[Effect of vasopressin in the rostral ventrolateral medulla on pressor response induced by dPAG stimulation].

Experiments were performed on male SD rats anaesthetized with urethane (700 mg/kg) and chloralose (35 mg/kg). The results showed that mean arterial pressure (MBP) increased signifigantly and heart rate (HR) had no signifigant change by bilateral microinjection AVP(10 pmol/0.1 microliter/site) into the rostral ventrolateral medulla (rVLM), while both MBP and HR were not changed by application of an AVP-V1 receptor antagnoist. Microinjection of an AVP-V1 receptor antagonist into the bilateral rVLM inhibited partially the pressor response induced by midbrain defence area stimulation. The above results suggest that AVP in the rVLM can elevate MBP and midbrain defence area stimulation can cause pressor response. Both these effects are related to activation of AVP-V1 receptors in the rVLM.