NEUROPEPTIDE Y ATTENUATES NEURONAL APOPTOSIS AFTER EPILEPTIFORM DISCHARGE IN HIPPOCAMPAL NEURONS BY REGULATING AMPA RECEPTOR

Yichao Wang¹, Jisen Li², Jian Ren^{3, *} 

¹Department of Neurology, Hanzhong People's Hospital, Shaanxi, 723000, China - ²Department of Neurosurgery, Linyi Traditional Chinese Medicine Hospital, Linyi, 276699, China - ³Department of Neurological Diseases Center, The Third Affiliated Hospital of Chongqing Medical University (Gener Hospital), Chongqing, 401120, China

Objective: To explore the effect of neuropeptide Y (NPY) on neuronal apoptosis after epileptiform discharge of hippocampal neurons by regulating amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor and its mechanism.

Methods: In this study, 34 newborn Sprague Dawley (SD) rats within 24 h of clean grade were selected. Their heads were severed, their brains were collected, and each bilateral hippocampus was isolated to obtain the purified neurons. After 12 d, the neurons were treated with magnesium-free extracellular fluid prepared in advance and were removed after 3h. Hippocampal neurons were randomly divided into a control group, a model group, and an NPY group. The hippocampal neurons in the control group were treated with normal extracellular fluid for 3 h, and those in the model group were treated with magnesium-free extracellular fluid for 3 h. Next, those in the NPY group were treated with 1 μmol/L of NPY for 30min and then cultured with magnesium-free extracellular fluid for 3 h. After the hippocampal neurons in each group were returned to a normal extracellular fluid culture for 12 h, further studies were conducted. Finally, the current densities, apoptotic rates, and protein and mRNA expression levels of glutamic acid receptor 2 (GluR2) subunit and caspase-3 of the hippocampal neurons in each group were compared.

Results: The current densities of hippocampal neurons in the model group and the NYP group were significantly lower than that of the control group (P<0.05). The current density of hippocampal neurons in the NYP group was remarkably higher than that of the model group (P<0.05). The GluR2 subunit mRNA expression levels of hippocampal neurons in the model group and the NPY group were dramatically lower than that of the control group (P<0.05). While the GluR2 subunit mRNA expression level of hippocampal neurons in the NPY group was higher than that of the control group (P<0.05). There was no statistically significant difference in GluR2 subunit protein expression levels among the hippocampal neurons in each group (P>0.05). The apoptosis rates of hippocampal neurons in the model group and the NPY group were markedly higher than that of the control group. The apoptosis rate of hippocampal neurons in the NPY group was significantly lower than that of the control group. The expression levels of caspase-3 protein and mRNA in the hippocampal neurons of model group and NPY group were remarkably higher than that of the control group (P<0.05). The expression levels of caspase-3 protein and mRNA in the hippocampal neurons of NPY group were significantly lower than that of the control group (P<0.05).

Conclusion: NPY can inhibit the apoptosis of hippocampal neurons after epileptiform discharge, and its mechanism may be realized by regulating the expression level of the GluR2 subunit of the AMAP receptor.