Cerebrospinal fluid sampling by lumbar puncture in rats – repeated measurements of nitric oxide metabolites

Simple methods for cerebrospinal fluid collection in fetal, neonatal, and adult rat

BACKGROUND

Cerebrospinal fluid (CSF) collection and its analysis are common medical practices useful in the diagnosis, therapy, and prevention of central nervous system (CNS) disorders. In recent years, several types of research have improved our insight into CSF and its role in health and disease. Yet, many characteristics of this fluid remain to be fully understood.

NEW METHODS

Here, we describe how to collect CSF from embryonic, postnatal, and adult stages of the rat. In adults, CSF can be collected through simple stereotaxic surgery to expose the membrane overlying the cisterna magna (CM) of an anesthetized rat and collection of CSF through micropipette puncture through the membrane. In embryos and pups, CSF is aspirated, using a fire-polished micro-capillary pipette, from the CM of animals.

RESULTS

Application of these methods provides the maximum volume of pure, uncontaminated CSF (embryonic day 19: 10-15 microliter, postnatal day 5: 20-30 microliter, adults: 100-200 microliter) with a success rate of approximately 95% in every age.

COMPARISON WITH EXISTING METHODS

Compared to the existing protocols, these methods obtain considerable volumes of CSF, which may accelerate the measurement of biological markers in this fluid. Also, these techniques do not require surgical skills and according to the practical points mentioned during sampling, the procedures can be performed in rapid fashion.

CONCLUSION

We describe simple methods for collecting CSF in live rats. These protocols provide clean, uncontaminated CSF for experiments to understand the exact role of this fluid in the development and maintenance of the CNS health.

A step-by-step guide for microsurgical collection of uncontaminated cerebrospinal fluid from rat cisterna magna

BACKGROUND

Cerebrospinal fluid (CSF) analysis is of significant clinical importance for the diagnosis of diseases. In humans, CSF is easily accessible and can be collected using minimally invasive methods. However, obtaining uncontaminated CSF from rats is still challenging.

NEW METHOD

This study described a microsurgical technique for sampling large quantities (>200 μL) of clear and non-blood-contaminated CSF from the rat cisterna magna in a comprehensible step-by-step guide and provided a graphical visualization.

RESULTS

CSF was sampled in 5-10 min (n = 29 animals; average surgical time 7.6 min). In visual control, 28 samples (97 %) of clear and uncontaminated CSF were obtained. The volume of CSF collected was 124-337 μL, with an average volume of 207 μL/sample. Using the Valsalva maneuver, we could collect higher volumes (up to 400 μL) several times.

COMPARISON WITH EXISTING METHOD(S)

There is no need for special surgical skills to perform this method accurately. The method takes a few minutes longer than a percutaneous puncture (<1 min in pups). However, the volume of CSF obtained using the percutaneous approach in adult rats (50-70 μL) is comparatively low.

CONCLUSIONS

We described a practical method of sampling CSF from rats that enables large volumes of CSF to be collected without blood contamination. No special surgical skills are required to use this method. With proper practice, the time between skin incision and CSF sampling is <10 min. Depending on the experimental design requirements, some additional time must be planned for wound closure.

Refinement of a model of repeated cerebrospinal fluid collection in conscious rats

The cannulation of the cisterna magna in rats for in vivo sampling of cerebrospinal fluid serves as a valuable model for studying the delivery of new drugs into the central nervous system or disease models. It offers the advantages of repeated sampling without anesthesia-induced bias and using animals as their own controls. An established model was retrospectively reviewed for the outcomes and it was hypothesized that by refining the method, i.e. by (1) implementing pathophysiological-based anesthesia and analgesia, (2) using state-of-the-art peri-operative monitoring and supportive care, (3) increasing stability of the cement-cannula assembly, and (4) selecting a more adaptable animal strain, the outcome in using the model - quantified by peri-operative mortality, survival time and stability of the implant - could be improved and could enhance animal welfare. After refinement of the technique, peri-operative mortality decreased significantly (7 animals out of 73 compared with 4 out of 322; P = 0.001), survival time increased significantly (36 ± 14 days compared with 28 ± 18 days; P < 0.001), as well as the stability of the cement-cannula assembly (47 ± 8 days of adhesion compared with 33 ± 15 days and 34 ± 13 days using two other cement types; P < 0.001). Overall, the 3R concept of Russell and Burch was successfully addressed and animal welfare was improved by (1) the reduction in the total number of animals needed as a result of lower mortality or fewer euthanizations due to technical failure, and frequent use of individual rats over a time frame; and (2) improving the scientific quality of the model.

