| Abstract: | Previous research has shown that exposure to inescapable shock produces a hormonally mediated opioid hypoalgesia in rats. In addition, it has a long-term sensitization effect on the opioid system that increases reactivity to a low dose of morphine. Recently, it has been shown that food deprivation also produces this sensitizing effect. In the present study, we test whether food deprivation alters the motivational or reinforcing consequences of an opiate. Subjects were food deprived for 48 hours and then, 24 hours after food was returned, trained in a place conditioning paradigm. They were tested for place preferences after one and two days of conditioning (2 drug pairings per day at .5 mg/kg). We found that food deprivation increased the strength of the place preference established by morphine. |
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