Recovery of protein synthesis in tolerance-induced hippocampal CA1 neurons after transient forebrain ischemia.
Protein synthesis at various recirculation times after 5-min transient forebrain ischemia was evaluated in gerbil hippocampal CA1 pyramidal neurons that had acquired tolerance to delayed-type ischemic injury. Evaluation was performed by observing polyribosomes under electron microscopy, and by [14C]leucine autoradiography. Hippocampal CA1 pyramidal neurons in the gerbils acquired stable and reproducible tolerance to delayed-type ischemic injury subsequent to a 5-min ischemia by pretreatment that consisted of loading two 2-min ischemic periods at a 1-day interval, followed by 48 h of recirculation. During the early phase following the 5-min ischemia, polyribosomal disaggregation, loss of dendritic microtubules, and significant suppression of radiolabeled leucine incorporation were observed in the tolerance-induced CA1 neurons as well as in the non-tolerance-induced neurons. While these findings persisted in the non-tolerance-induced neurons throughout the duration of the experiment, most of the tolerance-induced neurons demonstrated reaggregation of cytosomal ribosomes, increase in the number of dendritic microtubules, and restoration of impaired amino acid incorporation 24 h after the ischemia. These findings suggest that recovery of protein synthesis during the early post ischemic phase is essential for CA1 neuron survival after ischemic injury.
Furuta
S
S
Department of Neurological Surgery, Ehime University School of Medicine, Japan.
Ohta
S
S
Hatakeyama
T
T
Nakamura
K
K
Sakaki
S
S
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D005849:Gerbillinae; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000473:pathology; D007930:Leucine / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009474:Neurons / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism / Q000648:ultrastructure; D017966:Pyramidal Cells / Q000378:metabolism
D000596:Amino Acids; D009419:Nerve Tissue Proteins; D007930:Leucine