Tail pinch facilitation of self-stimulation in the rat--dependence upon dopamine and independence of opiates.

We have previously demonstrated that adult male Sprague-Dawley rats which are chronically maintained upon a schedule of intracranial reward (ICS) show elevated rates of response after a mild tail pinch. Both dopamine and opiates have been implicated in the mediation of other stress induced behavioral alterations, and may therefore also possibly be involved in the ICS effect. The present report replicated the initial finding of tail pinch induced facilitation of ICS, and further demonstrated that while opiate blockade failed to affect the ICS response dopaminergic blockage in fact inhibited it. These findings suggest neuropharmacological specificity for stress related behavioral change, and further implicate dopamine in stress responses.