[A study of sensory pathway in central nervous system of experimental tooth movement in rats]

To investigate whether ventral posteromedial thalamus nucleus (VPM) receive the stimulation from experimental tooth movement in rats through the conduction of spinal trigeminal caudal nucleus (Vc), thus to study the central sensory pathway of tooth movement.

2% fluorogold (FG) was injected into rat's VPM using microinjector through retrograde tracing technique. After 4-6 days, the experimental tooth movement was conducted in contra-side against FG injection. 2 hours later, animals were sacrificed and FOS protein immunocytochemical reaction was conducted. The sections were observed under Olympus fluorescence microscope.

FOS immunocytochemical-positive neurons were densely distributed in epilateral superfacial layer of Vc, being belt-like with more in dorsolateral 2 hours after experimental tooth movement; FG-labeled neurons were found in Vc and principle trigeminal nucleus complex, especially within the whole length of Vc, with more in layer I and the junction of layers I and II. There were both FOS immunocytochemically positive and FG-labeled neurons, approximately 5% of the whole FG-labeled neurons.

As a special oro-facial stimulation, there are corresponding parts in the central nervous system according to tooth movement. The stimulating message integrated in Vc and Vc has projective neurons to VPM, and VPM might be a relay station of the stimulating message of experimental tooth movement in rats.