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APPETITE, OBESITY, DIGESTION, AND METABOLISM

Oxytocin knockout mice demonstrate enhanced intake of sweet and nonsweet carbohydrate solutions

¹Department of Psychology, City University of New York, Brooklyn College, Brooklyn, New York; Departments of ²Neuroscience, ³Pharmaceutical Sciences, and ⁴Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania

Submitted 22 November 2006 ; accepted in final form 25 January 2007

Oxytocin knockout (OT KO) mice display enhanced intake of nutritive and nonnutritive sweet solutions (i.e., sucrose and saccharin) compared with wild-type (WT) mice of the same C57BL/6 background strain. The present study further investigated the differential behavioral response of OT KO and WT mice to sucrose solutions and also examined intake preferences of OT KO and WT mice for palatable but nonsweet isocaloric solutions of carbohydrate and fat. A progressive ratio operant licking procedure demonstrated that OT KO and WT mice display a similar motivational drive to consume 10% sucrose. A series of two-bottle intake tests revealed that OT KO mice consume significantly larger amounts of both sweet and nonsweet carbohydrate solutions (i.e., sucrose, Polycose, and cornstarch) compared with WT cohorts. Intake pattern analyses revealed that OT KO mice overconsume carbohydrate solutions by initiating more drinking bouts compared with WT mice; bout sizes did not differ between the genotypes. In contrast, OT KO and WT mice did not differ in their intake of Intralipid, a palatable soybean oil emulsion. These findings indicate that the absence of OT in mice does not affect their appetitive drive to consume palatable sucrose solutions. Instead, the absence of OT may increase daily intake of palatable sweet and nonsweet solutions of carbohydrate (but not fat) by selectively blunting or masking processes that contribute to postingestive satiety.

ingestive behavior; sucrose; Polycose; cornstarch; lipid; operant licking

This article has been cited by other articles:

				J. A. Miedlar, L. Rinaman, R. R. Vollmer, and J. A. Amico Oxytocin gene deletion mice overconsume palatable sucrose solution but not palatable lipid emulsions Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1063 - R1068. [Abstract] [Full Text] [PDF]