The Journal of Neurophysiology Vol. 88 No. 3 September 2002, pp. 1559-1567
Copyright ©2002 by the American Physiological Society

Synchronization of Ca²⁺ Oscillations Among Primate LHRH Neurons and Nonneuronal Cells In Vitro

 ¹Wisconsin National Primate Research Center and  ²Department of Pediatrics, University of Wisconsin, Madison, Wisconsin 53715-1261

Richter, T. A., K. L. Keen, and E. Terasawa. Synchronization of Ca²⁺ Oscillations Among Primate LHRH Neurons and Nonneuronal Cells In Vitro. J. Neurophysiol. 88: 1559-1567, 2002. Periodic release of luteinizing hormone-releasing hormone (LHRH) from the hypothalamus is essential for normal reproductive function. Pulsatile LHRH release appears to result from the synchronous activity of LHRH neurons. However, how the activity of these neurons is synchronized to release LHRH peptide in a pulsatile manner is unclear. Because there is little evidence of physical coupling among LHRH neurons in the hypothalamus, we hypothesized that the activity of LHRH neurons might be coordinated by indirect intercellular communication via intermediary (nonneural) cells rather than direct interneural coupling. In this study, we used an in vitro preparation of LHRH neurons derived from the olfactory placode of monkey embryos to assess whether nonneuronal cells, play a role in coordinating LHRH neuronal activity. We found that cultured LHRH neurons and nonneuronal cells both exhibit spontaneous oscillations in the concentration of intracellular Ca²⁺ ([Ca²⁺]_i) at similar frequencies. Moreover, [Ca²⁺]_i oscillations in both types of cell were periodically synchronized. Synchronized [Ca²⁺]_i oscillations spread as intercellular Ca²⁺ waves across fields of cells that included LHRH neurons and nonneuronal cells, although waves spread at a higher velocity among LHRH neurons. These results suggest that LHRH neurons and nonneuronal cells are functionally integrated and that nonneuronal cells could be involved in synchronizing the activity of the LHRH neurosecretory network.