Effect of arcuate nucleus activation on neuronal activity in subfornical organ

Experiments were done in urethane anesthetized rats to investigate the effect of activation of the arcuate nucleus (Arc) on the discharge rate of single units in the subfornical organ (SFO). Extracellular recordings were made from 51 spontaneously active neurons histologically verified in the SFO. Of these units, 19 (37%) were inhibited (mean latency 7.3 +/- 1.1 ms) and 14 (28%) were excited (mean latency 12.8 +/- 3.2 ms) during electrical stimulation of the Arc. The remaining 18 units did not alter their firing frequency during stimulation of the Arc. These data suggest that the Arc may be involved in the modulation of neural and humoral events related to body fluid homeostasis and cardiovascular regulation by altering the activity of SFO neurons.