Balance Beam Test Research Articles

An analysis of four different methods of producing focal cerebral ischemia with endothelin-1 in the rat

Endothelin-1 (ET-1), a potent vasoconstrictor, reduces local blood flow to levels that produce ischemic injury when injected directly into brain tissue. The purpose of this study was to compare 4 different methods of inducing focal ischemia with ET-1: (1) topical application to the forelimb motor region of the cortex, (2) intracerebral injection into the forelimb motor region of the cortex, (3) a combination of intracortical and intrastriatal injections and 4. injection of ET-1 adjacent to the middle cerebral artery (MCA). We examined the effect of delivery method and dose of ET-1 on lesion size, inter-animal variability and behavioral outcome on 3 separate tests of motor function and limb preference. We calculated success rate as the percentage of animals that survived surgery and developed a significant impairment (>20% decrease in performance post-surgery) in the staircase-reaching test. All 4 methods produced similar deficits in the staircase, balance beam, and cylinder tests, but the application of ET-1 adjacent to the MCA, though widely used, provided the lowest success rate. The combined cortical and striatal ET-1 produced a high success rate and consequently we examined cerebral blood flow (CBF), the apparent diffusion coefficient (ADC) and T2-weighted magnetic resonance imaging (MRI) changes for this model. We found that infarct volume measured using T2-weighted MRI correlated with histological measurements and that ADC and CBF together predicted which areas will suffer permanent injury. The combined cortical and striatal injection model offers a number of advantages for studies of recovery of function.

890. Improvement of Behavior and Mortality Following CNS Administration of AAVrh.10hCLN2 to CLN2 −/− Mice, a Model LINCL (Battan Disease) a Fatal Childhood Neurological Disorder (Batten Disease)

Top of pageAbstract Late infantile neuronal ceroid lipofuscinosis (LINCL) is a fatal pediatric neurodegenerative disease resulting from mutation of the CLN2 gene encoding for a tripeptidyl peptidase (TPP-I). Deficiency of TPP-I results in aberrant degradation of membrane proteins in the lysosome with development of inclusion bodies, leading to diffuse neuronal cell death. We have compared CNS gene transfer of CLN2 with serotype 2, 5, 8 and rh.10 AAV vectors and observed that AAVrh.10 provided the highest levels of TPP-I protein in the CNS of rodents. In order to assess the functional consequences of AAVrh.10CLN2 CNS administration, a total of 1.6|[times]|1011 genome copies of AAVrh.10hCLN2, was administered into 4 locations per hemisphere of CLN2 |[minus]|/|[minus]| mice ages 7 to 8 wk and the mice were assessed weekly for performance in tests that combine motor and sensory skills. The treated CLN2 |[minus]|/|[minus]| mice were compared to untreated CLN2 |[minus]|/|[minus]| mice (negative controls) and wild type (CLN2 +/+) mice (positive controls). Analysis of TPP-I levels in the brain demonstrated the AAVrh.10CLN2-treated mice had levels higher than the wild type control (CLN2 +/+) in all regions of the brain. Analysis of neuronal lipofucsin-associated autofluorescence, a hallmark of the disease, demonstrated between 40 to 45 % decrease for the treated CLN2|[minus]|/|[minus]| mice in the injected areas in comparison to the untreated CLN2 |[minus]|/|[minus]| mice. In a test for gait analysis, for wild type mice, the footprints for the hindpaws are largely superimposed on those for the front paws and there was no dragging. In untreated CLN2 |[minus]|/|[minus]| mice, by the age of 21 wk, there was poor gait with dragging of feet and no clear coordination of location between the forepaw and the ipsilateral hindpaw. However, in the 21 wk CLN2 |[minus]|/|[minus]| mice treated with AAVrh.10hCLN2, there was better coordination of the paws and much less dragging. In a grip strength test, the treated mice had a better performance than untreated CLN2 |[minus]|/|[minus]| mice (p 0.05). In a balance beam test, the treated mice had a better performance than untreated CLN2 |[minus]|/|[minus]| mice (p<0.005, ANOVA with group as factor and time as covariate), although the performance of AAVrh.10hCLN2 treated CLN2 |[minus]|/|[minus]| mice was not as good as wild type mice (p<0.005). Kaplan-Meier analysis of survival curves also showed that there was a statistically significant survival advantage of AAVrh.10hCLN2 treated CLN2 |[minus]|/|[minus]| mice over the untreated CLN2 |[minus]|/|[minus]| mice. The median age of survival of the injected CLN2 |[minus]|/|[minus]| mice was 147 days compared to 118 days for the uninjected CLN2 |[minus]|/|[minus]| mice (p<0.01). Together, this data suggests the conclusion that AAVrh.10CLN2 is a suitable candidate for preclinical development for the treatment of LINCL.

