = 0.8 mm, matrix size = 256*256 mm2, flip angle = 80&#176;, field of view (FOV) = 30*30 mm2, scan time = 6 min 24 s; magnetic resonance angiography (MRA) parameters were set as follows: TE = 4.4 ms, TR = 12 ms, NEX = 4, slices = 80, slice thickness = 0.4 mm, matrix size = 256*256 mm2, flip angle = 80&#176;, FOV = 30*30 mm2, scan time = 16 min 23 sec 40 ms.</li>
	<li>Fix the animal on the MRI scanning table, calibrate the brain position by positioning scanning, and perform T2WI and MRA sequence scanning after confirming the position.</li>
	<li>Use continuous anesthesia via the animal anesthesia machine during the detection. Then, euthanize the SD rats by intraperitoneal injection of excessive pentobarbital.</li>
	<li>Image acquisition and post-processing: after collecting the image data, in order to observe the state of the thread plug in the SSS more clearly, use the pseudo color enhancement method to display the T2WI image of the rat brain.</li>
</ol>

<ol>
	<li>Bousser, M. G., Ferro, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+venous+thrombosis:+an+update.">Cerebral venous thrombosis: an update.</a> Lancet Neurology. 6 (2), 162-170 (2007).</li><li>Guenther, G., Arauz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+venous+thrombosis:+A+diagnostic+and+treatment+update.">Cerebral venous thrombosis: A diagnostic and treatment update.</a> Neurologia. 26 (8), 488-498 (2011).</li><li>Stam, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thrombosis+of+the+cerebral+veins+and+sinuses.">Thrombosis of the cerebral veins and sinuses.</a> New England Journal of Medicine. 352 (17), 1791-1798 (2005).</li><li>Einh&#228;upl, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EFNS+guideline+on+the+treatment+of+cerebral+venous+and+sinus+thrombosis+in+adult+patients.">EFNS guideline on the treatment of cerebral venous and sinus thrombosis in adult patients.</a> European Journal of Neurology. 17 (10), 1229-1235 (2010).</li><li>Coutinho, J. M., Zuurbier, S. M., Stam, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Declining+mortality+in+cerebral+venous+thrombosis:+a+systematic+review.">Declining mortality in cerebral venous thrombosis: a systematic review.</a> Stroke. 45 (5), 1338-1341 (2014).</li><li>Gotoh, M., Ohmoto, T., Kuyama, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+study+of+venous+circulatory+disturbance+by+dural+sinus+occlusion.">Experimental study of venous circulatory disturbance by dural sinus occlusion.</a> Acta Neurochir (Wien). 124 (2-4), 120-126 (1993).</li><li>Miyamoto, K., Heimann, A., Kempski, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microcirculatory+alterations+in+a+mongolian+gerbil+sinus-vein+thrombosis+model.">Microcirculatory alterations in a mongolian gerbil sinus-vein thrombosis model.</a> Journal of Clinical Neuroscience. 8 (4), (2001).</li><li>Ungersb&#246;ck, K., Heimann, A., Kempski, a. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+Blood+Flow+Alterations+in+a+Rat+Model+of+Cerebral+Sinus+Thrombosis.">Cerebral Blood Flow Alterations in a Rat Model of Cerebral Sinus Thrombosis.</a> Stroke. 24 (4), (1993).</li><li>R&#246;ttger, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+model+of+reversible+sinus+sagittalis+superior+thrombosis+in+the+rat:+magnetic+resonance+imaging+changes.">A new model of reversible sinus sagittalis superior thrombosis in the rat: magnetic resonance imaging changes.</a> Neurosurgery. 57 (3), 573-580 (2005).</li><li>Chen, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photothrombosis+combined+with+thrombin+injection+establishes+a+rat+model+of+cerebral+venous+sinus+thrombosis.">Photothrombosis combined with thrombin injection establishes a rat model of cerebral venous sinus thrombosis.</a> Neuroscience. 306, 39-49 (2015).</li><li>Yang, H., Meng, Z., Zhang, C., Zhang, P., Wang, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishing+a+new+rat+model+of+central+venous+sinus+thrombosis+and+analyzing+its+pathophysiological+and+apoptotic+changes.">Establishing a new rat model of central venous sinus thrombosis and analyzing its pathophysiological and apoptotic changes.</a> Journal of Neuroscience Methods. 203 (1), 130-135 (2012).</li><li>Longa, E. Z., Weinstein, P. R., Carlson, S., Cummins, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+middle+cerebral+artery+occlusion+without+craniectomy+in+rats.">Reversible middle cerebral artery occlusion without craniectomy in rats.</a> Stroke. 20 (1), 84-91 (1989).</li><li>Fluri, F., Schuhmann, M. K., Kleinschnitz, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+ischemic+stroke+and+their+application+in+clinical+research.">Animal models of ischemic stroke and their application in clinical research.</a> Drug Design, Development and Therapy. 9, 3445-3454 (2015).</li><li>Wang, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+tissue+pH+in+an+experimental+model+of+acute+stroke+-+Determination+of+graded+regional+tissue+pH+changes+with+non-invasive+quantitative+amide+proton+transfer+MRI.">Mapping tissue pH in an experimental model of acute stroke - Determination of graded regional tissue pH changes with non-invasive quantitative amide proton transfer MRI.</a> Neuroimage. 191, (2019).</li><li>Liu, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+Vigilin+as+a+Potential+Ischemia+Biomarker+by+Brain+Slice-Based+Systematic+Evolution+of+Ligands+by+Exponential+Enrichment.">Identification of Vigilin as a Potential Ischemia Biomarker by Brain Slice-Based Systematic Evolution of Ligands by Exponential Enrichment.</a> Analytical Chemistry. 91 (10), 6675-6681 (2019).</li></ol>

