The FASEB Journal, Vol 5, 217-222, Copyright © 1991 by The Federation of American Societies for Experimental Biology

RESEARCH COMMUNICATIONS

Stimulated rise in neuronal calcium is faster and greater in the nucleus than the cytosol

DA Przywara, SV Bhave, A Bhave, TD Wakade and AR Wakade
Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201.

Calcium is an important regulator of a variety of neuronal activities including gene expression. However, it is not clear how Ca2+ influx affects intracellular Ca2+ concentration [( Ca2+]i) in the nucleus. We have taken advantage of laser photometry, the Ca2(+)-sensitive dye Indo- 1 that allows ratio imaging, and confocal microscopy to eliminate the influences of unequal cell geometry and dye distribution. We show that Ca2+ influx into sympathetic neurons causes a significantly greater and faster increase in [Ca2+]i in the nucleus than in the cytosol. The differential increase in nuclear [Ca2+]i was apparent when Ca2+ entered from the extracellular medium during K+ depolarization, ionomycin or acetylcholine treatment, and brief periods of electrical stimulation. When intracellular Ca2+ was mobilized by caffeine the rise in nuclear [Ca2+]i was again greater than in any other region of the neuron. The increased nuclear Ca2+ levels were uniform throughout the nucleus and not associated with the nuclear envelope. The differential rise in nuclear Ca2+ was eliminated by acridine orange binding to nucleic acids. Nonexcitable cells (astrocytes, oligodendrocytes, and fibroblasts) did not show differential distribution of Ca2+ after ionomycin treatment. These results support the idea that activity- dependent gene regulation in sympathetic neurons may be mediated by changes in Ca2+ concentration at the level of the chromatin material.

This article has been cited by other articles:

				M. Mazzanti, J. O. Bustamante, and H. Oberleithner Electrical Dimension of the Nuclear Envelope Physiol Rev, January 1, 2001; 81(1): 1 - 19. [Abstract] [Full Text] [PDF]

				C. P. Taylor, M. L. Weber, C. L. Gaughan, E. J. Lehning, and R. M. LoPachin Oxygen/Glucose Deprivation in Hippocampal Slices: Altered Intraneuronal Elemental Composition Predicts Structural and Functional Damage J. Neurosci., January 15, 1999; 19(2): 619 - 629. [Abstract] [Full Text] [PDF]

				S. M. Valenzuela, D. K. Martin, S. B. Por, J. M. Robbins, K. Warton, M. R. Bootcov, P. R. Schofield, T. J. Campbell, and S. N. Breit Molecular Cloning and Expression of a Chloride Ion Channel of Cell Nuclei J. Biol. Chem., May 9, 1997; 272(19): 12575 - 12582. [Abstract] [Full Text] [PDF]

				J.-P. Humbert, N. Matter, J.-C. Artault, P. Köppler, and A. N. Malviya Inositol 1,4,5-Trisphosphate Receptor Is Located to the Inner Nuclear Membrane Vindicating Regulation of Nuclear Calcium Signaling by Inositol 1,4,5-Trisphosphate J. Biol. Chem., January 5, 1996; 271(1): 478 - 485. [Abstract] [Full Text] [PDF]

				A Ghosh and M. Greenberg Calcium signaling in neurons: molecular mechanisms and cellular consequences Science, April 14, 1995; 268(5208): 239 - 247. [Abstract] [PDF]