Operant responding for sucrose by rats bred for high or low saccharin consumption

Blake A. Gosnell, Anaya Mitra, Ross A. Avant, Justin J. Anker, Marilyn E. Carroll, Allen S. Levine

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


The use of rats differing in the intake of sweet substances has highlighted some interesting parallels between taste preferences and drug self-administration. For example, rats selectively bred to consume high (HiS) or low (LoS) amounts of a 0.1% saccharin solution (when compared to water consumption), show corresponding differences across several measures of cocaine self-administration (HiS > LoS). In this study, we measured whether the two strains also differ when response requirements are imposed for obtaining a sucrose reinforcer. Male HiS and LoS rats were measured for operant responding for sucrose pellets under fixed-ratio (FR) schedules of 1, 3, 5 and 10 and under a progressive-ratio (PR) schedule, during which the response requirement for each successive pellet increased exponentially. The effect of systemic naltrexone (0.3, 1 and 3 mg/kg) on PR responding for sucrose pellets was also tested. Under all FR and PR schedules, the number of pellets obtained by the LoS rats were significantly lower than those obtained by the HiS rats. Although the LoS weighed more than the HiS rats, this difference does not appear to explain differences in operant behavior. No strain differences in the effect of naltrexone were observed; the 3 mg/kg dose reduced the number of pellets obtained in both strains. Measures of locomotor activity taken prior to operant trials suggest that the differences in responding were not due to differences in general activity levels. These studies provide further characterization of the HiS and LoS rat lines by demonstrating that motivation to consume sucrose is greater in HiS than in LoS rats.

Original languageEnglish (US)
Pages (from-to)529-533
Number of pages5
JournalPhysiology and Behavior
Issue number4
StatePublished - Mar 30 2010

Bibliographical note

Funding Information:
Supported by the National Institute of Health Grants R01DA021280 (ASL, BAG, RAA, AM), P30DK50456 (ASL), K05DA015267 , R01DA003240 , R01DA019942 , P20DA024196 (MEC), F31DA023301 (JJA) and T32DE007288 (AM). The content is solely the responsibility of the authors and does not necessarily represent the official views of NIDA, NIDDK, NIDCR or NIH.


  • Locomotor activity
  • Naltrexone
  • Opioid
  • Reward
  • Saccharin
  • Sucrose


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