The authors declare that they have no competing financial interests.

In this study, a new type of CVST model was successfully established by inserting a self-made thread plug into the SSS of SD rats. Additionally, laser-speckle blood-flow imaging and small-animal MRI were combined to monitor changes in blood flow on the brain surface of SD rats before and after the embolization in order to standardize ischemic timing and location.
In 1989, Longa et al. made a reversible MCA occlusion model by retrogradely inserting a self-made nylon suture into the external car...

Cerebral venous sinus thrombosis (CVST) is a rare disease of the cerebral venous system that accounts for only 0.5-1.0% of all causes of stroke but has a relatively high occurrence rate in children and young adults1. During autopsy, CVST was found to be the cause of 10% of cerebrovascular disease deaths2. Thrombosis can occur in any part of the intracranial venous system. The superior sagittal sinus (SSS) is one of the most commonly affected areas in CVST and can involve multiple blood vessels. Owing to stenosis or occlusion of the venous sinuses, intracranial venous return is blocked, which is often accompanied by increased intracranial pressure3. The clinical manifestations of CVST are complex and vary over time; although there is a lack of specificity of symptoms, the most common symptoms include headache (77.2%), seizures (42.7%), and neurological deficits (39.9%). In severe cases, coma and even death may occur4,5. In recent years, due to the overall improvement of medical and health standards and public health awareness, the proportion of related risk factors has changed, the proportion of trauma and infection has decreased, and the proportion of CVST caused by pregnancy, puerperium, oral contraceptives, and other reasons has gradually increased5.
At present, the pathogenesis of CVST is still not well understood. To explore CVST in depth, further pathophysiological research is needed. However, most of these research methods are invasive and therefore difficult to implement clinically. Owing to many limitations of clinical research, animal models have irreplaceable advantages in terms of basic and translational research.
The cause of CVST is complex, as its initial onset is often unrecognized and the location of thrombus formation is highly variable. Fortunately, animal models can achieve better control of these factors. In the past few decades, a variety of CVST animal models have been established, and each model has its own disadvantages. According to different production methods, they can be roughly divided into the following categories: the simple SSS-ligation model6,7; the SSS internal-injection-accelerator model8; the ferric-chloride-induced SSS thrombosis model9; the photochemical-induced SSS thrombosis model10; and the self-made embolism-occlusion SSS model11. However, most of these models are unable to circumvent invasive damage to the animal's cerebral cortex and are not able to accurately control the ischemic time and location. In some models, the thrombus will recanalize spontaneously; in other models, the SSS becomes permanently occluded. In addition, complicated operations and/or serious injuries may affect subsequent pathophysiological findings in these models.
