Protective effect of spleen-yin-nourishing recipe on amyloid beta-peptide-induced damage of primarily cultured rat hippocampal neurons and its mechanism.

OBJECTIVE: To observe the relationship among amyloid beta-peptide (Abeta)-induced neurotoxicity, serum-inducible kinase (SNK)-spine-associated Rap guanosine triphosphatase activating protein (SPAR) pathway and N-methyl-D-aspartate receptor (NMDAR), and to explore the mechanism of the protective effect of spleen-yin nourishing recipe (Zibu Piyin Recipe, ZBPYR) in hippocampal neurons against Abeta-induced neurotoxicity. METHODS: The Abeta(1-40) powder was dissolved in 1 x PBS and incubated at 37 degrees centigrade, and then aggregated fibrillar Abeta(1-40) was obtained 72 h later. We used rat primary hippocampal neurons as cell model. ZBPYR-containing serum was gained by the method of serum pharmacology. ZBPYR-containing serum was added to the culture 1 h before Abeta(1-40) (5 micromol/L) exposure. Cells were harvested 2 h after Abeta(1-40) exposure for total RNA extracting. Then the mRNA expression levels of SNK, SPAR and NMDAR subunits NR1, NR2A and NR2B were detected by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: After 2-hour Abeta(1-40) exposure, we found that the expression level of SNK mRNA was up-regulated and the expression levels of SPAR, NR1, NR2A and NR2B mRNAs were down-regulated in hippocampal neurons as compared with control group (P < 0.01, P < 0.05). While with ZBPYR-containing serum pretreatment, the expression level of SNK mRNA was down-regulated and the levels of SPAR, NR1, NR2A and NR2B were up-regulated as compared with Abeta(1-40) exposure, and 2% ZBPYR-containing serum showed the best effect (P < 0.05). CONCLUSION: Abeta-induced neurotoxicity was related to SNK-SPAR pathway and NMDAR; ZBPYR-containing serum can protect neurons from Abeta-induced neurotoxicity, and this protective effect may be performed by regulating the expression of NMDAR and blocking of the SNK-SPAR pathway.

Decreased expression of spine-associated Rap guanosine triphosphatase-activating protein (SPAR) in glutamate-treated primary hippocampal neurons.

Spine-associated Rap guanosine triphosphatase-activating protein (SPAR) is an important regulator of activity-dependent remodeling of synapses. It is also critically involved in both mature dendritic spine formation and the maintenance of spine maturity. Glutamate is a major neurotransmitter of the brain, and is involved in all aspects of cognitive function, as it is the primary transmitter utilized by the cortical and hippocampal pyramidal neurons. Glutamate has also been associated with neuronal dendritic spine damage. The precise molecular mechanisms underlying dendritic spine damage following glutamate-induced neurotoxicity remain unknown. In the current study, we measured mRNA and protein expression levels of SPAR and serum-inducible kinase (SNK) in primary hippocampal neurons following glutamate treatment. Expression of SPAR and SNK was altered by glutamate treatment, indicating that the SPAR and SNK signaling pathways may be involved in the damage to dendritic spines in hippocampal neurons following excitotoxicity induced by glutamate.