A technique for intracisternal collection and administration in a rhesus macaque

Dosing, collection, and quality control issues in cerebrospinal fluid research using animal models

Cerebrospinal fluid (CSF) is a complex fluid filling the ventricular system and surrounding the brain and spinal cord. Although the bulk of CSF is created by the choroid plexus, a significant fraction derives from the interstitial fluid in the brain and spinal cord parenchyma. For this reason, CSF can often be used as a source of pharmacodynamic and prognostic biomarkers to reflect biochemical changes occurring within the brain. For instance, CSF biomarkers can be used to diagnose and track progression of disease as well as understand pharmacokinetic and pharmacodynamic relationships in clinical trials. To facilitate the use of these biomarkers in humans, studies in preclinical species are often valuable. This review summarizes methods for preclinical CSF collection for biomarkers from mice, rats, and nonhuman primates. In addition, dosing directly into CSF is increasingly being used to improve drug levels in the brain. Therefore, this review also summarizes the state of the art in CSF dosing in these preclinical species.

Supraspinal actions of nociceptin/orphanin FQ, morphine and substance P in regulating pain and itch in non-human primates

BACKGROUND AND PURPOSE

Nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor agonists display a promising analgesic profile in preclinical studies. However, supraspinal N/OFQ produced hyperalgesia in rodents and such effects have not been addressed in primates. Thus, the aim of this study was to investigate the effects of centrally administered ligands on regulating pain and itch in non-human primates. In particular, nociceptive thresholds affected by intracisternal N/OFQ were compared with those of morphine and substance P, known to provide analgesia and mediate hyperalgesia, respectively, in humans.

EXPERIMENTAL APPROACH

Intrathecal catheters were installed to allow intracisternal and lumbar intrathecal administration in awake and unanaesthetized rhesus monkeys. Nociceptive responses were measured using the warm water tail-withdrawal assay. Itch scratching responses were scored from videotapes recording behavioural activities of monkeys in their home cages. Antagonist studies were conducted to validate the receptor mechanisms underlying intracisternally elicited behavioural responses.

KEY RESULTS

Intracisternal morphine (100 nmol) elicited more head scratches than those after intrathecal morphine. Distinct dermatomal scratching locations between the two routes suggest a corresponding activation of supraspinal and spinal μ receptors. Unlike intracisternal substance P, which induced hyperalgesia, intracisternal N/OFQ (100 nmol) produced antinociceptive effects mediated by NOP receptors. Neither peptide increased scratching responses.

CONCLUSIONS AND IMPLICATIONS

Taken together, these results demonstrated differential actions of ligands in the primate supraspinal region in regulating pain and itch. This study not only improves scientific understanding of the N/OFQ-NOP receptor system in pain processing but also supports the therapeutic potential of NOP-related ligands as analgesics.

An improved technique for cerebrospinal fluid collection of cisterna magna in Rhesus monkeys

BACKGROUND

Currently-used cerebellomedullary cistern puncture method for collecting cerebrospinal fluid (CSF) from monkeys is simple, inexpensive, and practical, but with high risk for brainstem injury and CSF blood contamination. An improved technique was thus developed and characterized.

METHOD

Magnetic resonance imaging was used to identify the space and position of the cisterna magna in monkeys. Accordingly, a newly defined procedure for needle punctuation was tested in comparison with the traditional method. Blood contamination in CSF samples and brainstem injury were determined to define the superior of the improved method over the transitional method.

RESULTS

The cisterna magna in monkeys was found to be a "▽" shape. The needle was punctured into the cisterna magna aiming at the wider superior gap avoided brainstem injury. The improved method showed that the rate of blood contamination in the CSF samples was reduced from 66.7% to 16.7%, the higher rate of blood contamination was associated with higher risk for brainstem injury.

COMPARISON WITH EXISTING METHODS

In traditional method, the needle is punctured aiming at the inferior gap with high density of blood vessels. In improved method, the needle is punctured aiming at the superior gap, pointing to the nose root while advancing the needle and avoiding injury to blood vessels.

CONCLUSIONS

This improved technique not only avoids blood contamination of CSF, but also prevents brainstem injury during the process of CSF collection. It is recommended for adaptation for CSF collection in monkeys.

CD8+ T cells maintain suppression of simian immunodeficiency virus in the central nervous system

Human immunodeficiency virus (HIV) accesses the brain early in infection and can lead to neurocognitive disorders. The brain can also serve as a viral reservoir, but how virus is controlled in the brain is unknown. To examine this, CD8-depleting monoclonal antibody was injected into the cerebrospinal fluid of rhesus monkeys with chronic simian immunodeficiency virus (SIV) infection. This treatment led to the rapid increase of SIV in the brain. Virus in the brain is maintained by active suppression from the host immune system. This dynamic interaction can be manipulated in efforts to control and eradicate virus from the brain and other reservoirs.

Access to cerebrospinal fluid in piglets via the cisterna magna: optimization and description of the technique

The collection of cerebrospinal fluid is necessary in order to determine its composition. It can then be used to diagnose various diseases. The aim of the study was to develop and optimize a technique for performing safe centesis for the collection of cerebrospinal fluid in piglets and its injection through the cisterna magna. The study was divided into three phases: (1) anatomical study of cadavers, (2) in vivo application of the technique and (3) observation of recovery time. The proposed technique resulted in a safe puncture of the cisterna magna. The authors identified and confirmed the correspondence of the crista occipitalis and the wings of the atlas with the external landmarks on the cadaver by means of direct radiological visualization. The punctures were performed successfully at the first attempt in 11 out of 12 anaesthetized piglets. The technique herein described provides a reproducible safe and easy route for approaching the cisterna magna for cerebrospinal fluid collection, drug administration and gene delivery.