In the present study, a thread plug was inserted into the SSS of Sprague-Dawley (SD) rats to successfully establish a CVST model that minimized damage, enabled precise controllability, and yielded good stability. Additionally, small-animal magnetic resonance imaging (MRI) and laser-speckle blood-flow imaging were combined to verify the model's effectiveness. We evaluated changes in cerebral blood flow before and after establishment of our model, as well as evaluated the stability of our model, laying a foundation for further studies exploring the occurrence, development, and related pathophysiological mechanisms of CVST.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2 mL syringe</td>
			<td>Becton,Dickinson and Company</td>
			<td>301940</td>
			<td></td>
		</tr>
		<tr>
			<td>brain stereotaxic instrument</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>68025</td>
			<td></td>
		</tr>
		<tr>
			<td>dissecting microscope</td>
			<td>Wuhan SIM Opto-technology Co.</td>
			<td>SIM BFI-HR PRO</td>
			<td></td>
		</tr>
		<tr>
			<td>high-speed skull drill</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>78046</td>
			<td></td>
		</tr>
		<tr>
			<td>laser-speckle blood-flow imaging system</td>
			<td>Wuhan SIM Opto-technology Co.</td>
			<td>SIM BFI-HR PRO</td>
			<td></td>
		</tr>
		<tr>
			<td>needle holder</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>F31022-12</td>
			<td></td>
		</tr>
		<tr>
			<td>needle thread</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>F33303-08</td>
			<td></td>
		</tr>
		<tr>
			<td>scissors</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>S13029-14</td>
			<td></td>
		</tr>
		<tr>
			<td>silica gel</td>
			<td>Heraeus Kulzer</td>
			<td>302785</td>
			<td></td>
		</tr>
		<tr>
			<td>small animal anesthesia machine</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>R540</td>
			<td></td>
		</tr>
		<tr>
			<td>small-animal MRI</td>
			<td>Bruker Medical GmbH</td>
			<td>Biospec 94/30 USR</td>
			<td></td>
		</tr>
		<tr>
			<td>tweezers</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>F11029-11</td>
			<td></td>
		</tr>
		<tr>
			<td>vascular forceps</td>
			<td>Shenzhen RWD Life Technology Co., Ltd</td>
			<td>F22003-09</td>
			<td></td>
		</tr>
	</tbody>
</table>

establishment of a rat model of superior sagittal-sinus occlusion via a thread-embolism method

The mechanisms contributing to the natural onset of cerebral venous sinus thrombosis (CVST) are mostly unknown, and a variety of uncontrollable factors are involved in the course of the disease, resulting in great limitations in clinical research. Therefore, the establishment of stable CVST animal models that can standardize a variety of uncontrollable confounding factors have helped to circumvent shortcomings in clinical research. In recent decades, a variety of CVST animal models have been constructed, but the results based on these models have been inconsistent and incomplete. Hence, in order to further explore the pathophysiological mechanisms of CVST, it is necessary to establish a novel and highly compatible animal model, which has important practical value and scientific significance for the diagnosis and treatment of CVST. In the present study, a novel Sprague-Dawley (SD) rat model of superior sagittal sinus (SSS) thrombosis was established via a thread-embolization method, and the stability and reliability of the model were verified. Additionally, we evaluated changes in cerebral venous blood flow in rats after the formation of CVST. Collectively, the SD-rat SSS-thrombosis model represents a novel CVST animal model that is easily established, minimizes trauma, yields good stability, and allows for accurately controlling ischemic timing and location.

