Injection Of Cerebrospinal Fluid Research Articles

Behavioral Activity and Anxiety of Rats under Open Field Conditions in the Norm and after Parenteral Introductions of Xenogenic Cerebrospinal Fluid

We studied the effects of injections of xenogenic cerebrospinal fluid (CSF) on behavioral phenomena in rats under open field conditions. Parenteral introduction of xenogenic liquor in adult male and female rats resulted in appreciable changes in the indices of spontaneous motor activity in the open field. Single and double CSF injections promoted intensification of motor and orientational/research activity followed by inhibition of the respective behavioral manifestations. Repeated CSF injections were accompanied by a gradual decrease in the behavioral activity of rats. In males and females, these changes were nearly synchronous. Injections of CSF also influenced the seasonal dynamics of behavioral phenomena in rats and cyclic changes in the activity of females during the estrous cycle. In the whole, CSF injections exerted more powerful effects than the action of main natural biological regulators (photoperiod and sex cycle). The presence of significant amounts of biologically active substances in the liquor, which are responsible for complex effects on links of the neuroendocrine regulatory system of recipients, is the probable basis of the revealed effects.

Systemic Gene Delivery in Large Species for Targeting Spinal Cord, Brain, and Peripheral Tissues for Pediatric Disorders

Adeno-associated virus type 9 (AAV9) is a powerful tool for delivering genes throughout the central nervous system (CNS) following intravenous injection. Preclinical results in pediatric models of spinal muscular atrophy (SMA) and lysosomal storage disorders provide a compelling case for advancing AAV9 to the clinic. An important translational step is to demonstrate efficient CNS targeting in large animals at various ages. In the present study, we tested systemically injected AAV9 in cynomolgus macaques, administered at birth through 3 years of age for targeting CNS and peripheral tissues. We show that AAV9 was efficient at crossing the blood–brain barrier (BBB) at all time points investigated. Transgene expression was detected primarily in glial cells throughout the brain, dorsal root ganglia neurons and motor neurons within the spinal cord, providing confidence for translation to SMA patients. Systemic injection also efficiently targeted skeletal muscle and peripheral organs. To specifically target the CNS, we explored AAV9 delivery to cerebrospinal fluid (CSF). CSF injection efficiently targeted motor neurons, and restricted gene expression to the CNS, providing an alternate delivery route and potentially lower manufacturing requirements for older, larger patients. Our findings support the use of AAV9 for gene transfer to the CNS for disorders in pediatric populations.

Evidence of endoplasmic reticular stress in the spinal motor neurons exposed to CSF from sporadic amyotrophic lateral sclerosis patients

We have earlier reported that intrathecal injection of cerebrospinal fluid (CSF) from sporadic Amyotrophic Lateral Sclerosis patients (ALS-CSF) into neonatal rats and supplementation of rat spinal cord cultures with ALS-CSF induces motor neuron degeneration via aberrant neurofilament phosphorylation and Golgi apparatus fragmentation. Intracellular aggregates immunoreactive to ubiquitin, phosphorylated neurofilaments and choline acetyl transferase (ChAT) were prominently seen in NSC-34 cells exposed to ALS-CSF. Protein aggregation could cause stress on endoplasmic reticulum (ER) and may precede Golgi fragmentation. Here we assessed the effect of ALS-CSF on the expression of GRP-78 and caspase-12 proteins, the markers of ER stress responses, in NSC-34 cells and rat spinal cords by immunochemistry and immunoblotting. Both in vitro and in vivo, increased expression of these proteins accompanied elevated active caspase-12 levels. Apoptotic nuclei and nuclear translocation of caspase-12 were noted in some cells. In vitro, the occurrence of ER stress was supported by electron microscopic observations of numerous free polyribosomes and fragmented ER cisternae. Aggregated mSOD1 protein causes ER stress in familial ALS. ER stress is also reported in the autopsy samples of sporadic ALS. Thus our observation of ER stress may be linked to the protein aggregation, viz. phosphorylated neurofilaments and ChAT, reported earlier.

