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Krizo.Jessica.Dissertation.2016.pdf (3.27 MB)

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Regulation of Food Anticipatory Activity

Krizo, Jessica Ann
http://orcid.org/0000-0001-5363-7353
http://rave.ohiolink.edu/etdc/view?acc_num=kent1470307781

Abstract Details

2016, PHD, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
Circadian rhythms of physiology and behavior are driven by a circadian clock located in the suprachiasmatic nucleus of the hypothalamus. This clock is synchronized to environmental day/night cycles by photic input, which is dependent on the presence of mature brain-derived neurotrophic factor (BDNF) in the SCN. Mature BDNF is produced by the enzyme plasmin, which is converted from plasminogen by the enzyme tissue plasminogen activator (tPA). In this study, we evaluate circadian function in mice lacking functional tPA. KO mice have normal circadian periods, but show an increased proportion of daily wheel-running activity during the day and a slightly reduced overall level of wheel-running activity. When placed on daily cycles of restricted food availability, the difference between activity level disappears. Despite the increased wheel-running activity in KO mice, neither they nor wild type mice entrain to 24-hour cycles of restricted food availability in constant darkness. When daily restricted feeding occurs with the animals housed in a skeleton photoperiod (15 min of light at the beginning and end of the day only), some though not all of the difference between genotypes is eliminated. These data suggest that tPA plays a fundamental role in regulating the response of circadian clocks to both photic and feeding signals. In addition, female mice exhibit significantly less FAA than males, and we sought to investigate the mechanism for this difference. Females showed no daily changes in FAA that might correspond to the estrous cycle, suggesting that variation in estrogen levels are not responsible for the difference between males and females. Therefore we hypothesized that testosterone might be responsible for sex differences in FAA. Male and female mice were randomly selected for gonadectomy (GDX) and sham procedures. Following surgical procedures mice were individually housed in 12:12 LD and placed on 4-hr daily restricted feeding. In males, orchiectomy significantly decreased overall wheel-running activity compared to both intact and sham groups but did not affect levels of FAA. In females, ovariectomy (OVX) decreased overall wheel-running activity compared to both intact and sham groups but FAA was increased in both sham and OVX groups. We then added groups in which testosterone or estradiol were replaced in GDX mice. Testosterone replacement in males significantly increased activity at baseline but did not alter the activity levels during restricted feeding or influence levels of FAA. Estrogen replacement did not significantly alter activity levels at any point. Taken together, these data suggest that the sex difference in female locomotor response to restricted feeding is not a function of circulating gonadal steroids.
Eric Mintz, PHD (Committee Chair)
Colleen Novak, PHD (Committee Member)
John Johnson, PHD (Committee Member)
Mary Ann Raghanti, PHD (Committee Member)
Stephen Fountain, PHD (Committee Member)
161 p.
Behavioral Sciences; Biology; Neurosciences
circadian; restricted feeding; fasting; sex differences; estrogen; testosterone; locomotor activity

Recommended Citations

Citations

  • Krizo, J. A. (2016). Regulation of Food Anticipatory Activity [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1470307781

    APA Style (7th edition)

  • Krizo, Jessica. Regulation of Food Anticipatory Activity. 2016. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1470307781.

    MLA Style (8th edition)

  • Krizo, Jessica. "Regulation of Food Anticipatory Activity." Doctoral dissertation, Kent State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1470307781

    Chicago Manual of Style (17th edition)

kent1470307781
572
© 2016, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.