Behavioral and Histological Evaluation of a Focal Cerebral Infarction Rat Model Transplanted With Neurons Induced from Bone Marrow Stromal Cells

Neurons can be specifically induced from bone marrow stromal cells (MSCs) with extremely high efficiency using gene transfection of the Notch intracellular domain and subsequent treatment with basic-fibroblast growth factor, forskolin, and ciliary neurotrophic factor. We investigated the behavioral and histologic efficacy of such bone marrow stromal cell-derived neuronal cell (MSDNC) transplantation into a focal cerebral infarction model in rats. A left middle cerebral artery occlusion (MCAO) was performed on adult Wistar rats. MSDNC transplantation into the ipsilateral hemisphere was performed on day 7 after MCAO. The behavioral analyses were conducted on days 14, 21, 28, 35, and 36-40, and a histologic evaluation was performed on day 41. MSDNC-transplanted rats showed significant recovery compared with controls (MCAO without cell transplantation) in beam balance, limb placing, and Morris water maze tests. Histologically, transplanted cells migrated from the injection site into the ischemic boundary area, including the cortex, corpus callosum, striatum, and hippocampus. Transplanted MSDNCs were positive for MAP-2 (84% +/- 8.11%), whereas only a small number of cells were positive for GFAP (1.0% +/- 0.23%). The survival rates of MSDNCs and MSCs 1 month after transplantation were approximately 45% and 10%, respectively. These results suggest that use of MSDNCs may be a promising therapeutic strategy for cerebral infarction.

Scheduled access to ethanol results in motor impairment and tolerance in female C57BL/6J mice

We recently reported a method where water-restricted mice were given scheduled access to ethanol followed by access to water. C57BL/6J mice would repeatedly self-administer ethanol in amounts that produced high and stable blood ethanol concentrations (BEC) [Finn DA, Belknap JK, Cronise K, Yoneyama N, Murillo A, Crabbe JC. A procedure to produce high alcohol intake in mice. Psychopharmacol 2005;178:471–480]. The studies reported here demonstrate that behavioral signs of motor impairment result from these high alcohol intakes, and that there was some evidence of tolerance development across repeated sessions. Female C57BL/6J mice were allowed 30 min access to ethanol (5% v/v) followed by 2.5 h access to water either: every 3rd day for 12 days; every 2nd day for 28 days; or every 2nd day for 9 days. On intervening days, mice had 3 h access to water. A control group had daily access to water only. Mice consumed 2–2.5 g/kg ethanol in 30 min, resulting in BECs of 1.4–1.5 mg/ml. Motor impairment was assessed using the accelerating or fixed speed rotarod, balance beam or screen test. In all studies, mice were tested for motor impairment immediately after 30 min access to ethanol or water. In Experiment 1, ethanol-exposed mice had shorter latencies to fall from the fixed speed rotarod and more foot slips on the balance beam than the control group, indicating motor impairment. After drinking ethanol, mice also fell from a screen more quickly than during sober pretraining. In Experiment 2, mice tested (without prior training) for motor impairment and tolerance on the fixed speed rotarod at 6.5 and 10 RPM showed repeated motor impairment in the ethanol group, but did not develop tolerance. In Experiment 3, mice were first given rotarod training at 10 RPM. Following each fluid access period, performance was impaired in mice self-administering ethanol at 10, but not 15 RPM, when compared to control mice. There was no evidence of tolerance across days. However, on the last day, all mice were tested at both RPM following an i.p. injection of 2 g/kg ethanol. Ethanol-experienced mice were less impaired at both RPM than the ethanol-naïve mice, indicating tolerance development according to this between-groups index. These results suggest that C57BL/6J mice will repeatedly consume alcohol in amounts that produce motor impairment under these scheduled fluid access conditions, and that a modest degree of tolerance can be detected using appropriate tests.

