Neurotensin self-injection in the ventral tegmental area

Earlier work with the conditioned place-preference paradigm suggested that neurotensin (NT) acts as a behavioral reinforcer when microinjected into the ventral tegmental area (VTA) of the midbrain. We report here that animals will perform an operant task to obtain microinfusions of NT into the VTA. Rats reliably pressed a lever to obtain NT infusions while neglecting an identical but inactive lever. Substitution of saline for NT initiated response extinction; following the reintroduction of NT, reliable responding resumed. These results extend earlier work suggesting that NT in the VTA can be a positive reinforcer.