Abstract 980: Intrathecal methotrexate induces focal cognitive deficits and alters CNS folate physiology in rats

Abstract Background: In order to reduce the persistent neurologic toxicity of therapy for childhood acute lymphoblastic leukemia (ALL), many treatment protocols avoid cranial radiation, relying instead on intrathecal chemotherapy to prevent central nervous system relapses. Nevertheless a significant subset of survivors treated without radiation manifest persistent focal deficits in cognitive function. The folate antagonist methotrexate (MTX), a key component of prophylactic intrathecal therapy, is suspected to contribute to treatment-induced cognitive dysfunction. Our goal was to establish a rodent model to isolate the cognitive and neurotoxic effects of MTX after direct administration into cerebrospinal fluid (CSF). Methods: Adult Long-Evans rats were given either intrathecal MTX 0.5mg/kg or artificial CSF via transcutaneous puncture at the level of the cisterna magna. Three days later, all rats subsequently underwent a battery of behavioral tests designed to assess cognitive domains frequently impaired among children treated for ALL, including spatial memory, visual memory, and motor coordination. Indicators of folate physiology (folate and homocysteine) in CSF and serum were measured using high performance liquid chromatography. Concentrations of interleukin-1β, IL-6, and tumor necrosis factor-α were measured in CSF to assess whether intrathecal MTX induces an inflammatory response. Results: Intrathecal MTX administration reliably produced both visual and spatial memory deficits, without altering general activity or motor coordination. MTX administration was associated with a significant reduction in both CSF and serum folate concentrations, along with an increase in CSF homocysteine. At 24 hours post-injection of MTX, CSF folate decreased by 75% and CSF homocysteine was increased 4-fold, relative to baseline. Intrathecal injection of both MTX and artificial CSF was associated with a significant rise in CSF IL-6 within 6 hours, which then returned to baseline by 24h. Conclusion: We have established an animal model in which intrathecal MTX induces cognitive dysfunction that mimics clinically observed toxicity, in association with a rapid fall in CSF folate and increase in CSF homocysteine. A non-specific, transient increase was seen in the proinflammatory cytokine IL-6 within CSF. This proinflammatory response does not appear sufficient to cause cognitive deficits, as it was observed among both groups of rats, while toxicity was demonstrated among only those who received MTX. This model will allow us both to further investigate the pathophysiology of treatment-induced cognitive dysfunction and to test protective interventions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 980.

Metabolic analysis of body fluids by capillary electrophoresis using noncovalently coated capillaries

The potential of capillaries noncovalently coated with charged polymers for the metabolic analysis of body fluids by CE is illustrated. Firstly, the usefulness of a coating consisting of a triple layer of polybrene–dextran sulfate–polybrene for the fast analysis of organic acids is described. The CE system allowed direct injections of CSF, plasma and urine samples, yielding good separation efficiencies. RSDs for migration times and peak areas of organic acids in plasma were <3% and <5%, respectively. The usefulness of the system is illustrated by the profiling of organic acids in plasma and urine samples. Secondly, a CE system comprising a bilayer coating of polybrene–poly(vinylsulfonate), which provides a considerable EOF at low pH is described. This system was combined with TOF-MS and used for the fast analysis of amino acids in cerebrospinal fluid (CSF) and urine with minimal sample pretreatment. RSDs for migration times and peak areas of amino acids in CSF and urine were <2% and <10%, respectively. The applicability of the system is demonstrated by the profiling of endogenous low-molecular weight metabolites in CSF from a healthy individual and a patient with complex regional pain syndrome.

Gastrin-releasing peptide and pruritus: More than just scratching the surface

A gastrin-releasing peptide receptor mediates the itch sensation in the spinal cord. Sun YG, Chen ZF. Itching, or pruritus, is defined as an unpleasant cutaneous sensation that serves as a physiological self-protective mechanism to prevent the body from being hurt by harmful external agents. Chronic itch represents a significant clinical problem resulting from renal diseases and liver diseases, as well as several serious skin diseases such as atopic dermatitis. The identity of the itch-specific mediator in the central nervous system, however, remains elusive. Here we describe that the gastrin-releasing peptide receptor (GRPR) plays an important part in mediating itch sensation in the dorsal spinal cord. We found that gastrin-releasing peptide is specifically expressed in a small subset of peptidergic dorsal root ganglion neurons, whereas expression of its receptor GRPR is restricted to lamina I of the dorsal spinal cord. GRPR mutant mice showed comparable thermal, mechanical, inflammatory and neuropathic pain responses relative to wild-type mice. In contrast, induction of scratching behaviour was significantly reduced in GRPR mutant mice in response to pruritogenic stimuli, whereas normal responses were evoked by painful stimuli. Moreover, direct spinal cerebrospinal fluid injection of a GRPR antagonist significantly inhibited scratching behaviour in three independent itch models. These data demonstrate that GRPR is required for mediating the itch sensation rather than pain, at the spinal level. Our results thus indicate that GRPR may represent the first molecule that is dedicated to mediating the itch sensation in the dorsal horn of the spinal cord, and thus may provide a central therapeutic target for anti-pruritic drug development.

