Effect of vitamin D and omega-3 on the expression of endoplasmic reticulum-associated protein degradation and autophagic proteins in rat brain

Abstract

Objectives Valosin-containing protein (p97/VCP) and its cofactor, small p97/VCP-interacting protein (SVIP), are involved in the endoplasmic reticulum-associated degradation pathway (ERAD). We investigated the cellular localization of vitamin D receptor (VDR), ERAD, and autophagic proteins (LC3B and p62) in rat brain tissue.Methods There were four groups consisting of 24 Wistar albino rats: control and treatment groups for vitamin D, omega-3, and both vitamin D and omega-3. Brain tissues were stained with hematoxylin-eosin, azan trichrome, and toluidine blue for histopathological evaluation. The immunohistochemistry assay was performed for VDR, p97/VCP, SVIP, LC3B, and p62 in rat brain sections.Results The immunoexpression of VDR and p97/VCP was significantly increased in hippocampus and cortex of brain tissue from the vitamin D-supplemented group. Furthermore, the protein expression level of SVIP reached the highest level in vitamin D-treated group. LC3B and p62 revealed reduced expressions in vitamin D-treated group in rat brain and hippocampus, in contrast to p97/VCP, SVIP, and VDR.Conclusions Vitamin D and omega-3 supplementations had no negative effects at a cellular level on hippocampus and cortex of the brain tissue. Vitamin D increased the expression of the proteins that are related to the ERAD pathway, whereas it reduced the expression of the proteins in the autophagy pathway. Also, in this study, SVIP expressions were shown in rat hippocampus and cortex of the brain tissue.