Elsevier

Neuroscience Letters

Volume 407, Issue 1, 16 October 2006, Pages 1-5
Neuroscience Letters

Ultrastructural features of hippocampal CA1 synapses with respect to synaptic enhancement following repeated PKA activation

https://doi.org/10.1016/j.neulet.2006.07.057Get rights and content

Abstract

We reported previously that repeated activations, but not a single activation, of cyclic AMP-dependent protein kinase (PKA), led to a slowly developing (requiring ∼1 week to develop) long-lasting (lasting ≥3 weeks) enhancement of synaptic transmission efficiency in the organotypic slice culture of the rat hippocampus. It was accompanied by an increase in the number of synapses identified immunohistochemically. To answer the question of whether the “perforated synapse”, which is known to occur transiently after the induction of long-term potentiation (LTP) in combination with the enlargement of postsynaptic density (PSD), is involved also in this slow/persistent synaptic enhancement, we examined the ultrastructural changes after the repeated activations of PKA. The answer was partially yes (occurrence of perforated synapses was increased) but partially no (the increase in the number of perforated synapses was not transient but persistent; mean apparent size of PSD did not increase). These results suggest that the mechanism of the slow/persistent synaptogenesis shares limited features with the mechanism of the quick/transient morphogenesis after LTP.

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Acknowledgements

The authors are grateful to Drs. Y. Kuroda and T. Tashiro for discussion and encouragement. The authors also thank Drs. Y. Shinoda and N. Taniguchi-Ishigaki for discussion and technical advice. This work was supported by a grant-in-aid from the Japanese Ministry of Education, Culture, Sports, Science and Technology and by the 21st Century COE Program of the Ministry.

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