The effect of naloxone on food-motivated behavior in the obese Zucker rat.

摘要: We assessed differences in food reinforced behavior between obese and lean Zucker rats with a progressive ratio schedule 3 (PR3) which subject emitted three additional lever-presses each time reinforcer was delivered. The number of responses required for eventually exceeded its value, termed the ”break point”, sensitive measure motivated behavior. Break points were higher than controls grain pellets (27.5 versus 9.5, P=0.01) but not sweet (51.6 38.5, P=0.31). determined if naloxone (0.01–3.0 mg/kg, SC), reduces free intake rats, affects Zuckers controls. Naloxone reduced break both to similar extent when working either or pellets. Under free-access feeding conditions, again decreased pellet similarly rats. appeared decrease consumption greater point groups. These results show that (1) exhibit levels performance only less valued pellet, (2) independent genotype, (3) appears more effectively given access food.