Characterization of a New Rat Model of Penetrating Ballistic Brain Injury

Penetrating brain injury (PBI) is a leading cause of mortality and morbidity in modern warfare and accounts for a significant number of traumatic brain injuries worldwide. Here we characterize the pathophysiology of a new rat model of PBI that simulates the large temporary cavity caused by energy dissipation from a penetrating bullet round. Male Sprague-Dawley rats (250-300 g) were subjected to a simulated ballistic wound to the right frontal hemisphere implemented by an inflatable penetrating probe. Three levels of injury severity were compared to control animals. Neurological and physiological outcome was assessed over a 3-day recovery period and brain tissue collected at 72 h for histopathological evaluation. Brain-injured regions included the ipsilateral frontal cortex and striatum with volumetric increases in intracranial hemorrhage (5-18 mm3) and lesion size (9-86 mm3) related to severity. Similarly, hemispheric swelling increased (3-14%) following PBI, associated with a significant rise in intracranial pressure. Astrogliosis was present in regions adjacent to the core-injury along with microglial and leukocyte infiltration. Injury remote to the lesion was observed in the cerebral peduncle that may have accounted, in part, for observed neurological deficits. Neurological and balance beam testing revealed sensorimotor deficits that persisted through 72 h. Severe electroencephalographic disturbances included the occurrence of cortical spreading depression, slow-waves, and brain seizure activity. In conclusion, this rat PBI model replicates diverse, salient features of clinical PBI pathology, generates reproducible and quantifiable measures of outcome, and is scalable by injury severity, rendering it an attractive vehicle for experimental brain trauma research.

Constrained Control Design for Magnetic Bearing Systems

We study control problems in magnetic bearing systems that are subject to both input and state constraints. Apart from the usual restrictions on voltages and currents in the circuit systems, most magnetic bearing systems are subject to a severe state constraint: the motion of the rotor (the suspended object) is only allowed in an extremely small airgap, otherwise the collision of the rotor and the stator would cause severe damages. Traditional methods for avoiding a collision include increasing the airgap and increasing the currents, which would usually result in unnecessarily large capacity of power supply and power loss. In this paper we present a systematic approach for dealing with all the input and state constraints by using some recently developed tools for constrained control design. Issues on the stability region, robustness, disturbance rejections, and transient response are addressed. We hope that by dealing with the constraints properly, safety operation can be ensured with relatively small currents and power consumption. Experiments on the balance beam test rig in our laboratory show that the design techniques are effective.

A clinically oriented experiment on the effect of mixed culture of neonate spinal cord transplantation on recovery of spinal cord injury

In spinal cord injuries, direct trauma by edges of sublaxated or dislocated vertebrae and indirect ischemia as a result of vascular injury necrotize the neural tissue. After spinal cord injury, tissue loss appears as micro- or macrocavitation. Accumulations of non-neuronal cells substitute spared tissue and halts axon regrowth. Lack of supporting cells (secreting trophic factors and matrix) aggravates the condition. In this study, mixed culture of neonatal spinal cord cells were transplanted as potential source of trophic factors, matrix formers, new substitutional elements and myelinating units. Rats injured by impinging between the blades of a titanium clip (1.16 N closing force). Cells were grafted (2 * 10^6 cells in 8 microliters) subarachnoidally 7 days post-injury. Subjects were followed up for 2 months by behavioral (BBB score, Beam Balance Test, Foot Fault Test, Hopping Reflex, Pedal Withdrawal Reflex, Bracing Reflex, Lateral Tactile Reflex and Foot Static Index) and then were sacrificed and assessed by histological (axon density and demyelination distribution) and magnetic resonance imaging (sparing area and lesion length) techniques. Histological and imaging values significantly increased (P

