Publication Date

8-2023

Advisor(s) - Committee Chair

Noah Ashley, Michael Smith, Simran Banga

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

Sleep is one of the body’s greatest and most basic needs. Chronic sleep loss (<6 hours a day) is linked to many cardiovascular issues, diabetes, and inflammatory conditions and has been shown to lower life expectancy. Obstructive sleep apnea (OSA) is a complication that causes sleep fragmentation in >8% of adults from developed countries, and many with OSA may be unaware of their condition. Having long-term OSA is linked to neuroinflammation caused by activated microglia in the brain, but the mechanics of this inflammation are not well understood. It is known that glucocorticoids, steroid hormones produced and released from the adrenal glands, have a suppressive effect on microglia. The purpose of this study is to explore the role that glucocorticoids have upon microglia activation induced by chronic sleep fragmentation (SF). C57BL/6J mice were adrenalectomized (ADX; to prevent the natural production of glucocorticoids), sham-adrenalectomized (sham), or adrenalectomized and provided with corticosterone in drinking water (ADX + Cort) and then placed in a special chamber that induces sleep fragmentation for a period of eight weeks. After brains were collected, microglial activation was assessed based on quantity and morphology in the cingulate cortex, hippocampus, and hypothalamus. There were significant differences in microglial cell count between sleep treatments within sham treatments, but no significant differences in microglial soma size. Corticosterone treatment had a strong effect upon microglial cell number in hippocampus: ADX treatment increased cell count while corticosterone treatment in ADX mice reversed this effect. There were minimal effects of chronic SF upon microglial cell count or soma size. Taken together, these findings provide mixed support for hormonal regulation of microglial activity during chronic sleep fragmentation.

Disciplines

Biology | Endocrinology | Immunology and Infectious Disease | Life Sciences | Neuroscience and Neurobiology | Physiology

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