Effect of Marine Collagen Peptides on Physiological and Neurobehavioral Development of Male Rats with Perinatal Asphyxia

Asphyxia during delivery produces long-term deficits in brain development. We investigated the neuroprotective effects of marine collagen peptides (MCPs), isolated from Chum Salmon skin by enzymatic hydrolysis, on male rats with perinatal asphyxia (PA). PA was performed by immersing rat fetuses with uterine horns removed from ready-to-deliver rats into a water bath for 15 min. Caesarean-delivered pups were used as controls. PA rats were intragastrically administered with 0.33 g/kg, 1.0 g/kg and 3.0 g/kg body weight MCPs from postnatal day 0 (PND 0) till the age of 90-days. Behavioral tests were carried out at PND21, PND 28 and PND 90. The results indicated that MCPs facilitated early body weight gain of the PA pups, however had little effects on early physiological development. Behavioral tests revealed that MCPs facilitated long-term learning and memory of the pups with PA through reducing oxidative damage and acetylcholinesterase (AChE) activity in the brain, and increasing hippocampus phosphorylated cAMP-response element binding protein (p-CREB) and brain derived neurotrophic factor (BDNF) expression.

Mass spectrometric analysis of rat cerebrospinal fluid proteins following exposure to the neurotoxicant carbonyl sulfide

RATIONALE

Using a proteomic-based approach we have investigated possible altered expression of a range of cerebral spinal fluid (CSF) proteins following exposure to the neurotoxicant carbonyl sulfide (COS). CSF is ideal for the investigation of markers of brain injury or disease since it is secreted from several central nervous system structures and changes in the CSF composition may reflect brain insult and many pathological processes.

METHODS

Animals were placed in exposure chambers and were exposed to 0 ppm or 500 ppm COS for 1, 2 or 3 days, 6 h per day. After the last inhalation exposure, 50-70 μL CSF sample was obtained by lumbar puncture. CSF samples were analyzed by electrospray ionization mass spectrometry (ESI-MS) on either a Premier quadrupole time-of-flight (QTOF) or an Agilent 6340 ion trap and by matrix-assisted laser desorption/ionization (MALDI)-MS on a 4800 MALDI-TOF/TOF analyzer.

RESULTS

The dynamic range of abundance of the identified proteins spanned over more than three orders of magnitude. The four most abundant proteins identified (albumin, cystatin C, serotransferrin, transthyretin) are major proteins that are present in both CSF and blood at high levels but the fifth most abundant protein identified (prostaglandin H2D isomerase) is the second most abundant protein in human CSF and is secreted and synthesized in the rat central nervous system. No significant differences were observed between COS-treated CSF samples and the control CSF samples because of blood contamination.

CONCLUSIONS

Quantitative MS protein analyses of rat CSF is limited by the low sample volumes that can practicably be obtained from rats and the low protein concentrations in rat CSF. Results of this work suggest a clear need for CSF collection that would minimize blood contamination. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA.

High performance collection of cerebrospinal fluid in rats: evaluation of erythropoietin penetration after osmotic opening of the blood-brain barrier