A gastrin-releasing peptide receptor mediates the itch sensation in the spinal cord

Itching, or pruritus, is defined as an unpleasant cutaneous sensation that serves as a physiological self-protective mechanism to prevent the body from being hurt by harmful external agents. Chronic itch represents a significant clinical problem resulting from renal diseases and liver diseases, as well as several serious skin diseases such as atopic dermatitis. The identity of the itch-specific mediator in the central nervous system, however, remains elusive. Here we describe that the gastrin-releasing peptide receptor (GRPR) plays an important part in mediating itch sensation in the dorsal spinal cord. We found that gastrin-releasing peptide is specifically expressed in a small subset of peptidergic dorsal root ganglion neurons, whereas expression of its receptor GRPR is restricted to lamina I of the dorsal spinal cord. GRPR mutant mice showed comparable thermal, mechanical, inflammatory and neuropathic pain responses relative to wild-type mice. In contrast, induction of scratching behaviour was significantly reduced in GRPR mutant mice in response to pruritogenic stimuli, whereas normal responses were evoked by painful stimuli. Moreover, direct spinal cerebrospinal fluid injection of a GRPR antagonist significantly inhibited scratching behaviour in three independent itch models. These data demonstrate that GRPR is required for mediating the itch sensation rather than pain, at the spinal level. Our results thus indicate that GRPR may represent the first molecule that is dedicated to mediating the itch sensation in the dorsal horn of the spinal cord, and thus may provide a central therapeutic target for antipruritic drug development.

(‐)‐Deprenyl alleviates the degenerative changes induced in the neonatal rat spinal cord by CSF from amyotrophic lateral sclerosis patients

Previous studies from our laboratory suggest the presence of toxic factor(s) in the cerebrospinal fluid (CSF) of patients with amyotrophic lateral sclerosis (ALS) which induces degenerative changes in the spinal cord neurons. The present work was carried out to investigate the role of (-)-deprenyl in attenuating these degenerative changes. CSF samples from ALS and non-ALS neurological patients were injected into the spinal subarachnoid space of 3-day-old rat pups, followed by a single dose (0.01 mg/kg body weight) of (-)-deprenyl, administered 24 h after CSF injection. After a further period of 24 h, the rats were sacrificed and the spinal cord sections were stained with antibodies against phosphorylated neurofilament (NF, SMI-31 antibody) and glial fibrillary acidic protein (GFAP). Activity of lactate dehydrogenase (LDH) was also measured. (-)-Deprenyl injection resulted in a significant (61%) decrease in the number of SMI-31 stained neuronal soma in the ventral horn of the spinal cord of ALS CSF exposed rats. This was accompanied by a reduction in the astrocytes immunoreactive for GFAP. There was also a significant (35%) decrease in the LDH activity following (-)-deprenyl treatment. These results suggest that (-)-deprenyl may confer neuroprotection against the toxic factor(s) present in ALS CSF.

Anti-kindling effect of slow repetitive transcranial magnetic stimulation in rats

The cerebrospinal fluid (CSF) of animals exposed to electroconvulsive shock (ECS) has anticonvulsant properties when injected into naive animals. The present study investigated whether the CSF of humans exposed to 1 or 10 Hz repetitive transcranial magnetic stimulation (rTMS) has similar properties. Using a 4 day rat flurothyl kindling seizure model we found that the kindling rate was significantly decreased by intraventricular injection of CSF from depressed patients exposed to 1 Hz rTMS. The CSF from patients that underwent 10 Hz rTMS showed a trend toward an increased kindling rate. These results support the similarity of ECS and rTMS and suggest that 1 Hz and 10 Hz rTMS produce distinct physiologic changes.

Experimental intracerebral hemorrhage in the mouse: histological, behavioral, and hemodynamic characterization of a double-injection model.

