Date of Award

5-23-2010

Document Type

Honors Thesis

Department

Neuroscience

First Advisor

Mary Niblock

Second Advisor

Teresa Barber

Third Advisor

Charles Zwemer

Abstract

Central chemoreceptors are cells in the brain that regulate breathing through projections to respiratory control nuclei such as the ventral respiratory column (Guyenet et al., 2008). These cells have been found along the ventral surface of the brainstem including in the retrotrapezoid nucleus (RTN). Central chemoreceptors are capable of detecting pH changes in cerebral spinal fluid resulting from changing carbon dioxide (CO2) levels in the mouse’s surroundings. In the current study, central chemoreceptors were identified by exposing c-fos promoter driven tau-lacZ reporter (FTL) positive transgenic mice to room air, 5%, and 10% CO2 for 70 minutes. Activated cells were then identified using x-gal histochemistry. In a previous study, a sex difference had been discovered between male and female central chemoreceptors in the RTN when FTL mice were exposed to 5% CO2. The males expressed central chemoreceptor stimulation, while the females did not. In the current study, it was shown that female RTN central chemoreceptors are activated when exposed to a 10% CO2 environment. Analysis has shown that there is no sex difference between males and females when exposed to 10% CO2. These findings suggest that the female RTN requires higher CO2 to turn on c-fos. Perhaps this is due to females having either a higher CO2 threshold in the RTN or a different chemosensing cell population working at lower CO2 levels. Further, these sex differences may have implications in respiratory disorders such as Sudden Infant Death Syndrome (SIDS) and sleep apnea, both of which are more common in males.

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