MEDIAN PREOPTIC NUCLEUS NEURONS ACTIVATED FOLLOWING CHRONIC INTERMITTENT HYPOXIA PROJECT TO THE PARAVENTRICULAR NUCLEUS

Purpose: Chronic Intermittent Hypoxia (CIH) is a model for the arterial hypoxemia seen in sleep apnea and is associated with hypertension and increased sympathetic tone. In rats, the MnPO demonstrates increased FosB expression following CIH. A major projection from the MnPO is to the paraventricular nucleus (PVN). This projection may serve as one possible pathway for increased sympathetic tone and sustained hypertension in CIH. The purpose of this study is to further characterize MnPO neurons transcriptionally activated by CIH and determine if they project to the PVN. Methods: Isoflurane anesthetized adult male rats were microinjected with 200nl of a retrograde tracer, flourogold, unilaterally into PVN. Rats were then exposed to CIH for 7 days through 3 minute periods of hypoxia (10% oxygen) and 3 minute periods of normoxia (21% oxygen) for 8 hours per day (0800-1600 h). Controls were not exposed to to room air. Forebrains were fixed through paraformaldehyde perfusion and later processed for immunohistochemistry. Antibodies used were goat polyclonal FosB (1:2000). The sections were imaged using an Olympus DSU confocal microscope. Results: In the MnPO, CIH exposure increased FosB positive cells (Control 7.75± l.l; CIH 25.7±4.4; P<0.05) and colocalization of FosB with flourogold positive cells (Control 0.67±0.4; CIH 7.25±1.2; P<0.05). Conclusions: These results show that MnPO neurons transcriptionally activated by CIH project to the PVN. P01 HL88052