Histochemical and enzymatic characterization of perineuronal nets in the retrosplenial cortex of adult albino rat

الملخص EN

The extracellular matrix (ECM) in the central nervous system (CNS) is found dispersed in neutrophil or preferentially organized into fenestrated or reticular coats, the so-called per neuronal nets (PNs), around the soma, initial dendrites and axon proximal segment of certain neuronal subsets.

These coatings have been shown to characterize the microenvironment of individual neurons and the chemo architecture of some brain regions including the retrosplenial cortex (RSC).

In the present study, the histochemical characteristics of retrosplenial ECM in the adult albino rats was described with a cationic iron colloid (CIC) for sulfated glycoconjugates (proteoglycans, PGs) and certain plant lections from Vickie villas agglutinin (VVA), Wisteria floribunda agglutinin (WFA) or Glycine max agglutinin (SBA) for Nacetylgalactosamine containing glycoconjugates (glycoproteins, GPs).

The PNs were detected on the surface of some neurons distributing throughout the cortical layers II-V which might presented direct interconnections with each other.

In addition to hyaluronic and link proteins, the PNs were enriched with sulfated PGs and/or GPs with terminal N-acetylgalactosamine.

The per neuronal coats were differentially identified as belonging to three types depending upon their molecular composition together with stain ability to the CIC-lection double technique.

First, coats exclusively formed of PGs that stained blue with iron colloid and digested with hyaluronidase but not erased by endo-alpha-N-acetylgalactosaminidase ; second, coats formed of GPs that stained yellow with plant lecterns and erased by endo-alpha-Nacetylgalactosaminidase but not abolished with hyaluronidase; and third, complex coats that formed of PGs networks decorated with glycoprotein molecules which stained greenish to dark-brown with the CIClectin double staining.

This type of per neuronal coating was digested with hyaluronidase/endo-alpha-Nacetylgalactosaminidase.

The findings of present investigation would be contribute as baseline for future experimental studies searching for biological significance of net-associating neurons and enzymatic or pharmaceutical regulation of ECM molecules in the CNS.

In conclusion, the differential distribution of protein containing substances (GPs and/or PGs) in the microenvironment of some retrosplenial neurons might reflect certain functional aspects concerned with processing of navigation or episodic memory.

In addition, the present data would be expanding for other mammalian species including the human.