Distribution of hyaluronan in the central nervous system of the frog

Abstract

The qualitative and quantitative distribution pattern of hyaluronan (HA), a component of the extracellular matrix (ECM), was studied in the frog central nervous system by using a highly specific HA probe and digital image analysis. HA reaction was observed in both the white and the gray matter, showing a very intense staining around the perikarya and dendrites in the perineuronal net (PN). In the telencephalon, strong reaction was found in different parts of the olfactory system, in the pallium, and in the amygdala. In the diencephalon, intensive staining was found in the nucleus of Bellonci, the dorsal habenula, the lateral and central thalamic nuclei, and the subependymal zone of the third ventricle. In the mesencephalon, layers of optic tectum displayed different intensities, with the strongest reaction in layers B, D, F, 3, and 5. Other structures of the mesencephalon showed regional differences. The PN was especially intensively stained around the perikarya of the toral nuclei, the oculomotor and trochlear nuclei, and the basal optic nucleus. In the rhombencephalon, the granular layer of cerebellum, the vestibulocochlear nuclei, the superior olive, the spinal tract of the trigeminal nerve, and parts of the reticular formation showed the most intense reaction in the PN. In the spinal cord, considerable HA staining was found in the white matter and around the perikarya of motoneurons. The present study is the first description of the HA-positive areas of frog brain and spinal cord demonstrating the heterogeneity of HA distribution in the frog central nervous system.

The effect of vestibular nerve section on the expression of the hyaluronan in the frog, Rana esculenta

“…The HA reaction was negative in the vestibulocochlear nerve, and it was intensive in the transitional zone of intact animals in accordance with our previous results (Matesz et al 2005;Szigeti et al 2006). A positive HA reaction has been shown along the white matter of the neuraxis, especially in the vestibulocochlear, vestibulospinal and vestibulocerebellar tracts.…”

“…The TZ of the vestibulocochlear nerve was recognized as the extension of CNS tissue into the PNS (Fraher 1992;Toesca 1996). The very strong HA reaction of TZ was abruptly changed into the negative reaction of peripheral part of the nerve (Szigeti et al 2006). Out of six-eight images taken from both sides per individual animal only two-five were suitable for analyzing because of technical artefacts.…”

“…For the detection of HA (Tammi et al 1989(Tammi et al , 1994Matesz et al 2005;Szigeti et al 2006) a specific biotinylated hyaluronan binding probe (bHABP) (kindly provided by R. Tammi and M. Tammi, Department of Anatomy University of Kuopio, Kuopio, Finland) was applied. The sections were incubated overnight in a final dilution of 1:10 (5 lg/ml PBS) at 4°C, and the signal was subsequently visualized with the avidin/biotin (ABC) staining kit (Vector Laboratories, Burlingame, CA, USA) and diaminobenzidine (DAB, 0.5 mg/ml in PBS) according to the manufacturer's instructions.…”

“…The area-integrated mean optical density values (AIOD) were then calculated by weighing the intensities of pixels from the ROIs by the numbers of pixels in the ROI, and the AIODs were used as a measure of optical density of HA reaction. The method used for the measurement of optical density was detailed by Szigeti et al (2006).…”

“…An intriguing ECM macromolecule found both in the peripheral and central nervous system is hyaluronan (HA). It is ubiquitously present in many mammalian species (Margolis et al 1975;Delpech et al 1989;Eggli et al 1992;Gong et al 1994;Yasuhara et al 1994) and in the frog (Matesz et al 2005;Szigeti et al 2006) showing regional differences in the brain and spinal cord.…”