Primary cold-sensitive neurons in acutely dissociated cells of rat hypothalamus

Local warming or cooling of the preoptic and anterior hypothalamus (PO/AH) areas evokes various thermoregulatory responses in mammals. We have hypothesized that warm- and cold-sensitive neurons recorded in the PO/AH are multiple thermostats that regulate the core temperature against heat and cold, respectively. However, since the proportion of cold-sensitive neurons is low, it is still controversial whether primary cold-sensitive neurons exist in the PO/AH. To answer this question, we investigated cold-sensitive neurons with Ca2+ imaging in acutely dissociated PO/AH cells. Their threshold temperatures were 27.3 +/- 0.44degreesC (mean +/- SEM, n = 55). In extracellular recordings cooling evoked discharges in these cold-sensitive neurons. We conclude that primary cold-sensitive neurons with low threshold temperatures exist in PO/AH. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.