Chronic catheterization of the spinal subarachnoid space.

Area of Science:

• Neuroscience
• Pharmacology
• Surgical Techniques

Background:

• Accurate drug delivery to the central nervous system is crucial for research.
• Existing methods may involve anesthesia or invasive procedures, potentially confounding results.
• A need exists for a reliable method to administer substances to the spinal subarachnoid space in conscious animals.

Purpose of the Study:

• To describe and validate a surgical procedure for chronic indwelling catheterization of the spinal subarachnoid space in rats and rabbits.
• To assess the diffusion characteristics and brain penetration of substances administered via this route.
• To evaluate the biocompatibility and long-term tolerance of the implant.

Main Methods:

• A polyethylene catheter (PE-10) was inserted through the atlanto-occipital membrane and secured to the skull in rats and rabbits.
• Calibration studies utilized bromophenol blue dye, 3H-naloxone, and 14C-urea to track injectate distribution.
• Behavioral observations and histological examination of spinal cords were conducted.

Main Results:

• Limited rostro-caudal diffusion of injectates along the spinal axis was observed.
• Spinal subarachnoid administration resulted in minimal drug levels in the brain, even for lipophilic compounds like naloxone.
• No detectable behavioral changes or spinal cord pathology were noted, even with catheters in place for up to 4 months.

Conclusions:

• The described atlanto-occipital catheterization technique provides a reliable method for localized drug delivery to the spinal subarachnoid space in unanesthetized animals.
• This method minimizes systemic drug exposure and is well-tolerated, supporting its use in chronic pharmacological and neurobiological research.
• The technique offers a valuable tool for studying spinal cord function and drug effects without the confounding variables of anesthesia or systemic administration.