To establish the SD-rat SSS-thrombosis model via the suture method, the suture should be prepared in advance (Figure 1A), and the equipment required for the experiment (Figure 1B) should be prepared. Due to the delicate nature of the operation, the preparation of the model needs to be completed under a dissecting microscope. The main steps are shown in Figure 2. To facilitate the description of the specific details of the blood-flow...

Watch this Scientific Journal Video about Establishment of a Rat Model of Superior Sagittal-Sinus Occlusion via a Thread-Embolism Method at JoVE.com

Establishment of a Rat Model of Superior Sagittal-Sinus Occlusion via a Thread-Embolism Method

Here, we establish a novel Sprague-Dawley (SD) rat model of superior sagittal sinus (SSS) thrombosis via a thread-embolization method, and the stability and reliability of the model were verified.

The mechanisms contributing to the natural onset of cerebral venous sinus thrombosis (CVST) are mostly unknown, and a variety of uncontrollable factors ...

establishment-rat-model-superior-sagittal-sinus-occlusion-via-thread

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Neuroscience

3.4K Views.  the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University. Here, we establish a novel Sprague-Dawley (SD) rat model of superior sagittal sinus (SSS) thrombosis via a thread-embolization method, and the stability and reliability of the model were verified. 

Video: Establishment of a Rat Model of Superior Sagittal-Sinus Occlusion via a Thread-Embolism Method

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans2,3. In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO.

Surgical induction of ischemic brain damage in the rat is a widely used model for stroke research. Here we demonstrate the induction of focal cerebral ischemia by occlusion of the middle cerebral artery. Visualization of the resulting infarct by histological staining and magnetic resonance imaging is also shown.

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable ...

A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located in the organs of the abdomen and thorax. The vagus nerve communicates information from stimuli such as heart rate, blood pressure, bronchopulmonary irritation, and gastrointestinal distension to the nucleus of solitary tract of the medulla. The cell bodies of the vagus nerve are located in the nodose and petrosal ganglia, of which the majority are located in the former. The nodose ganglia contain a wealth of receptors for amino acids, monoamines, neuropeptides, and other neurochemicals that can modify afferent vagus nerve activity. Modifying vagal afferents through systemic peripheral drug treatments targeted at the receptors on nodose ganglia has the potential of treating diseases such as sleep apnea, gastroesophageal reflux disease, or chronic cough. The protocol here describes a method of injection neurochemicals directly into the nodose ganglion. Injecting neurochemicals directly into the nodose ganglia allows study of effects solely on cell bodies that modulate afferent nerve activity, and prevents the complication of involving the central nervous system as seen in systemic neurochemical treatment. Using readily available and inexpensive equipment, intranodose ganglia injections are easily done in anesthetized Sprague-Dawley rats.

Afferent vagal signaling transmits important information to central nervous system from receptors located in organs of the abdomen and thorax. The nodose ganglia of vagus nerves contain many types of receptors that modulate vagal activity. This protocol describes a method of local injections of neurochemicals into the nodose ganglia.

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located ...

