Dopamine effects on thermosensitive neurons in hypothalamic tissue slices.

To understand the role of hypothalamic dopamine in thermoregulation, single unit activity was recorded in vitro, from constantly perfused tissue slices of rat preoptic area and anterior hypothalamus, PO/AH. The firing rate and thermosensitivity of individual PO/AH neurons were determined before, during and after tissue perfusion with media containing dopamine. Dopamine excited 41% of the warm-sensitive neurons, inhibited 100% of the cold-sensitive neurons, and had no effect on 83% of the temperature-insensitive neurons. In addition, dopamine decreased the local thermosensitivity of most cold-sensitive neurons. There were no major differences between these neuronal types in terms of the time course or latency of dopamine's effect. These results are consistent with the hypothesis that dopamine is involved in hypothalamic synapses controlling thermoregulatory responses which oppose increases in body temperature.