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Neural Plasticity
Volume 2014, Article ID 938235, 12 pages
http://dx.doi.org/10.1155/2014/938235
Research Article

Nociceptive Neurons Differentially Express Fast and Slow T-Type Ca2+ Currents in Different Types of Diabetic Neuropathy

1International Center of Molecular Physiology of National Academy of Sciences of Ukraine, 4 Bogomoletz Street., Kyiv 01024, Ukraine
2State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology of National Academy of Sciences of Ukraine, 4 Bogomoletz Street, Kyiv 01024, Ukraine

Received 3 November 2013; Revised 24 December 2013; Accepted 30 December 2013; Published 18 February 2014

Academic Editor: Dong-ho Youn

Copyright © 2014 Eugen V. Khomula et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

T-type Ca2+ channels are known as important participants of nociception and their remodeling contributes to diabetes-induced alterations of pain sensation. In this work we have established that about 30% of rat nonpeptidergic thermal C-type nociceptive (NTCN) neurons of segments L4–L6 express a slow T-type Ca2+ current (T-current) while a fast T-current is expressed in the other 70% of these neurons. Streptozotocin-induced diabetes in young rats resulted in thermal hyperalgesia, hypoalgesia, or normalgesia 5-6 weeks after the induction. Our results show that NTCN neurons obtained from hyperalgesic animals do not express the slow T-current. Meanwhile, the fraction of neurons expressing the slow T-current did not significantly change in the hypo- and normalgesic diabetic groups. Moreover, the peak current density of fast T-current was significantly increased only in the neurons of hyperalgesic group. In contrast, the peak current density of slow T-current was significantly decreased in the hypo- and normalgesic groups. Experimental diabetes also resulted in a depolarizing shift of steady-state inactivation of fast T-current in the hyperalgesic group and slow T-current in the hypo- and normalgesic groups. We suggest that the observed changes may contribute to expression of different types of peripheral diabetic neuropathy occurring during the development of diabetes mellitus.