A major limitation of intracerebral hemorrhage (ICH) research is the lack of reproducible animal models. The present study was conducted to validate in the mouse the double-injection method of ICH initially developed in the rat. We investigated the effect of intrastriatal injection of blood or cerebrospinal fluid (CSF) on cerebral blood flow (CBF), neurological score, hematoma volume, and brain swelling. Male C57BL/6 mice were anesthetized with halothane/nitrous oxide delivered by face mask. Rectal and cranial temperatures were regulated at 37 degrees C to 37.5 degrees C. Mice were placed in a stereotactic frame, and a 30-gauge stainless steel cannula was introduced through a burr hole into the left striatum. Each mouse received a 5-microL injection of either whole blood or CSF (over 3 minutes), followed 7 minutes later by 10 microL injected over 5 minutes. The injection cannula was slowly withdrawn 10 minutes after the second injection. Control mice had only cannula insertion. CBF was studied by laser Doppler perfusion imaging. Neurological status was evaluated on days 1 and 2. After 2 days, hematoma volume and brain swelling were calculated. Physiological values were stable. Mice with ICH but not those with CSF or cannula alone had a marked, persistent neurological deficit and a highly reproducible hematoma, whose mean+/-SEM volume was 2.0+/-0.2 mm3 compared with a lesion size of 0.2+/-0.1 mm3 in mice with CSF. Residual swelling of the ipsilateral hemisphere at 48 hours was 5.7% in the hematoma and 1.5% in the CSF groups. Relative CBF in the neocortex ipsilateral to the injection site declined by approximately 45% to 60% during the first 20 minutes after cannula insertion/injection in all groups but began to renormalize at approximately 25 to 30 minutes in the CSF and cannula-only groups; in the hematoma group, cortical hypoperfusion of approximately 35% to 50% persisted during the 90-minute measurement period. The present ICH model in mice produces a consistent neurological deficit, hypoperfusion, hematoma volume, and brain swelling. This model closely mimics human hypertensive basal ganglionic ICH and should be useful for the evaluation of pharmaceutical therapies. Laser Doppler perfusion imaging is a useful new technique to quantify relative CBF changes and can be used for studies of dynamic changes of CBF in this in vivo model of ICH in mice.

Novel intrathecal delivery system for treatment of spinal cord injury

A novel, localized method for potential delivery of therapeutic agents to the injured spinal cord was investigated. The strategy consists of a polymeric drug solution that gels after injection into the subarachnoid space (SAS). By dispersing therapeutic agents in the polymeric solution, a method is provided for localized delivery to the spinal cord. To determine whether intrathecal injection of this drug delivery system (DDS) would affect cerebrospinal fluid (CSF) flow, a spinal canal model was built using dimensional analysis. Blocking up to 52% of the modeled subarachnoid space of the spinal canal caused minimal pressure differences (9.22 ± 1.45 Pa), suggesting that implantation of a DDS would not subject the spinal cord to increased pressure. The safety of the DDS was also assessed in vivo by injecting collagen into the SAS of Sprague Dawley rats. Controls received injections of artificial CSF (aCSF). Collagen or aCSF was injected at the T2-T3 spinal level of both uninjured rats and rats injured with a 20 g compression clip. The injected collagen persisted in the SAS for at least 8 weeks post-implantation and did not elicit an inflammatory reaction in either uninjured or injured animals. Long-term functional behavior was evaluated with the Basso, Beattie, and Bresnahan (BBB) scale weekly for 8 weeks. Functional behavior was similar in the collagen and aCSF groups, also indicating that the DDS was safe. This minimally invasive DDS may provide an alternative, safe method to deliver therapeutic agents intrathecally.

Intrathecal transplantation of neuroblastoma cells decreases heat hyperalgesia and cold allodynia in a rat model of neuropathic pain

Intrathecal grafting of cells as biological pumps to deliver monoamines, endorphins, and/or trophic factors, has been shown to be effective in treating chronic pain both in experimental animals and in clinical trials. We have tested whether intrathecal implantation of neuroblastoma cells reduces heat hyperalgesia and cold allodynia in a rat model of neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. Behavioral tests and cerebrospinal fluid (CSF) collection were performed before CCI, 1 week later (after which, vehicle or NB69 cells were intrathecally injected) and at 4, 7, and 14 days post-injection. Both CSF sampling and injection of the cells were performed by direct lumbar puncture. Intrathecal grafting of 4×10 6 NB69 neuroblastoma cells reduced to basal levels the nociceptive response to heat in nerve-injured hindpaws, while the response of control limbs remained unchanged. Similarly, the allodynic response to cold elicited by acetone evaporation decreased in the animals implanted with NB69 cells. An increase in the concentrations of dopamine and serotonin metabolites of around 150% was observed in the CSF of animals that received grafts of NB69 cells. These data suggest that the monoamines released by NB69 cells in the intrathecal space produce analgesia to neuropathic pain in rats.

