title: Effects of chronic stress and corticosterone on sialidase activity in the rat hippocampus.
abstract: Sialidases are acid exoglycosidases that catalyse the removal of sialic acid from non-reducing end of sialoglucoconjugated substrates. Synaptic plasticity depends on sialylation state of proteins and lipids mediated by sialic acid-metabolizing enzymes. Since chronic stress causes both, hippocampal atrophy and impairment of learning, it is reasonable to investigate whether sialidase is implicated in these processes. In this study, we tested effects of chronic stress (immobilization, 2h daily, 21 days) or chronic corticosterone administration (5 mg/kg, sc, daily) on sialidase activity and sialylated NCAMs expression in rat hippocampus. The results showed that chronic stress affects hippocampus-depended spatial learning in the Barnes maze. Both, stress (p > 0.05) and corticosterone (p < 0.001), increased latencies to enter the escape tunnel of the maze in comparison to control animals. Similar but not significant differences between control and other experimental groups were observed in the numbers of errors. Chronic stress (p > 0.05) and corticosterone (p < 0.05) decreased sialidase activity in the brain homogenates and synaptosomes (p < 0.05, both). In the stressed animals, these changes were related to significantly higher expression of polysialic acid. These results indicate that changes in sialidase activity caused by stress and chronic corticosterone administration reflect disturbances of polysialylated glycoconjugates known to be related to synaptic plasticity in hippocampus.
authors.affiliation: Department of Clinical Pharmacology, Medical University of Bialystok, Waszyngtona 15A, 15-274, Bialystok, Poland. pwielgat@gmail.com
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Wielgat
authors.forename: Anna
authors.initials: A
authors.lastname: Walesiuk
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Braszko
mesh_terms: D000818:Animals; D002908:Chronic Disease; D003345:Corticosterone / Q000494:pharmacology*; D004195:Disease Models, Animal; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology*; D007103:Immobilization / Q000379:methods / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012794:Sialic Acids / Q000378:metabolism; D013315:Stress, Psychological / Q000201:enzymology* / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
chemical_list: D019006:Neural Cell Adhesion Molecules; D012794:Sialic Acids; C021319:polysialic acid; D009439:Neuraminidase; D003345:Corticosterone