Survey of the extracellular matrix macromolecule distribution in the brainstem of rodents

The intercellular space of the central nervous system is rich in macromolecules of extracellular matrix (ECM). Recent studies have hypothesized that the ECM has important role in the responses of cells to the changes of their environment. In our previous study we have demonstrated that the expression of chondroitinsulfate proteoglycans (CSPGs), key molecule of ECM in the nervous system, is changing in vestibular nuclei following the injury of vestibular nerve. We intend to investigate whether the expression of CSPGs shows similar modification in the brainstem areas that are connected with the vestibular nuclei. In the present study, we have made a detailed ECM-mapping of CSPGs in order to compare the changes of expression pattern. Experiments were performed on adult mice and rats. On anesthetized animals the brainstem was removed and immersed into Sainte-Marie’s fixative. The paraffin embedded specimens were cut in transverse and sagittal plane and biotinylated Wisteria floribunda agglutintin (WFA) was applied to detect the CSPGs. The WFA reaction showed an area–dependent distribution in the gray and white matter of brainstem. In the gray matter, the WFA positivity displayed a homogenous or fine granular appearance in the neuropil. The perikarya and dendrites were surrounded with a narrow area representing the perineuronal net (PN). In the mesencephalon, the WFA reaction was intensive in the eye moving motor nuclei, red nucleus and substantia nigra. In the rhombencephalon, each somatomotor cranial nerve nucleus displayed moderate or strong reaction. The PN was intensively stained in the magnocellular nucleus of reticular formation, trapezoid body and the inferior olive. The white matter showed a very intensive reaction in the cerebellar peduncle. The heterogeneous distribution of CSPGs in the neural network of brainstem underlying the gaze and posture control may indicate their different involvement in the restoration of vestibular function following the nerve injury.

This work was supported by OTKA K 67641 and MTA-TKI 242.