Liposome-mediated transfer of the bcl-2 gene results in neuroprotection after in vivo transient focal cerebral ischemia in an animal model.

Acute cerebral ischemia causes hypoxic neuronal cell death by necrosis and apoptosis. Expression of anti-apoptotic transgenes in ischemic brain may provide a useful therapeutic strategy for alleviation of postischemic damage. The present study investigates liposome-mediated transfer of the human bcl-2 protein in a rat model of focal transient ischemia due to middle cerebral artery (MCA) occlusion. Two different types of plasmid vectors were used for bcl-2 expression: one driven by the constitutive cytomegalovirus promoter (pCMV) and another based on the hypoxia-inducible human vascular endothelial growth factor promoter (pHRE). Cationic liposome/plasmid DNA complexes (lipoplexes) were injected directly into the cerebrospinal fluid (CSF) of rats immediately after MCA occlusion. The brains of treated and control animals were analyzed 48 h later. Infarct volumes and numbers of apoptotic cells were quantified. Occlusion of the MCA resulted in ipsilateral cerebral infarcts in all study animals. Transfer of the bcl-2 gene resulted in high level widespread protein expression in the case of the pCMV-bcl2 plasmid, while animals treated with the pHRE-bcl2 vector showed lower expression levels of bcl2 which were in addition limited to the ischemic area. Treatment with pCMV-bcl2, but not with pHRE-bcl2, was able to significantly reduce the infarct volume, which was 109 +/- 8 mm(3) for pCMV-bcl2, 152 +/- 29 mm(3) for pHRE-bcl2, and 155 +/- 18 mm(3) for control animals. Animals transfected with either vector showed a significant reduction in numbers of apoptotic cells in the infarct and penumbra area compared with controls. There were no short-term neurological side-effects of the CSF injection of lipoplexes or of bcl-2 expression. In conclusion, the hypoxia-inducible bcl-2 expression mediated by intrathecal lipoplexes may represent a novel, biologically safe and lesion-selective therapeutic approach for neuroprotection after acute cerebral ischemia. DOI: 10.1038/sj/gt/3301676

Brain amiloride-sensitive Phe-Met-Arg-Phe-NH(2)--gated Na(+) channels and Na(+)-induced sympathoexcitation and hypertension.

Dietary and cerebrospinal fluid (CSF) Na(+) may act through brain amiloride-sensitive, Phe-Met-Arg-Phe-NH(2) (FMRFamide)-gated Na(+) channels (FaNaChs) to cause sympathoexcitation and hypertension. We hypothesized that FaNaChs cause sympathoexcitation via the activation of brain "ouabain" and the brain renin-angiotensin system. In conscious Wistar rats, intracerebroventricular (ICV) infusion of Na(+)-rich (0.3 mol/L) artificial CSF (aCSF) and ICV injection of angiotensin II or ouabain increase renal sympathetic nerve activity (RSNA), blood pressure (BP), and heart rate (HR). ICV benzamil, an amiloride analogue, did not affect baseline values and blocked the responses to ICV infusions of Na(+)-rich aCSF but not ICV angiotensin II or ouabain. ICV FMRFamide also increased RSNA, BP, and HR. Blocking brain "ouabain" with ICV antibody Fab fragments abolished the responses to both ICV FMRFamide and Na(+)-rich aCSF. In conscious spontaneously hypertensive rats (SHR) on a high salt intake for 6 weeks, prolonged ICV but not intravenous infusion of benzamil at 10 to 20 microg/h significantly decreased RSNA, BP, and HR in a dose-related manner. The extent of these responses was significantly smaller in SHR on regular salt intake. These findings suggest that benzamil-blockable brain FaNaChs represent the major mechanism through which a small increase in CSF Na(+) by ICV Na(+)-rich aCSF in Wistar rats or high salt intake in SHR initiates sympathoexcitation and hypertension. Enhanced Na(+) entry through FaNaChs appears to activate brain "ouabain" and the brain renin-angiotensin system and, thereby, increases the sympathetic outflow. Brain FaNaChs appear to contribute to the worsening of hypertension in SHR on a high salt diet and, to a small extent, to the maintenance of hypertension in SHR on a regular salt diet.

