Fig 5. HDAC2 inhibition alleviated the hippocampal ultrastructure impairment caused by maternal isoflurane exposure (transmission electron microscopy, ×6000).

The hippocampal ultrastructure showed apparent abnormality with the increase of isoflurane exposure time. The ultrastructure showed no differences compared to the control group when isoflurane exposure time was 2h (I2N). When isoflurane exposure time lengthen to 4h, the neuron number decreased, the nuclei became irregular, cytoplasmic area decreased, mitochondrial number decreased, and we observed evidence of disordered mitochondrial cristae. The quantity of rough endoplasmic reticulum, ribosome and Golgi apparatus decreased, and the ribosomes exhibited degranulation (I4N). When the exposure time prolonged to 8h, all of these changes became more prominent, there were fewer neurons with dilated intercellular space. Dissolved mitochondrial cristae and swollen Golgi apparatus could be observed (I8N). HDAC inhibition alleviated the impairments, but did not increase the neuronal number (I4S and I8S group).