Effect Of Acute Hypotension On DA Content And D₁R Expression In The Medial Vestibular Nucleus In Conscious Rats

The vestibular organ is an vital sensory system for the body’s position and movement state.And the medial vestibular nucleus(MVN)is an important nucleus of vestibular reflex.Stimulation of vestibular organ can affect blood pressure and heart rate.On the contrary changes of blood pressure also influence the function of the vestibule.In the early phase of the experiment,we found that glutamate are involved in the process of acute hypotension.However,the participation of dopamine and its D1 receptor in the vestibular nucleus simulated by acute hypotension has not been discussed.Results as follows:1.Unilateral labyrinth model:After the vestibular organ injury,the nystagmus reached the peak at 1d,and return to normal after 5 d;the head leaning was gradually augmented at 0.5 d,and not weakened after 3d;the level rotation was exacerbation at 0.25 d,and reached to normal at 7d.2.After unilateral labyrinth,the content of DA in MVN area was measured.The ipsilateral reached the peak at 0.5 d and recovered to normal after 7 d;the contralateral reached the peak at 0.25 d and return to normal after 7 d.3.After unilateral labyrinth 14 d,the content of DA have no change in the ipsilateral group following SNP intravenous injection,while the DA of contralateral group was increased in MVN.4.D1 receptor immunoreactive neuron was weakly expressed in the medial vestibular nucleus after SNP intravenous injection,while the D1R was significant expressed in the control group.After unilateral labyrinth of 14 d,contralateral group was weakly expressed and the ipsilateral group was expressed.5.D1 receptor protein was weakly expressed in the medial vestibular nucleus after SNP intravenous injection,while D1R protein was expressed significantly in the control group.After unilateral labyrinth of 14 d,the contralateral group was weakly expressed and the ipsilateral group was expressed significantly.These results suggest that:The SNP-induced acute hypotension influence the activity of the neurons in the MVN,DA and D1R are involved in this process.