Intracerebroventricular injection of murine leptin enhances the postprandial metabolic rate in the rat

Energy balance is achieved by means of a concomitant control of both food intake and energy expenditure. Leptin, synthesized in the adipose tissue, acts on brain structures and lowers body weight by inhibiting food intake and in parallel by enhancing energy expenditure i.e. metabolism or one of its components. Recording distinctly these components allowed us to assess the effect of an acute intracerebroventricular injection of leptin on both feeding pattern and background metabolism (i.e. energy expenditure free from the part of locomotor activity), respiratory quotient, feeding-related metabolism and locomotor activity-related metabolism. Leptin injection to Sprague–Dawley male rats induced an inhibition of feeding that began 90 min after the treatment and lasted 1 h before to return to the control feeding pattern level. Considering this late behavioral effect, it appeared that leptin may act during the postprandial period so that we recorded the different metabolic parameters following a 3 g calibrated meal itself preceded by leptin vs. artificial cerebrospinal fluid injection. Postprandial respiratory quotient was rapidly lowered in leptin-treated animals and subsequent background metabolism increased for 6 h. Thus it appeared that leptin increased the duration of the postprandial metabolic rate via the recruitment of endogenous fat stores. Enhancement in the thermic effect of food may be the reason for feeding behavior inhibition to be delayed.

Analysis and Validation of a Mathematical Model for Intracranial Pressure Dynamics

Lumped parameter, compartmental models provide a promising Method for mathematically studying the dynamics of human intracranial pressure. In this modeling approach, a system of fully time-dependent differential equations for interacting compartmental pressures is obtained by considering the intracranial system to be confined within the almost-rigid skull and developing continuity equations associated with conservation of mass. Intracranial volumes and flows are related to compartmental pressure differences through compliance and resistance parameters. In the nonlinear case where compliances are not constant, there is a lack of physical information about these parameters. Consequently, it is vital that any mathematical model with an assumed pressure-dependent compliance be validated through comparison with experimental data. The present work develops a logistic representation for the compliance between the cerebrospinal fluid and brain matter compartments. The nonlinear mathematical model involving this logistic compliance is validated here by comparing its predicted response for bolus injections of cerebrospinal fluid to laboratory data generated in an animal model. Comparison with the animal studies fully supports the validity of the mathematical model with the logistic compliance.

Autoradiographic determination of local cerebral blood flow and local cerebral glucose utilization during chemical stimulation of the nucleus tractus solitarii of anesthetized rats

This study was conducted to determine whether the decrease in cerebral blood flow (CBF) observed during chemical stimulation of the nucleus tractus solitarius (NTS) can be explained by a decrease in cerebral metabolism. In anesthetized (urethane and chloralose), paralyzed and artificially ventilated rats, neurons in the NTS were chemically stimulated by microinjection of l-glutamate. Local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were quantified in 43 brain structures by quantitative autoradiographic techniques using [ 14 C] iodoantipyrine and 2- [ 14 C] deoxyglucose, respectively. During chemical stimulation of the NTS ( n=6), LCBF decreased significantly in 32 of the 43 structures investigated when compared to either a control group with artificial cerebrospinal fluid injection ( n=6), or a controlled hemorrhage group ( n=5). In the controlled hemorrhage group, blood pressure was decreased to a degree comparable to that induced by microinjection of l-glutamate into the NTS. Mean blood flow of all structures investigated was significantly ( P<0.01) lower in the stimulation group than that in the control group and in the hemorrhage group. No significant differences in LCGU were observed between the three investigated groups in all structures examined except for an increase in LCGU in the chemically stimulated NTS site. It is concluded that the decrease in LCBF measured in most brain structures during chemical stimulation of the NTS is not caused by a decrease in LCGU in these structures and may therefore be explained by neurogenic influences on brain vessels.

Neuropeptide Y treatment and food deprivation increase cyclic AMP response element-binding in rat hypothalamus.