An important issue to be considered when studying a new drug for treatment of central nervous system (CNS) diseases is its ability to cross the blood-brain barrier (BBB) and distribute throughout the brain. As cerebrospinal fluid (CSF) has demonstrated to be an invaluable reservoir to study CNS availability of therapeutic proteins, we have developed an improved method for CSF sampling from the cisterna magna of rats. The technique enables the simple and rapid collection of adequate quantities (50-75 μl) of blood-free CSF, rendering a high percentage of animal survival (99%) without clinic or neurological consequences. Its success in avoiding blood contamination of CSF lays in the use of a mixture of lidocaine/ephinephrine topically injected in the rat's suboccipital area and neck. Another relevant feature of the methodology is its low cost, since the puncture device can be easily assembled with cheap and available materials and, more importantly, neither expensive stereotaxic equipment nor frame is required. The present method is demonstrated by studying the CSF pharmacokinetics of recombinant human erythropoietin (rhEPO), a well-studied therapeutic candidate for neurological diseases. Moreover, we applied this technique to evaluate a strategy of osmotic disruption of the BBB to achieve a faster delivery of rhEPO into the CNS.

The comparison of three methods of drawing cerebrospinal fluid in rabbit

Component analysis of cerebrospinal fluid (CSF) is frequently required to probe the cause of disease, pathologic mechanisms and effective drugs in the experimental study of central nervous system. An ideal way of drawing CFS is very important for the successful analysis. However, pros and cons of types of CSF drawing have never been analyzed and compared. The purpose of this study was to choose an ideal method of obtaining CSF in rabbits by comparing the three usual ones: skull drilling, lumbar puncture and atlanto-occipital membrane puncture. In the study, the rabbits were randomly divided into three groups: skull drilling group, lumbar puncture group and atlanto-occipital membrane puncture group, and our modified puncture needles were used. The rates of success, operating time and repeatability, etc. of the three methods were compared. The results suggest that the atlanto-occipital membrane puncture method is the best. The method was the simplest, fastest, and most repeatable of the three, furthermore, with this method, the most CSF was drawn and achieved the highest success rate.

Insulin increases central apolipoprotein E levels as revealed by an improved technique for collection of cerebrospinal fluid from rats

Cerebrospinal fluid (CSF) provides an invaluable analytical window to the central nervous system (CNS) because it reflects the dynamically changing complement of CNS constituents. We describe an improved method for sampling CSF in rats that is easy to perform. It has a 96% success rate of CSF collection and consistently yields large volumes (150-200 μl) of CSF. The blood contamination rate is also low (6%) as determined by both visual inspection and the lack of molecular detection of apolipoprotein B, a plasma-derived protein, which is absent in the CNS. This improved method of CSF sampling can have broad applicability in physiological and pharmacological evaluation for diverse CNS targets. We used this technique to provide proof of principle by examining the effect of intraperitoneal insulin on the level of apolipoprotein E (apoE) in the CSF. Insulin (0.5 and 1 U/kg) led to a significant increase of insulin in both plasma and CSF at 2 h after intraperitoneal administration and decreased blood glucose for at least 2h. ApoE concentrations in CSF, but not in plasma, were also significantly increased, and its time-course was inversely correlated with the alterations in blood glucose over 2 h. These results provide a pharmacological validation of the novel CSF sampling and validation procedure for sampling rat CSF.

Preclinical prediction of human brain target site concentrations: considerations in extrapolating to the clinical setting

The development of drugs for central nervous system (CNS) disorders has encountered high failure rates. In part, this has been due to the sole focus on blood-brain barrier permeability of drugs, without taking into account all other processes that determine drug concentrations at the brain target site. This review deals with an overview of the processes that determine the drug distribution into and within the CNS, followed by a description of in vivo techniques that can be used to provide information on CNS drug distribution. A plea follows for the need for more mechanistic understanding of the mechanisms involved in brain target site distribution, and the condition-dependent contributions of these mechanisms to ultimate drug effect. As future direction, such can be achieved by performing integrative cross-compare designed studies, in which mechanisms are systematically influenced (e.g., inhibition of an efflux transporter or induction of pathological state). With the use of advanced mathematical modeling procedures, we may dissect contributions of individual mechanisms in animals as links to the human situation.

Cerebrospinal fluid concentrations of nitric oxide metabolites in spinal cord injury

STUDY DESIGN

Multiple center study to evaluate cerebrospinal fluid (CSF) concentrations of nitric oxide metabolites [NOx] in relation to neurologic severity and prognosis in spinal cord injury (SCI).

OBJECTIVE

To examine whether CSF [NOx] correlates with neurologic severity and recovery in SCI.

