Decerebration by global ischemic stroke in rats

A detailed surgical method for mechanical decerebration of the rat

Surgical methods currently employed for the mechanical decerebration of a rat are only briefly described in the literature; hence, an information void exists for researchers wishing to adopt this technique successfully. Decerebration can lead to a high rate of mortality owing to cranial bleeding, particularly if the operator is inexperienced and uninformed. The illustrated methodology presented here describes, in detail, steps in the decerebration process and indicates effective approaches, such as reversible occlusion of a carotid artery, the combined use of tissue adhesive and haemostatic sponge, and perisurgical monitoring of blood pressure, by which to control blood loss and thus maintain mean postsurgical blood pressure within acceptable physiological parameters. By using this methodology, animal losses can be minimized, particularly in the early stages of adoption of the technique, ultimately reducing the numbers required for a study of this nature.

Experimental animal models of neurogenic bladder dysfunction

Neurogenic bladder is related to various types of neurogenic disease and injury, including cerebrovascular accident, brain tumor, spinal cord injury, and Parkinson's disease. The results of urodynamic study show different types of detrusor and sphincter function. According to these urodynamic results, the physician decides on a treatment plan, such as anticholinergics or alpha-blockers. In the development of a new medication, it is necessary to test the medication's efficacy and toxicity by using a laboratory animal. The proper laboratory animal should have several characteristics. These are biological similarity to humans, a short generation period, and an environment that is easy to control. We describe the development of laboratory animals for the study of neurogenic bladder by decerebration, stroke, and spinal cord injury.

Frequency-current relationships of rat hindlimb alpha-motoneurones

The purpose of this study was to describe the frequency-current (f-I) relationships of hindlimb alpha-motoneurones (MNs) in both anaesthetized and decerebrate rats in situ. Sprague-Dawley rats (250-350 g) were anaesthetized with ketamine and xylazine (KX) or subjected to a precollicular decerebration prior to recording electrophysiological properties from sciatic nerve MNs. Motoneurones from KX-anaesthetized rats had a significantly (P < 0.01) hyperpolarized resting membrane potential and voltage threshold (Vth), increased rheobase current, and a trend (P = 0.06) for a smaller after-hyperpolarization (AHP) amplitude compared to MNs from decerebrate rats. In response to 5 s ramp current injections, MNs could be categorized into four f-I relationship types: (1) linear; (2) adapting; (3) linear + sustained; and (4) late acceleration. Types 3 and 4 demonstrated self-sustained firing owing to activation of persistent inward current (PIC). We estimated the PIC amplitude by subtracting the current at spike derecruitment from the current at spike recruitment. Neither estimated PIC nor f-I slopes differed between fast and slow MNs (slow MNs exhibited AHP half-decay times > 20 ms) or between MNs from KX-anaesthetized and decerebrate rats. Motoneurones from KX-anaesthetized rats had significantly (P < 0.02) hyperpolarized ramp Vth values and smaller and shorter AHP amplitudes and decay times compared to MNs from decerebrate rats. Pentobarbitone decreased the estimated PIC amplitude and almost converted the f-I relationship from type 3 to type 1. In summary, MNs of animals subjected to KX anaesthesia required more current for spike initiation and rhythmic discharge but retained large PICs and self-sustained firing. The KX-anaesthestized preparation enables direct recording of PICs in MNs from intact animals.

A new reproducible focal cerebral ischemia model by introduction of polyvinylsiloxane into the middle cerebral artery: a comparison study

A reliable focal cerebral ischemia model is essential in evaluating the efficacy and safety of neuroprotective therapy for stroke. We present a focal embolic ischemic model of rat with reproducible and predictable brain infarction by comparing it with two other most commonly used focal cerebral ischemia models. To produce embolic focal cerebral ischemia, 30 male Wistar rats were subjected to injection of 30 microl hydrophilic polyvinylsiloxane (PVS) or an autologous thrombus or intraluminal filament occlusion in the right middle cerebral artery (MCA) (n = 10 in each group). The percent of brain infarct volume at 48 h after ischemia, neurobehavioral score at 2 h before and after ischemia, intracranial hemorrhagic incidence, and premature reperfusion rate at 3 h after ischemia by MCA angiography were assessed respectively and compared between the focal cerebral models. We found that PVS-induced focal cerebral ischemia had more consistent brain infarct size with less dispersion (32.2+/-7.4%, CV = 0.23) than that with an intraluminal filament occlusion (27.6+/-11.4%, CV = 0.41) or an autologous thrombus embolization (27.2+/-11.8%, CV = 0.43). Injection of PVS also caused more severe neurobehavioral deterioration (3.8+/-0.4) than those produced by two other models (filament, 3.1+/-0.9, P = 0.02; thrombotic, 3.5+/-0.5, P = 0.08). Additionally, animals with PVS-induced focal cerebral ischemia suffered less intracranial hemorrhage (PVS, 0/10, filament, 3/10, thrombotic, 3/10), and less premature reperfusion as determined by MCA angiography (PVS, 0/10, filament, 4/10, thrombotic, 3/10). Our data suggests that permanent focal cerebral ischemia with high reproducibility and low mortality can be achieved by introducing PVS into the right MCA.