Abstract: | In the present study, the distribution of parvalbumin(PV) and calbindin D 28k(CB) Like immunoreactivities( LI) in the central pathway of trigeminal proprioception of the rat was examined by the immunohistochemical method. The results indicated that PV and CB LI in the pathway showed the following distribution characteristics. (1) Nearly all neurons in the mesencephalic trigeminal nucleus(Vme) showed PV LI. Both the cell bodies and the processes displayed high to moderate immunostaining. Most neurons of PV LI were large (18~30 μm), pseudounipolar neurons; medium sized multipolar ones could be occasionally seen. (2) At the level of caudal part of the subnucleus oralis of the spinal trigeminal nucleus often occurred two well separated areas of high intensity of PV LI in the dorsomedial part of the subnucleus oralis of the spinal trigeminal nucleus and its adjacent lateral reticular formation(Vodm LRF): one was large, the other was small; and the cell bodies were round, triangular or irregular in shape(9~16 μm). Neurons with CB LI in Vodm LRF were multipolar with different size and shape, and showed similar distribution pattern to that of PV. (3) PV LI neurons were multipolar with short processes in the “zone shaped area”. In the caudolateral part of supratrigeminal nucleus (Vsup CL), PV LI neurons were sparsely distributed. However, a large number of neurons in the whole dorsomedial part of the principal sensory trigeminal nucleus (Vpdm) expressed PV LI. A few cell bodies and processes in the two newly found nuclei, the area ventral to the motor trigeminal nucleus (AVM) and the area dorsal to the superior olivary nucleus (ADO), were also labeled. By comparison, the neurons displaying CB LI in these nuclei were smaller in number and sparsely distributed, they were round, triangular or irregular in shape and larger in size(11~18 μm),and beaded varicosities could be easily seen along the axons. In ADO the distribution region of CB LI neurons was slightly more dorsomedial than that of PV LI. The present results indicated that the two main calcium binding proteins, PV and CB, were widely distributed in the central pathway of the trigeminal proprioception of the rat, and suggested that PV and CB might play important roles in the transmission of the trigeminal proprioceptive information. (Figures A F on plate 50) |