SUMMARY OF BACKGROUND DATA

Inducible nitric oxide synthase is expressed in rat spinal cord immediately after SCI. Excessive nitric oxide production is cytotoxic, causing neuronal apoptosis with subsequent neurodysfunction in the spinal cord. We previously reported a significant correlation between initial [NOx] after incomplete cervical cord injury (CCI) and neurologic recovery at the final follow-up in 25 cases.

METHODS

Ninety-six cases (SCI group), including 76 patients with CCI and 20 patients with thoracic cord injury were examined. Mean follow-up period was 11 months. The control group comprised 40 cases (3 healthy volunteers and 37 patients with neither pain nor neurologic disorders). CSF [NOx] were measured using the Griess method. Severity of neurologic impairment was assessed using Frankel's classification and the American Spinal Injury Association motor score (ASIA MS). Degree of neurologic recovery was assessed using Frankel's classification and the ASIA motor recovery percentage.

RESULTS

CSF [NOx] did not differ significantly among the control, CCI, and thoracic cord injury groups at the initial examination. In the CCI group, [NOx] in the Frankel A and B classes were significantly higher than [NOx] in the control group at 5 to 14 days, in the Frankel A and B classes at 0 to 4 days, and in the Frankel C and D classes at 5 to 14 days. Also, in the CCI group at 5 to 14 days, [NOx] correlated significantly with ASIA MS and motor recovery percentage.

CONCLUSION

There was a significant correlation between CSF [NOx] at the pathologic early subacute stage (approximately 5-14 days) and neurologic severity and recovery in SCI.

Significant correlation between cerebrospinal fluid nitric oxide concentrations and neurologic prognosis in incomplete cervical cord injury

In animal models of spinal cord injury (SCI), inducible NO (nitric oxide) synthase is expressed in the spinal cord immediately after sustaining SCI. Excessive NO production has cytotoxic effects and induces neuronal apoptosis, causing neural degeneration and neurodysfunction in the spinal cord. Little is known, however, about the relationship between NO(x) (NO metabolites: nitrite and nitrate) levels in the cerebrospinal fluid (CSF) and neurologic severity or recovery in clinical cases. The objective of the present study was to examine the correlation between CSF NO(x) levels and neurologic severity or recovery in SCI. Twenty-five patients with incomplete cervical cord injury (CCI) were examined. Eight cases were treated conservatively (non-operated group). Seventeen cases underwent surgical intervention (operated group). NO(x) levels in the CSF were measured using the Griess method. The severity of the neurologic impairment was assessed using Frankel's classification and the American Spinal Injury Association motor score (ASIA MS). The degree of neurologic recovery was assessed using Frankel's classification and the ASIA motor recovery percentage (MRP). There was no significant difference in the NO(x) levels between the CCI group (NO(x) levels: 5.9 +/- 0.7 microM) and the 36 control subjects (1 volunteer and 35 patients without neurologic disorders, NO(x) levels: 4.9 +/- 0.3 microM). There was no significant difference in NO(x) levels and MRP between the non-operated group and the operated group. The NO(x) levels in total SCI group were significantly correlated with the ASIA MS and MRP. There was a significant correlation between CSF NO(x) levels and neurologic severity or recovery in incomplete CCI.

Nitric oxide in cerebrospinal fluid and local inducible nitric oxide synthase after cauda equina compression in rats

We investigated the time course of changes in nitric oxide metabolite (NO2- plus NO3-: NOx) levels in the cerebrospinal fluid and the expression of local inducible nitric oxide synthase following cauda equina compression in rats. Cerebrospinal fluid NOx levels were significantly increased from 12 h to 3 days after compression, and decreased thereafter. Histologically, inducible nitric oxide synthase immunoreactivity was observed in macrophages that infiltrated the dura mater on days 1 and 3 after compression, but not in foamy macrophages in the parenchyma of the cauda equina observed afterwards. The pattern of NOx levels coincided with the appearance of inducible nitric oxide synthase labeled macrophages, indicating a critical role of these cells as the main synthesizers of NOx in the acute stage of cauda equina compression.