Intranasal IGF-1 Protects against Transient Focal Cerebral Ischemia in Rats following Middle Cerebral Artery Occlusion (MCAO)

P71 Insulin-like growth factor-1 (IGF-1) has been shown to protect against stroke in rats when administered intracerebroventricularly. However, this administration method is not practical in humans as it requires surgery with the risk of infection. Intranasal (IN) delivery is a noninvasive method of bypassing the blood-brain barrier to deliver IGF-1 to the brain [Thorne et al. (1999) Growth Hormone and IGF Research 9: 387]. We have assessed the therapeutic potential of IN IGF-1 in rats following experimentally-induced focal cerebral ischemia and reperfusion. Rats were given a total of three 75 μg doses of IGF-1 (Chiron Corp.) IN over the course of the 72 hour study: 10 minutes after the onset of two hours of MCAO and then again 24 and 48 hours later. Five neurologic tests assessing motor, sensory, vestibulomotor and somatosensory functions were performed at 4, 24, 48 and 72 hours after the onset of MCAO under blinded conditions. Infarct volume, hemispheric swelling and pathological changes were evaluated at 72 hours after MCAO following euthanasia and coding for blind analysis. IGF-1 treatment significantly reduced the corrected infarct volume by 71 % (p=0.002) and hemispheric swelling by 37 % (p=0.017) when compared to vehicle-treated controls. In addition, the postural reflex and flexor response tests showed significant neurologic improvement with IGF-1 treatment (p=0.016 and 0.019 respectively). The adhesive-backed paper test showed borderline significance in both the contact and removal times (p=0.0573 and p=0.042 respectively). The forelimb placing and beam balance tests showed a clear recovery trend but did not reach statistical significance. While IGF-1 does not significantly cross the blood-brain barrier following traditional peripheral routes of administration, it can be delivered to the brain directly from the nasal cavity following intranasal administration. IN IGF-1 reduced both infarct volume and cerebral edema and also significantly reduced neurologic deficits following MCAO. Our study indicates IN delivery of IGF-1 holds significant promise as a noninvasive and efficacious method for treating stroke.

Neurobehavioral protection by the neuronal calcium channel blocker ziconotide in a model of traumatic diffuse brain injury in rats.

Abnormal accumulation of intracellular calcium following traumatic brain injury (TBI) is thought to contribute to a cascade of cellular events that lead to neuropathological conditions. Therefore, the possibility that specific calcium channel antagonists might exert neuroprotective effects in TBI has been of interest. The focus of this study was to examine whether Ziconotide produces such neuroprotective effects. The authors report that the acceleration-deceleration model of TBI developed by Marmarou, et al., induces a long-lasting deficit of neuromotor and behavioral function. The voltage-sensitive calcium channel blocker Ziconotide (also known as SNX-111 and CI-1009) exerts neuroprotective effects in this model of diffuse brain injury (DBI) in rats. The dose and time of injection of Ziconotide chosen for the present study was based on the authors' previous biochemical studies of mitochondria. Rats were trained in a series of motor and memory tasks, following which they were subjected to DBI using the Marmarou, et al., model. At 3, 5, and 24 hours, all rats were injected with 2 mg/kg Ziconotide for a total cumulative dose of 6 mg/kg Ziconotide. Control brain-injured animals were injected with an equal volume of saline vehicle at each of these time points. The rats were tested for motor and cognitive performance at 1, 3, 7,14, 21, 28, 35, and 42 days postinjury. Saline-treated rats displayed severe motor and cognitive deficits after DBI. Compared with saline-treated control animals, rats treated with Ziconotide displayed better motor performance during inclined plane, beam balance, and beam walk tests; improved memory while in the radial arm maze; and improved learning while in the Morris water maze. These results demonstrated that the acceleration-deceleration model, which had been developed by Marmarou, et al., induces severe motor and cognitive deficits. We also demonstrated that Ziconotide exhibits substantial neuroprotective activity in this model of TBI. Improvement was observed in both motor and cognitive tasks, even though treatment was not initiated until 3 hours after injury. These findings support the development of neuronal N-type calcium channel antagonists as useful therapeutic agents in the treatment of TBI.