A Protocol for Measuring Cue Reactivity in a Rat Model of Cocaine Use Disorder

Cocaine use disorder (CUD) follows a trajectory of repetitive self-administration during which previously neutral stimuli gain incentive value. Cue reactivity, the sensitivity to cues previously linked with the drug-taking experience, plays a prominent role in human craving during abstinence. Cue reactivity can be assessed as the attentional orientation toward drug-associated cues that is measurable as appetitive approach behavior in both preclinical and human studies. Herein describes an assessment of cue reactivity in rats trained to self-administer cocaine. Cocaine self-administration is paired with the presentation of discrete cues that act as conditioned reinforcers (i.e., house light, stimulus light, infusion pump sounds). Following a period of abstinence, lever presses in the cocaine self-administration context accompanied by the discrete cues previously paired with cocaine infusion are measured as cue reactivity. This model is useful to explore neurobiological mechanisms underlying cue reactivity processes as well as to assess pharmacotherapies to suppress cue reactivity and therefore, modify relapse vulnerability. Advantages of the model include its translational relevance, and its face and predictive validities.&#160;The primary limitation of the model is that the cue reactivity task can only be performed infrequently and must only be used in short duration (e.g., 1 hour), otherwise rats will begin to extinguish the pairing of the discrete cues with the cocaine stimulus. The model is extendable to any positively reinforcing stimulus paired with discrete cues; though particularly applicable to drugs of abuse, this model may hold future applications in fields such as obesity, where palatable food rewards can act as positively reinforcing stimuli.

Cue reactivity is conceptualized as sensitivity to cues linked with drug-taking experiences that contribute to craving and relapse in abstinent humans. Cue reactivity is modeled in rats by measuring attentional orientation toward drug-associated cues that results in appetitive approach behavior in a cue reactivity test following self-administration and forced abstinence.

Cocaine use disorder (CUD) follows a trajectory of repetitive self-administration during which previously neutral stimuli gain incentive value. Cue ...

A Rat Model of Mild Intrauterine Hypoperfusion with Microcoil Stenosis

Intrauterine hypoperfusion/ischemia is one of the major causes of intrauterine/fetal growth restriction, preterm birth, and low birth weight. Most studies of this phenomenon have been performed in either models with severe intrauterine ischemia or models with gradient degree of intrauterine hypoperfusion. No study has been performed in a model on uniform mild intrauterine hypoperfusion (MIUH). Two models have been used for studies of MIUH: a model based on suture ligation of either side of the arterial arcade formed with the uterine and ovarian arteries, and a transient model based on clipping the bilateral ovarian arteries and aorta having patency. Those two rodent models of MIUH have some limitations, e.g., not all fetuses are subjected to MIUH, depending on their position in the uterine horn. In our MIUH model, all fetuses are subjected to a comparable level of intrauterine hypoperfusion. MIUH was achieved by mild stenosis of all four arteries feeding the uterus, i.e., the bilateral uterine and ovarian arteries.
Arterial stenosis was induced by metal microcoils wrapped around the feeding arteries. Producing arterial stenosis with microcoils allowed us to control, optimize, and reproduce decreased blood flow with very little inter-animal variability and a low mortality rate, thus enabling accurate evaluation. When microcoils with an inner diameter of 0.24 mm were used, the blood flow in both the placenta and fetus was mildly decreased (approximately 30% from the pre-stenosis level in the placenta). The offspring of our MIUH model clearly demonstrates long-lasting alterations in neurological, neuroanatomical and behavioral test results.

Mild intrauterine hypoperfusion was produced by artery stenosis with metal microcoils wrapped around the uterine and ovarian arteries in rats at embryonic day 17. This procedure produced prenatal hypoperfusion and intrauterine growth restriction.

Intrauterine hypoperfusion/ischemia is one of the major causes of intrauterine/fetal growth restriction, preterm birth, and low birth weight. Most studies ...

A Rat Model of Central Fatigue Using a Modified Multiple Platform Method

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed as a water tank with narrow platforms on the bottom. The model rats were put into the tank and stood on the platforms for 14 h (18:00 - 8:00) per day for a consecutive 21 days, with a blank control group set for contrast. At the end of modeling, rats in the model group showed an obvious fatigued appearance. To assess the model, we performed several behavioral tests, including the open field test (OFT), the elevated plus maze (EPM) test, and the exhaustive swimming (ES) test. The results showed that anxiety, spatial cognition impairment, poor muscle performance, and declined voluntary activity presented in model rats confirm the diagnosis of&#160;central fatigue. Changes of the central neurotransmitters also verified the result. In conclusion, the model successfully simulated central fatigue, and future study with the model may help reveal the pathological mechanism of the disease.

