Long-term Potentiation and Depression after Unilateral Labyrinthectomy in the Medial Vestibular Nucleus of Rats

Abstract

We previously demonstrated in rat brainstem slices that high-frequency stimulation (HFS) of the vestibular afferents induces long-term potentiation (LTP) in the ventral part (Vp) of the medial vestibular nucleus (MVN) and long-term depression (LTD) in the dorsal part (Dp). Both LTP and LTD depend on N-methyl-D-aspartate receptor activation, which increases synaptic efficacy; however, in the Dp, LTP reverses to LTD because of the activation of γ-aminobutyric acid-ergic neurons. Here we show that the probability of inducing long-term effects in the MVN of rat brainstem slices is altered after unilateral labyrinthectomy (UL). In fact, LTP occurs less frequently in the ventral contra-lesional side compared with sham-operated rats. In the dorsal ipsi-lesional side, LTD is reduced and LTP enhanced, while the opposite occurs in the dorsal contra-lesional side. These changes in synaptic plasticity may be useful for re-balancing the tonic discharge of the MVN of the two sides during vestibular compensation, and for enhancing the dynamic responses of the deafferented MVN neurons in the long term.

• long-term depression
• long-term potentiation
• vestibular compensation

Pettorossi VE, Dutia M, Frondaroli A, Dieni C, Grassi S. Long-term potentiation and depression after unilateral labyrinthectomy in the medial vestibular nucleus of rats. Acta Otolaryngol 2003; 123: 182–186.

Pettorossi VE, Dutia M, Frondaroli A, Dieni C, Grassi S. Long-term potentiation and depression after unilateral labyrinthectomy in the medial vestibular nucleus of rats. Acta Otolaryngol 2003; 123: 182–186.