Abstract: A chondroitin sulfate having a decreased molecular weight which has utilization as an inhibitor of peritoneal disorder caused by long-term use of a peritoneal dialysis fluid containing glucose or a polysaccharide thereof as an osmotic agent, utilization as an osmotic agent in a peritoneal dialysis fluid, and the like. The chondroitin sulfate having a decreased molecular weight of the present invention as a means for achieving the object is characterized by having a weight average molecular weight of from 1000 to 20000 and containing a constituent disaccharide unit represented by the following structural formula in an amount of from 65% to 100% (molar ratio) of the total: -[4GlcA?1-3GalNAc(6S)?1]- (wherein GlcA represents a D-glucuronic acid residue; GalNAc represents an N-acetyl-D-galactosamine residue; ?1-3 represents a ?1-3 glycosidic linkage; ?1-4 represents a ?1-4 glycosidic linkage; and (6S) indicates that position 6 of the monosaccharide residue is sulfated).

Abstract: An object of the present invention is to provide a substance which is able to be an active ingredient for the improvement of dysfunction caused by nerve damage. An improving agent for dysfunction due to nerve damage of the present invention as a means for resolution thereof is characterized in that it comprises an endo-?-N-acetylglucosaminidase type enzyme which hydrolyzes an N-acetylglucosamide bond in a keratan sulfate backbone as an active ingredient. When the improving agent of the present invention is administered, clinical improvement is achieved in motor neuron dysfunction and sensory neuron dysfunction such as neuropathic pain represented by a pain caused by allodynia and hyperalgesic reaction of the object to be treated.