Chronic push-pull brain perfusion in unrestrained rhesus macaques.

Area of Science:

• Neuroscience
• Endocrinology
• Primate Research

Background:

• Studying neuroendocrine regulation in unrestrained primates is challenging due to the need for continuous monitoring.
• Previous methods often restricted animal movement, limiting the naturalistic observation of hormone secretion patterns.

Purpose of the Study:

• To develop and validate a system for simultaneous local brain perfusion and peripheral blood sampling in freely moving macaques.
• To enable the collection of high-resolution temporal data on neurosecretions and peripheral hormones.

Main Methods:

• A novel system involving a calvarial headpiece with push-pull cannulas (PPC), a tether, and a fluid swivel was designed.
• Rhesus macaques underwent surgery for jugular catheterization and PPC implantation into key brain regions.
• Continuous brain perfusate and plasma samples were collected over 14-70 hours for radioimmunoassay analysis.

Main Results:

• The system allowed for the collection of brain perfusates and peripheral blood samples at 10- to 30-minute intervals.
• Pulsatile patterns of gonadotropin-releasing hormone, luteinizing hormone, and cortisol were successfully quantified.
• Normal endocrine profiles were observed, indicating the system's physiological compatibility.

Conclusions:

• The developed system is a valuable tool for studying neurosecretory patterns in unrestrained simians.
• This methodology facilitates research into the dynamic regulation of the neuroendocrine system.
• It offers a significant advancement for in-vivo studies of brain-endocrine interactions.