Intrahypothalamic (IHT) administration of neuropeptide Y (NPY) induces a robust feeding response in rats. We have shown previously that NPY-induced feeding is mediated by a pertussis-toxin-sensitive G protein in rats. NPY receptors are coupled to cAMP and Ca2+. Because these second messengers are known to activate cAMP response element binding proteins, (CREB), cAMP response element modulators, or activating transcription factor 1, we investigated the involvement of these transcription factors in NPY-induced feeding in rats. Compared with control injections of cerebrospinal fluid (1 microl), IHT administration of NPY increased cAMP response element (CRE) binding to rat hypothalamic nuclear extracts in a time-dependent manner, as detected by an electrophoretic mobility shift assay. In contrast, IHT administration of the anorectic neuropeptide, pituitary adenylate cyclase activating polypeptide, strongly inhibited the CRE binding. Food deprivation for 48 hr also increased CRE binding, whereas 8 hr of refeeding normalized CRE activity. Preincubation of the hypothalamic nuclear extracts of NPY-treated and unfed rats with antibody specific to CREB blocked CRE binding, whereas preincubation with phosphoCREB antibody retarded the migration of CRE-protein complex, indicating that phosphoCREB is involved in this process. Consistently, immunohistochemical studies with food-deprived rats showed an intense phosphoCREB signal in the paraventricular nuclei and ventromedial hypothalamus in comparison to rats fed ad libitum. Hypothalamic calcium/calmodulin-dependent protein kinase II activity was also increased by IHT-NPY. These results suggest that calcium/calmodulin-dependent protein kinase II induced phosphorylation of CREB may be involved in regulating feeding behavior induced by NPY.

Brain tumor uptake of thallium‐201 from the cerebrospinal fluid compartment: A preliminary study of uptake and diffusion dynamics

AbstractThallium‐201 (201Tl) has become a potent diagnostic tool for imaging brain tumors. Since intrathecal injections of 201T1 result in high resolution images of normal brain, experiments were designed to study tumor uptake and diffusion of 201T1 subsequent to cerebrospinal fluid (CSF) injection. A1SA5 astrocytoma cells were injected into the rat caudoputamen. Two weeks post‐implantation, rats received lateral ventricle injections of 201T1. Deeply anesthetized rats were perfused with 4.0% buffered formalin. Brains were removed, sectioned, and processed for autoradiography. Autoradiographs (ARGs) were developed and mounted sections were stained with hematoxylin and eosin. ARGs reveal a high degree of tumor to background resolution. Small tumor processes and cellular metastasis parallel to fiber tracts are readily visualized. 201TI labeling in areas of no apparent histologic disease, immediately surrounding and caudal to tumors, is suggestive of uptake by cells undergoing transformation. These studies are the first to demonstrate tumor uptake subsequent to 201T1 CSF injection and provide insights into the movement of 201T1 through tumor and adjacent neuropil. © Wiley‐Liss, Inc.

Vitamin E Prevents the Place Learning Deficit and the Cholinergic Hypofunction Induced by AF64A

The present study examined whether pretreatment with vitamin E would attenuate the place learning impairment and the neurochemical deficits induced by intracerebroventricular (icv) injection of the cholinotoxin ethylcholine mustard aziridinium ion (AF64A). Male Sprague-Dawley rats were pretreated by intra-muscular injection of either vitamin E or saline 24 h and 15 min prior to surgery. They were then infused bilaterally into the cerebroventricles with AF64A (3 nmol/side) or artificial cerebrospinal fluid (CSF). Following 14 days of postoperative recovery, the rats were trained to acquire a place learning task in a water maze for two blocks of four trials a day for 5 days. Following the 40th trial a probe trial was used to assess memory for the platform location. After completion of behavioral testing, hippocampal high-affinity choline uptake (HAChU) was assessed. The groups which had received either saline or vitamin E pretreatment followed by icv injection of CSF did not differ significantly on any parameter measured and were therefore pooled as control group. Animals which had been pretreated with vitamin E and had received icv injection of AF64A exhibited neither significant impairment in water maze performance nor significant decreases in HAChU. In contrast, animals which had been pretreated by saline followed by icv injection of AF64A were significantly impaired in acquisition of the place learning task as well as during the probe trial and had reduced HAChU in the hippocampus. These findings indicate that vitamin E may have a neuroprotective effect in the septohippocampal cholinergic system.