The effects of human corticotrophin releasing factor on motor and cognitive deficits after impact acceleration injury

Corticotrophin releasing factor has been shown in several models of tissue injury to be an effective treatment for edema. In a previous study we demonstrated this ability in two models of traumatic brain injury (TBI). The aim of this study was to assess whether human corticotrophin releasing factor (hCRF) could additionally improve motor and cognitive deficits. Adult male Sprague-Dawtey rats were randomised into five groups and injured with the Impact Acceleration Model of TBI. Groups I and II received sham injury followed by treatment with either drug vehicle or 100 γg kg-1 hCRF respectively. Group III was injured with no treatment; Group IV animals were injured and treated with 50 γg kg-1 hCRF and Group V were injured and treated with 100 γg kg-1. Animals were assessed both before and after injury with a battery of standardised neuropsychological tests including the Morris Water Maze, the Beam Walk Test, the Beam Balance Test and the Inclined Plane Test. Both 50 γg kg-1 and 100 γg kg-1 hCRF caused significant improvements in motor and cognitive functioning, confirming that in addition to edema-reducing properties, human corticotrophin releasing factor is also capable of improving motor and cognitive functioning. Given the beneficial experimental effects of this compound, hCRF may be a useful clinical treatment, which requires formal evaluation. [Neurol Res 2000; 22: 665-673]

The impact-acceleration model of head injury: Injury severity predicts motor and cognitive performance after trauma

This study examines neuropsychological dysfunction after varying severities of the Impact Acceleration Model of diffuse traumatic brain injury. Adult rats (340 g-400 g) were divided into five groups, and exposed to varying degrees of Impact Acceleration Injury (1 m, 2 m, 2.1 m/500 g and second insult). After injury, animals were allowed to recover; acute neurological reflexes, beam walk score, beam balance score, inclined plane score, and Morris Water Maze score were then assessed at multiple time points. Injury of all severities caused significant motor and cognitive deficits. With milder injuries these effects were transient; however, with more severe injuries no recovery in function was seen. The addition of hypoxia and hypotension made a moderate injury worse than a severe injury. The acute neurological reflexes, the beam balance test and the inclined plane test distinguished between the more severely injured groups, but were affected less by mild injury. The beam walk test was sensitive to mild injury, but appeared unable to distinguish between the severe groups. The Morris Water Maze was sensitive for all injury groups, but appeared to adopt a different response profile with secondary insult. This study has for the first time characterized the degree of motor and cognitive deficits in rodents exposed to differing severities of Impact Acceleration Injury. These data confirm that the tests considered, and the Injury Model used, provide a useful system for the consideration of potential therapies which might ameliorate neuropsychological deficits in diffuse brain injury. [Neurol Res 1999; 21: 742-754]

Abstracts of literature

Abstracts of literature

Delayed treatment with aminoguanidine decreases focal cerebral ischemic damage and enhances neurologic recovery in rats.

Delayed treatment with aminoguanidine (AG), a relatively selective inhibitor of inducible nitric oxide synthase, ameliorates brain damage produced by occlusion of the rat's middle cerebral artery (MCA). We investigated whether the protection exerted by AG is dose-dependent and whether it is associated with improved neurologic outcome. We also studied the effect of the timing of administration of AG relative to the induction of cerebral ischemia. Halothane-anesthetized spontaneously hypertensive rats underwent permanent MCA occlusion distal to the lenticulostriate branches. Neurologic deficits were assessed daily by the postural reflex test and beam balance test. Infarct volume was determined in thionin- stained sections 96 hours after ischemia and values corrected for swelling. Treatment with AG (intraperitoneally, twice daily), starting 24 hours after MCA occlusion, decreased neocortical infarct volume in comparison to vehicle-treated rats. After correction for swelling, the decrease was 8 +/- 12% at 50 mg/kg (n = 8; P > .05; analysis of variance), 25 +/- 13% at 100 mg/kg (n = 7; P < .05), 30 +/- 16% at 200 mg/kg (n = 7; P < .05) and 32 +/- 9% at 400 mg/kg (n = 5; P < .05). Twenty-four hours after induction of ischemia neurologic deficits scores did not differ between treated and untreated rats (P > .05). However, from 48 to 96 hours after ischemia, neurologic deficits improved significantly in rats treated with AG (100 to 400 mg/kg) compared to rats in which vehicle was administered (P < .05). The decrease in neocortical infarct volume was greatest when AG (100 mg/ kg; twice daily) was administered 12 (26 +/- 17%; n = 9) or 24 hours (25 +/- 13, n = 7) after MCA occlusion. The findings show that AG decreases ischemic brain damage dose-dependently and improves neurologic recovery. Delayed treatment with AG may be a therapeutic strategy to selectively target the evolution of ischemic damage that occurs in the post-ischemic period.

