Does the median preoptic nucleus contribute to sympathetic hyperactivity in spontaneously hypertensive rats?

• The median preoptic nucleus (MnPO) contributes to the tonic control of blood pressure.
• The MnPO is involved in the tonic regulation of renal sympathetic activity (RSNA).
• The MnPO contributes to the increase of RSNA in spontaneously hypertensive rats (SHR).
• The MnPO is involved in the hypertension observed in (SHR).

The present study sought to determine the involvement of median preoptic nucleus (MnPO) in the regulation of the cardiovascular function and renal sympathetic activity in normotensive (NT) and spontaneously hypertensive rats (SHR). MnPO inhibition evoked by Muscimol (4 mM) nanoinjections, elicited fall in MAP and renal sympathoinhibition in NT-rats. Surprisingly, in SHRs these responses were greater than in NT-rats. These results demonstrated, for the first time that MnPO was involved in the tonic control of sympathetic activity in NT and SHRs. Furthermore, our data suggest the MnPO involvement in the increased sympathetic outflow and consequent arterial hypertension observed in SHRs.