An improved drug infusion pump for injecting nanoliter volumes subcortically in awake rats.

A new drug infusion pump capable of injecting nanoliter volumes of drug solution into the brains of awake rats has been constructed which incorporates a new "turntable" commutator and a compact tubing compressor mechanism requiring no gears. Injector cannulas inserted into guide cannulas permanently mounted in the rat's skull are connected to the drug pump by spring-protected, PE 10 tubing. Drug solutions are delivered when the pump rollers compress the drug-filled PE 10 tubing. An additional animal-activated switch and motorized mechanism rotates the drug pump in response to the animal's movements so that the PE 10 drug reservoir is not twisted. Testing the drug pump's performance in vivo with injections of 14C-nicotine into the caudate nucleus shows that drug delivery is both reliable and reproducible.