ABSTRACT
Brain-pancreas relative protein (BPRP) is a novel protein that we found in our laboratory. Previously we demonstrated that it is involved in ischemia and depression. In light of the putative association between diabetes and clinical depression, and the selective expression of BPRP in brain and pancreas, the present study examined whether BPRP levels are affected by induction of diabetes by alloxan injection in rats and exposure to high glucose levels in PC12 cells. Western blot and immunohistochemical analyses revealed that BPRP levels were decreased in the hippocampal CA1 neurons of diabetic rats 4 and 8 weeks post-alloxan injection and in PC12 cells 48 h after exposure to high concentrations of glucose. BPRP protein levels were not affected by osmolarity control treatments with mannitol. Follow-up pharmacological experiments in PC12 cells revealed that glucose-induced BPRP down-regulation was markedly attenuated by the calpain inhibitors N-acetyl-Leu-Leu-norleucinal (ALLN) or calpeptin, but not the proteasome-specific inhibitor carbobenzoxy-Leu-Leu-leucinal (MG132). The ability of calpain inhibitors to specifically counter the effects of high glucose exposure on BPRP levels further suggests that BPRP and calpain activity may contribute to diabetes complications in the central nervous system.
Subject(s)
Calpain/antagonists & inhibitors , Cysteine Proteinase Inhibitors/pharmacology , Diabetes Mellitus, Experimental/metabolism , Glucose/metabolism , Nerve Tissue Proteins/metabolism , Neurons/drug effects , Animals , Calpain/metabolism , Diabetes Mellitus, Experimental/enzymology , Dipeptides/pharmacology , Down-Regulation , Half-Life , Hippocampus/embryology , Hippocampus/metabolism , Insulin/metabolism , Leupeptins/pharmacology , Male , Neurons/enzymology , Neurons/metabolism , PC12 Cells , Rats , Rats, Sprague-Dawley , Time FactorsABSTRACT
There are increasing experimental evidence and clinical data showing that insulin plays an important role in the CNS. Insulin can be found at high level in the brain of some animals. Insulin receptors and insulin-second messengers systems are present in neurons and glial cells. The pathogenesis of some neurological diseases is related with insulin level or insulin sensitivity. Insulin-like growth factors also have a modulatory role in neuronal function. Insulin and neurotrophic factors including insulin-like factors have generated considerable excitement for their potential as therapy for a wide variety of degenerative neurological disorders, for which there is currently no treatment.
Subject(s)
Central Nervous System Diseases/physiopathology , Insulin/physiology , Receptor, Insulin , Animals , Central Nervous System Diseases/drug therapy , Humans , Insulin/therapeutic use , Mice , Rats , Receptor, Insulin/metabolism , Receptors, Somatomedin , Somatomedins/physiology , Somatomedins/therapeutic useABSTRACT
The biochemical effects of permanent focal ischemia following unilateral occlusion of the middle cerebral artery in rats were studied by determining the content of specific proteins of the affected areas in the cerebral hemisphere. Brain proteins were prepared 72 h after the occlusion and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. A significant increase in 66 and 80 kDa components and a paradoxical decrease in 260 kDa protein occurred in the ischemic brain tissues. The 66 and 80 kDa protein bands were identified as albumin and transferrin, respectively. The 260 kDa protein was analyzed by peptide mass fingerprinting (PMF) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The isoelectric point of the 260 kDa protein was 4.65 determined by isoelectric focusing. The data obtained from PMF were used in searching the protein database for homologous components. Three proteins with partial homology were identified. They were the microtubule-associated protein 1A, protein-tyrosine phosphatase zeta precursor (phosphacan), and protein kinase A anchoring protein 6. Polyclonal antibodies against the 260 kDa protein were raised and used to immunolocalize the antigen in various tissues. Positive staining occurred with brain neurons and pyramidal cells, islet cells, podocytes of kidney glomeruli, and endothelial cells of the venous sinuses of the spleen. The localization of 260 kDa protein strongly implies its function in these tissues. Its physiological and pathophysiological significances need to be clarified in future.
Subject(s)
Brain Ischemia/metabolism , Databases, Protein/statistics & numerical data , Proteins/analysis , Animals , Brain Chemistry/physiology , Male , Proteins/metabolism , Rats , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: To study the protective effects and its mechanism of Panaxatriol Saponins isolated from Panax notoginseng (PTS) on focal cerebral ischemia in rat brain. METHOD: The influences of PTS on cerebral water content and three specific proteins (VEGF, HSP70 and transferrin) related with cerebral ischemia were studied with unilateral occlusion of the middle cerebral artery (MCAO) and Western Blot. RESULT: PTS 12.5 mg.kg-1 i.p. x 7 d (5 d before MCAO and 2 d after MCAO) inhibited the increase of cerebral water content caused by MCAO and influenced contents of HSP70 and transferrin, but had no influence on VEGF protein level. CONCLUSION: PTS shows a protective effect on focal cerebral ischemia in rat brain by alleviating cerebral edema, up-regulating the expression of HSP70, down-regulating transferrin and maintaining blood-brain barrier.