Traumatic brain injury in rats results in increased expression of Gap-43 that correlates with behavioral recovery

Traumatic brain injury is associated with behavioral deficits, often in the absence of histopathological or ultrastructural changes. To determine whether membrane remodeling occurs, immunocytochemical techniques were used and the density and distribution of GAP-43 were measured. GAP-43 is a membrane-bound protein, which, when phosphorylated, is thought to regulate metabolic pathways involved in membrane remodeling and neurite growth. Moderate central fluid percussion injury (FPI, 1.9–2.2 atm.) was performed on anesthetized, spontaneously hypertensive Wistar rats (SHR). Behavioral reflex recovery was consistent with moderate levels of brain injury. One, 3, 5, 7 and 9 days after injury, both sham control ( n=4) and FPI ( n=4) animals were sacrificed, the brains were removed, cryosectioned and processed. Density measurements were taken from histological sections taken at interaural 6.20 mm and bregma −2.80 mm and were found to be statistically greater ( P<0.05) than background grey matter readings in the agranular cortices, the frontal, hindlimb, parietal 1 and 2 cortices, and the hippocampus and dentate gyrus, excluding the pyramidal and granular cell layers. Density measurements taken in forelimb and hindlimb cortical regions correlate with forelimb and hindlimb recovery in foot-fault and beam balance tests ( P<0.05). We interpret these data to indicate neuronal membrane remodeling as a result of the disruption of neuronal membranes due to the impact and shearing forces associated with the FPI. The disruption and remodeling of neuronal membranes are in areas that are consistent with the loss and recovery of locomotor and spatial behavior as a result of FPI.

Prolonged severe hemorrhagic shock and resuscitation in rats does not cause subtle brain damage.

Some patients who survived severe hemorrhagic shock (HS) seem to exhibit persistent subtle neurobehavioral deficits. This finding is of concern if limited hypotensive fluid resuscitation is applied in hypotensive victims with penetrating trauma. This study was designed to determine whether subtle brain damage would occur in rats after severe prolonged HS. We hypothesized that rats surviving HS with mean arterial pressure (MAP) controlled at 40 mm Hg for 60 minutes would recover with slight permanent brain damage in terms of cognitive function without morphologic loss of neurons and that rats surviving HS with MAP at 30 mm Hg for 45 minutes (60 minutes were not tolerated) would have grossly abnormal brain function and loss of neurons. Under light nitrous oxide-halothane anesthesia, spontaneously breathing rats underwent MAP-controlled HS (HS phase I), volume resuscitation to normotension and invasive monitoring to 60 minutes (resuscitation phase II), and observation to 10 days with detailed assessment of cognitive function (observation phase III). Five conscious rats served as normal controls. Three treatment groups were compared: group 1, shams (11 of 12 rats survived to 10 days); group 2, HS at MAP 40 mm Hg for 60 minutes (10 of 17 rats survived); group 3, HS at 30 mm Hg for 45 minutes (10 of 14 rats survived). On post-HS day 10, all normal controls and all survivors of all three groups were functionally normal with overall performance category = 1 (normal) (overall performance category 1 = normal, 5 = death) and neurologic deficit scores < or = 7% (neurologic deficit scores 0-10% = normal, 100% = brain death). Post-HS beam balance, beam walking, and Morris water maze test results in HS groups 2 and 3 showed latencies not significantly different from those in shams and normal controls. Light microscopic scoring of five selectively vulnerable brain regions and other regions in five coronal sections revealed no ischemic (pyknotic, shrunken, eosinophilic) neurons in any of the survivors to 10 days. There was no statistical difference between normal controls, sham animals, and both HS groups in the number of normal neurons counted in the hippocampal CA-1 region in the 10-day survivors. All nonsurvivors died with intestinal necrosis. HS at MAP 40 mm Hg for 60 minutes or MAP 30 mm Hg for 45 minutes does not cause subtle functional or histologic brain damage in surviving rats. Controlling MAP at 30 mm Hg carries a risk of sudden cardiac arrest. These data suggest that limited fluid resuscitation, to maintain MAP at about 40 mm Hg, as recommended for victims of penetrating trauma with uncontrolled HS, is safe for the brain.

