Abstract: Objective To observe neuron changes of hippocampus CA1 induced by ischemic acute kidney injury (IAKI) in rats. Methods Based on successful established IAKI animal models light and electron microscope, immunohistochemical (IHC)staining and Western blot were used for the present observations. Results Pyknotic neurons in CA1 of hippocampus were found after renal 60 min ischemia and 24 h reperfusion. The examinations of electron microscope provided facts that swollen mitochondria and dilated endoplasmic reticule in cytoplasm and shrinkage nucleus with no pyknotic chromatin were found in the pyknotic neurons. IHC staining observations revealed that the pyknotic neuron showed negative caspase-3 staining but positive PARP-1 staining. In addition, immunoblot analysis provided that only PARP-1 expressed much stronger in IAKI associated hippocampus. Conclusion The pyknotic neurons induced by IAKI might be of PARP-1 mediated cell death and of cytoplasmic death morphologically.