Transcription factor ΔFosB acts within the nucleus of the solitary tract to increase mean arterial pressure during exposures to intermittent hypoxia

Abstract

ΔFosB is a member of the activator protein-1 family of transcription factors. ΔFosB has low constitutive expression in the central nervous system and is induced after exposure of rodents to intermittent hypoxia (IH), a model of the arterial hypoxemia that accompanies sleep apnea. We hypothesized ΔFosB in the nucleus of the solitary tract (NTS) contributes to increased mean arterial pressure (MAP) during IH. The NTS of 11 male Sprague-Dawley rats was injected (3 sites, 100 nl/site) with a dominant negative construct against ΔFosB (ΔJunD) in an adeno-associated viral vector (AAV)-green fluorescent protein (GFP) reporter. The NTS of 10 rats was injected with AAV-GFP as sham controls. Two weeks after NTS injections, rats were exposed to IH for 8 h/day for 7 days, and MAP was recorded using telemetry. In the sham group, 7 days of IH increased MAP from 99.8 ± 1.1 to 107.3 ± 0.5 mmHg in the day and from 104.4 ± 1.1 to 109.8 ± 0.6 mmHg in the night. In the group that received ΔJunD, IH increased MAP during the day from 95.9 ± 1.7 to 101.3 ± 0.4 mmHg and from 100.9 ± 1.7 to 102.8 ± 0.5 mmHg during the night (both IH-induced changes in MAP were significantly lower than sham, P < 0.05). After injection of the dominant negative construct in the NTS, IH-induced ΔFosB immunoreactivity was decreased in the paraventricular nucleus ( P < 0.05); however, no change was observed in the rostral ventrolateral medulla. These data indicate that ΔFosB within the NTS contributes to the increase in MAP induced by IH exposure. NEW & NOTEWORTHY The results of this study provides new insights into the molecular mechanisms that mediate neuronal adaptations during exposures to intermittent hypoxia, a model of the hypoxemias that occur during sleep apnea. These adaptations are noteworthy as they contribute to the persistent increase in blood pressure induced by exposures to intermittent hypoxia.