Elsevier

Neuroscience

Volume 201, 10 January 2012, Pages 338-348
Neuroscience

Regeneration, Repair, and Developmental Neuroscience
Research Paper
Optical analysis of developmental changes in synaptic potentiation in the neonatal rat corticostriatal projection

https://doi.org/10.1016/j.neuroscience.2011.11.023Get rights and content

Abstract

We applied voltage-sensitive dye imaging to neonatal rat cortical slice preparations and analyzed developmental changes in synaptic plasticity, long-term potentiation (LTP), in the corticostriatal projection. Coronal slice preparations were dissected from postnatal 1- to 21-day (P1–P21) rats, and the transmembrane voltage-related optical signals evoked by cortical stimulation were recorded using a 464ch optical recording system with the voltage-sensitive absorption dye. In the striatum, the optical signal was composed of a fast spike-like signal followed by a slow signal, which corresponded to an action potential and an excitatory postsynaptic potential (EPSP), respectively. The slow signal could be detected at the P1 stage, suggesting that the EPSP is already expressed in the corticostriatal projection at least at early stages after birth. On the other hand, the slow signal was potentiated with a single shot of tetanic stimulation and the potentiation lasted at least 1 h, which is considered to correspond to long-term potentiation. With ontogenetic examinations, we found that (1) the EPSP could be potentiated with tetanic stimulation from the P9 stage and that (2) after the LTP induction, the potentiation was maintained for a longer time in the postnatal 3W stage than in the 2W stage. These results suggest that characteristics of LTP change dynamically during postnatal development.

Highlights

▶We optically examined developmental changes in LTP in the neonatal cortico-striatum. ▶The EPSP-related slow signal could be detected from the postnatal day 1 (P1) stage. ▶From the P9 stage, the slow signal was potentiated by tetanus. ▶The LTP was maintained for a longer time in the 3W stage than in the 2W stage. ▶The results suggest dynamic change in characteristics of LTP during ontogenesis.

Section snippets

Preparations

Experiments were carried out in accordance with the guidelines of the US National Institutes of Health and Komazawa Women's University for the care and use of laboratory animals. All efforts were made to minimize the number of animals used and their suffering. All of the experiments were performed at Komazawa Women's University. Neonatal Wistar rats (Saitama Experimental Animals Supply Co., Saitama, Japan) at postnatal day 1–21 (P1–P21) were decapitated under ether anesthesia. Their brains were

Optical detection of the LTP in the corticostriatal projection

Fig. 1 illustrates examples of optical recordings made in a postnatal 17-day (P17) corticostriatal slice preparation stained with the voltage-sensitive oxonol dye NK3630 (RH482). The upper and lower panels show optical responses detected prior to and 2 h after tetanic stimulation (100 Hz/1 s duration, 1 shot), respectively. The signals were evoked by electrical stimulation to the corticostriatal projection, and the recordings were made by averaging four trials using a 464-element photodiode

Discussion

In this study, we applied optical imaging with voltage-sensitive dyes to the corticostriatal projection in neonatal rat cortical slice preparations. The results obtained are summarized as follows: (1) The LTP in the corticostriatal projection is detectable with the optical imaging technique, (2) the EPSP can be potentiated with tetanic stimulation from the P9 stage, and (3) after LTP induction, the potentiation is maintained for a longer time in the postnatal 3W stage than in the 2W stage. We

Acknowledgments

This research was supported by grants from the Monbu-Kagaku-Sho of Japan, Human Frontier Science program, and Opto-Medical Institute Inc in Takanawa, Tokyo.

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