Sleep-disordered breathing (SDB) is more prevalent in adult men than in women and its occurrence increases after menopause, in line with several studies establishing that progesterone is a potent respiratory stimulant, that reduces the frequency of apnea in postmenopausal women. It is know that progesterone is synthetized in the ovaries of adult females, but also in the central and peripheral nervous system in males and females and that acts through nuclear (nPR) and membrane receptors (mPR) in the cell. The brain expresses mPRs, and a recent study from Dr. Joseph's laboratory,of Laval University, shows that reducing expression of mPR Beta increases 3 times the frequency of apnea in adult males and female mice (recorded during sleep), and reduced the ventilatory responses to hypoxia and hypercapnia. However, the localization of mPR Beta in brain structures that contribute to the control of respiration is not fully described. Therefore, the present study aims to evaluate the localization of mPR Beta in the respiratory areas of the brainstem in male and female rats. We will verify if the neurons that express mPR Beta are activated by hypoxia and assess whether neurons that express mPR Beta also express Phox-2b, a transcription factor used as a marker of neurons involved in respiratory chemoreflex.
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