title: Sex chromosome complement influences operant responding for a palatable food in mice.
abstract: The procurement and consumption of palatable, calorie-dense foods is influenced by the nutritional and hedonic value of foods. Although many factors can influence the control over behavior by foods rich in sugar and fat, emerging evidence indicates that biological sex may play a particularly crucial role in the types of foods individuals seek out, as well as the level of motivation individuals will exert to obtain those foods. However, a systematic investigation of food-seeking and consumption that disentangles the effects of the major sex-biasing factors, including sex chromosome complement and organizational and activational effects of sex hormones, has yet to be conducted. Using the four core genotypes mouse model system, we separated and quantified the effects of sex chromosome complement and gonadal sex on consumption of and motivation to obtain a highly palatable solution [sweetened condensed milk (SCM)]. Gonadectomized mice with an XY sex chromosome complement, compared with those with two X chromosomes, independent of gonadal sex, appeared to be more sensitive to the reward value of the SCM solution and were more motivated to expend effort to obtain it, as evidenced by their dramatically greater expended effort in an instrumental task with progressively larger response-to-reward ratios. Gonadal sex independently affected free consumption of the solution but not motivation to obtain it. These data indicate that gonadal and chromosomal sex effects independently influence reward-related behaviors, contributing to sexually dimorphic patterns of behavior related to the pursuit and consumption of rewards.
authors.affiliation: Department of Psychology, University of California, Los Angeles.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Seu
authors.affiliation: Department of Psychology, University of California, Los Angeles.|Department of Psychiatry, Yale University.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Groman
authors.affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles.|The Brain Research Institute, University of California, Los Angeles.
authors.forename: Arthur P
authors.initials: AP
authors.lastname: Arnold
authors.affiliation: Department of Psychology, University of California, Los Angeles.|Department of Psychiatry & Biobehavioral Sciences, University of California, Los Angeles.|The Brain Research Institute, University of California, Los Angeles.
authors.forename: J David
authors.initials: JD
authors.lastname: Jentsch
mesh_terms: D000818:Animals; D003216:Conditioning, Operant; D005260:Female; D005518:Food Preferences; D005838:Genotype; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012201:Reward; D012727:Sex Characteristics; D012730:Sex Chromosomes / Q000235:genetics*; D051876:Sex-Determining Region Y Protein / Q000235:genetics; D013649:Taste
chemical_list: D012739:Gonadal Steroid Hormones; D051876:Sex-Determining Region Y Protein
keywords: Feeding; gonad; hormone; instrumental conditioning; motivation; operant conditioning; reinforcement; reward; sex chromosome; sex differences