Here, we present a protocol to introduce a rat model of central fatigue using the modified multiple platform method (MMPM).

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed ...

A Volumetric Method for Quantification of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a subtype of hemorrhagic stroke. Cerebral vasospasm that occurs in the aftermath of the bleeding is an important factor determining patient outcome and is therefore frequently taken as a study endpoint. However, in small animal studies on SAH, quantification of cerebral vasospasm is a major challenge. Here, an ex vivo method is presented that allows quantification of volumes of entire vessel segments, which can be used as an objective measure to quantify cerebral vasospasm. In a first step, endovascular casting of the cerebral vasculature is performed using a radiopaque casting agent. Then, cross-sectional imaging data are acquired by micro computed tomography. The final step involves 3-dimensional reconstruction of the virtual vascular tree, followed by an algorithm to calculate center lines and volumes of the selected vessel segments. The method resulted in a highly accurate virtual reconstruction of the cerebrovascular tree shown by a diameter-based comparison of anatomical samples with their virtual reconstructions. Compared with vessel diameters alone, the vessel volumes highlight the differences between vasospastic and non-vasospastic vessels shown in a series of SAH and sham-operated mice.

The goal of this article is to present a method that allows a 3-dimensional reconstruction of the cerebrovascular tree in mice after micro computed tomography and determination of volumes of entire vessel segments that can be used to quantify cerebral vasospasm in murine models of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a subtype of hemorrhagic stroke. Cerebral vasospasm that occurs in the aftermath of the bleeding is an important factor ...

A Hydrophobic Tissue Clearing Method for Rat Brain Tissue

Hydrophobic tissue clearing methods are easily adjustable, fast, and low-cost procedures that allows for the study of a molecule of interest in unaltered tissue samples. Traditional immunolabeling procedures require cutting the sample into thin sections, which restricts the ability to label and examine intact structures. However, if brain tissue can remain intact during processing, structures and circuits can remain intact for the analysis. Previously established clearing methods take significant time to completely clear the tissue, and the harsh chemicals can often damage sensitive antibodies. The iDISCO method quickly and completely clears tissue, is compatible with many antibodies, and requires no special lab equipment. This technique was initially validated for the use in mice tissue, but the current protocol adapts this method to image hemispheres of control and transgenic rat brains. In addition to this, the present protocol also makes several adjustments to preexisting protocol to provide clearer images with less background staining. Antibodies for Iba-1 and tyrosine hydroxylase were validated in the HIV-1 transgenic rat and in F344/N control rats using the present hydrophobic tissue clearing method. The brain is an interwoven network, where structures work together more often than separately of one another. Analyzing the brain as a whole system as opposed to a combination of individual pieces is the greatest benefit of this whole brain clearing method.

Here we present a hydrophobic tissue clearing method that allows for the viewing of target molecules as part of intact brain structures. This technique has now been validated for F344/N control and HIV-1 transgenic rats of both sexes.

Hydrophobic tissue clearing methods are easily adjustable, fast, and low-cost procedures that allows for the study of a molecule of interest in unaltered ...

Applying the RatWalker System for Gait Analysis in a Genetic Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta. Gait abnormalities, including decreased arm swing, slower walking speed, and shorter steps are common in PD patients and appear early in the course of disease. Thus, the quantification of motor patterns in animal models of PD will be important for phenotypic characterization during disease course and upon therapeutic treatment. Most cases of PD are idiopathic; however, the identification of hereditary forms of PD uncovered gene mutations and variants, such as loss-of-function mutations in Pink1 and Parkin, two proteins involved in mitochondrial quality control that could be harnessed to create animal models. While mice are resistant to neurodegeneration upon loss of Pink1 and Parkin (single and combined deletion), in rats, Pink1 but not Parkin deficiency leads to nigral DA neuron loss and motor impairment. Here, we report the utility of FTIR imaging to uncover gait changes in freely walking young (2 months of age) male rats with combined loss of Pink1 and Parkin prior to the development of gross visually apparent motor abnormality as these rats age (observed at 4-6 months), characterized by hindlimb dragging as previously reported in Pink1 knockout (KO) rats.

