SIGNALING IN THE RAT CAROTID BODY By

ii Carotid bodies contain blood oxygen-sensing cells expressing leptin and leptin receptor isoforms. Whether leptin is involved in chemoreception in the carotid body is unknown. Experiments were completed to investigate leptin signaling in carotid body glomus cells during intermittent hypoxia (IH). Rats were subjected to IH for 8 hours/day for 1, 7, 95 days or to systemic leptin injections. Immunohistochemical and Western bot analysis were used to localize leptin, its receptors and downstream signaling proteins in glomus cells. IH resulted in increased circulating and local leptin, increased activation of STAT3 and Fra-1 expression suggesting an activation of a leptin signaling system within these cells. Captopril treatment prior to IH eliminated the increased plasma and carotid body leptin in IH suggesting angiotensin II may exert an effect on leptin in glomus cells. The data suggest that leptin acting in the carotid body activates glomus cells and may play a modulatory role in th