Accumulating evidence suggests that structures within the lamina terminalis; the organum vasculosm of the lamina terminalis (OVLT), the median preoptic nucleus (MnPO) and/or the subfornical organ (SFO); are required for the development of DOCA-salt hypertension. Lesion of the anteroventral tissue lining the third ventricle (AV3V), which destroys cell bodies in the OVLT and MnPO, as well as efferent projections from the SFO to the OVLT and MnPO, abolishes DOCA-salt hypertension in the rat. However, the individual contribution of these structures to DOCA-salt hypertension is unknown. The present study was designed to determine whether an intact SFO is required for hypertension development in the DOCA-salt model. In uninephrectomized SFO lesioned (SFOx; n = 6) and SHAM (n = 8) Sprague-Dawley rats, 24-h mean arterial pressure (MAP) and heart rate (HR) were continuously recorded telemetrically 4 days before and 36 days after DOCA implantation (100 mg/rat; s.c.); 24-h sodium and water balances were measured throughout the protocol. No differences in control MAP, HR, sodium and water balances were observed between groups. Following DOCA implantation, the magnitude of the elevation of MAP was similar between groups (∼ 40 mm Hg) so that by Day 40, MAP was 148 ± 5 mm Hg in SFOx and 145 ± 4 mm Hg in SHAM rats. The magnitude of decrease in HR from control values was similar in both groups. Differences in sodium and water balances were not observed between groups. We conclude that the SFO alone does not play a significant role in the development of mineralocorticoid-salt hypertension.
Bibliographical noteFunding Information:
The authors would like to thank Dr. William Engeland for his advice on use of the immersion fix method for histological verification of SFO lesions. We also thank Jessica Armstrong for technical assistance with the histology. This work was supported by a grant from the National Heart Lung and Blood Institute of the National Institutes of Health (HL64178).
- Circumventricular organ
- DOCA-salt hypertension
- Subfornical organ
- Sympathetic nervous system