Moderate, long-term, alcohol consumption potentiates normal, age-related spatial memory deficits in rats.

A modified "Samson" sucrose fading procedure was used to establish voluntary consumption of a 20% ethanol (EtOH) solution in male Sprague-Dawley rats for 18 consecutive months. Intakes were stable over the life span, and corresponded to the moderate to high levels of intake typically observed in human "social" drinkers and alcoholics. The Morris Water Maze (WM), Olton Radial Arm Maze (RM), and a "balance beam" test were used to assess the effects of alcohol and aging on spatial memory and motor function. Aged EtOH-consuming rats (AGED/ALC) demonstrated impaired task acquisition, relative to aged controls (AGED), not reaching criterion performance in either spatial memory task even when given four additional days of training. AGED/ALC rats scored significantly lower on percent correct out of the first eight arm entries, and committed more perseverative errors in the RM. There were no significant performance differences between AGED and AGED/ALC rats on a balance beam test of fine motor coordination and equilibrium, suggesting that deficits observed in the RM and WM were not related to differential motor functioning. These results demonstrated that long-term, moderate, oral self-administration of EtOH, within the range typically consumed by humans, had adverse effects on spatial memory in rats, and that such a pattern of EtOH consumption seemed to exacerbate the decline in cognitive functioning associated with normal aging.

Chronic aluminum fluoride administration: I. Behavioral observations

This study examined the behavioral effects of chronic ingestion of various monofluoroaluminum complexes (AlF3) in drinking water. Forty young adult male Long-Evans rats were divided into four groups of 10 rats each. The groups received different concentrations of AlF3 in the drinking water from three sample solutions having a total Al concentration of 0.5, 5.0, and 50 ppm, respectively, or double-distilled deionized water on an ad lib. basis for 45 weeks. General decline of bodily appearance was observed in the lowest concentration AlF3 group, and animals in this group succumbed in greater numbers during the course of the study than those in any other group. Examinations of performance in an open field, an analysis of walking patterns, and a balance beam test did not find any difficulties indicative of motor disorder. Indeed, on the initial trial on the balance beam, the AlF3-treated animals exhibited superior performance. No group differences were found in behavior assessed by spontaneous alternation or by a modified Morris water maze test. When retested in the Morris maze after a low dose of scopolamine (0.4 mg/kg), the control animals took longer to reach the platform while the AlF3-treated rats were not affected. In an olfactory preference test, the AlF3-treated animals failed to show preferences exhibited by the controls, indicating a possible olfactory impairment. The level of Al in the brains of the AlF3-exposed rats, as determined by direct current plasma analysis, was almost double that of the control animals. There was a similar trend for the Al content found in the kidneys.

Motor performance, histologic damage, and calcium influx in rats treated with NBQX after focal ischemia.