Here we describe the RatWalker system, built by redesigning the MouseWalker apparatus to accommodate for the increased size and weight of rats. This system uses frustrated total internal reflection (FTIR), high-speed video capture, and open-access analysis software to track and quantify gait parameters.

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic (DA) neurons in the substantia nigra pars ...

A Rat Model of EcoHIV Brain Infection

It has been well studied that the EcoHIV infected mouse model is of significant utility in investigating HIV associated neurological complications. Establishment of the EcoHIV infected rat model for studies of drug abuse and neurocognitive disorders, would be beneficial in the study of neuroHIV and HIV-1 associated neurocognitive disorders (HAND). In the present study, we demonstrate the successful creation of a rat model of active HIV infection using chimeric HIV (EcoHIV). First, the lentiviral construct of EcoHIV was packaged in cultured 293 FT cells for 48 hours. Then, the conditional medium was concentrated and titered. Next, we performed bilateral stereotaxic injections of the EcoHIV-EGFP into F344/N rat brain tissue. One week after infection, EGFP fluorescence signals were detected in the infected brain tissue, indicating that EcoHIV successfully induces an active HIV infection in rats. In addition, immunostaining for the microglial cell marker, Iba1, was performed. The results indicated that microglia were the predominant cell type harboring EcoHIV. Furthermore, EcoHIV rats exhibited alterations in temporal processing, a potential underlying neurobehavioral mechanism of HAND as well as synaptic dysfunction eight weeks after infection. Collectively, the present study extends the EcoHIV model of HIV-1 infection to the rat offering a valuable biological system to study HIV-1 viral reservoirs in the brain as well as HAND and associated comorbidities such as drug abuse.

Here, we present a protocol to establish a new rat model of active HIV infection using chimeric HIV (EcoHIV), which is critical for enhancing our understanding of HIV-1 viral reservoirs in the brain and offering a system to study HIV-associated neurocognitive disorders and associated comorbidities (i.e., drug abuse).

It has been well studied that the EcoHIV infected mouse model is of significant utility in investigating HIV associated neurological complications. ...

Induction and Assessment of Levodopa-induced Dyskinesias in a Rat Model of Parkinson's Disease

Levodopa (L-DOPA) remains the gold-standard therapy used to treat Parkinson&#39;s disease (PD) motor symptoms. However, unwanted involuntary movements known as L-DOPA-induced dyskinesias (LIDs) develop with prolonged use of this dopamine precursor.&#160;It is estimated that the incidence of LIDs escalates to approximately 90% of individuals with PD within 10&#8211;15 years of treatment. Understanding the mechanisms of this malady and developing both novel and effective anti-dyskinesia treatments requires consistent and accurate modeling for pre-clinical testing of therapeutic interventions. A detailed method for reliable induction and comprehensive rating of LIDs following 6-OHDA-induced nigral lesioning in a rat model of PD is presented here. Dependable LID assessment in rats provides a powerful tool that can be readily utilized across laboratories to test emerging therapies focused on reducing or eliminating this common treatment-induced burden for individuals with PD.

This article describes methods to induce and evaluate levodopa-induced dyskinesias in a rat model of Parkinson&#39;s disease. The protocol offers detailed information regarding the intensity and frequency of a range of dyskinetic behaviors, both dystonic and hyperkinetic, providing a reliable tool to test treatments targeting this unmet medical need.

Levodopa (L-DOPA) remains the gold-standard therapy used to treat Parkinson&#39;s disease (PD) motor symptoms. However, unwanted involuntary movements ...