A simple cannula assembly for chronic bilateral brain infusion in freely moving rats

Osmotic minipumps provide a means for the chronic infusion of agents into the brain of the awake unrestrained animal. This paper describes the construction of a simple and inexpensive cannula assembly to be used with an osmotic minipump for the bilateral infusion of brain regions in the rat. The cannula/catheter assembly employs the use of a Y-joint, thereby allowing the investigator to use only one osmotic minipump per animal. This reduces the flow rate and decreases the cost of an experiment. Chronic infusion of the ventral septal area with saline using this system failed to alter the circadian rhythm of body temperature, except for a significant decrease in the amplitude of the rhythm.