2,3-Dihydroxy-6-nitro-7-sulfamoylbenzo(F)-quinoxaline (NBQX), an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist, has been reported to provide neuronal protection after global ischemia. The objectives of this study were to evaluate the neuroprotective effects of NBQX initiated after focal cortical ischemia and to validate a method for measuring functional outcome in this model. Male spontaneously hypertensive rats (SHRs) were exposed to various durations of transient or permanent tandem middle cerebral artery (MCA) occlusion. Studies compared motor performance using balance beam and prehensile-traction tests, calcium-calmodulin (Ca-CaM) binding by immunohistochemistry, and infarct volume between NBQX-treated animals [intravenous (i.v.) 5 mg/kg/h x 6 h or intraperitoneal (i.p.) 30 mg/kg q 30 min x 3 begun postischemia] and controls. All ischemic groups performed less well than sham-operated controls on the motor performance tasks in proportion to the severity of ischemia. No significant improvement in motor performance was noted in the NBQX-treated versus the control animals after 1 h or permanent MCA/CCA occlusion. Treatment with NBQX (i.v. or i.p. dosing) did not reduce Ca-CaM binding after 1 h of occlusion with 1 h of reperfusion or after 2 h of occlusion. Similarly, there was no reduction in infarct size between NBQX-treated and control animals after 24 h of permanent MCA/CCA occlusion (74.6 +/- 7.1 vs. 80.1 +/- 6.0 ml; ns) or after 1 h of occlusion with 23 h of reperfusion (55.1 +/- 4.4 vs. 47.4 +/- 6.2 ml; ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelationship of brain edema, motor deficits, and memory impairment in rats exposed to focal ischemia.

We investigated the relations of brain edema, ion shifts, motor performance, and memory impairment using a focal ischemia model in rats. Cortical infarction was produced by ligation of the middle cerebral artery and the ipsilateral common carotid artery combined with temporary occlusion of the contralateral common carotid artery for 1 hour. Water content and sodium, potassium, and calcium concentrations were measured until Day 14 after the ischemic insult. Significant edema formation was observed; it peaked on Day 3 (p less than 0.001) and then declined. The tissue sodium concentration changed in a manner similar to that of water content, but the tissue potassium concentration changed in an opposite fashion. Massive accumulation of calcium was detected as early as Day 1 after ischemia (almost four times the normal level). The increased calcium concentration was sustained even up to Day 14. Motor performance examinations performed on Day 3, including inclined plane, balance beam, and prehensile tests, demonstrated significantly reduced (p less than 0.001) motor ability that did recover even by Day 7. Passive avoidance learning was carried out on Day 2, followed by a memory retention test on Day 3. Significant memory dysfunction was observed in ischemic compared with sham-operated rats (p less than 0.001). A high correlation coefficient (r = 0.91, p less than 0.01, n = 13) was obtained between water content and calcium concentration on Day 3. Both the total motor score and the degree of disturbance of the passive avoidance reaction also correlated well with water content.

Motor performance in rats exposed to severe forebrain ischemia: effect of fasting and 1,3-butanediol.

Functional assessment of animals following experimental cerebral ischemia is often difficult due to the passive nature of many neurologic exams. We attempted to increase the objectivity of motor function evaluation by adapting quantifiable behavioral tests and actively testing rats' motor capability following a cerebral ischemic insult. It was hypothesized that active testing would reveal motor deficits which were not readily apparent upon casual observation and that such testing would provide a more sensitive means of experimental neurologic assessment. Wistar rats were exposed to reversible severe forebrain ischemia using the four-vessel occlusion technique. Motor function was evaluated using the total motor score (sum of scores for screen test, balance beam test, and prehensile-traction test) over the 48 hours which followed 20 minutes of cerebral ischemia. To manipulate neurologic outcome, rats were fed or fasted the day prior to ischemia and then pretreated with either 1,3-butanediol or saline. Fasted saline-treated animals demonstrated improved total motor performance compared with fed animals by 48 hours after ischemia. There was no improvement in motor performance by fasted vs. fed rats from among the butanediol-treated animals. Pretreatment with butanediol resulted in significantly better total motor performance among fasted rats 24 hours after ischemia; however, by 48 hours postischemia, no difference was detectable. This is the first demonstration of motor deficits produced by four-vessel occlusion in rats. The motor tests devised appear to be adequately sensitive to detect changes in motor function that are not apparent with passive observation in this model.