Two major classes of addictive disorder in humans relate to nicotine use and to excessive food consumption. The concept of food as a commodity with abuse potential has become popular coincident with the obesity epidemic, but little work has directly compared food with drug reward. The present studies will compare the way in which the internal change resulting from either glucose or nicotine self-administration by rats may be preferentially associated with distinctive oral taste cues. Intravenously (IV) self-administered nicotine is thought to be only a weak reinforcer in rats. In contrast, humans readily become dependent upon nicotine, and withdrawal is difficult. These differences may arise in part because the cues associated with nicotine intake in humans include its flavor while in rat studies the cues are almost always changes in illumination. The main goal of this proposal is to determine whether intravenous self-administration of nicotine by rats is facilitated when a coincident taste or flavor cue is associated with nicotine delivery. First, it is important to establish strictly parallel procedures by which we can compare nicotine with nutrient delivery. The first experiment proposes to modify a published procedure in which intragastric delivery of glucose and water produces a strong sensory preference for a flavor paired with glucose delivery. Rats fitted with intragastric and intraoral catheters will be studied on alternating days in conditions in which consumption of a distinctive flavor cue (the CS+) is associated with delivery of glucose and consumption of a different flavor cue (the CS-) is associated with water infusion. The flavor cue will be delivered either through the rat licking naturally or by a nosepoke response for intraoral delivery of the flavor solution. Preference will be assessed by comparing intakes when both flavors are present. This will be compared with a situation in which illumination changes but no taste cue occur following completion of lever presses. Having identified key parameters, the design will be applied to intravenous delivery of nicotine as the reinforcer. We will again determine whether a nicotine-paired flavor becomes preferred. In the final proposed study, we will determine whether IV glucose as a reinforcer is either similar to or different from either IG glucose or IV nicotine as reinforcer. These studies may help to develop ways in conditioned preferences can be manipulated to prevent or treat certain addictive disorders, including overeating. ? ? ?
| Grebenstein, Patricia E; Harp, Joseph L; Rowland, Neil E (2013) The effects of noncontingent and self-administered cytisine on body weight and meal patterns in male Sprague-Dawley rats. Pharmacol Biochem Behav 110:192-200 |
| Grebenstein, Patricia E; Thompson, Ian E; Rowland, Neil E (2013) The effects of extended intravenous nicotine administration on body weight and meal patterns in male Sprague-Dawley rats. Psychopharmacology (Berl) 228:359-66 |
