Activation of α7 Nicotinic Acetylcholine Receptor Protects Against 1-Methyl-4-Phenylpyridinium-Induced Astroglial Apoptosis

Astrocytes, as the largest population of glial subtype, play crucial roles in normal brain function and pathological conditions, such as Parkinson's disease (PD). Restoring the functions of astrocyte is a promising new therapeutic target for PD. Astrocytes can express multiple types of neurotransmitter receptors, including functional alpha 7 nicotinic acetylcholine receptor (alpha 7nAChR). Previously, we found that a non-selective alpha 7nAChR agonist nicotine exerted a protective effect against H2O2-induced astrocyte apoptosis via an alpha 7nAChR-dependent pathway. However, the molecular mechanism of the antiapoptotic response of astroglial alpha 7nAChR has not been studied. In the present study, using pharmacological inhibition and genetic knockout of alpha 7nAChR, we assessed the antiapoptotic effects of an alpha 7nAChR agonist PNU-282987 in primary cultured astrocytes treated with 1-methyl-4-phenylpyridinium (MPP+). PNU-282987 promoted the viability of astrocytes, alleviated MPP+ induced apoptosis, and decreased the number of GFAP(+)/TUNEL+ cells. Meanwhile, PNU-282987 upregulated the expression of the antiapoptotic protein Bcl-2 and downregulated the expression of the apoptotic protein Bax and cleaved-caspase-3. Moreover, the suppression of the JNK-p53-caspase-3 signaling may underlie the neuroprotective property of PNU-282987. Therefore, PNU-282987 ameliorates astroglial apoptosis induced by MPP+ through alpha 7nAChR-JNK-p53 signaling. Our findings suggest that PNU-282987 may be a potential drug for restoring astroglial functions in the treatment of PD.