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Multigenerational effects of pre-conception circadian disruption by light at night

Cissé, Yasmine-marie Nirina, Cisse

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Neuroscience Graduate Studies Program.
Over the past several billion years, virtually all organisms have been selected to develop endogenous biological rhythms of about 24-hours, or circadian rhythms. Proper synchronization of internal circadian rhythms to the consistent solar cycle provides adaptive anticipation of daily patterns in the environment. However, in the past century the world has undergone a marked increase in nighttime illumination allowing for the development of “24-hr societies” and night shift work. Night shift workers provided the initial evidence for the increased risk of mood disorders, cancer development, and metabolic disorders associated with chronic exposure to light at night, but similar risks are beginning to be reported in the general population. Virtually every individual and organism in the developed world is exposed to aberrant nighttime lighting. Exposure to dim light at night (dLAN; 5 lux) disrupts molecular timekeeping mechanisms and alters rhythmic production of endocrine messengers of circadian time in nocturnal rodents. Chemical disruption of hormone signaling or release in a primary organism has the potential to alter physiology and behavior in offspring and grand-offspring through persistent changes in the epigenome. However, no studies to date have investigated the impact of the systemic disruption induced by dLAN on future generations. In this dissertation, I provide evidence for the multigenerational effects of dim nighttime light exposure prior to conception on offspring physiology and behavior. The transgenerational effects of endocrine disruption are often secondary to changes in endocrine function. Melatonin and glucocorticoids act as the humoral signals of circadian time to peripheral tissues; exposure to dLAN flattens rhythmic production cortisol and eliminates nightly melatonin. In addition to their roles in circadian timekeeping, these hormones reciprocally regulate one another’s receptor expression and have opposing actions in regulating affective behavior and immunity, systems altered by exposure to dLAN. Therefore, I first investigated whether pre-conception dLAN altered expression of melatonin (MT1) and glucocorticoid (GR) receptors in offspring. The effects of pre-conception exposure to dLAN on offspring hippocampal and splenic MT1 and GR expression are described in Chapters 2 and 4, respectively. The effects of pre-conception dLAN on offspring hippocampal endocrine receptor expression are considered along with assessments of offspring depressive-like behavior in Chapter 2. Increased depressive-like behavior in adult Siberian hamsters exposed to dLAN are dependent on increases in hippocampal tnf-a, suggesting interactions of immune and mood regulation. Therefore, in Chapters 3 and 4 I investigate the effects of pre-conception dLAN on innate and adaptive immune measures. Offspring febrile, cytokine, and functional immune responses to an endotoxin challenge in response to parental dLAN are described in Chapter 3. In Chapter 4, immune phenotyping is extended with reports of T-cell and B-cell mediated immune challenges as proxies of offspring adaptive immune function. Finally, Chapter 4 concludes with an investigation of alterations to the splenic epigenome as a mediator for changes in immune responsiveness. Overall, these data outline the multigenerational consequences of dim but ecologically relevant levels of nighttime lighting on physiology and behavior.
Randy Nelson (Advisor)
Courtney DeVries (Committee Member)
Benedetta Leuner (Committee Member)
Zachary Weil (Committee Member)
Michael Bailey (Committee Member)
131 p.

Recommended Citations

Citations

  • Cissé, Cisse, Y.-M. N. (2017). Multigenerational effects of pre-conception circadian disruption by light at night [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512163356982794

    APA Style (7th edition)

  • Cissé, Cisse, Yasmine-marie. Multigenerational effects of pre-conception circadian disruption by light at night. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1512163356982794.

    MLA Style (8th edition)

  • Cissé, Cisse, Yasmine-marie. "Multigenerational effects of pre-conception circadian disruption by light at night." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512163356982794

    Chicago Manual of Style (17th edition)